Hayward Heat Pump 120KBTU Struggling to Heat

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collinsbj911

Member
Jan 1, 2024
7
Goodyear, AZ
This is my first post so go easy on me. Just had a pool finished here in Goodyear AZ, 10000 Gallon pool with a Hayward Omnilogic setup. The Heat Pump is a 120KBTU and for the life of me I cannot get the pump to heat up the pool beyond 77 degrees F. The variable pump has been running 24/7 at 90% with the heat pump on 24/7 as well. Starting temperature a four days ago was 55 Degrees F. Target Temp is 86 Degrees F. Nightime temps have been down in the low 40's but recovering to 60-70 degrees during the day. Currently no pool cover (on order but haven't received it yet). For example at 6:30am this morning the outside temp was 53 Deg F Pool was at 72 Degrees F. Daytime high was around 63 degrees today. Pool temp rose to 77 Degrees and stayed there for the past 6 hours. Here is what I know:

Currently No Cover (On Order)
Variable Pump set to 90%
Water Flow in Return Manifold is 45GPM
No Air Bubbles in the System
Skimmer Off - Quick Skim Slightly Open
Heat Pump is commanding heat
Heat Pump exhaust air is 10-12 Deg F cooler than Ambient
Normal returns are OFF and in floor returns are ON
Water Temp exiting the heads is 2-3 Degrees F warmer than the pool water
Even with Pump at 90% and Heat Pump on All Night, Losing 2 Degrees of Water Temperature
Doesn't make a difference if I run it in bO mode for OmniLogic or control the pump from its own panel, same result.
No Error Messages on Heat Pump
Condensation on tubing inside the heat pump.

Any help is appreciated. If I am expecting too much in the middle of the AZ winter you can tell me that too. I am new to in-ground pools, I understand the plumbing and the electrical side just fine but have never run a pool heat pump so don't really know what to expect.

Thanks in advance.
 
Welcome to TP.

I think your HP is doing all it can for you. You are seeing its limitations as the air gets colder.

A cover will make a big difference in retaining the heat you are generating.
 
10-12 on the discharge air is very good, so your unit is working great. As AJW said, the temp drop at night without a cover is most definitely what's losing your heat. At 77 you're losing as much energy as you're gaining.

A gas heater obviously has way more power and could raise this number, but you'd still be losing that energy and therefore losing money. Not to mention gas heater install cost. If you're not content, I'd be looking for an automatic pool cover solution long term. Short term, perhaps for now a budget solution would be to throw a solar cover on the water. Unless of course you'd rather keep that cash pocketed for the auto cover quote, lol.
 
Biskitz said:
10-12 on the discharge air is very good, so your unit is working great. As AJW said, the temp drop at night without a cover is most definitely what's losing your heat. At 77 you're losing as much energy as you're gaining.

A gas heater obviously has way more power and could raise this number, but you'd still be losing that energy and therefore losing money. Not to mention gas heater install cost. If you're not content, I'd be looking for an automatic pool cover solution long term. Short term, perhaps for now a budget solution would be to throw a solar cover on the water. Unless of course you'd rather keep that cash pocketed for the auto cover quote, lol.
Click to expand...
Solar cover is coming to see if it can help me over the cold nights. If not guess the pool
Season won’t include the winter for us! Thanks for your informative response!
 
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HEYYYYYY

we have very similar setups

I'm in Cali, and weather here has been 60s at best, and easily dipping in 40s overnight.

I too have about a 10K galloon pool and I too have a 120K BTU heat pump, although its an Aquacal

First of all I want to thank you for even conducting these tests because I dont even bother to turn my heat pump on because I'm aware of its limitations. Which you dont seem to lol. BUT at the same time, Im surprised by your results that you have been able to still get the pool temps up to 77 degrees despite the cold weather and the Heat pump limitations.

With that said, I can tell you what you havnt done which will help tremendously because I have done it. POOOOL COVER. Get one ASAP.

You wasted a lot of energy and losing the heat overnight. If you had a pool cover, yoou wouldnt have lost all that heat, and would no problem getting above 80 based on the results you are getting now without the cover.

My best personal WOW moment when I first got the heat pump was last year before spring. Everyone around here only gets solar roof heating. No one ever recommends heat pumps due to low humid area, and persuation by the pool builders to not run them etc. But I went against the grain. Anyways, it was 60s to to 70 at the highest ambient temp, with pool starting temp at 60. No sun, always overcast, and in fact even rained slightly. I always had a pool cover, so im good at working them and know a good technique that works for me. I personally seen its benefits the year prior without the heat pump. So on this occasion, I decided lets test the heat pump, I set it at 80-85, I covered the pool, and only ran the heat pump during the day. Once sun went down, turned off the pumps. Kept pool cover on of course, then started again the next day. I got the pool in the 80s in just the hours of the day from sun down to sunset in 2 days.

So definitely get a pool cover, it will help a lot with heat pump. Now your results are making me want to try and heat it now since I have the same setup WITH pool cover.
 
redturboeclipse said:
HEYYYYYY

we have very similar setups

I'm in Cali, and weather here has been 60s at best, and easily dipping in 40s overnight.

