Mammoth 3/4 to 5 Tons: Single Circuit Horizontal and Vertical (U-Vintage) - Manual (Page 8)

8
MAMM-WSHP-IOM-1UB (September 2011)
Supply Piping
1. All heat pumps should be connected to supply and
return piping in a two-pipe reverse return
configuration. A reverse return system is inherently
self-balancing and requires only trim balancing
where multiple quantities of heat pumps with
different flow and pressure drop characteristics
exist in the same loop. Check for proper water
balance by measuring differential temperature
reading across the water connections. To insure
proper water flow, the differential temperature
should be between 10°F to 14°F for heat pumps in
the cooling mode.
2. The piping may be steel, copper, or PVC. Avoid
dissimilar metal fittings as they may corrode. If the
use of dissimilar metals is unavoidable, use
dielectric isolation at that connection point.
3. Supply and return run-outs usually join the heat
pump via short lengths of high pressure flexible
hose which are sound attenuators for both heat
pump operating noise and hydraulic pumping
noise. One end of the hose should have a swivel
fitting to facilitate removal for service. Hard piping
can also be brought directly to the heat pump. This
option is not recommended since no vibration or
noise attenuation can be accomplished. The hard
piping must have a union to facilitate heat pump
removal.
4. Make sure that threaded fittings are sealed. Teflon
tape can be used to provide a tight seal.
5. Supply and return shutoff valves are required at
each heat pump. The return valve is used for
balancing and should have a “memory stop” so that
it can always be closed off but can only be
reopened to the proper position for the flow
required.
6. No heat pump should be connected to the supply
and return piping until the water system has been
cleaned and flushed completely. After the cleaning
and flushing has taken place, the initial connection
should have all valves wide open in preparation for
the water system flushing.
Condensate Piping
1. Condensate piping can be steel, copper, or PVC.
Each unit includes a condensate connection.
2. The condensate disposal piping must be trapped.
Vertical units are internally trapped and horizontal
units must be externally trapped. The piping must
be pitched away from the heat pump not less than
¼” per foot. The unit is supplied with a 1-1/4” male
pipe fitting to accommodate the condensate drain
connection.
3. Do not locate any point in the drain system above
the drain connection of any unit.
4. The condensate piping system must be vented at
its highest point.