Hayward Heat Pump Pro HP21104T Not Operating Properly

[harleysilo]

Hi Everyone,

I have a Hayward Heat Pump that has been misbehaving. A few weeks ago I had a service tech put it through the paces but during diagnosis the 1 AMP fuse burned out and he didn't have one on the truck. He's scheduled to come out this Wednesday. I ordered some 1 AMP fuses to have on hand, pooped one in and it came to life. It has proceeded to display the following behavior.

Cold mornings mid 50's to low 60's won't come on and displays error code LP for low pressure.
Cold mornings mid 50's to low 60's starts up just fine.
Turn down requested temp and unit doesn't not shut off.

The unit is putting out air that is 8-10 degrees cooler than ambient temperatures, and it is producing about 1 degree per hour rise in temp when running.

Today it has been running non-stop since 7:30 this morning and it just cut off. The only thing i noticed upon inspection is that the fan motor casing (very top of unit) is 125 degrees in the shade, it's 84 outside right now, seems a little on the hot side but I've never checked it before. I only checked it because after turning the breaker off and on and waiting for the ~5 min. delay I can here it try to turn on, but the fan doesn't turn on, and then it displays LP.

Manual says if LP is displayed to check for airflow blockage, but this is giving me the LP error code before it starts running. The Tech did not hook it up to gauges to check as we could get it to operate after the fuse burned out. The coils and fins look like they may have some green growing on them and I certainly could clean them with a hose. It seems to me like maybe the fan overheated and that is why it stops. It's done this over the past few days and I'll go out to check and it will be running again.

I'm just trying to be able to give my tech something to work with so he doesn't waste time like last time with the lack of fuse. If it needs a fan motor I'd like one on the truck etc.

Many thanks for any input!

 

[harleysilo]

So about 30 mins ago it started back up. there is a 24 degree temp difference between ambient temps and air blowing out of the unit (i've never measured one that large but understand humidity and air temp impact this). The temp of the fan casing is now 90 degrees.

 

[ajw22]

What specific model Hayward HP do you have?

At 50F, which is the minimum operating temperature, the HP will only put out about 2/3 of its rated BTUs.

The tech should check the pressures as the first step.

From the manual...

LP & LP3 Shortage of refrigerant gas in the unit or faulty low pressure
control. The digital display will show LP3 after 3 LP faults and shut
down your pool heater. The pool pump will also be stopped for protection
if the unit’s internal time clock feature is used. If LP or LP3
occurs you should call for service.

 

[harleysilo]

HP21104T

 

[swamprat69]

Found your manual: https://hayward-pool-assets.com/ass...manuals/HeatPro-Owners-HP2xxxxT-HP2xxxxBT.pdf
Found these references in the manual
High / Low Refrigerant Pressure Switches
The low-pressure switch senses the refrigerant pressure in the sealed refrigeration system to protect
against certain conditions that could be detrimental to compressor life. The switch turns the heat
pump off in the event of loss of refrigerant, fan motor failure, evaporator freeze-up, or airflow
blockage. The heat pump will automatically reset the switch after the system pressure returns to
normal operating conditions. The display will show “LP”, if this switch is tripped.

Low Ambient Temperature
If the air outside the heat pump is too cold, the heat pump will not operate. The actual point at which the unit
will cease operating due to low temperature varies. Current weather conditions, the amount of sunlight reaching
the heat pump, and the installation quality are primary contributors to this event. The shutdown will occur near
50°F (10°C). This is not a “fixed” range. Low outside air temperatures will activate the systems defrost function
by lowering the evaporator’s outlet temperature. The fan motor will operate independently for 15 minutes in
attempts to raise the evaporator coil temperature, at which time the heat pump’s control system will check the
temperature to see if the coil has warmed up sufficiently to return to normal operation. The control system will
run through three 15 minute cycles checking the coil temperature. In the event that the coil does not return to
normal operating temperature following the three 15 minute cycles, the heat pump’s control system will shut the
unit down completely for 2 hours (display will show “dEF”). After the 2-hour period, the unit will restart to
check the evaporator temperature and try to resume normal operation. The heat pump control will continue this
cycle until the evaporator temperature returns to normal.

If your heat pump is operating normally the fan motor should be cooled by the cold air moving over it. It is possible that the fan motor is overheating from a weak or open run capacitor and shutting off because the internal temperature sensor in the windings is opening the power to it. The same could happen due to the bearings seizing or bearing wear. If the fan shuts down, the unit would shut off on the Refrigerant Low Pressure Switch. Also look at the section for Low Ambient Temperature.