BIASI Riva Plus HE M296.24SM/C, M296.28SM/C gas boiler Service manual

Wall hung, fanflue, roomsealed, high efficiency gas boiler

Service manual

Riva Plus HE

Models

M296.24SM/C

M296.28SM/C

G.C. Appl. No.

47-583-17

CoMbi boilER

47-583-18

CoMbi boilER

leave this manual adjacent to the gas meter

1 ovERall infoRMaTion . . . . . . . . . . . . . . . . . . . . 4

1.1 Overall View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1.2 Hydraulic diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

2 GEnERal aCCESS and EMPTyinG HydRauliC

CiRCuiTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2.2 Body panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2.3 Control panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2.4 Access to the sealed chamber . . . . . . . . . . . . . . . . . .6

2.5 Emptying the primary circuit . . . . . . . . . . . . . . . . . . . .6

2.6 Emptying the d.h.w. circuit . . . . . . . . . . . . . . . . . . . . .6

3 diaGRaMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.1 Wiring diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

3.2 Functional flow diagrams . . . . . . . . . . . . . . . . . . . . . .8

3.3 Circuit voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

4 faulT findinG . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5 PRiMaRy HEaT ExCHanGER . . . . . . . . . . . . . . . 12

5.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

5.2 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

5.3 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

6 CondEnSinG HEaT ExCHanGER . . . . . . . . . . . 14

6.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

6.2 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

6.3 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

7 d.H.w. HEaT ExCHanGER. . . . . . . . . . . . . . . . . . 16

7.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

7.2 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

8 PuMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

8.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

8.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

8.3 Removal pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

8.4 Removal electrical capacitor . . . . . . . . . . . . . . . . . . .18

9 THREE way divERTER valvE . . . . . . . . . . . . . . 19

9.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

9.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

9.3 Removal of the electric actuator . . . . . . . . . . . . . . . .19

9.4 Removal of the tree way diverter valve. . . . . . . . . . .20

9.5 Removal of the diverter group. . . . . . . . . . . . . . . . . .20

10 ElECTRoniC ConTRol/iGniTion P.C.b. . . . . . 21

10.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

10.2 Selection and adjustment devices. . . . . . . . . . . . . . .21

10.3 Checking the temperature. . . . . . . . . . . . . . . . . . . . .22

10.4 Operation lights. . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

10.5 Setting the boiler control function modes . . . . . . . . .23

10.6 Useful output setting . . . . . . . . . . . . . . . . . . . . . . . . .23

10.7 Reignition frequency setting . . . . . . . . . . . . . . . . . . .24

10.8 Ignition gas pressure adjustment . . . . . . . . . . . . . . .25

10.9 Setting the tree way diverter valve operation mode .25

10.10 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

10.11 Removal of the electronic control p.c.b. . . . . . . . . . .26

10.12 Thermal control in the mode . . . . . . . . . . . . . . . .28

10.13 Thermal control in the mode. . . . . . . . . . . . . . . .28

10.14 Ignition and control sequence . . . . . . . . . . . . . . . . . .29

11 ModulaTinG GaS valvE . . . . . . . . . . . . . . . . . . 30

11.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

11.2 Nomenclature of the parts. . . . . . . . . . . . . . . . . . . . .30

11.3 Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

11.4 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

11.5 Removal of the on-off operators coils . . . . . . . . . . . .31

11.6 Removal of the gas valve . . . . . . . . . . . . . . . . . . . . .31

TablE of ConTEnTS

12 PRiMaRy CiRCuiT PRESSuRE SwiTCH . . . . . . 32

12.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

12.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

12.3 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

13 ExPanSion vESSEl and TEMPERaTuRE-PRES-

SuRE GauGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

13.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

13.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

13.3 Removal of the expansion vessel . . . . . . . . . . . . . . .33

13.4 Removal of the temperature-pressure gauge . . . . . .33

14 d.H.w. flow SwiTCH, filTER and flow liMi-

TER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

14.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

14.2 Nomenclature and location of parts . . . . . . . . . . . . .34

14.3 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

14.4 Removal of the sensor . . . . . . . . . . . . . . . . . . . . . . .34

14.5 Removal of the flow switch group and d.h.w. circuit filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

14.6 Flow limiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

15 TEMPERaTuRE PRobE . . . . . . . . . . . . . . . . . . . . 36

15.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

15.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

15.3 Removal of the c.h. Temperature probe . . . . . . . . . .36

15.4 Removal of the d.h.w. Temperature probe . . . . . . . .36

16 by-PaSS valvE . . . . . . . . . . . . . . . . . . . . . . . . . . 38

16.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

16.2 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

17 fan and aiR PRESSuRE SEnSoR. . . . . . . . . . . 39

17.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

17.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

17.3 Removal of the Fan. . . . . . . . . . . . . . . . . . . . . . . . . .40

17.4 Removal of the Air pressure sensor . . . . . . . . . . . . .40

18 iGniTion and dETECTion ElECTRodES . . . . 41

18.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

18.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

18.3 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

19 SafETy THERMoSTaT. . . . . . . . . . . . . . . . . . . . . 42

19.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

19.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

19.3 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

20 fluE TEMPERaTuRE PRobE nTC. . . . . . . . . . . 43

20.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

20.2 Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

20.3 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

21 CondEnSaTE TRaP. . . . . . . . . . . . . . . . . . . . . . . 44

21.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

21.2 Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

22 SHoRT SPaRE PaRTS liST. . . . . . . . . . . . . . . . . 45

- 3 -

ovERall infoRMaTion

1 ovERall infoRMaTion

1.1 overall view

Airpressur sensor

Fan

Flue temperature probe NTC

Condensing heat exchanger

Burner

Divertervalve

Gasvalve

figure 1.1

1.2 Hydraulic diagram

Central heating (c.h.) operation

D.h.w. heat exchanger

Pump

Domestic hot water (d.h.w.) operation

figure 1.2

- 4 -

GEnERal aCCESS and EMPTyinG HydRauliC CiRCuiTS

2 GEnERal aCCESS and EMPTyinG

HydRauliC CiRCuiTS

2.1 nomenclature

a

1

2

6

3 figure 2.2

To remove the side panels loosen the screws B and C (Figure

2.3), bring the base of the panels away from the boiler and lift them, freeing them from the top hooks.

figure 2.1

1 Right side panel

2 Front panel

3 Control panel lid

4 Control panel cover

5 Servicepanel

6 Left side panel

5

4

2.2 body panels

warning: isolate the boiler from the mains electricity supply before removing any covering or component.

For the most part of the check and maintenance operations it is necessary to remove one or more panels of the case.

The side panels can be removed only after the removal of the front panel.

To remove the front panel remove screws A (Figure 2.2), lift the panel and remove it.

d b

C figure 2.3

- bottom view of the boiler

2.3 Control panel


To gain access to the parts located inside the control panel proceed as follows:

1 Remove the front panel of the case

2 Loosen the screws B and C (Figure 2.3).

3 Remove the screws D

4 Move the lower part of the side panels as indicated in Figure

2.4 and pull the control panel.

When completely pulled out, the panel can rotate 45° downwards to facilitate the service operations on the internal parts.

- 5 -

GEnERal aCCESS and EMPTyinG HydRauliC CiRCuiTS

2.5 Emptying the primary circuit

1 Close the c.h. circuit flow and return cocks.

2 Remove the front and right panels of the boiler.

3 Open the drain tap I (Figure 2.7) until the boiler is completely emptied.

4 Close drain tap again once the emptying has been completed.

figure 2.4

5 Remove the screws E and remove the service panel (Figure

2.5);

6 To gain access to the electronic regulation PCB remove the screws F and remove the control panel lid (Figure 2.5);

f f

E i figure 2.7

2.6 Emptying the d.h.w. circuit

5 Close the d.c.w. inlet cock;

6 Open one or more hot water taps until the boiler has been completely emptied.

figure 2.5

2.4 access to the sealed chamber

G

G figure 2.6

To gain access to the parts contained in the sealed chamber it is necessary to remove the lid of the sealed chamber. For this purpose, remove the front and side panels of the case, remove the screws G as indicated in Figure 2.6 and remove the lid.

