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Part number 550-142-054/0411
27
GV90+ gas-fired water boiler — Boiler Manual
Figure 34 Piping layout — typical for multiple GV90+ boilers, with DHW storage heaters (4-boiler system)
Suggested DHW
boiler-side pipe
sizing
(for max 0.04
feet head loss per foot of
total equivalent length,
TEL)
Flow rate Size Flow rate Size
1 – 4 gpm ¾” 22 – 45 gpm 2”
4 – 8 gpm 1” 45 – 75 gpm 2½”
8 – 14 gpm 1¼” 75 - 140 gpm 3”
14 – 22 gpm 1½” 140 – 290 gpm 4”
Legend — Figure 34
1 Flow/check valve (each boiler)
2 Isolation valves (when used)
3 Caps
4 Easy-Fit® Manifold (supply) — layout and
size per page 24
5 Easy-Fit® Manifold (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 GV90+ Boiler Manual
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 Easy-Fit® Manifold
26 DHW boiler-side supply Easy-Fit® Manifold
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.
This piping is sug-
gested only. The
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.
Multiple boiler water piping (continued)