C. BACKFLOW PREVENTER. HTP Elite FT, 387

21

C. BACKFLOW PREVENTER

Use a backflow preventer specifically designed for hydronic installations. This valve should be installed on the cold water fill supply line per local codes (see Piping Details, Part 5, Section G).

D. SYSTEM WATER PIPING METHODS

EXPANSION TANK AND MAKE-UP WATER

1. Ensure that the expansion tank is designed and sized to correctly handle system water volume and temperature. For sizing information, refer to expansion tank manufacturer’s sizing guidelines or the latest ASHRAE expansion tank sizing standards.

Expansion tanks must be sized according to total system volume. This includes all length of pipe, all fixtures, boilers, etc. Failure to properly size system expansion could result in wasted time, money, and possible property damage, personal injury, or death.

MODEL

EFT-55 / EFT-80

EFT-110

EFT-155

EFT-199

EFT-285

EFT-399

ADDED VOLUME TO SYSTEM BY ELITE FT BOILER

GALLONS

2.2

2.6

6.2

6.1

6.1

7.9

Table 3

Undersized expansion tanks cause system water to be lost from the relief valve, causing make-up water to be added. Eventual boiler failure can result due to excessive make-up water addition.

SUCH FAILURE IS NOT COVERED BY WARRANTY.

2. The expansion tank must be located as shown in Part 5, Boiler Piping, or following recognized design methods. See expansion tank manufacturer’s instructions for details.

3. Connect the expansion tank to the air separator only if the air separator is on the side of the circulator. Always install the system fill connection at the same point as the expansion tank connection to the system.

DO NOT

install automatic air vents on closed type expansion tank systems. Air must remain in the system and return to the tank to provide an air cushion. An automatic air vent would cause air to leave the system, resulting in improper operation of the expansion tank.

DIAPHRAGM (OR BLADDER) EXPANSION TANK

Always install an automatic air vent on top of the air separator to remove residual air from the system.

E. CIRCULATORS

DO NOT

use the boiler circulator in any location other than the ones shown in this manual. The boiler circulator location is selected to ensure adequate flow through the boiler. Failure to comply with this caution could result in unreliable performance and nuisance shutdowns from insufficient flow.

Sizing Space Heat System Piping

1. See Piping Details, Part 5, Section G. In most diagrams, the space heating system is isolated from the boiler loop by the primary/secondary connection.

2. Size the piping and components in the space heating system using recognized design methods.

LP-387 REV. 3.4.15