- 6 -

diaGRaMS

3 diaGRaMS

3.1 wiring diagram

L N bn gnye bu

Pump Fan

3 2

1

2

1

M

~ bu bk bn

3

M

~ bn bu gnye

M

~ bu bn gnye

Primary circuit pressure switch bk bk

2

1

P

3 rd ye gy

Flame detection electrode bn bn bu bk bu bk bn bu

*wh *rd *bk bn bu bn bu bu t rd rd wh bu bn bu gnye gy gy bn bu rd rd ye gy wh bu bk bk rd rd wh wh bu bu rd ye gn bk rd gy ye bu bn bu gnye

1

Modulating gas valve chamber over heat bk bk bk wh wh t t bu bu rd wh gn

Time switch

figure 3.1

* = alternative bu = blue bk = black rd = red gy = grey gn = green ye = yellow og = orange gnye = green/yellow

- 7 -

diaGRaMS

3.2 Functional flow diagrams

General layout

J1---1 Fuse 3,15 A

L

PTC Transformer

J3---5

J3---3

J3---4

J3---1

Pump

J3---2

J2---5 J2---4

J1---2

N

Heat request on d.h.w.

J1---1 Fuse 3,15 A

L

PTC Transformer

J3---5

J3---3

J3---4

J3---1

Pump

J3---2

J2---5 J2---4

J1---2

N

L --- LINE N --- NEUTRAL

ACTIVE CIRCUIT

INACTIVE CIRCUIT

Heat request on c.h.

J1---1 Fuse 3,15 A

L

PTC Transformer

J3---5

J3---3

J3---4

J3---1

Pump

J3---2

J2---5 J2---4

J1---2

N

figure 3.2

- 8 -

diaGRaMS

3.3 Circuit voltages

Electrical voltages with burner on

Pump

Supply network

3 way diverter valve

Modulating

Gas valve

Fan during c.h. or d.h.w. operation only during c.h. operation only during d.h.w. operation

figure 3.3

Air pressure sensor

- 9 -

4 faulT findinG

--- (8)

--- (7) or)

) perat rators witch e e alv sv be pro emp.

rob mp.p

itte circu

.b.) go ilter es ope atin p.c

sur res itp circu h off nic b.

odul ve(m n--ve(o switc tro ttings p.c.

valve lec ow nic

.fl

.w

rter es(E ctro erse val val

.w.f

.w.t

pas r de e l at e senso

TC ctro ost trod vesse aug ele ve eN rm eg val ion s the ion ect ety prob ctor ans ety sur elec ition ssure pre

Det

Saf

Pres

Ign

Air

Saf

Flue

Inje

Exp

Fan

D.h

Gas

Main

Ele

Fus

Dive

Boil

Gas

D.h

Main

D.h

By---

Pump

--- (4)

--- (3)

--- (2)

--- (1) ap ndtr ea pip ger ain ne han lyli line exc s edr nsat cuit cuit eat .h

.w

.cir

.w

.cir

pipe ply sup upp ers

Conde

D.h

Flue

Gas

Pow

C.h

D.h

faulT findinG

- 10 d pre lam nal sig out k--Loc

ON OFF

--- (8)

--- (7)

--- (4)

--- (3)

--- (2)

--- (1) ap or)

) ndtr perat rators witch e e alv sv be pro emp.

.b.) go rob mp.p

itte circu ilter es ope atin sur p.c

res itp circu h off b.

nic odul ve(m n--ve(o ttings switc tro p.c.

valve lec ow nic

.fl

.w

rter es(E ctro erse val val

.w.f

.w.t

pas r de l e at e senso

TC ctro trod ost aug eg vesse ele ve rm eN val ion s ion the ect ety prob ctor ans ety sur elec ssure pre ition

Pres

Saf

Det

Air

Ign

Exp

Inje

Flue

Saf

Fan

Main

Gas

D.h

Fus

Ele

By---

D.h

Main

D.h

Gas

Boil

Dive

Pump ea pip ger ne ain han lyli line exc s edr cuit nsat cuit eat .h

.w

.cir

.w

.cir

pipe ply sup upp ers

D.h

Conde

Gas

Flue

D.h

C.h

Pow

faulT findinG

d pre lam nal sig out k--Loc

OFF F

- 11 -

a

PRiMaRy HEaT ExCHanGER

5 PRiMaRy HEaT ExCHanGER

5.1 function

The primary heat exchanger A in Figure 5.1 has the function of transferring heat produced from combustion of the gas to the water circulating in it.

b l

C

C

G figure 5.1

The hydraulic circuit is composed of 8 elliptical pipes connected in parallel (Figure 5.2).

figure 5.2

5.2 Removal


1 Remove the case panels and the sealed chamber lid (section

"Body panels" page 5).

2 Empty the primary circuit of the boiler.

3 Remove the combustion chamber lid B by unscrewing the screws C (Figure 5.3).

4 Remove the screws D and the plate E.

5 Remove the clip F.

6 Loosen the connection G and slightly move the pipe H upwards.

7 Remove the clip I and the safety thermostat J and the c.h. temperature probe K. It is not necessary to disconnect it from the wiring.

- 12 -

figure 5.3

8 Loosen the connection L and move the pipe M downwards freeing it from the connection of the primary het exchanger.

9 Remove the clip N.

10 Loosen the connection O.

11 Free the pipe P from the connection of the condensing heat exchanger; lift and and rotate it towards right.

12 Remove the heat exchanger by sliding it forwards.

13 Reassemble the boiler carrying out the removal operations in reverse order. Fit the clip I with the arrow pointing upwards as illustrated in Figure 5.3.

n

P

J i

K

M

E f

H d o

PRiMaRy HEaT ExCHanGER

iMPoRTanT: do not force the connection G when tighting it.

5.3 Cleaning

If there are deposits of soot or dirt between the blades of the heat exchanger, clean with a brush or non-metallic bristle brush.

In any case, avoid any actions that can damage theprotective varnish with which the exchanger has been covered.

warning: after cleaning or replacement as detailed above, if it deemed necessary to undertake a combustion analysis, refer to the appropriate chapter

Maintenance of the installation instructions manual.

- 13 -

a

CondEnSinG HEaT ExCHanGER

6 CondEnSinG HEaT ExCHanGER

6.1 function

The return water flows through the condensing heat exchanger A in Figure 6.1 and Figure 6.2.

By reducing the combustion products temperature, the latent heat of the vapour is transferred to the water circuit, allowing an extra gain of useful heat.

The condensed vapour is then drained through the condensate trap B and the draining pipe C.

d b

C figure 6.1

6.2 Removal





3 Remove the fan D in Figure 6.2 (see section "Removal of the

Fan" page 40).

4 Disconect the connectors of the flue temperature probe NTC

E.

5 Remove the clip F.

6 Completely loosen the connection G and slightly move the pipe H upwards.

7 Remove the clip I.

8 Loosen the connection J.

9 Free the pipe K from the connection of the condensing heat exchanger; lift and and rotate it towards right.

10 Using pliers, remove the spring L moving it to wards right and disconnect the rubber pipe M.

11 Rotate the exchanger as indicated by the arrow and remove it towards the front of the boiler.

J figure 6.2

12 Reassemble the exchanger carrying out the removal operations in reverse order.

warning: to lubricate the o-ring gaskets exclusively use a silicone base grease compatible to be in contact with foods and approved by the local water authorities.

after reassembling ensure that the fan-exchanger and exchanger-elbow gaskets are correctly mounted and ensure a good sealing.



- 14 -

M

G

K

E a l i f

H

CondEnSinG HEaT ExCHanGER

6.3 Cleaning

1 Using pliers, remove the spring L moving it to wards right and disconnect the rubber pipe M (Figure 6.3).

2 Unscrewing the screws N (Figure 6.3).

3 Remove the condensing heat exchange lid O (Figure 6.3) moving torwards the front of the boiler.

If there are deposits of soot or dirt on the exchanger lid, clean with a brush or non-metallic bristle brush.

n l o

M figure 6.3

4 Reassemble the exchanger carrying out the removal operations in reverse order.




- 15 -

d.H.w. HEaT ExCHanGER

7 d.H.w. HEaT ExCHanGER

7.1 function

The d.h.w heat exchanger A in Figure 7.1 and Fig. 4 allows the instantaneous transfer of heat from the primary hydraulic circuit to the water destined for d.h.w use.

d

C a b

E f figure 7.3

6 Completely unscrew the two Allen key screws G (Figure 7.4) which hold the exchanger to the plastic groups.

a figure 7.1

The schematic structure is shown in Figure 7.2.

Primary hydraulic circuit

Domestic hot water circuit

figure 7.2

7.2 Removal


1 Remove the front and right hand side panels of the case.

2 Empty the primary circuit and the d.h.w circuit of the boiler.

3 Remove the pump B in Figure 7.3 (see section "Removal pump" page 17).

4 Remove the clip C and remove the primary circuit pressure switch D by lifting it upwards. It is not necessary to disconnect it from the wiring.

