Service manual

Residential Digital Packaged Units GT-PC Series - 60Hz Puron
®
Rev.: 14 June, 2013
20
Closed Loop - External Central Pumping Applications
High and
Low Voltage
Knockouts
Vibration Isolation Pad
To Thermostat
Internal Motorized
Modulating Valve
Water Out
Shut Off
Ball Valves
for Isolation
Water In
Figure 18: Typical Closed Loop with Central Pumping Application (with Internal Modulating Motorized Valve Shown)
/RFN5HOHDVH
Sizes 026-049 Sizes 064-072
Closed Closed
Open Open
Figure 19: Internal Modulating Motorized
Valve Positions
GT-PC packaged units are available with a modulating
water valve option for closed-loop applications with external
central pumping (designated by a 5 in the 11th position of
the unit model number). With this option, the Modulating
Valve is regulated by the Communicating DXM2 board based
on entering and leaving water temperature (ΔT). The DXM2
board outputs a 0-10v signal to determine valve position
(fl ow rate). The modulating valve defaults to closed position
if it loses signal but still has 24V power running to it. If the
motorized modulating valve loses both signal from the DXM2
board AND 24V power, it will remain in the same position it
was in when it lost 24V power.
Note: The Cv (fl ow coeffi cient) of the valve used in these
units is DIFFERENT that the Cv of the valve used in the
open loop unit. It is not advisable for use in open loop
applications as sound/noise issues may result. Units with
the water circuit for closed loop, central pumping option are
only available with a copper water coil.
To manually open the internal modulating motorized water
valve in YG026 – 049 push down on the handle to unlock
it. Then rotate the handle to the open position as shown
in Figure 19. This fully opens the valve for fl ushing. Once
fl ushing is complete, return the valve handle to its normally
closed position.
To manually open the internal modulating motorized water
valve in YG064 – 072, push down on the lock release button
while turning the handle to the open position as shown in
Figure 19. This fully opens the valve for fl ushing. Once
fl ushing is complete, press the lock release again and return
the valve handle to its normally closed position.