Shut Off Valves
There are 3 shut off valves required for an
integrated combo system as follows:
•
One valve (a) on the cold water side of the
water heater upstream of the heating loop
connection. This valve has the ability to
isolate the hot water (domestic and space
heating) from the household cold water
supply. This valve is required on every water
heater whether or not the water heater is
used for space heating.
•
One valve (b) on the hot water supply side
of the heating loop, downstream of its
connection to the domestic water.
•
One valve (c) on the return side of the
heating loop upstream of its connection to the
domestic cold water.
The two valves in the heating loop allow the
heating loop to be isolated for service or repair.
Drain Valve
A drain valve is required to allow the heating loop
to be drained for service or repair and to remove
air from the heating loop when commissioning a
system. The drain valve should be near the low
point of the return piping system upstream of the
shut off valve and is preferred to be near the
water heater.
Throttling Valve
The throttling (balancing) valve is used to reduce
the water flow rate and thereby increase the
water temperature drop. This is done to ensure
proper activation of the water heater thermostat.
This valve should be a globe or balancing valve.
Check Valves
A spring loaded check valve is required in the
heating loop to help minimize thermo-siphoning
of hot water throughout the heating loop when
heating is not called for and cold water back
flowing through the heating loop when domestic
hot water is used. The valve will have a water
flow direction arrow marked on it’s exterior
surface and must be installed with that arrow
pointing downstream.
* Check valves should always be installed in a
vertical rise with the flow of water shown.
8
(a)
H
C
(b)
(c)
Supply
Return
SHUT OFF VALVES
CHECK VALVE
