Install Instructions

ManualsBrandsLochinvar ManualsBoilers285,000 BTU Output Two Stage Spark Ignition Copper-Fin Boiler (LP Gas)

4 Hydronic piping (continued)

Installation & Service Manual

Low Temperature Bypass

Requirements

This piping is like a primary/secondary boiler installation with a

bypass in the secondary boil er piping. Inlet water temperatures

below 140°F (60°C) can excessively cool the prod ucts of

combustion re sult ing in condensation on the heat exchanger and

in the flue. Condensation can cause operational prob lems, 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 in crease the boiler inlet temperature above 140°F

(60°C). This should prevent the prod ucts of com bus tion from

condensing in most in stal la tions.

The bypass should be fully sized with a bal anc ing valve to allow

for proper adjustment. A valve must also be provided on the

boiler discharge, after the by pass. 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 high er

temperature boiler discharge water is mixed with the system

water to maintain the de sired lower system tem per a ture. A

remote low tem per a ture range operator is recommended to

control the boiler operation for temperatures lower than 100°F.

This remote op er a tor should be wired across the R and W

terminals (see Room Ther mo stat Connection and Terminal Strip

Instructions in Section 5 of this manual).

Three Way Valves

The installation of a three way valve on this boiler is not

generally recommended because most piping meth ods allow the

three way valve to vary flow to the boil er. This boiler is a low

mass, high ef fi cien cy unit which requires a constant water flow

rate for proper op er a tion.

Low flow rates can re sult 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 can

cause operational prob lems and non-warrantable failures of the

boiler. If a three way valve must be installed, please pipe in a

primary/secondary system. Based on boiler sizing and system

flow requirements, this piping may still result in boiler short

cycling.

Boiler Flow Rates

 CAUTION

The maximum flow rate through the boil-

er with a copper heat exchanger must not

ex ceed 30 GPM.

The heat exchanger is generally capable of op er at ing within

the flow rates of a residential heating system. Should the flow

rate exceed the maximum allowable flow rate through the

boiler 30 GPM) an external bypass must be installed. The

bypass should be fully sized with a balancing valve to al low

for proper ad just ment of flow. Flow rate can be determined by

measuring the temperature rise through the boiler.

The basic guide for minimum flow in this boiler is based on a

40°F temperature rise in most in stal la tions. Low er flow and

a higher temperature rise is acceptable if the boiler system is

specifically de signed for the char ac ter is tics of a higher tem-

per a ture rise. A system not specifically designed for a higher

temperature rise may experience over heat ing of the boiler

water. This can cause short burn er on cycles, system noise

and in ex treme cases, a knocking flash to steam. These con di-

tions can lead to operational problems and non-war rant able

fail ures of the boiler. High temperature rise systems must be