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Thread: Minimum temperature to run pool heater?

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    Minimum temperature to run pool heater?

    Hello,
    Newbie to pools here...I have a pool with a purex triton 250 heater. Currently in Houston the pool water temp. has been averaging about 55-58 degrees.

    Is this too cold to run the heater and expect it to get up to 80 degrees or so, in the spa part of the pool? Was wondering if there was a min. temperature, and if not how long should I expect it to take to heat the water to this temperature. Its a small 3 person spa, and I had heard of rough estimates of water temp increasing 10 degrees per hour.

    One other question on pump setup - if I wish to only heat the spa and not the pool, how should the pump levers be set? eg the intake and return switches.

    The Triton 250 seems to have a dual on-off-on switch so I am not sure which "on" position it should be in, to heat only the spa, if that is possible.

    Thanks in advance and sorry if these questions are confusing!
    Aaron
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    JasonLion's Avatar
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    Re: Minimum temperature to run pool heater?

    As long as you are only heating the spa the heater should be fine and able to get things up to temperature without trouble. It should continue working down into the high 30s. I would expect quite a bit better than 10 degrees per hour at the start, slowing down a bit as the water gets warmer (and heat loss to the environment gets higher).

    How you set the valves depends on how your plumbing is done. Every pool is different. If you post pictures of everything we can probably figure it out for you, or there might be labels of some kind. The key is to adjust things so all water flow is from and to the spa, with nothing going to/from the pool.

    The two positions on the heater switch are the same except for which temperature setting they use. There should be two temperature settings, one used in each position. They assume that you will set one of them to the desired pool temperature, and the other to the desired spa temperature and that they are used that way. Since you can adjust either temperature to whatever you want, it doesn't really make any different which one you use.
    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

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    mitch08's Avatar
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    Re: Minimum temperature to run pool heater?

    I get about 1 degree per minute when heating my spa.

    Heating the pool under those conditions is a completely different story.

    As Jason said above. As long as you are pulling all water from the spa and returning all water to the spa, you can only be heating the spa and I think you will get great results.

    I wish I could do it but my pools closed and sitting under 2ft of snow in NY
    18x38 Inground Liner (25k gal) Paver surround, multi-speed pump, DE Filter, Raised spill over spa, TF-100

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    Re: Minimum temperature to run pool heater?

    Hello,
    I have posted some pictures of my setup - perhaps you can tell me which way to set the switches for suction, return. There are two switches which will not move. I really appreciate your help!

    Thanks, Aaron[attachment=0:3ljs9ldq]pool suction.JPG[/attachment:3ljs9ldq][attachment=1:3ljs9ldq]return.JPG[/attachment:3ljs9ldq][attachment=2:3ljs9ldq]spa suction.JPG[/attachment:3ljs9ldq]
    Attached Images Attached Images
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    Re: Minimum temperature to run pool heater?

    Picture of my heater, I am not sure if I understood the reply. It doesnt matter which 'on' switch you select (up or down), as long as I set the spa temp to hi and the pool temp to lo?

    (This is for my question about how to heat only the spa).
    Thanks, Aaron[attachment=0:yggvgr6b]heater.JPG[/attachment:yggvgr6b]
    Attached Images Attached Images
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    Re: Minimum temperature to run pool heater?

    Picture of spa, for reference.
    Thanks, Aaron
    Attached Images Attached Images
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    Re: Minimum temperature to run pool heater?

    Thanks for the advice,
    I found my problem, I was not moving the "return" lever to set it on only the spa. That one seems to only be moveable while the pump is off, the others I can switch back and forth while the pump is running.
    So I guess I was heating the pool *and* the spa!
    Once I did that the temp got up to 72 degrees, then stopped. The heater had turned off. The dials were set for pool temp COLD all the way, spa temp HOT all the way. I had turned the heater onto the bottom 'on' position.

    I then turned the pool temp up to HOT, so both knobs were HOT. And then turned the on switch onto the upper 'on' switch.
    Then the temp went up to 102 at which point I stopped!

    So I am not sure if it is the upper switch that did it, or both dials. I am thinking both dials need to be set, since if I have the suction, return, etc all set to spa, no heat will be going to the pool. Does this sound right?

    Thanks again, Aaron
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    Richard320's Avatar
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    Re: Minimum temperature to run pool heater?

    Quote Originally Posted by AB
    Thanks for the advice,
    I found my problem, I was not moving the "return" lever to set it on only the spa. That one seems to only be moveable while the pump is off, the others I can switch back and forth while the pump is running.
    So I guess I was heating the pool *and* the spa!
    Once I did that the temp got up to 72 degrees, then stopped. The heater had turned off. The dials were set for pool temp COLD all the way, spa temp HOT all the way. I had turned the heater onto the bottom 'on' position.

    I then turned the pool temp up to HOT, so both knobs were HOT. And then turned the on switch onto the upper 'on' switch.
    Then the temp went up to 102 at which point I stopped!

    So I am not sure if it is the upper switch that did it, or both dials. I am thinking both dials need to be set, since if I have the suction, return, etc all set to spa, no heat will be going to the pool. Does this sound right?

