Installation, Operation & Maintenance Manual

BOILER PIPING

A. WATER BOILER PIPING – SINGLE

BOILER

1. Refer to the PB Heat Water Installation Survey and

Hydronics Institute Residential Hydronic Heating

Installation Design Guide.

2. Figure 4.1 shows typical supply and return piping for

a boiler system. If the system expansion tank is

located on the boiler loop, it should be located on the

supply side of the boiler with the system circulator

pumping away from the expansion tank connection.

3. If the boiler is piped in a secondary loop separate

from the system expansion tank, the boiler circulator

should be located on the return side of the boiler

pumping away from the common piping.

4. Return water should not reach the boiler return

connection at less than 130°F under normal

operating conditions. If the system return

temperature is expected to be below 130°F the boiler

should be piped in a secondary loop with a bypass

arrangement to assure water returning to the boiler is

above 130°F. For more information on bypass piping

consult the PB Heat Water Installation Survey.

5. If the boiler and distribution system is used in

conjunction with a refrigeration system, pipe the

chilled medium in parallel with the boiler and

provide isolation valves to prevent chilled water form

entering the boiler. See Figure 4.2.

6. If the boiler is connected to a heating coil in a forced

air combination heating and cooling system, install

flow control valves to prevent gravity circulation of

the boiler water during cooling cycles.

7. A hot water boiler installed above radiation level or

as required by the Authority having jurisdiction, must

be provided with a low water cut-off device either as

part of the boiler or at the time of installation.

4. BOILER PIPING

Figure 4.1

Figure 4.2: Piping to Isolate Boiler from Chilled Medium on Chiller Systems