I too have about a 10K galloon pool and I too have a 120K BTU heat pump, although its an Aquacal

First of all I want to thank you for even conducting these tests because I dont even bother to turn my heat pump on because I'm aware of its limitations. Which you dont seem to lol. BUT at the same time, Im surprised by your results that you have been able to still get the pool temps up to 77 degrees despite the cold weather and the Heat pump limitations.

With that said, I can tell you what you havnt done which will help tremendously because I have done it. POOOOL COVER. Get one ASAP.

You wasted a lot of energy and losing the heat overnight. If you had a pool cover, yoou wouldnt have lost all that heat, and would no problem getting above 80 based on the results you are getting now without the cover.

My best personal WOW moment when I first got the heat pump was last year before spring. Everyone around here only gets solar roof heating. No one ever recommends heat pumps due to low humid area, and persuation by the pool builders to not run them etc. But I went against the grain. Anyways, it was 60s to to 70 at the highest ambient temp, with pool starting temp at 60. No sun, always overcast, and in fact even rained slightly. I always had a pool cover, so im good at working them and know a good technique that works for me. I personally seen its benefits the year prior without the heat pump. So on this occasion, I decided lets test the heat pump, I set it at 80-85, I covered the pool, and only ran the heat pump during the day. Once sun went down, turned off the pumps. Kept pool cover on of course, then started again the next day. I got the pool in the 80s in just the hours of the day from sun down to sunset in 2 days.

So definitely get a pool cover, it will help a lot with heat pump. Now your results are making me want to try and heat it now since I have the same setup WITH pool cover.
Click to expand...
Hey There,

Thanks for responding to my question, and yes I understand that a cover is a necessity if the insanity I started was even going to be possible which is why I stated it was on order :) That said, I got the cover, just an inexpensive 16mil solar cover cut to fit, bubble side down. Unfortunately now our nights here in Goodyear have dropped all the way down to around 29 Deg F which has not helped my experiment much at all. Here is what I know based on my costly experiment:

-When lows are in the mid 40's and highs in the mid 60's I am able to heat the pool to 77 without a cover.
-When lows are in the 20's and highs in the mid 50's its a useless battle because the heat pump is only efficient above 50 Deg F, even with a cover.
-I had stopped my experiment to save some $$$ and wait for the pool cover. so pool dropped to 55 degrees.
-Once cover arrived I was able to bump it from 55 to 65 in a single day, and the cover held the temp quite well, dropping only 1 degree overnight.
-As soon as the temps dropped into the upper 30's at night the Hayward Omni system turns on the variable pump and reports ON FREEZE PROTECTION! Unfortunately the freeze protection circulates all the 65 degree water from the pool through the cold pipes and it looses about 5 degrees overnight even with the cover in place.
Morale of the story. If temps are going to drop below 40 degrees at night, it is pointless to try to heat the pool at least the way mine is programmed at the moment with the Freeze Protection
-Anything over 40 at night and 55-65 in the day is adequate for heating and with a pool cover you should easily get to 80+ within a few days.


I am eager for some milder nights to finish my experiment. Sucks having a brand new pool just sitting there but I guess that is how the ball bounces.

Thanks for sharing your experience with the heat pump, I too have started to run the pump only during the hours where the ambient air is >50 Degrees which usually equates to 9:30-10:00am until just after sunset, but that has all been on hold due to the very cold nights. I recall my wife and I saying to the pool company we wanted to swim all year, and they cleverly stated that the heat pump would extend our swim season. I now understand what they meant by that statement. In a perfect world if you wanted to swim in the winter, it would make sense to have a gas heater to assist getting the pool to temperature then let the heat pump keep it there, or at least it sounds like a decent method to the madness. Thoughts?
 
collinsbj911 said:
Water Flow in Return Manifold is 45GPM
Click to expand...

collinsbj911 said:
Water Temp exiting the heads is 2-3 Degrees F warmer than the pool water
Click to expand...

collinsbj911 said:
10000 Gallon pool
Click to expand...

collinsbj911 said:
The Heat Pump is a 120KBTU
Click to expand...
45 gpm = 2,700 gph = 22,518 lb/hr.

3 degrees in temperature increase at 45 gpm = 67,554 btu/hr.

For a 10,000 gallon pool, the temperature rise should be about 0.81 degrees Fahrenheit per hour at 67,554 btu/hr.

Your heat pump should show the performance at different weather conditions.
 

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What are the dimensions of the pool?

What is the model number for the heat pump?

What is the surface area of the pool?

What is the wind speed?

How much water are you losing to evaporation?
 
If the pool is about 300 square feet and you are losing 67,554 btu/hr, then that is about 225 btu per square foot per hour.

Evaporation is the largest cause of heat loss and a cover will reduce evaporation by a significant amount.

As the water temperature increases, the loss rate also increases and the loss rate will eventually be equal to the gain rate and this will result in an equilibrium where the water reaches the maximum temperature possible at the gain rate.
 
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