    Thanks again, Aaron
    Actually, the heater doesn't know whether you're heating the pool or the spa; the valves don't talk to it. My setup is very similar to yours. I manually set the valves to spa in and spa out, and use the heater control on my heater. The spa one doesn't seem to do anything. There are some threaded holes on my heater that are blocked off. I'm guessing there is some way to have two different heat exchangers working, in which case, two different settings would be needed.

    When the water is cold like it is now - about 56 - it heats up almost 1 degree/minute until about 70, then seems to slow down. I lose less heat by blocking the air intake on the spa jets. I learned the name of the setup last year, but forgot. Something loop. I just hold a plastic lid from a yogurt tub against the air inlet and let the vacuum hold it there. No cold air gets into the spa that way. The more aeration, the faster it cools, and the more the heater runs.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Re: Minimum temperature to run pool heater?

    Richard, that is an interesting idea!

    Is it called a Hartford loop?

    I have 1 more switch on my pool equipment - titled 'air blower'. When I turn it on it just makes a lot of bubbles in the spa. Is it needed for heating, or just an effect kind of like jets in a hot tub?

    Thanks again for explaining the non-working switch on the heater! I will stick to the pool temp switch from now on!
    Aaron
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    Richard320's Avatar
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    Re: Minimum temperature to run pool heater?

    Quote Originally Posted by AB
    Richard, that is an interesting idea!

    Is it called a Hartford loop?

    I have 1 more switch on my pool equipment - titled 'air blower'. When I turn it on it just makes a lot of bubbles in the spa. Is it needed for heating, or just an effect kind of like jets in a hot tub?

    Thanks again for explaining the non-working switch on the heater! I will stick to the pool temp switch from now on!
    Aaron
    I've got one of those blowers, too. I think it's for aesthetics....If you have lots of bubbles everywhere, no one can see what's below the water line, and a lot of women appreciate that.

    I've noticed that fine silt settles in those air holes, so when you do turn on the blower, the water clouds up. So I run it occassionally just to get that stuff in circulation so the filter can grab it. It also works real good to aerate the water when you're trying to lower TA
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Minimum temperature to run pool heater?

    From the pics it doesnt appear that you have two heat exchangers. So I'm guessing that the switch just chooses which thermostat setting to use as previously suggested.

    It sounds to me that when the switch was down it used the pool temp setting which you said was set to cold. When you put the switch up it used the spa setting and went hot since the spa control was set to hot.

    I suggest you play around with it some more: switch dow, both dials set to cold to set a baseline then try pool hot and see what happens. Next night switch down and pool cold and spa hot. Then repeat with the switch up. You'll know for sure that way.
    15,600 Gallon, 16' x 32' In-Ground Vinyl Pool
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    mitch08's Avatar
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    Re: Minimum temperature to run pool heater?

    I have almost the exact same setup. And I also have the exact same heater. The spa temp dial doesnt do anything for me. There is nothing hooked up to it.
    The determination of whether you are heating the spa or the pool will be controlled by where you are returning the hot water to.

    The biggest issue you are going to have with that heater is keeping a consistant temperature in your spa. Unlike the pool which you can just set to hi and forget until you reach the desired temp, the spa temp is always changing. And 1 or 2 degrees makes a huge difference. 102 might be too cool but 105 might boil you.
    That is almost impossible to control without a digital thermostat.

    My pool guy is a genius. He took a digital refrigerator thermostat that goes very high and very low and hooked it up into the heater.
    The thermometer is on a wire that goes directily into the plumbing. It is very accurate and allows me to set the spa at a specific temp.
    It will hold the temperature of the spa within 1 degree.

    It completely transformed the experience we are able to have at the spa. I use it for the pool temp also but it isnt nearly as important for that.
    I highly suggest you look into doing this so you can keep the spa an accurate temp.
    18x38 Inground Liner (25k gal) Paver surround, multi-speed pump, DE Filter, Raised spill over spa, TF-100

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    Re: Minimum temperature to run pool heater?

    That is a great idea about the digital temp. What is the ballpark $ for hooking up a setup like that? I will ask my guy if he can do the same.
    I also noticed, that once the temp is at 105 degrees or something too high, it wont come down easily! Even with the heater off it stays that hot for 15 min or so. I was surprised because I thought it would instantly cool down.
    Thanks, Aaron
    15'x30' 10K gal, in-ground, cartridge filter, waterfall, spa, The Pool Cleaner, Purex Triton 250 heater, pool built ~1999.

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    mitch08's Avatar
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    Re: Minimum temperature to run pool heater?

    Yup they will stay hot for a while. If you need to call it down, mix in some pool water with your valves

    The device itself is pretty cheap. Probably about $60. I had to replace it one time over the last 3 years or so.
    The initial job was done by my pool guy but once done I was able to follow what he did and replace it. Pretty simple.

    I paid him about $300 for the total setup with the device.
    If you want I will get you the model number and device name.
    18x38 Inground Liner (25k gal) Paver surround, multi-speed pump, DE Filter, Raised spill over spa, TF-100

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