Tranquility THW - 50 & 60Hz R410A - ClimateMaster Geothermal Heat Pumps - Rev.: 30 June, 2008B
8
Typical open loop piping is shown in Figure 2. Shut
off valves should be included in case of servicing.
Boiler drains or other valves should be ‘tee’d’ into the
line to allow acid flushing of just the heat exchanger.
Pressure temperature plugs should be used so that flow
and temperature can be measured. Piping materials
should be limited to PVC SCH80 or copper.
Due to the
pressure and temperature extremes, PVC SCH40
is not recommended.
Water quantity should be
plentiful and of good quality. Consult Table 2 for water
quality guidelines. The unit can be ordered with either
a copper or cupro-nickel water heat exchanger. Copper
is recommended for closed loop systems and open
loop ground water systems that are not high in mineral
content or corrosiveness. In conditions anticipating heavy
scale formation or in brackish water, a cupro-nickel heat
exchanger is recommended. In ground water situations
where scaling could be heavy or where biological growth
such as iron bacteria will be present, a closed loop
system is recommended. Heat exchanger coils may over
time lose heat exchange capabilities due to a build up of
mineral deposits inside. These can be cleaned only by a
qualified service mechanic as acid and special pumping
equipment are required.
Desuperheater coils can likewise become scaled and
possibly plugged. In areas with extremely hard water, the
homeowner should be informed that the heat exchanger
may require occasional acid flushing.
Expansion Tank and Pump
Use a closed, bladder-type expansion tank to minimize
mineral formation due to air exposure. The expansion tank
should be sized to handle at least one minute run time
of the pump to prevent premature pump failure using its
drawdown capacity rating. The pump should be sized to
the home’s domestic water load (5-9 gpm [19-34 l/m]) plus
the heat pump water load. Discharge water from the unit
is not contaminated in any manner and can be disposed
of in various ways depending on local building codes; i.e.
recharge well, storm sewer, drain field, adjacent stream
or pond, etc. Most local codes forbid the use of sanitary
sewer for disposal. Consult your local building and zoning
department to assure compliance in your area.
Water Control Valve
Note the placement of the water control valve. Always
maintain water pressure in the heat exchanger by placing
water control valves at the outlet of the unit to prevent
mineral precipitation. Pilot operated or Taco slow closing
valve’s solenoid valves are recommended to reduce water
hammer. If water hammer persists, a mini-expansion tank
can be mounted on the piping to help absorb the excess
hammer shock. Insure that the total ‘VA’ draw of the valve
can be supplied by the unit transformer. For instance the
Taco slow closing valve can draw up to 35VA. This can
overload smaller 40 or 50 VA transformers depending
on the other controls employed. A typical pilot operated
GROUND-WATER HEAT PUMP SYSTEMS
solenoid valve draws approximately 15VA. Note the
special wiring diagram of the AVM valve (Figure 9).
f
low Regulation
Flow regulation can be accomplished by two methods.
First, most water control valves have a built in flow
adjustment. By measuring the pressure drop through the
unit heat exchanger, flow rate can be determined and
compared to Table 7. Simply adjust the water control
valve until the desired flow is achieved. Secondly, a flow
control device may be installed. The devices are typically
an orifice of plastic material that is designed to allow a
specified flow rate. These are mounted on the outlet of
the water control valve. On occasion, these valves can
produce a velocity noise that can be reduced by applying
some back pressure. This is accomplished by slightly
closing the leaving isolation valve of the well water setup.
Low Temperature Cutout
The water low temperature cutout setpoint should be
activated to avoid freeze damage to the unit. Consult the
low temperature cutout section of the controls description
for instructions.
�
CAUTION!
�
CAUTION! Refrigerant pressure activated water regulating
valves should never be used with ClimateMaster equipment.
�
CAUTION!
�
CAUTION!
Many units installed with a factory or field
supplied manual or electric shut-off valve.
DAMAGE WILL
OCCUR
if shut-off valve is
closed
during unit operation. A
high pressure switch must be installed on the heat pump side
of any field provided shut-off valves and connected to the
heat pump controls in series with the built-in refrigerant circuit
high pressure switch to disable compressor operation if water
pressure exceeds pressure switch setting. The field installed
high pressure switch shall have a cut-out pressure of 300
psig and a cut-in pressure of 250 psig. This pressure switch
can be ordered from ClimateMaster with a 1/4” internal flare
connection as part number 39B0005N02.
