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S
Shutoff ValveSu
pp
l
y
to S
y
ste
m
Indirect Water Heater
(
Stora
g
e Tank With Coil
)
3 Port Zone Valve
R
Cold Water Feed
Return from S
y
ste
m
Drain Coc
k
Circulatin
g
Pum
p
s
Figure 22.
6.
INTEGRATED SYSTEM WITH MULTIPLE HEATING ZONES AND NO
PRIORITY FOR DOMESTIC HOT WATER, USING ZONE VALVES-----
Where the boiler output is large relative to the heating capacity of the coil in the
indirect water heater priority for domestic hot water is not necessary. Further, with
multiple heating zones there is less likelihood that all zones will call for heat at once
and require full boiler output for heating. Because the tank is usually close to the
boiler, the pressure drop through the coil circuit will generally be less than through a
heating zone circuit, which will provide some measure of priority for domestic hot
water. This can be enhanced by increasing the pipe size to the coil e.g. if 3/4 inch
pipe is used on the heating zones run 1 inch pipe to the coil. (See Figure 23.) Should
priority for domestic hot water be mandatory, it can be provided as shown in Wiring
Section, Figure 24.
28
Installation, Operation, And Service Instructions