5 Remove the clip E and remove the electric actuator F by pulling it. It is not necessary to disconnect it from the wiring.

- 16 -

G figure 7.4

7 Move the exchanger towards the rear of the boiler and extract it.

Reassemble the d.h.w. heat exchanger carrying out the removal operations in the reverse order.


warning: when reassembling the exchanger be sure to put the off center location/securing pin indicated in figure 7.5 towards the left side of the boiler.

figure 7.5

PuMP

8 PuMP

8.1 function

The pump A in Figure 8.1 and Figure 8.4 has the function of making the water in the main circuit circulate through the main heat exchanger, the condensing heat exchanger and therefore through the c.h. system (during the c.h. function) or through the secondary heat exchanger (during the d.h.w. function).

Remove the air release plug from the pump. Start the boiler and with a screwdriver, turn the rotor in the direction of the arrow.

If there is a defect in starting, the rotor will begin to turn normally only starting it manually.

Check that the impeller is integral with the rotor.

With the boiler off remove the front and right hand side case panels, lower the control panel and empty the primary circuit.

Remove the pump head by undoing the screws which hold it to the pump body and check that the impeller is firmly joined to the rotor.

480 Ω

a

213 Ω

figure 8.1

Coil 2

Coil 1

figure 8.2

8.2 Checks


Check that the pump is not seized and that the movement of the rotor is not subject to mechanical impediments.

With the boiler off, remove the front panel. Remove the air release plug of the pump and turn the rotor with a screwdriver.

Check the electrical continuity.

With the boiler off, remove the front panel and disconnect the connector B (Figure 8.4).

Measure the electrical resistance between the pump supply connections.

Electrical resistance of the windings (at ambient temperature) must be about 213 Ω (coil 1) and 480 Ω (coil 2) (Figure 8.2).

Check the absence of starting defects.

With the boiler off remove the front case panel.

8.3 Removal pump





3 Disconnect the connector B (Figure 8.4) following the indications given on the connector box.

4 Disconnect the earth connector T (Figure 8.4).

5 Loosen the connection D (Figure 8.3),and pull up and turn to the left the pipe E.

6 Remove the locking plate F (Figure 8.4).

- 17 -

C

PuMP

8.4 Removal electrical capacitor


1 Remove the front and right hand side case panels.

2 Disconnect the connector B (Figure 8.4) following the indications given on the connector box.

3 Remove the connector M of the cover box by levering with a screwdriver in as shown in (Figure 8.5).

E

M d figure 8.3

figure 8.5

4 Remove the capacitor connection block N freeing it from the hook O and pulling it as indicated by the arrow (Fig. 7.6).

n o

T b a f

G figure 8.4

7 Unscrew the two screws G that hold the pump on the frame and remove the pump.

Reassemble the pump carrying out the removal operations in the reverse order. When reassembling the pump, check the correct location of the O-ring gasket in the inlet port of the pump that seals the connection between the pump and the return water group.

figure 8.6

- 18 -

THREE way divERTER valvE

9 THREE way divERTER valvE

9.1 function

The diverter valve A (Figure 9.1) has the function of modifying the hydraulic circuit of the boiler by means of an electric command given by the electronic control p.c.b. in order to send the water that exits the primary heat exchanger towards the c.h. system or towards the d.h.w. heat exchanger.

b a

Spindle B visible

figure 9.2

D.h.w. mode

b

9,4 Kohm

Open circuit wh = white bk = black bu = blue

* = alternative

Spindle B not visible

figure 9.1

9.2 Checks

warning: check the electrical continuity.

Figure 9.2 indicates the relationship between the electric command coming from the electronic control p.c.b. and the position of the actuator B (brass spindle) when the boiler operates in

d.h.w. mode.

Figure 9.3 indicates the relationship between the electric command coming from the electronic control p.c.b. and the position of the actuator B (brass spindle) when the boiler operates in

c.h.

mode.

In both figures the relationship between the position of the actuator and the resistance of the motor windings (the motor must be disconnected from the wiring) is also given.

Open circuit

9,4 Kohm rd = red wh = white bk = black bu = blue bn = brown

* = alternative

figure 9.3

C.h. mode

9.3 Removal of the electric actuator


1 Remove the front case panel.

2 Disconnect the connectors C (Figure 9.4).

3 Remove the fixing spring D and remove the actuator B.

Reassemble the actuator carrying out the removal operations in the reverse order.

When reassembling the actuator, refer to Figure 9.2 or to the wiring diagramin section "Checks" page 19 for the correct wiring connection.

- 19 -

THREE way divERTER valvE

d

C

9.5 Removal of the diverter group

1 Remove the front and both side case panels.


3 Remove the electric actuator (section "Removal of the electric actuator" page 19).

4 Remove the fixing spring H (Figure 9.6) and remove the primary circuit pressure switch I.

b i

H figure 9.4

9.4 Removal of the tree way diverter valve

1 Remove the front and both side case panels.


3 Remove the electric actuator (section "Removal of the electric actuator" page 19).

4 Remove the fixing spring E (Figure 9.5)

5 Remove the tree way diverter valve F by levering with a screwdriver in as shown in Figure 9.5.

K figure 9.6

5 Disconnect d.h.w. temperature probe, respectively J (Figure

9.7).

f

G

J

E figure 9.5

Reassemble the tree way diverter valve carrying out the removal operations in the reverse order.


warning: when reassembling the tree way diverter valve be sure that the tree way diverter is correctly oriented by matching the reference G with the notch of the water group figure 9.5.

figure 9.7

6 Unscrew the connector K (Figure 9.6), the c.h. flow connector and the d.h.w. outlet connector.

7 Remove the d.h.w. heat exchanger (section "Removal" page

16).

8 Unscrew the screws and remove the diverter group

9 Reassemble the diverter group carrying out the removal operations in the reverse order.


- 20 -

ElECTRoniC ConTRol/iGniTion P.C.b.

10 ElECTRoniC ConTRol/iGniTion P.C.b.

10.1 function

Inlet Information

On the Electronic control/ignition p.c.b.......

Function control

C.h. temperature adjustment

D.h.w. temperature adjustment

Boiler reset button

(control panel fascia)

From other boiler devices....

C.h. temperature probe NTC

D.h.w. temperature probe NTC

D.h.w. flow switch

Primary circuit pressure switch

Air pressure sensor


Safety thermostat

Flame detection electrode

Room thermostat (if fitted)

Time switch

(i.e. heating the dwelling or heating the water for d.h.w. use) and operating in order to keep the temperature of the hydraulic circuits constant.

This is obviously possible within the useful power and maximum working temperature limits foreseen.

Generally, the Electronic control/ignition p.c.b. receives inlet information coming from the boiler (the sensors) or from the outside (knobs, room thermostat, etc.), processes it and consequently acts with outlet commands on other components of the boiler (Figure 10.1).

The Electronic control/ignition p.c.b. is also a full sequence ignition device and does a sequence of operations (ignition cycle) which lead to the ignition of the gas at the burner.

It checks the presence of the flame during the entire period in which it is activated, supplies the fan and checks its functioning by means of the signal coming from the air pressure sensor.

The Electronic control/ignition p.c.b. has a safety function and any incorrect interventions or tampering can result in conditions of dangerous functioning of the boiler.

The Electronic control/ignition p.c.b. can lock the functioning of the boiler (lock state) and stop its functioning up to the resetting intervention. The lock is signalled by the lighting of the lock-out signal lamp and the device can be reset only by using the boiler reset button placed on the control panel fascia.

Some components which are connected to the device can activate the lock state. The causes of a lock state could be:

• The intervention of the safety thermostat (overheat of the primary circuit).

• The intervention of the flue temperature probe (overheat of the combustion products).

• A fault on gas supply.

• Faulty ignition (faulty ignition electrodes, theirwiring or connection).

• Faulty flame detection (faulty detection electrode, its wiring or connection).

• Gas injectors blocked.

• Faulty modulation gas valve (faulty on-off operators or not electrically supplied).

• Faulty Electronic control/ignition p.c.b..

Other components like the air pressure sensor can temporarily stop the ignition of the burner but allow its ignition when the cause of the intervention has stopped.

Figure 10.27 shows the sequence of the operations that are carried out at the start of every ignition cycle and during normal functioning.

Outlet command

Pump

Three way diverter valve

On---off operators (gas valve)

Modulation operator (gas valve)

Fan

Ignition electrodes

Appliance operation lights*

Lock---out signal lamp*

*control panel fascia

10.2 Selection and adjustment devices

On the Electronic control/ignition p.c.b. several selection, adjustment and protection devices are located (Figure 10.2).

