Lochinvar 065 Low Temperature Return Water Systems, Radiant Floor and Snow Melt Heating Systems

Installation and Service Manual

The installer must ensure that the boiler has adequate flow without excessive temperature rise. Low system flow can result in overheating of the boiler water which can cause short burner ON cycles, system noise and in extreme cases, a knocking flash to steam. These conditions indicate the need to increase boiler flow by installation of a larger circulator pump or the installation of a system bypass. System noise may also indicate an oversized boiler.

￿CAUTION: At no time should the system pressure be less than 12 PSIG.

temperature protection valve (LTV) that is factory preset to maintain 140°F inlet water to the boiler regardless of the system return water temperature. See Table K for available valve kits.

Table - K

LTV Valve Kits

Input

LTV Valve Kit

Btu/hr

495,000 - 745,000VAL3048

985,000 - 2,065,000 VAL3047

Figure 26 - Primary/Secondary Piping of a Single Boiler

Be sure to install the LTV valve per the piping diagrams included with the kits. Alternatively, a bypass as shown in FIG. 28 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 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

PRV

MAKE-UP

WATER

EXPANSION TANK

LWCO (OPTIONAL)

TO SYSTEM

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

SYSTEM PUMP

12" OR 4 PIPE	AIR SEPARATOR
DIAMETERS

FROM SYSTEM

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 22).

SECONDARY

BOILER PUMP

Figure 27 - Primary/Secondary Piping of Multiple Boilers

Low Temperature Return Water Systems

Any non-condensing boiler and venting system will develop operational problems when exposed to inlet water temperatures below 140°F. Lochinvar offers a low

Radiant Floor and Snow Melt Heating Systems

This type of heating boiler application operates in a low temperature range which requires a boiler bypass as described under Low Temperature Bypass Requirements. A non-metallic rubber or plastic tubing installed in a radiant (in floor) system must have an oxygen barrier to prevent oxygen from entering the system through the walls of the installed tubing. Excessive oxygen absorption into the system will result in an accelerated rate of corrosion causing a sludge buildup. This excessive corrosion will also damage the boiler and system components.

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