Hayward Temp Sensor Blocking Heat Pump

erbepool

New member
Feb 12, 2025
4
DFW Texas
Pool Size
15400
Surface
Fiberglass
Chlorine
Salt Water Generator
I just had a new pool put in. I noticed on the omnilogic app today that the pump was running at 100%. The heater is at a set point of 60°, outside temp is 45°, and current pool temp is 50°. I would expect the heater would be on with these conditions, but status says “Ready”. I inquired with my pool builder and he is saying “You're outside temperature is 45°. The heater will only kick on if your outside weather temperature is higher than the water temperature currently 50°.” “The unit has a temp sensor to detect the outside temperature. They designed it so it doesn't come on unless it can actually start heating.” Can someone explain this to me?
 

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Welcome to TFP.

You have an Heat Pump.

Heat pumps, like AC systems, have a low air temperature shutoff. Typically around 50F. Below that they will not run as the refrigerant and heat exchange is not effective.

What specific model number heat pump do you have?

 
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Heat Pump Performance depends on the ambient conditions.

Ambient Air Temperature / Water temperature / Relative Humidity.

80/80/80 means Ambient Air Temperature = 80 F / Water temperature = 80 F / Relative Humidity 80%.

At 80/80/80, the heat pump produces 120,000 btu/hr.

At Ambient Air Temperature = 50 F / Water temperature = 80 F / Relative Humidity 63% the performance is 75,000 btu/hr, which is 62.5% of full performance.

So, the heat pumps are like solar where the performance depends on the weather and some people want to prevent operation in low air temp weather.

You can change the low air temp set point.

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Here is a Heat Loss Calculator based on the below chart.


For example, if the air is 50 and the water is 80, then you will lose 106 btu/hr per square foot at 0 mph air speed and 70% humidity.

If the pool is 450 square feet, then you will lose about 47,700 btu/hr.

At 50/80/63, you will gain 75,000 btu/hr.

So, net gain is 27,300 btu/hr when heating.

If the loss rate exceeds the gain rate, then the heater cannot keep up.

The breakeven point is a loss of 167 btu/hr/sqft.

For example, if the air is 50 and the water is 80, then you will lose 167 btu/hr per square foot at about 0.7 mph air speed.

So, you could maintain the water at 80 degrees if the heater runs continuously.


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Welcome to TFP.

You have an Heat Pump.

Heat pumps, like AC systems, have a low air temperature shutoff. Typically around 50F. Below that they will not run as the refrigerant and heat exchange is not effective.

What specific model number heat pump do you have?

Hayward SP32950VSP
 
Thank you for the reply’s! I may just leave it alone but if for some reason I want to heat the pool when it’s colder, how would I change the low air temp set point?
 
Thank you for the reply’s! I may just leave it alone but if for some reason I want to heat the pool when it’s colder, how would I change the low air temp set point?
Edit the Configuration in your Omni controller and lower the Minimum Allowed Air Temperture.
 

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