Low Temperature Return Water Systems | Lochinvar 999

Hydronic Heating Boilers and Domestic Water Heaters

INSTALLATION Continued

Table - O

LTV Valve Kits

Input

LTV Valve Kit

Btu/hr

399,999 - 750,000VAL3048

990,000 - 2,070,000 VAL3047

Be sure to install the LTV valve per the piping diagrams

included with the kits. Alternatively, a bypass as shown in

FIG. 38 may be piped into the system. This piping is like a

primary/secondary boiler installation with a bypass in the

secondary boiler piping. Inlet water temperatures below 140°F

(60°C) can excessively cool the products of combustion

resulting in condensation on the heat exchanger and in the flue.

Condensation can cause operational problems, bad

combustion, sooting, flue gas spillage and reduced service life

of the vent system and related components. The bypass allows

FIG. 36 Primary/Secondary Piping of a Single Boiler

part of the boiler discharge water to be mixed with the cooler

boiler return water to increase the boiler inlet temperature

above 140°F (60°C). This should prevent the products of

combustion from condensing in most installations. The bypass

should be fully sized with a balancing valve to allow for proper

adjustment. A valve must also be provided on the boiler

discharge, after the bypass. Closing this discharge valve forces

water through the bypass. Start boiler adjustment with the

bypass valve in the full open position and the boiler discharge

valve half open. A small amount of the higher temperature

boiler discharge water is mixed with the system water to

maintain the desired lower system temperature. A remote low

temperature range operator is recommended to control the

boiler operation based on the lower system temperature. (See

Terminal Strip Connection Options starting on

page 40).

FIG. 37 Primary/Secondary Piping of Multiple Boilers