Comfort-Aire HKV300A - Manual (Page 15)

Installation, Operation & Maintenance HKV SERIES Heat Controller, LLC
14
Antifreeze
In areas where minimum entering loop temperatures drop
below 40°F (5°C) or where piping will be routed through areas
subject to freezing, anti-freeze is needed. Alcohols and glycols
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antifreeze may be better suited for your area . Freeze protection
should be maintained to 15°F (9°C) below the lowest expected
entering loop temperature. For example, if 30°F (-1°C) is the
minimum expected entering loop temperature, the leaving loop
temperature would be 25 to 22°F (-4 to -6°C) and freeze protec-
tion should be at 15°F (-10°C) e.g. 30°F - 15°F = 15°F (-1°C
- 9°C = -10°C). All alcohols should be premixed and pumped
from a reservoir outside of the building when possible or intro-
duced under water level to prevent fuming. Initially calculate the
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age by volume shown in Table 2 for the amount of antifreeze.
Antifreeze concentration should be checked from a well mixed
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Low Water Temperature Cut-Out Setting CXM Control:
When an antifreeze is selected, the FP1 jumper (JW3) should
be clipped to select the low temperature (Antifreeze 10°F
[-12.2°C]) setpoint to avoid nuisance faults.
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
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Piping materials should be limited to PVC SCH80 or copper.
Note: Due to the pressure and temperature extremes, PVC
SCH40 is not recommended.
Water quantity should be plentiful and of good quality. Consult
Table 3 for water quality guidelines. The unit can be ordered
with either a copper or cupro-nickel water heat exchanger.
Consult Table 3 for recommendations. Copper is recommended
for closed loop systems and open loop ground water systems
that are not high in mineral content or corrosiveness. In condi-
tions 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 de-
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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 owner should
be informed that the heat exchanger may require occasional
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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
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adjacent stream or pond, etc. Most local codes forbid the use of
sanitary sewer for disposal. Consult your local building and zon-
ing 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 precipita-
tion during the off-cycle. Pilot operated slow closing 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 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. Most
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rate can be determined and compared to Table 7. Since the
pressure is constantly varying, two pressure gauges might be
needed. Simply adjust the water control valve until the desired
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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.
Ground-Water Heat Pump Applications
Ground-Loop Heat Pump Applications
Low Water Temperature Cut-Out Setting
For all open loop systems the 30°F (-1.1°C) FP1 setting (fac-
tory setting-water) should be used to avoid freeze damage
to the unit. See Freeze Protection Selection for closed loop
systems with anitfreeze.
CAUTION!
! !