Williamson-Thermoflo GWC-070 Manual page 27

GWC -
gas fired water boiler
Multiple boiler water piping
Piping layout — typical for multiple GWC boilers, with DHW storage heaters (4-boiler system)
Figure 34
1 Flow/check valve (each boiler)
2 Isolation valves (when used)
3 Caps
4 Secondary header (supply) — layout and size
per page 24
5 Secondary header (return) — layout and size
per page 24
6 Primary circulator
7 Expansion tank (diaphragm type)
8 System air eliminator
9 System automatic air vent
16 Cold water fill line — see Figure 32, page 25
for typical components
18 System supply
19 System return
20 Boiler relief valve and discharge piping,
installed per GWC Boiler Manual
Part number 550-142-056/0411
— Boiler Manual
Suggested DHW
boiler-side pipe
sizing
feet head loss per foot of
total equivalent length,
TEL)
Legend — Figure 34
21 Indirect-fired storage water heaters — Example is shown with a boiler
water circulator on each water heater. Alternatively, the water heaters could
be connected with reverse return piping, using a common circulator.
22 Boiler water inlet
23 Boiler water outlet
24 DHW boiler-side circulators
25 DHW boiler-side return secondary header
26 DHW boiler-side supply secondary header
27 Flow/check valves (to prevent induced or gravity flow in heating system or
DHW piping)
28 Check valve to prevent heat migration in heating system
29 Drain valves
30 Sensor for BCP (boiler control panel), when used
Note: See water heater manual for DHW piping — The DHW piping must also
be manifolded together since the boiler-side piping is manifolded. If DHW
heaters supply separate DHW circuits, provide an individual circulator for
each water heater, and control each circulator by its water heater's aquastat.
(continued)
Flow rate Size
1 – 4 gpm ¾"
4 – 8 gpm 1"
(for max 0.04
8 – 14 gpm 1¼"
14 – 22 gpm 1½"
layout above should be controlled
with a boiler sequencing panel that
provides DHW operation as well.
Wire the heating system circulator
to operate only on call for heat. Al-
ternatively, use the boiler sequencing
panel to provide domestic priority
by disabling the heating system cir-
culator any time there is a DHW call
for heat. The boiler internal circula-
tors operate on any call for heat,
whether heating system or DHW.
Offset the DHW boiler-side supply
and return manifolds as shown so
the total run of pipe and fittings to
each of the water heaters is approxi-
mately equal.
Flow rate Size
22 – 45 gpm 2"
45 – 75 gpm 2½"
75 - 140 gpm 3"
140 – 290 gpm 4"
This piping is sug-
gested only. The
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