USING HEAT PUMP FOR FIRST TIME....

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kaseydog

kaseydog

Well-known member
Jul 1, 2022
78
philadelphia
Pool Size
18300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite Pro (T-15)
Hello....with temps dipping into the 50's some nights and having some people over this weekend, we are testing out the heat pump for the first time. I've got the Hayward Summit XL 140k. Roughly 18,400 gallon pool.

To determine how long it will take to heat up, am I correct to use this calculation:
80% btu/weight of pool multiplied by 8.3. So for me: 112,000/153,000 (roughly) = .73.
So I can expect about 3/4 of a degree an hour? Is that a good rough estimate?

I'm at 76 degrees now and would like to be about 85. So figure about 12 hours?

Is there anything else I need to know?
 
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Get all your heating done the day before because it isn’t going to do anything overnight with temps in the 50s
 
Also have an auto cover. So I am wondering how much of that heat it will hold over night if it gets down to 57....
 
Also, do I need my pump on high, while the heat is on? I have a variable speed that goes down to 50% at 2pm....
 
You'll need enough flow from the pump to keep the heat pump running. I have a 2-speed pool pump, and our heat pump doesn't start with the pump on low. Just shows a "Lo Flo" on the screen and does nothing. Your calculation on heat gain seems close.

Once the ambient air temp hits 55 degrees or so, your pump will run but make no heat. NADA. They're designed this way. Keeping the cover on all night will help a lot to preserve what it made during the day. As a side note, I'm trying to get my pool temp down to 60 degrees for closing. At night, you can see the steam billowing off the uncovered pool. Since Sunday, our overnight temps have been in the mid 50's, and I have gone from 85 degrees to 71 in less than a week. Just pointing out that you can lose a large amount of heat at night if the pool is left uncovered.

On a good note, my temp goes from 76 to 85 MUCH faster than it goes from 60 to 70. Sunlight helps a bunch, obviously. Do not remove that cover for any reason until nearly party time, if possible.

Good luck on both the pool temp and the weather for your event!
 

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revitup said:
It’s either on or off.
Click to expand...
It is a variable speed pump.

Also, it is on a schedule where from 2-8 it operates at 50%. The heater was on but wasn't running, I guess because it had already hit the appropriate temperature. Then the pool temperature must have dipped slightly because the heater cranked up again and, with it, the pump jumped up to 100%.
 
Why would the temperature drop a degree while the heat pump is on? I have it set to 90 (gonna get nowhere near there today) but was hoping to get it to at least 80. I just noticed it went down from 78 to 77....
 
kaseydog said:
Why would the temperature drop a degree while the heat pump is on? I have it set to 90 (gonna get nowhere near there today) but was hoping to get it to at least 80. I just noticed it went down from 78 to 77....
Click to expand...
Heat pumps do exactly what the name implies, they only move BTUs, they do not generate heat like a gas heater does, so as the outdoor air temperature drops the number of BTUs extracted from the air drops and fewer BTUs are available for the pool water. The 112000 BTU rating of your heat pump is probably at an air temperature of 80 degrees, and the outside air temperature drops you will no longer get 112000 BTU. Many people purchase a heat pump for their pool with visions of swimming into late fall or even early winter. In reality, heat pumps are capable of raising the pool water about 10 degrees above air temperature, and sometimes you can get a little more and sometimes you will get a little less.

I see that you are in the Philadelphia area, so your temperatures right now are 70s during the day and 40-50s at night. With those air temps, it will be difficult (not impossible) to maintain 80 degrees water temperature. It doesn't matter what you set the thermostat, the equipment is only capable of moving a limited number of BTUs, and as the air temperature drops, that limited number of BTUS will be reduced.
 
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kaseydog said:
Why would the temperature drop a degree while the heat pump is on? I have it set to 90 (gonna get nowhere near there today) but was hoping to get it to at least 80. I just noticed it went down from 78 to 77....
Click to expand...

Assuming it’s working correctly, all heaters and coolers have a dead band associated with their thermostats. Typically it’s around 2°F. If you set the temp to 80F then the heater will get to 80°F and shutoff. Then it will not come back on again until the water temp reaches 78°F. The purpose of the dead band is to keep an appliance from short-cycling which can be especially damaging to a compressor.
 
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