Some of these devices are directly accessible by the user (function control, temperature adjustment potentiometers etc.) others are accessible by removing the service panel or the control panel lid.

figure 10.1

The fundamental function of the Electronic control/ignition p.c.b. is that of controlling the boiler in relation to the external needs

- 21 -

1 2


3 4 5 6

14

13 figure 10.2

12 11 10 9 8

1 x1 connector

2 x6 connector

3 x7 connector

4 x4 connector

5 x2 connector

6 x15 connector

7 x11 connector

8 Lock-out signal lamp

9 Boiler reset button

10 Function control / C.h. temperature adjustment

11 D.h.w. temperature adjustment

12 Appliance operation lights

13 x8 connector

14 Fuse 3,15 A F

7

10.3 Checking the temperature

The Electronic control/ignition p.c.b. makes it possible to separately adjust the c.h.water flowtemperature and d.h.w. outlet temperature.

The temperature of the water is converted into an electric signal by means of temperature probes.

The user, setting the desired temperature with the control panel knobs operates the variable elements (10 and 11 in Figure 10.2)

I of the electronic control p.c.b.

f the power requested is lower than 40% of the maximum power output then control is achieved by switching ON the burner at minimum power, then switching OFF (ON/OFF function). If the power requested is higher, then the burner is switched ON at maximum power and will control by modulating to 40% of the maximum power output.

During the c.h. operation (Figure 10.3), the signal coming from the c.h. temperature probe is compared to the signal given by the control panel through the adjustment made by the user (knob

). The result of such a comparison operates the modulation of the gas valve, consequently changing the useful output of the boiler.

figure 10.3

When the boiler functions in d.h.w. (Figure 10.4), the signal coming fromthe d.h.w. temperature probe is compared with the signal given by the control panel through the adjustment made by the user (knob ).

75°C

figure 10.4

- 22 -


Normally, the result of the comparison between these two signals directly operates the adjustment elements of the gas valvemodulation device, adjusting the useful output generated in order to stabilize the temperature of the exiting water.

If during the d.h.w. mode operation, the temperature of the primary circuit goes over 75°C, the useful output is automatically reduced so that the primary circuit cannot reach excessive temperatures.

The control sequences in function and in function are illustrated in detail in sections 10.2 and 10.3.

Faulty air pressure sensor

Lack of burner ignition (no ignition signal from the full seqence ignition device)

Safety thermostat lock out

Flue temperature probe NTC lock out

Flame detection error

Flame detection error

Lack of power supply or fauly electronic control p.c.b. *

10.4 operation lights

The Electronic control/ignition p.c.b. is provided with three lamps

(L.E.D. indicators) 12 in Figure 10.2 that give optical information during the operation of the boiler.

The green lamp on the left gives information whether the boiler is in stand-by mode or during the normal operation of the boiler.

The following table gives the relationship between the lamp indication and its meaning.

Lamp OFF

Lamp ON

Flashing lamp,alone or simultaneously with another lamp

Flashing lamp, alternate with another lamp

* These conditions are normal only for a short time when the power supply is applied to the boiler.

If permanent they indicate afaulty p.c.b.

Boiler in stand-by condition.

(function control in position).

Anti- freeze system active.

Boiler ON condition

(function control in or position)

10.5 Setting the boiler control function modes

It is possible to select the various boiler control function modes by using the function selector knob A and the D.h.w. temperature control knob B (Figure 10.5).

During the function modes setting, the boiler does not operate.

With the boiler switched ON ( or ) all the lamps (12 in

Figure 10.2) are activated.

The following table gives the relationship between each of the possible lamp combinations and their meaning.

b a d E

Normally operating boiler

(see the previous table for details)

C.h. operation

D.h.w. operation

Frost protect operation

D.h.w. operation

Excessive temperature on primary circuit

Faulty c.h. temperature probe NTC

Faulty d.h.w temperature probe NTC

Faulty flue temperature probe NTC

Faulty primary circuit

(no water or low c.h. pressure)

Faulty primary circuit

(absence of flow)

10.6 useful output setting

To set the useful output proceed as follows:

1 Remove the front panel of the case.

2 Take off the lid of the sealed chamber.

3 Switch on the appliance at the mains isolating spur.

4 Turn the boiler OFF positioning the function selector A as indicated in Figure 10.6.

figure 10.6

f b a d E

- 23 -


5 Disconnect the electrical connectors C of the C.h. temperature probe NTC in Figure 10.7.

Where:

Lamp ON

figure 10.10

At this step it is possible to visualize the current setting by keeping the reset button D pressed for more than 5 seconds. The lamps F will flash a number of times corresponding to the setting

Figure 10.11 (once for M296.24SM/C and M296.28SM/C).

4

M296.24SM/C

M296.28SM/C

7 flashes

C

Lamp OFF

1

7 figure 10.7

6 Keep pressed the reset button D for about 10 seconds until the lock-out signal lamp E blinks.

7 Connect the the electrical connectors C of the C.h. temperature probe NTC in Figure 10.7.

8 The lamps F should give the indication as in Figure 10.8 (useful output, first step). If not, press the reset button repeatedly to obtain it.

Where:

Lamp OFF

Lamp ON

figure 10.8

At this step it is possible to visualize the current setting by keeping the reset button D pressed for more than 5 seconds. The lamps

F will flash a number of times corresponding to the setting Figure

10.9 (once for M296.24SM/C and four times for M296.28SM/C).

M296.28SM/C

4 flashes

M296.24SM/C

1 flash

b

Setting No.

figure 10.11

12 To change the setting turn the knob B on a position corresponding to the boiler model (Figure 10.11).

By turning the knob B, the lock-out signal lamp E blinks quickly (2 per seconds) indicating that the setting has changed and must be memorised.

13 To memorize the setting keep pressed the reset button D for about 5 seconds until the lights F briefly blinks simultaneously.

14 To reset the boiler to the normal operation turn it OFF and ON by the function selector knob A.

10.7 Reignition frequency setting

It is possible to select the minimum time that must pass between two ignitions of the burner in c.h. function mode.

1 Turn the boiler ON positioning the function selector knob A as indicated in Figure 10.12.

b figure 10.9

9 To change the setting turn the knob B on a position corresponding to the boiler models (Figure 10.9). By turning the knob B, the lock-out signal lamp E blinks quickly (2 per seconds) indicating that the setting has changed and must be memorised.


11 Press the reset button D once until the lamps F give the indication as in Figure 10.10 (useful output, second step).

b a d E


3 The lamps F should give the indication as in Figure 10.13 (reignition frequency). If not, press the reset button repeatedly to obtain it.

Where: Lamp OFF

Lamp ON

figure 10.13

At this step it is possible to visualize the current setting by keep-

- 24 -


ing the reset button D pressed for more than 5 seconds. The lamps F will flash a number of times corresponding to the setting

(Figure 10.14).

7 Keep pressed the reset button D for about 5 seconds until the lock-out signal lamp E is switched OFF.

The boiler runs in c.h. mode and the lamps F give the indication as in Figure 10.17.

4 To change the setting turn the knob B on a position corresponding to the desired delay.


1 1/2

0

1

2

3

3

4

4

5

5 1/2

6

7

7

8 1/2 b

Delay (minutes)

Setting No.

figure 10.14


Where:

Lamp OFF

Flashing lamp, alone or simultaneously with an other lamp.

figure 10.17

8 Rotate the knob B on a position corresponding to an adequate ignition pressure.

Refer to the value indicated in the tables of the User/Installation manual (Technical information section, Gas pressures at the burner table).

By rotating clockwise the pressure increases.

9 Make a note of the position of the knob B.

10 Turn the boiler OFF and ON positioning the function selector knob A as indicated in Figure 10.18

6 To reset the boiler to the normal operation turn it OFF and

ON by the function selector knob A. In any case, the boiler automatically resets to its normal operation after 10 minutes.

Factory setting = 3 minutes

b a d E

10.8 ignition gas pressure adjustment

1 Turn the boiler OFF.


3 Open the gas valve outlet pressure test point (7, see section

11.2) and connect the gauge.

4 Turn the boiler ON positioning the function selector knob A as indicated in Figure 10.15 and ensure that the timer selector switch and room thermostat, if fitted, are set to “heat demand”.

Run the boiler in c.h. mode (do not open any d.h.w. tap).

b a d E


6 The lamps F should give the indication as in Figure 10.16. If not, press the reset button repeatedly to obtain it.

Where: Lamp OFF

Lamp ON

figure 10.16

11 Keep pressed the reset buttonD for about 10 seconds until the lock-out signal lamp E blinks.

12 Press the reset button D repeatedly (4 times) until the lamps

F give the indication as in Figure 10.19 (ignition pressure adjustment mode).

