Hayward HeatPro, Owner'S Manual, Page: 28 / 43

Heat Pump Pool / Spa Heater Owner’s Manual
27
FLOWRATE
MODELS: PE 42** / PE22** / HP-4* / PE 32**
The 3 ¼ HP is designed for nominal water flow of 45 gpm through the condenser. A minimum flow
of 20 gpm is required to insure sufficient heat removal from the condenser, thus avoiding overheating the
unit. Flow rates above 75 gpm will begin to create excessive pressure drop through the condenser and require
unnecessarily high pumping energy.
MODELS: PE 52** / HP-5*
The 5 HP is designed for nominal water flow of 55 gpm through the condenser. A minimum flow of
30 gpm is required to insure sufficient heat removal from the condenser, thus avoiding overheating the unit.
Flow rates above 75 gpm will begin to create excessive pressure drop through the condenser and require
unnecessarily high pumping energy.
EXTERNAL BYPASS
If the flow rate exceeds 75 gpm, a bypass loop must be installed around the heat pump (refer to page
20).
The bypass loop piping should be sized to provide approximately 40-60 gpm to the heat pump. Pump
capacity versus backpressure performance curves for the pump used in the pool system should be consulted to
determine the flow rate. This may require a pressure or flow gauge measurement at the pump discharge.
UNIONS
A detachable connection (union) must be utilized immediately adjacent the heater to facilitate
servicing and winterizing the unit. (See example on previous page)
INSTALLATION OF POOL HEATER ABOVE POOL SURFACE
If the pool heater is installed more than three feet above the surface of the pool water install directional flow
fittings on the end of the return water line to the pool. This will create adequate backpressure at the heater to
operate an important water pressure switch. A pool supply company can help you with directional flow
fittings.
In some cases, such as when the heater 6-8 feet above the pool surface, it may be necessary to install a
positive flow switch such as AQUALARM™ in the water line instead of the pressure switch.
INSTALLATION OF POOL HEATER
BELOW POOL SURFACE
A water pressure switch is integrated into our systems to ensure that
the unit only operates when water is flowing through the heat
exchanger. If a pool surface is above the heat pump, backpressure of
water from the pool can cause problems with an internal water
pressure switch setting. The water pressure switch is located in the
control panel of the heat pump. Backpressure from the pool can close
this switch, whose function is to tell the heat pump that the filter
pump is running. This pressure switch setting should be adjusted so
that the unit is running only while pool filter pump is operating.
Caution : If the heat pump runs for more than a couple of minutes
without the filter pump in combination, the unit will overheat and be damaged.
Adjustment Knob-
up decreases pressure setpoint
down increases the setpoint
Water Pressure Switch