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Isolation Valves
Flow Control Valves
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Figure 19.
2. MULTIPLE ZONING WITH CIRCULATORS -----
Each pump will require a separate relay (Honeywell R845A or White Rodgers 829A-
845, or equivalent). Install a flow control valve in each zone including the indirect
water heater to prevent gravity circulation. Install a balancing valve in each zone and
adjust so that flow in each zone is about the same. See Figure 19.
3. RADIANT PANEL OR OTHER LOW TEMPERATURE SYSTEM----
The temperature of the system water coming back to the return port of the boiler must
not be permitted to drop below about 135 Degree F for an extended period of time.
Return water temperatures of 130 Degree F or lower will cause condensation on the
exterior surface of the heat exchanger and corrosion and eventual heat exchanger
failure will result. Radiant floor and ceiling panel heating systems typically operate
with maximum supply water temperatures of 140 Degree F or less. A standard piping
arrangement would, under these circumstances, permit return water temperatures of
120 Degree F and lower. Accordingly, such systems must be piped such that the
return water temperature will be high enough at all times to prevent condensation.
See Figure 20.
Isolation Valves Circulatin
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Installation, Operation, And Service Instructions 25