Where:

Lamp OFF

Lamp ON

figure 10.19

13 Turn the knob B to the minimum (fully counterclockwise) and then on the position corresponding to the position obtained on step 8.

By turning the knob B, the lock-out signal lamp E blinks quickly (2 per second) indicating that the setting has changed and must be memorised.


15 To reset the boiler to the normal operation turn it OFF and ON by the function selector knob A checking the ignition pressure and that the burner lights up uniformly. In any case, the boiler automatically resets to its normal operation after 10 minutes.

10.9 Setting the tree way diverter valve operation mode

when replacing the Electronic control/ignition p.c.b., it must be set for the correct operation of the tree way diverter valve.

- 25 -


Note: the Electronic control/ignition p.c.b. spare part is fattory set on mode 1.

For all the models covered by this manual:

1 Turn the boiler ON positioning the function selector knob A as indicated in Figure 10.20.

2 Turn knob B as indicated in Figure 10.20.

10.10 Checks

Check that the fuses are complete

If the Electronic control/ignition p.c.b. does not supply any device (pump, fan, etc.) check that the fuses 14 (Figure 10.2) are complete.

If a fuse has blown replace it with one that has the same characteristics after having identified the reason for failure.

b a d E


4 Press the reset button D repeatedly (3 times) until the lamps

F give the indication as in Figure 10.21 (setting the tree way diverter valve mode operation).

Where:

Lamp OFF

Lock sequence

Start the boiler until the burner is ignited.

With the burner firing, interrupt the gas supply. The Electronic control/ignition p.c.b. must carry out three complete ignition cycles and then, after about 3 minutes, goes to lock-out state.

By turning the boiler on and off by means of the function switch the devicemust not unlock and the burner must not turn on.

Fan functioning device

With the boiler operating and the burner on, open the positive pressure test point of the Fan pressure connection devise. After opening it the burner must turn off.

Lamp ON

figure 10.21

At this step it is possible to visualize the current setting by keeping the reset button D pressed for more than 5 seconds. The lamps F will flash a number of times corresponding to the setting

(Figure 10.22).

5 Change the setting by turning the knob B on the position corresponding to the desired setting (Figure 10.22).



4

M296.24SM/C

M296.28SM/C

7 flashes

1

7

10.11 Removal of the electronic control p.c.b


when replacing the Electronic control/ignition p.c.b. it is advisable to go through the setting modes of the boiler.

1 Gain access to the parts located inside the control panel as explained in the section "Control panel" page 5 of this manual.

2 Remove all the wiring connected to the Electronic control/ ignition p.c.b..

To disconnect the connectors x1, x6 and x7 (1, 2 and 3 in

Figure 10.2) delicately flex the hook present on one side of each socket.

To disconnet the connectors x4 and x2 (4 and 5 in Figure

10.2) press delicately the hook present onone side of each connector.

3 Remove the spindles of the c.h. and d.h.w. temperature adjustment knobs by delicately pulling them with pliers in the direction shown by the arrows in Figure 10.23.

b

Setting No.

figure 10.22

At this step it is possible to visualize the current setting by keeping the reset button D pressed for more than 5 seconds. The lamps F will flash a number of times corresponding to the setting of Figure 10.22 that must be seven times.

7 To reset the boiler to the normal operation turn it OFF and ON by the function selector knob A checking the ignition pressure and that the burner lights up uniformly. In any case, the boiler automatically resets to its normal operation after 10 minutes.

figure 10.23

- 26 -


4 Unscrew the four screws that hold the Electronic control/ignition p.c.b. on to the control panel.

5 Remove it by lifting its rear edge and freeing it from any of the wiring.

6 Re-assemble the Electronic control/ignition p.c.b. following the removal procedures in the reverse order.

important

When re-assembling the Electronic control/ignition p.c.b.:

7 Fit the p.c.b. into the control panel by first inserting the front lower edge under the control knob shafts. Lower the rear edge and ensure that no wiring is trapped beneath.

8 Insert the spindles in the control panel knobs untill the notch

A (Figure 10.24) reaches the potentiometer edge. It is not necessary to force them in the knob.

9 While tightening the screws that fix the Electronic control/ignition p.c.b. on the control panel, keep the p.c.b. towards the control panel fascia making sure of the contact between the boiler reset button B and the tab C (Figure 10.24).

a a b

C figure 10.24

attention

After installing the Electronic control/ignition p.c.b. :

10 Make sure the c.h. ( ) and d.h.w. ( ) temperature adjustment knobs can move freely for the complete range.

If not, remove the spindle again as described at step 3, turn the knob half a turn and re-insert the spindle.

11 Operate the boiler and close the gas inlet cock so that the boiler goes into the safety lock-out state.

Verify the correct operation of the boiler reset button by pressing and releasing it.



- 27 -


10.12 Thermal control in the mode

Switch in the function mode

See functioning with the function control in the mode

(sec. 10.13)

YES

Taking water from the domestic hot water circuit?

NO

YES

Is primary circuit temperature higher than that selected?

NO

NO

Circulator off

Operates motorised valve

Ignition device off

Request for heat from room thermostat?

YES

Starts the circulator


Supplies the ignition device

figure 10.25

10.13 Thermal control in the mode

See functioning with the function control in the mode

(sec. 10.13)

YES

Switch in the function mode

Taking water from the domestic hot water circuit?

NO

YES

Is primary circuit temperature higher than that selected?

NO

NO

Circulator off


Ignition device off

Request for heat from room thermostat?

YES

Starts the circulator


Supplies the ignition device

figure 10.26

- 28 -


10.14 ignition and control sequence

Ignition request

YES lock memorised?

NO cancels lock

NO

Air pressure sensor at rest?

YES starts fan

NO

NO

Air pressure sensor at work?

YES beginning of wait period

NO presence of flame?


YES starts ignition discharges opens gas valve beginning of ignition period

YES

NO end of ignition period?

YES

NO flame presence?

closes gas valve stops fan interrupts ignition discharges memorizes lock turns on lock---out light

YES interrupts ignition discharges gas valve open

NO reset push---button pressed?

YES closes gas valve

YES flame presence?

NO

YES


NO

NO safety thermostat or flue temperature probe lock out?

YES

figure 10.27

- 29 -

ModulaTinG GaS valvE

11 ModulaTinG GaS valvE

11.1 function

The Modulating gas valve A in Figure 11.1 controls the gas inflow to the boiler burner.

7

3

8

2

1 a figure 11.1

By means of an electric command given to the on-off operators the passage of the gas through the Modulating gas valve can be opened or closed.

By means of an electric command given to the modulation operator the pressure can be varied and therefore the gas flow rate to the burner (modulation). The modulation operator has mechanical components which allow the adjustment of the minimum and maximum pressure exiting the valve.

11.2 nomenclature of the parts

- (figure 11.2)

1 Minimum gas pressure adjustment

2 Maximum gas pressure adjustment

3 Modulation operator’s electric connectors

4 On-off operators electric connector

5 On-off operators

6 Gas valve inlet pressure test point

7 Gas valve outlet pressure test point

8 Modulationoperator

6 figure 11.2

4 5

11.3 adjustment

for the pressure values refer to the Technical data section of the user manual and installation instructions.




2 Open the gas valve inlet pressure test point (6 in Figure 11.2) at the valve input, connect a suitable pressure gauge and check the gas pressure of the supply network.

3 Remove the gauge and close the pressure test point 6.

4 Open the gas valve outlet pressure test point (7 in Figure

11.2) and connect the gauge;

b

C figure 11.3

- 30 -

ModulaTinG GaS valvE

5 Remove the protection cap B (Figure 11.3) from the mechanical pressure adjustment components levering with a flat screwdriver in the slots C.

6 Start the boiler at its maximum power.

Operate the boiler in d.h.w. mode or ensure that theboiler isnot range ratedif the test iscarriedout in c.h. mode.

7 Rotate the maximumgas pressure adjustment (2 in Figure

11.2) until you obtain the required pressure (by rotating clockwise the pressure increases).

8 Turn the boiler off and disconnect one of the two connectors

(3 in Figure 11.2).

9 Start the boiler and rotate theminimum gas pressure adjustment (1 in Figure 11.2) until you obtain the required pressure

(by rotating clockwise the pressure increases).

