© 2017 PoolPak LLC. All rights reserved. MPK Series - Installation, Operation and Maintenance | 17
PoolPak
®
MPK Series IOM
Cold Surface Temperature Humidity Reset
The CPCS control system includes a sensor that measures the temperature of the coldest surface in the pool
enclosure, usually an exterior window or door frame. When the temperature of this surface approaches the
dewpoint temperature of the space, the controller lowers the humidity setpoint to activate dehumidification. This
function helps to prevent condensation on the cold surface. Typical locations for this condensate prevention surface
temperature sensor are north facing exterior walls, windows, window/door frames, and skylights.
Space Heating
The CPCS controller will first look at the outside air to see if the space heating requirement can be met with the
economizer mode. If conditions are unfavorable, the unit will either enable the compressors to perform space
heating by heat recovery or by enabling the auxiliary heat system.
Space heating via heat recovery provides full proportional control of the space dry bulb temperature by staging
compressor loading of unit capacity with humidity override. Heat is recovered automatically from the pool room
return air in the evaporator coil and then re-directed into the reheat condenser coil. For SEP models, the warm
natatorium air is passed through the evaporator before being exhausted. Therefore, the PoolPak unit is able to
capture the heat energy from the warm pool air.
If additional heating is needed, the CPCS Controller then turns on the auxiliary heat system. The PoolPak
automatically controls the output of the optional factory-installed auxiliary air-heating system which can be hot
water, steam, electric or gas.
On a call for space heating only (humidity is satisfied), the controller can be configured to perform the first stage(s)
of heat as auxiliary heat instead. If there is also a dehumidification need, mechanical dehumidification with the
compressors will always be the first stage. Regardless, this setting change allows a facility to use auxiliary heat more
often.
Smart Economizer (SEP)
The Smart Economizer utilizes the simultaneous operation of the heat recovery and economizer control sequence.
When the PoolPak compressor is operating in the heating and/or dehumidifying heat recovery mode return air
passes through the evaporator. The sensible and latent heat in the return air is transferred to the refrigerant. Air
leaving the evaporator is cold and saturated. The exact temperature and dew point of the air leaving the evaporator
is monitored and compared to outside air temperature and dew point. If the outside air is warmer and/or dryer than
the air leaving the evaporator, all the air leaving the evaporator is exhausted and 100% outside air is drawn into
the PoolPak. All the heat recovered in the PoolPak unit refrigerant is transferred to the supply air in the air reheat
condenser. The Smart Economizer can save energy in addition to a standard mixing box and economizer.
Flywheel Air Conditioning (SEP)
If the unit is not equipped with auxiliary air cooling, this control sequence can be activated. Flywheel air
conditioning uses the large thermal storage capacity of the swimming pool. During occupied times, the PoolPak
cools the natatorium air by removing the sensible and latent heat from the air using the evaporator and directing
it into the pool water condenser. The pool water temperature is allowed to rise a maximum of 2°F above the pool
water temperature set point. Automatic staging of cooling capacity occurs in response to air conditioning load.
Space Cooling (Optional)
The PoolPak MPK (SE and SEP) units are equipped with economizer sections. The CPCS will automatically select the
most economical method for space cooling. An economizer utilizes outside air rather than the refrigeration system
to achieve space cooling. A sensor connected to the CPCS monitors the outside air temperature. When appropriate,
the controller will disable the compressor and bring in cool outside air for economical operation.
If space cooling is required and the unit is equipped with an auxiliary refrigerant condenser (air-cooled or water-
cooled), the CPCS will activate the space cooling mode of operation. The air cooling mode of operation is
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