W iring Diagram s. Suburban SFV-42F, NT-24SP, SH-35, P-30S/40, P-40, SF-35, SH-42F, NT.12SE, SFV-42, NT.16SE

6.

Customer complains of unit going into lockout only once in a while:

a. Thoroughly check electrode and burner relationship.

b. Lockout can occur if the gas pressure fluctuates at the time the thermostat calls for heat. Pressure fluctuations can be caused by a malfunctioning gas bottle regulator, an obstruction or a kink in the gas line, or moisture in the gas bottle regulator or in the gas lines. It is difficult to check for these fluctuations that will not noticeably affect any other appliance in the coach. However, isolating the furnace from the coach gas system will determine if the gas system is responsible. This isolation procedure can be done by connecting a separate upright bottle, regulator and gas line directly to the furnace, eliminating the coach gas system. If the occasional lockout still exists, then the furnace should be thoroughly tested to determine the cause; however, if the furnace works properly on this separate system, then the coach gas system should be checked.

c. Check furnace return air and warm air discharge to be certain sufficient air flow is present to engage micro switch every time.

d. Check micro switch to be sure it moves freely.

e. Remove electrode and burner. Clean thoroughly.

f.

When moisture in the gas system is suspected as being the problem, especially where the horizontal type gas bottle is being used, the following steps should be take to prepare the gas system against further moisture problems:

Corrective Measures:

1. Disconnect gas bottle and drain it completely dry of all gas and all moisture.

2. Disconnect and blow out all gas lines completely dry.

3. Check pressure regulator on the gas bottle. Replace if necessary.

4. Add the drying agent. One half pint of methanol alcohol per

100 pound bottle capacity is recommended.

Precautions:

5. Never fill the gas bottle over 80%.

6. Do not use the gas bottle completely dry to avoid using up the drying agent.

We have found the above procedures to be effective in solving most occasional lockout problems, especially where the horizontal type gas bottle is used. All of these steps must be performed as described for the preparation of a contaminated gas system to be 100% effective.

Figure 21

P -30S w ith Tim e Delay

Figure 22

P -40 w ith Tim e Delay

30

31

Figure 23

R em ote Flam e Sense

W ith Tim e Delay

(N T M odels)

W ith Tim e Delay

Figure 25

(S F-20/25/30/35/42F)

Figure 26

Local Flam e Sense

(S F M odels)

W ith Tim e Delay

Figure 27

Fan C on trol B oard

(N T-12/16/20S and S E )

32

Figure 28

Fan C on trol B oard

(N T-24/30/34SP and N T-40)

Figure 29

Fan Control

P -30S

33

Figure 30

Fan C on trol B oard

P -40

34