10 Turn the boiler off and re-connect the wire to the modulating operator.

11 Start the boiler and check again the maximum gas pressure setting.

12 Turn the boiler off and disconnect the gauge.

G i

E important: after the gas pressure checks and any adjustment operations, all of the test pointsmust be sealed and replace the adjustment protection cap.

figure 11.5

J

11.4 Checks


Check the modulation operator coil


2 Disconnect the connectors D (Figure 11.5) from the modulating operator and measure the electrical resistance of the coil.

Its electrical resistance value must be approx. 80 Ω*.

Check the on-off operators coils


2 Disconnect the electrical connector E (Figure 11.5).

3 Measure the electrical resistance between the connector pins of the on-off operators as illustrated in Figure 11.4.

d f

H

11.6 Removal of the gas valve


1 Remove the front panel of the case as explained in the section "Control panel" page 5 of this manual.

2 Disconnect the connectors D and E (Figure 11.5).

3 Turn off the gas supply and disconnect the gas isolation cock connector from the inlet port of the gas valve.

4 Unscrew the connectors G and remove the pipe H.

5 Remove the rubber pipe I.

6 Unscrew the screws J and remove the valve.

7 Reassemble the valve carrying out the removal operations in reverse order.

Upper on-off operator approx. 6400 Ω*

after any service operation on the components of the gas circuit check all the connections for gas leaks.



Lower on-off operator approx. 920 Ω*

*at ambient temperature.

figure 11.4

11.5 Removal of the on-off operators coils



2 Disconnect the connector E (Figure 11.5).

3 Unscrew the screw F and remove on-off operator coils.

4 Reassemble the coils carrying out the removal operations in reverse order.

- 31 -

PRiMaRy CiRCuiT PRESSuRE SwiTCH

12 PRiMaRy CiRCuiT PRESSuRE SwiTCH

12.1 function

The Primary circuit pressure switch (A in Figure 12.1) function is to check the presence of water in the primary hydraulic circuit and that the pressure is above the minimun.

12.3 Removal


1 Remove the front and right hand side panels of the case, turn off the flow and return isolation valves and empty the primary circuit.

2 Remove the fixing spring B (Figure 12.3) and remove the primary circuit pressure switch A.

3 Disconnect the connectors.

a b a d figure 12.1

This device is connected to the electronic control p.c.b. and if, it does not activate the control board will indicate that a fault condition (see section "Operation lights" page 23) has occurred.

12.2 Checks


Electrical check

It is possible to verify the general operation of the switch by measuring the electric resistance between the contacts C and

N.O. of the switch.

1 Measure the electrical resistance between the tabs marked C and N.O. (Figure 12.2).

The contact must close (resistance zero) with c.h. pressure of

0,35 bar or higher.

n.o.

C figure 12.3

4 Reassemble the primary circuit pressure switch in reverse order of removal.


figure 12.2

- 32 -

ExPanSion vESSEl and TEMPERaTuRE-PRESSuRE GauGE

13 ExPanSion vESSEl and TEMPERaTuRE-

PRESSuRE GauGE

13.1 function

The Expansion vessel (D in Figure 12.1 function is to allow for the volume expansion of the c.h. circuit water due to the temperature rise.

G f

13.2 Checks

1 Turn off the flow and return isolation valves and empty the primary circuit of the boiler.

2 Remove the protective cap E (Figure 13.1) from the valve on the top of the expansion vessel and connect a suitable air pressure gauge.

E figure 13.2

3 Re-assemble the parts in reverse order of removal.

13.4 Removal of the temperature-pressure gauge

1 Remove the front and right hand side panels of the case, turn off the flow and return isolation valves and empty the primary circuit.

2 Remove the fork H and the probe holder spring I (Figure

13.3).

3 Squeeze the tabs J to release the temperature-pressure gauge K and remove it.

4 Re-assemble the parts in reverse order of removal.

i

H figure 13.1

Rear view of the boiler

3 Check the pre-load pressure and refer to the section Expansion vessel in the User manual and installation instructions for the correct value.

13.3 Removal of the expansion vessel

If there is at least 400 mm clearance above the boiler and the rear exit flue can be easily removed, the expansion vessel can be changed without removing the boiler.


1 Remove the front and left hand side panels of the case, turn off the flow and return isolation valves and empty the primary circuit.

2 Completely unscrew the connection F, the locknut G (Figure

13.2) and remove the expansion vessel from the top of the boiler.

figure 13.3

K

J

- 33 -

d.H.w. flow SwiTCH, filTER and flow liMiTER

14 d.H.w. flow SwiTCH, filTER and flow liMiTER

14.1 function

The d.h.w. flow switch A in Figure 14.1 is a device that generates an electrical signal when hot water is drawn.

7 Sensor holder spring

8 Sensor

2

1

3 figure 14.2

1

7

C b

14.2 nomenclature and location of parts

- (figure 14.3)

1 Flow switch plug

2 O-ring

3 Flow limiter (optional for M296.28SM/C)

4 Body

5 Float

6 Filter

- 34 -

a figure 14.1

When the flow rate through the d.h.w. circuit reaches about 2,5 litres/min’, the float 5 (Figure 14.3) is dragged upwards and themagnet in it, getting closer to the sensor 8, closes the electric contact that switches the boiler d.h.w operation ON.

4

5

6

7

8 figure 14.3

14.3 Checks


Sensor operation


2 Disconnect the connectors B (Figure 14.2) and measure the electrical resistance between the leads of the sensor. Without water being drawn, the contactmust be open. By opening a hotwater tap the contact must be close (electrical resistance zero Ω).

14.4 Removal of the sensor



2 Disconnect the connectors B and remove the sensor holder spring 7 (Figure 14.2 - Figure 14.3).

3 Remove the sensor.

14.5 Removal of the flow switch group and d.h.w. circuit filter


1 Remove the front panel of the case and empty the d.h.w. circuit.

2 Remove the fork C and pull up the flow switch plug 1 (Figure

14.2 - Figure 14.3) with the help of a screwdriver.

3 To remove the filter from the flow switch group separate the filter 6 from the body 4 (Figure 14.3) by levering it.

4 Reassemble the parts following the removing sequence in reverse order.

d.H.w. flow SwiTCH, filTER and flow liMiTER

14.6 flow limiter

The M296.24SM/C model is factory fitted with a 10 litre/min. flow limiter.

If on the M296.28SM/C model the flow rate of the d.h.w. circuit is too high, it is possible to limit it by installing a flow limiter. The following sizes are available:

Nominal flow rate (litres/min)

10

12

14

Color

Blue

Red

Pink

To install the flow limiter:

1 Remove the flow switch group as explained in the section

"Removal of the flow switch group and d.h.w. circuit filter" page 34.

2 Separate the flow switch plug 1 from the body 4 (Figure 14.4) levering with a screwdriver one of the two hooks.

1

4 figure 14.4

3 Insert the flow limiter 3 as shown in Figure 14.3.

4 Reassemble the group following the above sequence in reverse order.

- 35 -

TEMPERaTuRE PRobE

15 TEMPERaTuRE PRobE

15.1 function

The Temperature probe has the function of converting the temperature of the water in the hydraulic circuit where it is installed into an electrical signal (resistance).

The relation between temperature and electrical resistance is stated in Figure 15.1.

Ω

12500

12000

11500

11000

10500

10000

9500

9000

8500

8000

7500

7000

6500

6000

5500

5000

4500

4000

3500

3000

2500

2000

1500

1000

20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

figure 15.1

°C

15.2 Checks

Sensor operation


Disconnect the cable from the Temperature probe.

Measure the temperature of the pipe C where the Temperature probe is located and check the electrical resistance according to the graph in Figure 15.1.

15.3 Removal of the c.h. Temperature probe


1 Remove all the case panels and the sealed chamber lid.

a

On the boiler there are two Temperature probes. One on the output of the primary heat exchanger (c.h. Temperature probe) A in Figure 15.2 and Figure 15.3; one on the output of the d.h.w. heat exchanger (d.h.w. Temperature probe) B in Figure 15.2 and

Figure 15.4.

d

C figure 15.3

2 Remove the electric connector D and remove the c.h. Temperature probe A (Figure 15.3).

3 Reassemble the c.h.Temperature probe carrying out the removal operations in reverse order.

a

15.4 Removal of the d.h.w. Temperature probe


figure 15.2

c.h.

return c.h.

flow d.h.w.

inlet

- 36 -

b

d.h.w.

outlet

figure 15.4

b f E


2 Empty the d.h.w circuit of the boiler.

3 Remove the fixing spring E (Figure 15.4).

4 Remove the electric connector F and unscrew the d.h.w.

TEMPERaTuRE PRobE

Temperature probe B (Figure 15.4).

