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Thread: Max-E-Therm vs MasterTemp : Which to buy?

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    Join Date
    Sep 2008
    The Woodlands, Texas, USA

    Max-E-Therm vs MasterTemp : Which to buy?

    It's time for a new pool heater. Replacing my NG LAARS with a new NG fits my application the best.

    I do plan to purchase the model with the cupro-nickel heat exchanger.

    My understanding is the Pentair Mastertemp and Stay-Rite Max-E-Therm are the same heater except for the outer case.

    Any advantages/disadvantages to the round black case vs. the rectangular beige case?
    Perhaps one is insulated more than another??..... Maybe it doesn't matter.

    Also, page 4 of the Max-E-Therm owners manual states something like, "running this heater continuously with water colder than 68 degrees may cause condensation which could damage the heater and void the warranty." I called Pentair and asked what this meant. They provided no additional meaningful information. Sounds like one of those ways to wiggle out of honoring a warranty. Anyone know what this means? Anyone experience "condensation damage?" The efficiency is only 84% so this should be a non-condensing vent with vent gases exiting the heater much hotter than 212 degrees F. Practically in the winter my pool water is 55-60 degrees. Occasionally during the winter I heat the pool for a long weekend. Guess we will have some condensation and have to deal with it. In reality condensation is more related to temperature, humidity, and due point, so their warning is very general at best. My problem with the statement, is its generality. I don't know what problem I am to avoid or how to monitor for said problem, etc.

    As always, any help is appreciated.


    IG 24k plaster with overflow spa. Goldline PS-8 SWG. Tristar 0.75 HP filter pump, Polaris 280, large cartridge filter, 400k BTU NG Max-E-Therm HD, SR Smith Turbo Twister, Life Saver pool fence, ORP managed.

  2. Back To Top    #2
    XsAllOverIt's Avatar
    Join Date
    Dec 2010
    Mount Airy, Maryland

    Re: Max-E-Therm vs MasterTemp : Which to buy?

    Concerning the 68 degrees, if you are heating your pool or hot tub, you'll keep the temp at 70 degrees or higher at all times, so it really isn't an issue. When you're not heating it's not on. I've got a Max-E-therm and run my hot tub full-time during the winter and keep it at 70 degrees in pool mode and 100 or better in spa mode. When I want to go in the hot tub, I switch it from pool mode to hot tub mode. I believe that's what they would be referring to if I had set the full-time run position less than 68 degrees. If you're heating the pool for a long weekend, it won't ever be running less than 68 degrees either. So I believe what they are referring to is keeping the cut-off at 68 degrees - NOT going through the 68 degree threshold. It costs no more than $60/month to run at 70 degrees all winter so no worries there. I like my Max-E-therm. I would think if you're keeping it in the elements, the black would look better, otherwise I'm not sure. Mine has been running for 2 years with no issues.
    18 x 36 Inground Gunnite, White Plaster 21K gallon
    18" raised spa, 8' Diameter (620 gallon)
    Triton II Sand filter, Intellichlor IC40 SWG
    Pentair Pump, Max-E-Therm 400 BTU
    Lamotte ColorQ PRO 7-Plus test kit
    TFT-100 test kit

  3. Back To Top    #3
    mputegnat's Avatar
    Join Date
    Apr 2017
    Bee Cave, TX

    Re: Max-E-Therm vs MasterTemp : Which to buy?

    What did you end up going with? How has it worked out?
    Commercial General Contractor with high expectations. Central Texas, 13K Gal, in-ground, Pebble type finish, 500 Gal spa with spill over, irregular shape, Purex Triton MiniMax Plus 400 BTU Heater, Jandy pump (not sure model). Use pretty much only liquid chlorine, muriatic acid, occasional pellets to add CYA.

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