Tranquility
®
Water-to-Water (TMW) Series
R e v. : M a r c h 1 0 , 2 0 2 1
T H E S M A R T S O L U T I O N F O R E N E R G Y E F F I C I E N C Y
c l i m a t e m a s t e r.c o m
13
Ground-Water Heat Pump Applications, Cont’d.
Water quantity should be plentiful and of good quality.
Consult Table 1 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. It is
recommended to install an intermediate heat exchanger
to isolate an open loop from the heat pump loop on
open well systems. Heat exchangers 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.
In areas with extremely hard water, the owner 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. 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.
Low Water Temperature Cut-Out Setting -
For all open
loop systems the 35°F [1.7°C] LT1 setting (factory setting-
water) should be used to avoid freeze damage to the unit.
See Figure 4: “Low Water Temperature Cutout - LT1”.
⚠
CAUTION!
⚠
CAUTION!
Low temperature limit system will not allow leaving
load water temperature (cooling mode) or leaving source water
temperature (heating mode) to be below 42
°
F [5.6
°
C].
⚠
WARNING!
⚠
⚠
CAUTION!
⚠
CAUTION!
Many units are 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.
WARNING!
Never jumper terminal “A” from CXM or DXM
board #1 to CXM or DXM board #2 on multi-compressor/
control bound units. See Figure 5 in electrical section of this
document for motorized valve wiring.
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 solenoid valve draws
approximately 15VA.
Flow 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 Tables 7 and 8. Since the
pressure is constantly varying, two pressure gauges
might be needed. Simply adjust the water control valve
until the desired flow of 1.5 to 2 gpm per ton 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.