5 Reassemble the d.h.w. Temperature probe carrying out the removal operations in reverse order.


- 37 -

by-PaSS valvE

16 by-PaSS valvE

16.1 function

The By-pass valve A in Figure 16.1 is located between the c.h. water flowand return and its function is that of guaranteeing a minimum flow across the primary heat exchanger if the circulation across the c.h. system is completely closed.

The By-pass valve is inside of the diverter group.

a b a figure 16.1

16.2 Removal


1 Remove all the case panels.


3 Remove the locking plate B and pull up the by-pass valve A

(Figure 16.3).

figure 16.2

4 Reassemble the by-pass valve as illustrated in Figure 16.2 reversing the order of removal.


a attention: when reassembling the by-pass valve be sure that it is correctly oriented by matching the reference C with the notch d of the water group figure

16.3.

d

C figure 16.3

- 38 -

fan and aiR PRESSuRE SEnSoR

17 fan and aiR PRESSuRE SEnSoR

17.1 function

The function of the Fan A (Figure 17.1 and Figure 17.2) is to force the products of combustion through the condensing heat exchanger to the outside air via the flue system.

The Fan is supplied by the full sequence ignition device at the beginning of the ignition cycle.

Its correct functioning is controlled by means of an Air pressure sensor B (Figure 17.1 and Figure 17.2) .

b a

C a b figure 17.2

Check of the Air pressure sensor operation

This test must be carried out with the sealed chamber closed.

1 Remove the caps of the pressure test points located on the top of the boiler and connect a differential pressure gauge

(Figure 17.3).

2 Switch on the boiler.

figure 17.1

17.2 Checks

Check of the fan



2 Disconnect the connectors C (Figure 17.2) and measure the electrical resistance of the motor that has to be about:

43 Ω - M296.24SM/C

25 Ω - M296.28SM/C

(at ambient temperature).

figure 17.3

3 Run the boiler at minimum by disconnecting the gas valve modulation operator.

4 Compare the value on the gauge with the following:

75 Pa (0,75 mbar) - M296.24SM/C

92 Pa (0,92 mbar) - M296.28SM/C

5 Run the boiler at maximum (connect themodulation operator).

6 Compare the value on the gauge with the following:

125 Pa (1,25 mbar) - M296.24SM/C

155 Pa (1,55 mbar) - M296.28SM/C

7 With values less than:

64 Pa (0,64 mbar) - M296.24SM/C

82 Pa (0,82 mbar) - M296.28SM/C

The ignition is not allowed and appropriate fault indication is given (see section 10.4)

- 39 -

fan and aiR PRESSuRE SEnSoR

17.3 Removal of the fan


J


2 Disconnect the connectors C and the earth connection D

(Figure 17.4).

3 Disconnect the pipe E by the pressure test point F (Figure

17.4).

4 Unscrew the screw G and remove the bracket H (Figure

17.4).

E f

J i d

C pressure point P2 figure 17.5



a

H

G figure 17.4

5 Remove the Fan by sliding it towards left (se the arrow in

Figure 17.4).

6 Assemble the fan carrying out the removal operations in reverse sequence.

warning: Re-assembling the fan ensure that the hooks around the inlet port of the fan hung correctly on the flue hood.



17.4 Removal of the air pressure sensor



2 Disconnect the wires I from the Air pressure sensor.

3 Remove the pipe J from the Air pressure sensor.

4 Unscrew the screws which hold the Air pressure sensor to the frame.

5 Assemble the Air pressure sensor carrying out the removal operations in reverse sequence.

warning: to correctly connect the air pressure sensor, refer to figure 17.5.

- 40 -

iGniTion and dETECTion ElECTRodES

18 iGniTion and dETECTion ElECTRodES

18.1 function

Three electrodes are fitted on the burner. Two of them are the ignition electrodes and are fitted near the front part of the burner.

The ignition sparks take place between their metallic edges over the central ramp of the burner during the ignition sequence.

The third electrode is the detection electrode and it detects the presence of the flame.


1 Remove all the case panels, the sealed chamber lid and the combustion chamber lid.

2 Check for the integrity of the insulation of wires which connect the electrodes to the ignition device.

Ignition

Female

Detection

Male

18.3 Removal



2 Disconnect the electrode wires from the full sequence ignition device.

3 Remove the plate E (see Figure 5.3 on page 12).

4 Remove the burner by unscrewing the four screws placed at the right and left sides of the burner.

5 Unscrew the screws A (Figure 18.3) which hold the electrodes to the burner.

figure 18.1

18.2 Checks

Check the position of the electrode edges



2 Check for the correct distance between the metallic edges of the ignition electrodes (see Figure 18.2).

4 mm

Ignition

figure 18.2

3 Check the integrity of the detection electrode and ensure that its metallic edge is correctly placed over the ramp of the burner.

Check the connection wires.

a figure 18.3

6 Extract the electrodes from the burner.

7 Assemble the electrodes carrying out the removal operation in reverse order.

Refer to Figure 18.1 in order to recognise the electrodes and to correctly connect the wiring.

note: themetallic edge of the detection electrode is longer than the one of the ignition electrodes.



- 41 -

SafETy THERMoSTaT

19 SafETy THERMoSTaT

19.1 function

The safety thermostat A in Figure 19.1 and Figure 19.2 is a device that senses the temperature of the primary circuit water which flows in the outlet pipe of the primary heat exchanger.

If the temperature control system of the boiler fails and the temperature of the primary circuit reaches a dangerous temperature, the safety thermostat opens the electric circuit that supplies the on-off operators of the gas valve.

Consequently, the full sequence ignition device attempts to light the burner and, at the end, locks the boiler and lights the lock-out signal lamp.

19.3 Removal


1 Remove all the case panels and the lid of the sealed chamber.

b a

C a figure 19.1

19.2 Checks

Overheat temperature value

1 Set the temperature control knobs to their max. position and run the boiler in d.h.w. and c.h.

2 Allow the boiler to reach its maximum operating temperature

(monitor the temperature gauge on the instrument panel).

The boiler shouldmaintain a temperature below that of the safety thermostat and no overheat intervention should occur.


Electrical function

1 Remove all the case panels and the lid of the sealed chamber.

2 Disconnect the wiring B of the safety thermostat and check its electrical function. Normally (no intervention) the contact must be closed (electrical resistance zero Ω).

figure 19.2

2 Disconnect the wiring B (Figure 19.2).

3 Remove the spring C which holds the overheat thermostat on the pipe of the primary heat exchanger and remove it.

4 Reassemble the overheat thermostat carryingout the operations in reverse order.

5 Apply an adequate quantity of heat conducting compound between the pipe and the thermostat.



- 42 -

fluE TEMPERaTuRE PRobE nTC

20 fluE TEMPERaTuRE PRobE nTC

20.1 function

The Flue temperature probe NTC A in Figure 20.2 and Figure

20.3 senses the temperature of the combustion products that flow through the condensing heat exchanger.

The relation between temperature and electrical resistance is stated in Figure 20.1.

Ω

10500

10000

9500

9000

8000

7500

7000

6500

6000

5500

4500

4000

3500

3000

2000

1500

18500

18000

17500

17000

16500

15500

15000

14000

13500

13000

12500

12000

11500

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

figure 20.1

°C

If the temperature of the combustion products circuit reaches the limit temperature, the Flue temperature probe NTC reduces the gas flow rate to the burner. The temperature of the combustion products should decrease to a safe value temperature.

a

The use of kits different from the original isn’t however allowed, since the flue pipes are integral parts of the boiler.

If not, the electronic control p.c.b. attempts to light the burner and, at the end, locks the boiler and lights the lock-out signal lamp.

a b figure 20.3

20.2 Checks

Overheat temperature value

1 Set the temperature control knobs to their max. position and run the boiler in d.h.w. and c.h.

2 Allow the boiler to reach its maximum operating temperature

(monitor the temperature gauge on the instrument panel).

The boiler shouldmaintain a temperature below that of the

Flue temperature probe NTC and no overheat intervention should occur.

Temperature-resistance relationship.

1 Remove the probe (see section "Removal" page 43) to have it at room temperature.

2 The electric resistance of the Flue temperature probe NTC at room temperature of 20°C must be of approximately 12000 Ω

3 For other temperatures of the probe check the electrical resistance according to the graph (Figure 20.1).

20.3 Removal



2 Disconnect the wires B fromthe Flue temperature probe NTC

(Figure 20.3).

3 Unscrew and remove the thermostat probe A (Figure 20.3) from the condensing heat exchanger.

4 Assemble the Flue temperature probe NTC carrying out the removal operations in reverse sequence.

figure 20.2

In the case that the temperature of the combustion products reaches a potentially dangerous value, it stops the boiler operation. It is therefore allowed the use of plastic materials for the flue outlet pipes and bends.

