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Thread: Pentair MasterTemp 400 heaters shutting down with no error c

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    Pentair MasterTemp 400 heaters shutting down with no error c

    We have two MasterTemp 400 heaters heating an indoor junior Olympic sized pool. The pool was resurfaced in September of 2013 and since that time we have had problem after problem with our heaters - one of which I have since replaced. One of my heaters is 2 years old and the other I purchased in October of 2013. The trouble we are having is that the heaters won't run consistently. They shut off at different times of the day and night. The service heater light comes on but there is never an error code. One heater may keep running and the other shuts off. We have had all the plumbing redone and installed flow meters so we can monitor flow. We thought this repipe job would fix the problem but the heaters still continue to shut off. We had new gas lines ran with regulators for each heater but this has not fixed the problem either. We have had ignitors replaced, thermal regulators replaced, heat sensors replaced. We are at a loss. Anyone have any ideas? HELP!
    16' x 40' inground fiberglass saltwater pool

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    Mod Squad Bama Rambler's Avatar
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    Re: Pentair MasterTemp 400 heaters shutting down with no err

    Welcome to TFP.

    Without some sort of error code or some indication of why they're shutting down it's going to be really hard to figure out what's going on.

    According to the manual there's a set of LED's on the back of the board that tell you why it shut down. Can you tell us which LED's are lit or if they're blinking?
    Dave J. TFP Moderator
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    Re: Pentair MasterTemp 400 heaters shutting down with no err

    The Master Temp doesn't always show codes for failures. There are LEDs on the back of the circuit board (behind the thermostats) that light up for some of the errors.

    Have you contacted Pentair? They have a great network of field service technicians (employees) that will come out to your location and run diagnostics. Where are you located?

    Steve
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    Re: Pentair MasterTemp 400 heaters shutting down with no err

    The only LED that is lit is the "Service Heater" light. None of the other lights under the panel light up. I should also mention that with both heaters, after we get a Service Heater light we turn off the unit, turn it back on and the service heater light comes on for a second and then you hear the heater start up then the service heater light goes off. Right now, my older heater will run for about 15 to 20 minutes before it shuts off with the service heater light. The newer heater will run sometimes all day and most of the night before it shuts off. We have called Pentair and they are advising us to put a manometer on the heaters to check out the gas flow. Waiting on a pool repair guy to do that.
    16' x 40' inground fiberglass saltwater pool

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    Re: Pentair MasterTemp 400 heaters shutting down with no err

    When the pool was resurfaced, where the heaters disconnected until the water was balanced? It's possible that maybe the heat exchanger is gunked up if the units were still inline when the pool was resurfaced. I have seen companies that don't remove the units and then when they add water the residuals from the resurfacing gets in them and clogs up the heat exchanger. Sometimes it not real bad and doesn't cause the unit to knock and bang from over heating. You can also remove the header and see the copper tubes to see if they are coated at the ends with pool finishing junk. If they are, then you might have your answer.

    The clue is that the pool was resurfaced and then after that they started to now work correctly. Also, it is very rare that a heater would require an adjustment on the gas valve of the unit. If the valve was bad or bad flow, you wouldn't get it to light or it would go out rather quickly when it ignited.
    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 MasterTemp 400 heaters shutting down with no err

    I have a similar issue occurring with one of our Max e therm 400 btu heaters. It began when we added a second heater on to an existing gas line that originally had just one heater installed on it. New gas regulator valves were installed when it was plumbed in. Both heaters will run for fine for some unknown time frame before we discover the same service heater error the next day. My guess is that we need to upgrade our gas line to accommodate two heaters. I'm sure a monometer would help diagnose this problem but haven't gone there yet.
    In ground 25,000 gallon - vinyl liner - Sand filter - residential pool
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    Re: Pentair MasterTemp 400 heaters shutting down with no err

    Quote Originally Posted by Zadd
    I have a similar issue occurring with one of our Max e therm 400 btu heaters. It began when we added a second heater on to an existing gas line that originally had just one heater installed on it. New gas regulator valves were installed when it was plumbed in. Both heaters will run for fine for some unknown time frame before we discover the same service heater error the next day. My guess is that we need to upgrade our gas line to accommodate two heaters. I'm sure a monometer would help diagnose this problem but haven't gone there yet.
    The problem you might face is that the problem doesn't occur right away or is predictable. You would have to put the manometer on it and monitor is constantly to see if there is any fluctuation. Your gas provider should be able to look at the heaters requirements and provide you with the correct size of line needed to feed both units. You wouldn't need a manometer to determine this. I suggest you get your gas provider involved to make sure you have the correct size line feeding your units.
    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 MasterTemp 400 heaters shutting down with no error c

    Sorry to open this old thread. But I have a Pentair master temp 400 that is doing the same thing. It will run for hours. When the pool temp reaches the desired level it shuts off. When it needs to turn back on it will call for heat but doesn't light and instead throws a service light. It tries to call for heat 3 times and I know this because it makes a loud metallic sound when doing so. It doesn't make that noise on the first initial light, it just fires right up. I turn it off for a few minutes and it works again. Did anyone ever figure out the issue or a resolution?

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    Re: Pentair MasterTemp 400 heaters shutting down with no error c

    Quote Originally Posted by jmill012 View Post
    Sorry to open this old thread. But I have a Pentair master temp 400 that is doing the same thing. It will run for hours. When the pool temp reaches the desired level it shuts off. When it needs to turn back on it will call for heat but doesn't light and instead throws a service light. It tries to call for heat 3 times and I know this because it makes a loud metallic sound when doing so. It doesn't make that noise on the first initial light, it just fires right up. I turn it off for a few minutes and it works again. Did anyone ever figure out the issue or a resolution?
    I would first suggest this be a new thread on it own as your issue might not be anything close to this old thread.

    You need to remove the top of the unit and flip it over to see what if any other LEDs are lit when the unit goes into service mode. Also, is it the "Service Heater" LED or the "Service System" LED?
    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 MasterTemp 400 heaters shutting down with no error c

    A lot of the time it turns out to be a stack/ flue sensor even though it doesn't show a code for it!

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