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Thread: Heat Pump Size Help -

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    Join Date
    Jul 2011
    Location
    Northern KY
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    38

    Heat Pump Size Help -

    Hello TFP'ers!
    After doing tons of research, have decided on one of the Rheem heat pumps to heat my 25k gallon salt water pool. I'm trying to decide between the Rheem 6350ti and the 8350ti. The BTU difference on the two heater at 80,80,80 is 16,000 btu (133,000 vs 117,000). All of the reading that I've done says to size your heater to your pool, then buy one size bigger.

    However running the numbers, to heat my pool 20 degrees, it will take the 6350 36 hours, whereas it will take the 8350 32 hours. If that is correct, I'm not sure I can justify the extra $500 on the 8350 because if I'm waiting 30+ hours to heat up, another 4 isn't going to matter.

    Am I missing anything here? I'd prefer to stay away from any gas vs heat pump debates as I'm not considering gas for many reasons.
    Thanks in advance!
    -Bryan
    _________________________________________
    18x40 oval 25,000 Gallon In-Ground SWG Pool
    Pentair IntelliFlo VS+SVRS pump
    Sand Filter
    Rheem 8350ti Heat Pump

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    JasonLion's Avatar
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    May 2007
    Location
    Silver Spring, MD
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    37,879

    Re: Heat Pump Size Help -

    My attitude is get the largest unit you can afford and have electricity for. Heat pumps heat slowly, and any time savings over just about forever are going to be noticeable.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. Back To Top    #3

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    Jul 2011
    Location
    Northern KY
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    Re: Heat Pump Size Help -

    Quote Originally Posted by JasonLion View Post
    My attitude is get the largest unit you can afford and have electricity for. Heat pumps heat slowly, and any time savings over just about forever are going to be noticeable.
    Thanks for your input Jason!
    _________________________________________
    18x40 oval 25,000 Gallon In-Ground SWG Pool
    Pentair IntelliFlo VS+SVRS pump
    Sand Filter
    Rheem 8350ti Heat Pump

  4. Back To Top    #4

    Join Date
    Jul 2011
    Location
    Northern KY
    Posts
    38

    Re: Heat Pump Size Help -

    Anyone else have any thoughts on this?
    _________________________________________
    18x40 oval 25,000 Gallon In-Ground SWG Pool
    Pentair IntelliFlo VS+SVRS pump
    Sand Filter
    Rheem 8350ti Heat Pump

  5. Back To Top    #5

    In the Industry

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    Nov 2011
    Location
    Moberly,MO
    Posts
    978

    Re: Heat Pump Size Help -

    Without covering your pool a heat pump may not keep up with the heartless at night. What I would recommend is the largest heat pump and hope it will do it. Gas is the sure option but I know that isn't always a choice.
    Over 30 years in the pool business
    We build vinyl, fiberglass, stainless steel pools
    Certified in Hydraulics

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    ps0303's Avatar
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    Jul 2011
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    FL
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    Re: Heat Pump Size Help -

    I see you are on Northern Kentucky, when will you be trying to heat the pool? It's always best to use a solar cover to keep your heat money in the pool. Plus if it gets cooler at night when heating it, you won't lose as much of the heat in the night time hours. Also don't forget to add in your cost for the electrical work if you haven't already. No matter which unit you will still need a dedicated 240V supply.
    Paul
    http://www.gastekservices.com A word of caution: When working with gas and electrical you might want to consider a licensed contractor. Consider the value of your life and others around you. If you would like to provide a review of the help I provided, please use the following link to leave a review. gastek - Google Search,

  7. Back To Top    #7

    Join Date
    Jul 2011
    Location
    Northern KY
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    38

    Re: Heat Pump Size Help -

    Thanks for your replies swimpcmp and ps0303. It seems that in NKY most people around here run heat pumps (at least on newer pools). Several of my neighbors have heat pumps and they've never had problems keeping their pools in the mid-80's all season (May 1 - Sept 30). My one neighbor opens even earlier and closes later. Another neighbor that I talk to a lot has a 130btu and it has never had issues. Hence my question, is there really much difference between a 117 and a 133 btu pump? My pool temps drop around 10 degrees at night, so I think I might go for the bigger heat pump. And most importantly, I'll be looking at a thermal blanket of some sort to keep in that heat.

    And I'll be running the electric ps0303, so no costs there other than a breaker and some wire. I think everyone has sold me on the bigger unit, what's an extra $500 right?! Thanks for the advice, I really appreciate it!
    Happy swimming!
    -Bryan

    [EDIT] I imagine that I will simply set the heatpump for 83 and let it run all the time. Most of the mid-summer months the pool will be above 83 so it won't run. This would mainly run all the time in May, beginning June and September.
    _________________________________________
    18x40 oval 25,000 Gallon In-Ground SWG Pool
    Pentair IntelliFlo VS+SVRS pump
    Sand Filter
    Rheem 8350ti Heat Pump

  8. Back To Top    #8

    Re: Heat Pump Size Help -

    I agree with using the larger heat pump. I think that it will give better overall performance.

  9. Back To Top    #9

    In the Industry

    Join Date
    Nov 2011
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    Moberly,MO
    Posts
    978

    Re: Heat Pump Size Help -

    Keep in mind when ambient air temps reach a certain point a heat pump is not able to extract heat and heat the pool. I have a customer that opens mid march usually and doesn't get any heat into the pool until early April usually
    Over 30 years in the pool business
    We build vinyl, fiberglass, stainless steel pools
    Certified in Hydraulics

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