7
3.
Expansion Tank
: An expansion tank (such as a Bell
& Gossett Series HFT) is required to provide room
for expansion of the heating medium (water or glycol
solution). Consult the expansion tank manufacturer’s
instruction for specific sizing information. The
expansion tank is to be sized for the required system
volume and capacity. In addition, care must be taken
to size the expansion tank based on the proper
heating medium. Glycol solutions may expand more
than water for a similar temperature rise. Table 3.1
shows the approximate water volume of the boiler
for sizing the expansion tank and determining glycol
solution concentration.
4.
Flow Control Valve (Check Valve)
: Flow control
valves or check valves are used to prevent gravity
circulation by incorporating a weighted disc into the
check valve. These valves also prevent problems with
reverse circulation through parallel heating loops
which cause erratic behavior of the heating system
and prevent heat from reaching its intended load.
5.
Pressure Reducing Valve
: A pressure reducing valve,
such as the Bell & Gossett B-38 or a TACO #29, is
used in a hydronic system to automatically feed
water to the system whenever the pressure drops
below the set pressure. These valves should not be
used on glycol systems unless close supervision of
the glycol solution is practiced.
6.
Back Flow Preventer
: A back flow preventer (check
valve) is required by some jurisdictions to prevent
water in the hydronic system from backing up into
the city water supply if the supply pressure drops
below that of the heating system. This is especially
important on systems in which glycol solution is used
as a heating medium.
7.
Pressure Relief Valve
: The boiler pressure relief valve
is shipped separately for field installation. On the
WBV/WV™ boiler, this can be piped into the
connection provided next to the boiler supply (outlet)
connection or, alternatively, on the connection at the
rear of the boiler below the supply. The value is to
be installed as shown in Figure 3.2.
Pipe the discharge of the safety relief valve to within
12" of the floor and close to an open drain. The
discharge piping must be the same size or larger than
the relief valve outlet. DO NOT INSTALL A CAP OR
VALVE AT THE RELIEF VALVE OUTLET.
8.
Circulator
: Circulators for central heating distribution
should be sized and installed in accordance with
system requirements and pump manufacturers
recommendations.
9.
Indirect Water Heater
: An indirect water heater should
be piped to a dedicated zone as shown in Figure 3.3.
10.
Boiler Drain Valve
: Fittings are provided for
mounting the boiler drain valve in the return tapping
at the bottom rear of the boiler. See Figure 3.4. It is
recommended that the boiler return be piped to the
rear of the block, however for a front return locations
see Figure 3.5.
WATER PIPING
Figure 3.2: Pressure/Temperature Gauge & Relief
Valve Piping
Boiler Model
Water Volume, Gal (Liter)
WBV-03
11.75 (44.5)
WBV-04
14.75 (55.8)
WV-05
17.75 (67.1)
Table 3.1: Boiler Water Volume
Do not operate this appliance without installing the
pressure relief valve supplied with the boiler or one
with sufficient relieving capacity in accordance with
the ASME Rating Plate on the boiler.
WARNING
Pipe the discharge of the relief valve as close as
possible to the floor and away from high traffic areas.
Pipe the discharge close to a floor drain. Failure to
do so may result in personal injury and/or property
damage.
CAUTION
The relief valve must be mounted in a vertical upright
position. No other valve or restriction is to be
installed in this line.
CAUTION