- 43 -

CondEnSaTE TRaP

21 CondEnSaTE TRaP

21.1 function

The condensate trap A in Figure 21.1 and Figure 21.2 allows the discharge of the condensate via the condensate drain pipe avoiding in the mean time the escape of combustion products.

A plastic ball closes the trap outlet in case that the trap is empty.

21.2 Removal


1 Remove the front and right case panels.

2 Disconnect the trap from the draining pipe.

3 Using pliers, remove the spring B moving it upwards.

4 Disconnect the rubber pipe C.

5 Unscrew the nut D and lower the trap.

6 Disconnect the wirings from the trap.

7 Reassemble carrying out the removal operations in reverse order.

C b d a a figure 21.1

If the drain pipe is plugged or in any case in which the condensate isn’t correctly evacuated, the condensate level rises filling the trap and reaching the condensing heat exchanger.

When the condensate reaches the lower part of the exchanger obstructs the the exhaust gas flow and the boiler stops (no signal from the air pressure sensor).

figure 21.2

- 44 -

SHORT SPARE PARTS LIST

22 SHORT SPARE PARTS LIST

Key G.C. part no. Description

1

2

3

4

5

6

7

E83 - 121

H20 - 984

H20 - 985

H74 - 578

H74 - 604

H03 - 746

H74 - 576

8

9

H50 - 189

E83 - 178

10 E83 - 180

E83 - 181

11 H74 - 591

H74 - 592

12

13 E01 - 204

E01 - 205

14

173 - 148

173 - 149

H74 - 599

169 - 070

Burner (mod. M296.24SM/C)

Burner (mod. M296.28SM/C)

Injectors for natural gas (mod. M296.24SM/C)

Injectors for natural gas (mod. M296.28SM/C)

Injectors for LPG (mod. M296.24SM/C)

Injectors for LPG (mod. M296.28SM/C)

Expansion vessel (mod. M296.24SM/C, M296.28SM/C) 1

12

14

Main heat exchanger (mod. M296.24SM/C)

Main heat exchanger (mod. M296.28SM/C)

Fan (mod. M296.24SM/C)

Fan (mod. M296.28SM/C)

Gas valve

Air pressure sensor

Safety valve

Combustion chamber side panels

Combustion chamber rear panel (mod. M296.24SM/C) 1

1

2

Combustion chamber rear panel (mod. M296.28SM/C) 1

Combustion chamber front panel (mod. M296.24SM/C) 1

Combustion chamber front panel (mod. M296.28SM/C) 1

Electronic regulation p.c.b.

D.h.w. heat exchanger (M296.24SM/C)

D.h.w. heat exchanger (M296.28SM/C)

1

1

1

Pump 1

1

1

1

1

1

1

1

1

12

14

15 H74 - 545

16 169 - 010

17 H74 - 535

18 E83 - 101

19 H74 - 589

20 H44 - 170

21 169 - 016

22 H74 - 553

23 E83 - 127

24

25

26

27

E83 - 126

E83 - 122

E83 - 145

Primary circuit pressure switch

D.h.w. switch

Three way diverter valve (electric actuator)

Overheat thermostat


Fuse 3,15 AF

Temperature probe (d.h.w. circuit)

Temperature probe (main circuit)

Ignition electrode (left)

(mod. M296.24SM/C, M296.28SM/C)

Ignition electrode (right) 1

(mod. M296.24SM/C, M296.28SM/C)

Detection electrode (mod. M296.24SM/C, M296.28SM/C) 1

Temperature-pressure gauge 1

1

1

Recuperator

1

2

1

1

1

1

1

1

KI1004 102

KI1004 147

BI1213 109

KI1064 506

BI1172 103

BI1262 101

BI1262 102

BI1536 105

BI1536 113

BI1093 105

BI1536 103

BI1181 100

BI1326 100

BI1326 107

BI1326 108

BI1536 110

BI1536 111

BI2015 105

BI1001 101

BI1001 102

BI1542 100

BI1351 118

KI1042 107

BI1351 108

BI1172 105

BI1536 104

BI1295 108

KI1042 501

BI1442 106

BI1123 101

BI1123 103

BI1123 102

BI1475 108

BI1442 121

IMIT

Manufacturer’s reference

Polidoro

Polidoro

CIMM 6 litres

Fime

Fime

Sit 845

HUBA 0-3 mbar

Watts

Bertelli & Partners

WILO INTNFSL12/

6-HEP-1-12

ELTH - type 261

- 45 -

1

SHoRT SPaRE PaRTS liST

2

3

4

10

9

13

5

6

7 8

9

12

14

11

15 16 22

17 figure 22.1

- 46 -

18 19 20 21 23 24 25 26

27

*1796200000*

17962.1549.4 1011 48A5 UK

Biasi UK Ltd

Commercial Road

Leamore Enterprise Park

WALSALL

WS2 7NQ

Tel : 01922 714 600 www.biasi.co.uk

BIASI Riva Plus HE M296.24SM/C, M296.28SM/C gas boiler Service manual

Assistant Bot

Wall hung, fanflue, roomsealed, high efficiency gas boiler

Service manual

Riva Plus HE

Models

M296.24SM/C

M296.28SM/C

G.C. Appl. No.

CoMbi boilER

CoMbi boilER

leave this manual adjacent to the gas meter

1 ovERall infoRMaTion . . . . . . . . . . . . . . . . . . . . 4

2 GEnERal aCCESS and EMPTyinG HydRauliC

CiRCuiTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 diaGRaMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4 faulT findinG . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5 PRiMaRy HEaT ExCHanGER . . . . . . . . . . . . . . . 12

6 CondEnSinG HEaT ExCHanGER . . . . . . . . . . . 14

7 d.H.w. HEaT ExCHanGER. . . . . . . . . . . . . . . . . . 16

8 PuMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

9 THREE way divERTER valvE . . . . . . . . . . . . . . 19

10 ElECTRoniC ConTRol/iGniTion P.C.b. . . . . . 21

11 ModulaTinG GaS valvE . . . . . . . . . . . . . . . . . . 30

TablE of ConTEnTS

12 PRiMaRy CiRCuiT PRESSuRE SwiTCH . . . . . . 32

13 ExPanSion vESSEl and TEMPERaTuRE-PRES-

SuRE GauGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

14 d.H.w. flow SwiTCH, filTER and flow liMi-

TER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

15 TEMPERaTuRE PRobE . . . . . . . . . . . . . . . . . . . . 36

16 by-PaSS valvE . . . . . . . . . . . . . . . . . . . . . . . . . . 38

17 fan and aiR PRESSuRE SEnSoR. . . . . . . . . . . 39

18 iGniTion and dETECTion ElECTRodES . . . . 41

19 SafETy THERMoSTaT. . . . . . . . . . . . . . . . . . . . . 42

20 fluE TEMPERaTuRE PRobE nTC. . . . . . . . . . . 43

21 CondEnSaTE TRaP. . . . . . . . . . . . . . . . . . . . . . . 44

22 SHoRT SPaRE PaRTS liST. . . . . . . . . . . . . . . . . 45

ovERall infoRMaTion

1 ovERall infoRMaTion

1.1 overall view

1.2 Hydraulic diagram

Central heating (c.h.) operation

Domestic hot water (d.h.w.) operation

GEnERal aCCESS and EMPTyinG HydRauliC CiRCuiTS

2 GEnERal aCCESS and EMPTyinG

HydRauliC CiRCuiTS

2.1 nomenclature

2.2 body panels

2.3 Control panel

GEnERal aCCESS and EMPTyinG HydRauliC CiRCuiTS

2.5 Emptying the primary circuit

2.6 Emptying the d.h.w. circuit

2.4 access to the sealed chamber

diaGRaMS

3 diaGRaMS

3.1 wiring diagram

diaGRaMS

3.2 Functional flow diagrams

diaGRaMS

3.3 Circuit voltages

4 faulT findinG

faulT findinG

faulT findinG

PRiMaRy HEaT ExCHanGER

5 PRiMaRy HEaT ExCHanGER

5.1 function

5.2 Removal

PRiMaRy HEaT ExCHanGER

5.3 Cleaning

CondEnSinG HEaT ExCHanGER

6 CondEnSinG HEaT ExCHanGER

6.1 function

6.2 Removal

CondEnSinG HEaT ExCHanGER

6.3 Cleaning

d.H.w. HEaT ExCHanGER

7 d.H.w. HEaT ExCHanGER

7.1 function

7.2 Removal