Architect and Engineering Manual

36
HEAT PUMP CONDENSATE DISPOSAL
Since the outdoor coil is cold during heat pump
operation, the condensate water cannot be deposited
on the outdoor coil because the water would cause frost
to form on the coil. This frost would block the airflow
through the coil. Rather than allow this problem to occur,
heat pump units must dispose of the condensate in
another manner. The most widely used method of
disposing of heat pump condensate is with a
temperature-activated drain valve.
TEMPERATURE-ACTIVATED
DRAIN VALVE
This is a device mounted in the base
pan of a heat pump unit with a bellows
that expands on temperature rise and
contracts with temperature drop.
A shaft with a rubber plug on the end
is connected to the bellows. When the
outdoor temperature remains above a certain
temperature, the bellows is expanded and the plug fits
tightly into a hole in the bottom, or base pan, of the unit.
When the plug is blocking the hole, as it should be during
cooling operation, the condensate water is contained in
the base pan. At temperatures when heating is required,
the bellows contracts, the rubber plug is retracted from
the hole and the heat pump condensate water is allowed
to drain into the wall sleeve. The valve is fully open at
approximately 45°F.
DRAIN KITS
Although the Zoneline units are designed to dissipate
most of the condensate generated during normal
cooling operation, there may be times when abnormal
operating conditions cause more condensate than the
unit can dissipate. Heat pumps also generate condensate
that the unit may not be designed to dissipate. For these
reasons, if condensate dripping from the wall sleeve is
objectionable, an internal or external drain system should
be installed. See pages 37–38 for information covering
the drain systems and the RAD10 kit available to connect
to the wall sleeve.
INTERNAL CONDENSATE REMOVAL (ICR) SYSTEM
GE has developed an Internal Condensate Removal (ICR)
system for packaged terminal heat pumps. This system
has been offered as an option on Zoneline packaged
terminal Heat Pumps since 1982, and thousands of them
are in use. During heat pump operation, the ICR system
utilizes a small pump to lift the water from the base pan
and pump it into a collector tray positioned above the
indoor coil. The water drains from the collector tray and
drips onto the warm indoor coil where it is evaporated
into the room atmosphere. If an excess amount of water
is pumped to the indoor side, it is routed back to the
outdoor portion of the base pan.
The ICR system has proven to be an effective means of
minimizing the amount of heat pump condensate
dripping from the unit. However, if the restrictions of a
particular installation will allow absolutely no drippage
of condensate water from the wall sleeve, the installation
of an internal or external drain system is recommended.
COOLING CONDENSATE
Air conditioners produce condensate water as a result
of lowering the humidity of the area being conditioned.
When the indoor coil temperature is below the dew point,
moisture in the air condenses into water droplets on the
indoor coil. This water drains to a pan located under the
indoor coil and is routed through the weather barrier or
bulkhead (the partition separating the indoor and outdoor
sides of the unit) to the base pan on the outdoor side.
It is then picked up and dispersed against the outdoor coil
- which is hot when the unit is in the air conditioning mode
– where it is evaporated into the atmosphere by contact
with the hot outdoor coil. This evaporation process also
helps lower the temperature of the outdoor coil and
improves the operating efficiency of the unit.
SLINGER RING SYSTEMS
Packaged terminal units employ various means of
dispersing the condensate water. One of the most popular,
and most effective, means is by the use of a “slinger ring.”
A slinger ring is a ring around the circumference of the
outdoor fan. The design of the unit positions the slinger
ring very close to the bottom of the base pan so water
in the base pan is lifted by the rotating ring. Water picked
up by the slinger ring will be dispersed into the air stream
and deposited on the hot outdoor coil where it evaporates.
All Zoneline
®
Series packaged terminal air conditioners
and packaged terminal heat pumps utilize a slinger ring
for cooling condensate disposal.
CERTIFICATION TEST REQUIREMENTS
AHRI (Air Conditioning, Heating & Refrigerating Institute)
requires that all certified packaged terminal air conditioners
and packaged terminal heat pumps pass a cooling
condensate disposal test. One stipulation of the AHRI test
is that under standard rating conditions “the equipment
shall be started with its condensate collection pan filled
to the overflowing point.” In order to pass the AHRI
Condensate Disposal Test the unit must operate
continuously for four hours without condensed water
dripping, running, or blowing off the unit during the test
or after the unit has been turned off.
Under extremely high outdoor humidity conditions or
extreme operating conditions, such as exceptionally high
air infiltration (a door or window left open while the unit
is running, for instance) it is possible for any air conditioner
to be unable to dissipate all the cooling condensate
generated.
All Zoneline Series packaged terminal air conditioners
and packaged terminal heat pumps meet the condensate
disposal requirements of AHRI standards 310/380.
HEAT PUMP CONDENSATE
During the operation of a unit in the heat pump, or “reverse
cycle,” mode, the outdoor coil becomes the cold coil and
the indoor coil becomes the hot coil due to reversing the
flow of the refrigerant. When the temperature of the
outdoor coil is below the dew point, condensation will form
on the outdoor coil just as it does on the indoor coil during
cooling operation. Since the dew point is humidity and
temperature-related, there may be more condensate on
days when the relative humidity is high.
Units with ICR may not be installed in seacoast or other corrosive environment applications.
ICR model not compatible with RAKVENT1 kit and Makeup Air models.
CONDENSATE DISPOSAL SYSTEMS