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Thread: Hot Tub Won't Heat Above 93!

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    Hot Tub Won't Heat Above 93!

    Hello all! Basically this is my deal:
    I have a ThermoSpa Avalon from I think 2005. Has Balboa spa pack. Last week I got in and it was 104. Ahhhh the evening went on I started feeling a little cold which I thought was strange because usually the beer keeps me warm! I looked at the temp - 93! Wouldn't go back up...I thought, eh whatever and got out. A few days later it was at 104. I got in. About and hour later is was down to 93 again. I pulled the disconnect and let it sit for a day. Next day I plugged it back in and it DID heat the water up, but ONLY to 93. Not going above 93. Never had that happen before. My question is, I don't know what part failed. To my understanding it wouldn't be the heater because the heater either works, or doesn't work - right? It's heating the water from the outside temp to 93 so it must be working. The only other real component I can easily see is my pressure switch which I was gonna try to bypass but I really don't think that would be the issue either. I'm wondering if it's the high/low limit switch/sensor, but I don't know where that it is on mine. I could attach pics but I don't see where I can do that, at least from my phone...Any help would be greatly appreciated!

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    Mod Squad jblizzle's Avatar
    Join Date
    May 2010
    Tucson, AZ

    Re: Hot Tub Won't Heat Above 93!

    Welcome to TFP!!!

    While maybe not related, how is your spa powered? We have a spa that is only on 115V power and as such, the heater will NOT run if the jets are running. So, it will slowly get up to temperature, but then as you use it with the jets, the temp will drop because the heater is not on. When done, the heater will kick back on to warm it back up. This was my first thought, until I got to the end of your post which says that is seems to not even be heating back up which could be a different issue.
    Jason, TFP Moderator
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    Isaac-1's Avatar
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    May 2010
    SW Louisiana

    Re: Hot Tub Won't Heat Above 93!

    My guess is it is most likely a bad temperature sensor or bad heater safety switch. Depending on the model of heater the heater safety switch may be built in or not, it also may auto reset on power cycle so a momentary power outage could explain why it was cold, then hot then cold again.
    Indoor 20x40 35,000 gallon vinyl pool with 1.5 HP 2 speed Jandy FloPro pump, Hayward EC75 Perflex DE filter, 11 4x12 Techno-Solis solar panels w/ Aquasolar controller, Aquabot Turbo T Robot Cleaner. Also LMI metering chlorine dispenser pump and HotSpring Jetsetter
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    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Hot Tub Won't Heat Above 93!

    My bet is that the high temp cutout is the culprit. When they start failing they can open at lower and lower temps until they no longer work.
    Dave J. TFP Moderator
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