diagram, the same hydronic piping layout (at right of the dashed line) works
with hot water source and chilled water source. Switching between the heat
source and cold source is based on operating mode, and is controlled by outdoor
temperature change, a manual switch or combination of both. When switching from
winter mode to summer mode, the relay R6 is activated, system will supply chilled
water via the 3-way valve.
in which mode - winter or summer, as long as any of zone stats has demand
(calling for heat or cooling), the zone valve relay R12 and/or R13 are
activated as well as HC pump relay R1.
Winter mode, the controller calculates theoretical supply temperature to the
radiant zone: Flow Set, by our pre-set heating curve and outdoor temperature S5;
based on the calculation, the controller commands the 3-way mixing valve to open
for getting more hot water from heat source (S1 < Flow Set) or close for
allowing less hot water from heat source ( S1> Flow Set).
Summer mode, the controller calculates theoretical supply temperature to the
radiant zone: Flow Set, by our pre-set cooling
curve/constant value; based on the calculation, the controller commands the
3-way mixing valve to open for getting more cold water from cold source ( S1 >
Flow Set) or close for allowing less water from cold source ( S1< Flow
Set). Beside this, condensation control
is necessary in radiant cooling systems. the controller has a built-in
psychrometric chart algorithm. FRHd provides ambient temperature and relative
humidity of the radiant zone, and the controller calculates the dew points. So the controller keeps the lowest cold water supply temperature to the radiant
zone, but also ensures that this supply temperature is 4ºF above the dew points.
Heat Pump is the most versatile
heating/cooling source. The winter & summer operation switchover is
controlled by reversing valve that is part of the heat pump. The controller through the pre-wired dry contact relays in electrical enclosure can
talk to any heat pump equipped with external dry-contact signal for switching
the operating modes and calling compressor:
These concept diagrams have exactly same piping at
heating/cooling load side as above.
The difference is that 3-way diverting valve (relay R6) is
not used as its function has reversing valve inside heat pump. The individual
3-way mixing valve & HC pump are part of PAW K32 station supplied with the
kit. Beside only radiant heating/cooling zones the fancoils can be added. These
will require different supply temperatures: much higher in winter and lower in
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