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Thread: Pentair Master Temp 400 problems

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    Pentair Master Temp 400 problems

    Let me start for thanking everyone for any advice.

    I have a Pentair Master Temp 400. All our pool equipment was installed in 2008 by previous owners. Everything is pentair, control board, variable speed pump, chlorinator. The only thing I've had to replace is the chlorinator so far, but I'm getting there with the heater. What happens when I fire up the heater, after about ten seconds the pipes start to cavitate , the heater turns off and it sounds like there is a pile of rocks in the pipes. From what I've read, it's a problem (or results from past problems) with water chemistry and things gunked up in the unit. This would make sense since two summers ago I had to fire two separate pool guys for not showing up and/or letting chemistry get out of balance. Ever since that summer I've had problems with the heater.

    If I keep my PH levels on the very low side of the ideal range, I've had limited success with the heater...although it shuts on and off trying to get up to set temperature level and it still cavities, but sometimes it can get past that point and stay on. Our water is pretty "hard" where we live (Southern California) and I've noticed calcium flakes in our spa from time to time. Usually when the PH gets on the high side of the spectrum.

    I'm pretty handy with trouble shooting and repairs, but don't know exactly where to start and in which order to check things, etc. Again, any advice would be great.

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    Re: Pentair Master Temp 400 problems

    I suspect a broken bypass or thermal regulator based upon what you state it sounds like. The thermal regulator is behind a screw off cap between the in/out pipes in the heaters header. With the pump off, unscrew the cap and pull the regulator out. Note, if the regulator does not come out easily and feels like it hung up on something, then the bypass is broken and hanging in the way. If it comes out with no issues I'm sure you find it's all gunked up. Then use you fingers and stick them in the opening and feel up around towards the top middle and you should feel a round button like item, that's the bypass. If you feel it and it seems to be solid, then you are good with that. Just replace the thermal regulator.
    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,

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    Re: Pentair Master Temp 400 problems

    I took out the regulator. It seemed a little gummed up, but I've never seen one new so I'm not sure. I can't seem to get a photo small enough in some to attach, but there seems to be a rust color around main part of regulator. Spring is clean and looks fairly new.

    Is it possible to clean off the regulator? I gave it a quick brush with a toothbrush and got some red stuff off. Replaced and fired up the heater. It shook about a fraction as much as it did and shut off. Then fired up a second time, shaking a little, but this time has stayed on. Staying on now for ten minutes until it got to 92 degrees and won't go much more than that. I took regulator out a second time and red stuff was on back although not as much. Brushed it off a second time, but this time while I was doing this, water kept coming out of heater? Bypass?

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    Re: Pentair Master Temp 400 problems


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    Re: Pentair Master Temp 400 problems

    Put it in hot water (130 to 140 F) to see if it opens.

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    Re: Pentair Master Temp 400 problems

    Think back to when you removed the regulator. Did it mostly fall out for you? Or did you have to wiggle it around as if it was hung up on something inside? When your thermal reg has a problem, you won't usually get the banging you are experiencing. You would however if your by-pass had broken. Your regulator is sensitive to water chemistry. Yours (in the picture), should be replaced either way. That isnt a build up on it but more of an erosion. If you are still getting the banging after you replace the reg, I would suspect the by-pass, or the plumbing is reversed.

    Since it did function before, i would rule out the reversed plumbing.
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    Re: Pentair Master Temp 400 problems

    I stole this picture from the net. It shows you the location of the parts like the bypass #8. If you have to replace the bypass, you also need to replace #3 and #5. You can get both of them in a kit. Yes replace the thermal regulator. mastertemp_water.jpg
    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,

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    Re: Pentair Master Temp 400 problems

    From what I've been reading, Salt Water Pools and Pentair Master Temps have this problem with regulators frequently. I ordered one and will replace as soon as I get it. Oddly I had a service tech come out last year (5/15) and all he ended up doing was replacing the regulator. Amazing that I have to replace it less than a year later. Also amazing was how much that "repair" job cost, but that's another story.

    I'm hoping it's just the regulator since replacing the bypass is a little more extensive and I have yet to do anything that requires really opening up the unit. Like I said, I'm fairly good with repairs, but I'm not sure how extensive replacing all that would be.

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    Re: Pentair Master Temp 400 problems

    Has anyone replaced a bypass value on a master temp?

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    Re: Pentair Master Temp 400 problems

    I replace them regularly. What are you wanting to know?
    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,

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    Re: Pentair Master Temp 400 problems

    I found this old link: Mastertemp bypass valve

    Would you say this is accurate as far as a step by step guide? Anything you would add or discourage?

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    Re: Pentair Master Temp 400 problems

    Quote Originally Posted by Krisher View Post
    I found this old link: Mastertemp bypass valve

    Would you say this is accurate as far as a step by step guide? Anything you would add or discourage?
    Yup...
    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,

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    Re: Pentair Master Temp 400 problems

    Thanks to everyone for their advice, as soon as I get the bypass valve, I'll give it a try. Hopefully this resolves our heater problem. Otherwise I'll be adding to this thread.....

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    Re: Pentair Master Temp 400 problems

    Bypass valve was broken. The piece was stuck in a Jandy valve between heater and SWG. Replaced that and the Thermal Regulator. Heater works like a charm! Thanks everyone for their help. I love this website!

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