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Thread: New Heat Pump - How long to heat up

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    New Heat Pump - How long to heat up

    We recently installed a solarium 105,000 BTU heat pump that I purchased through poolheatpumps.com. The temps have not been great here in KS this week only in the low to mid 60's with on and off rain, not much wind. I have run my heat pump 24/7 since Friday morning and the water temp as of today (Sunday) is 74 degrees, which was about what it was yesterday as well. From what I have seen i should be able to get my pool up to the 80's even if my air temp is in the high 50's, but it does not seem to be getting even close. I do not have a cover on it yet - thought it would come Friday when the reel arrived. I would still think that I should be able to get that temp up higher in the daytime. Are we doing something wrong? Does anyone have a heat pump that could tell me how long it takes to heat the pool? BTW we have an 18 x 36 lagoon shape, sports pool (two sides are shallow, the middle about 6' deep) approx 180000 gallons of water.

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    JasonLion's Avatar
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    Re: New Heat Pump - How long to heat up

    Swimming pools need a tremendous amount of heat to warm up, several times as much heat as the average home. I have a 190,000 BTU gas heater on an 18x36 pool, probably just a little more water than yours, and it can take several days to warm the water by 10 degrees. In the middle of a warm sunny afternoon the water might gain a degree and hour, but in the middle of the night it is losing heat despite the heater running.

    Also, heat pump efficiency depends a great deal on the air temperature. Warmer air temperatures allow them to put more heat into the pool more easily. With the air around 50 degrees the heater isn't putting out it's full rated amount of heat.

    Using a cover will help a great deal. Even with the cover, expect the heater to take several days to get the water up to temperature.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Join Date
    Dec 2009
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    Re: New Heat Pump - How long to heat up

    If it has been cloudy and rainy, the heat pump will not heat the water with great efficiency. It will maintain, but not too much else. I've found with mine, if it's sunny, the HP will work when the temp is down to 54 or so. But, if it's raining, even if the air temp is 62-63, it wont do much more than maintain. Since I've owed my HP, rain seems to be the number one thing that will decrease the efficiency (besides air temp). The solor cover is a must as well. You will really notice a difference.

    Also, like Jason said, depending on the ambient temp, humidity, sunshine, etc, you will get a variable BTU output. This is one drawback in my mind to a HP as comparted to a gas heater. But, in most areas, the cost to run a HP far outweighs the negatives.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: New Heat Pump - How long to heat up

    Thank you for your responses. I believe my cover should be here today. In order to get the pool up to about 85 degrees, I guess I am not sure if I should run the pool pump and heat pump 24/7 or just run it during what would have been normal pump hours (for us would be 7 a.m. until 10 or 11 pm) or run it 24/7 until it is up to temp but then only during normal pump hours to maintain temp?

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    Re: New Heat Pump - How long to heat up

    The cover will greatly reduce heat loss at night.

    Basic math plus modifiers apply here - the basic math goes like this

    Water = 8.34lb per gallon. 1 BTU heats 1 pound 1 degree.
    You have around 150K pounds of water to heat up and let say your heater is 80% efficient. (a good average)

    Thats about 84K an hour delivered to the water- or a little better than 1/2 degree of rise per hour.
    Extrapolate from there. Modifiers would be ambient temps and wind cooling the pool making standing loss greater.
    Id run it 24/7 to get there if you are in the mid 60's. or around 40 hours of constant heating with no other losses.
    Id guess with losses you're talking about 3-4 days.

    You arent doing anything wrong- you just arent putting a tremendous amount of BTU into the water.


    Uncle Dave
    20K Gallon Gunnite pool/900 Gallon in ground Spa/2HP WhisperflowSpa
    Pentair Master temp 400/Hayward Sand Zebrite/Jandy RS-8 Aqualink/Jandy 2HP Epump
    12 - 4x10 Solar Panels/Barracuda G3/ BBB

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    Re: New Heat Pump - How long to heat up

    Wow Uncle Dave - good thing you get the math because math was never really my strong suit . Thanks for the insight. I will just keep plucking away and hope that my cover shows up sometime. Unfortunately it didn't show up today.

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    Re: New Heat Pump - How long to heat up

    Quote Originally Posted by jel3412
    Wow Uncle Dave - good thing you get the math because math was never really my strong suit . Thanks for the insight. I will just keep plucking away and hope that my cover shows up sometime. Unfortunately it didn't show up today.

    Happy to help!

    A cold pool is a basically an unused pool (my personal experience from a lifetime of pool ownership) you are wise to heat it.

    So hows it going?
    Where you at temp wise?


    U.D.
    20K Gallon Gunnite pool/900 Gallon in ground Spa/2HP WhisperflowSpa
    Pentair Master temp 400/Hayward Sand Zebrite/Jandy RS-8 Aqualink/Jandy 2HP Epump
    12 - 4x10 Solar Panels/Barracuda G3/ BBB

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