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Thread: Raypak - High 2 limit fault - checked unitherm governor, now what?

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    Raypak - High 2 limit fault - checked unitherm governor, now what?

    Over the weekend I was getting a high limit 2 fault after the heater was running for maybe a couple of hours. It was not a particularly hot day and water flow was about as strong as it gets (no blockages and freshly cleaned filter). After the first fault, I left the heater off for about 30 min with the pump running, then turned it back on. It fired up fine, ran for a few hours and then I got another high limit 2 fault.


    So, after some researching I decided to pull the unitherm governor and inspect. It had some cottonwood on it, but not so much that would seem to interfere with its operation. I cleaned it off, took it in the house and put it in some hot water and it appeared to be operating correctly in that it was opening/closing with the temp changes. The gasket for the governor was pretty mangled however - could this be the source of my problems? Maybe it is letting in some outside temperatures that are causing the fault?

    Any suggestions on next steps or is it best to replace the gasket and see if that solves things? (Open to suggestions on where to get the gasket as well.)


    Thanks,
    Paul
    Dedicated TFPer since 2012 with recommended test kit
    AGP, 30 foot, 21,000 gallons with these homemade islands
    Hayward 150 sq foot cartridge filter, 1HP Waterway pump
    Raypak 400K BTU NG Heater! (Model 406a - installed 2015)
    Pool installed in 2006? (just a guess, pool came with house I purchased in June 2012)

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Giving this a bump in hopes that heating guru Paul (ps0303) sees it. One other item of note - as I've been searching for the gasket for the unitherm governor (no luck finding the gasket alone so far) I am seeing these images, which include that large spring. I did not have the large spring when I pulled the cap and governor out??? (Part # is 062234B)
    Attached Images Attached Images
    Dedicated TFPer since 2012 with recommended test kit
    AGP, 30 foot, 21,000 gallons with these homemade islands
    Hayward 150 sq foot cartridge filter, 1HP Waterway pump
    Raypak 400K BTU NG Heater! (Model 406a - installed 2015)
    Pool installed in 2006? (just a guess, pool came with house I purchased in June 2012)

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Depending on the environment the heater is in, you could be having some venting issues, even if it is outside. Low gas pressure can cause sooting that would keep the heater from venting properly, and in time, overheat. Removing the pagoda and or the stackless top will reveal any leaves/debris that may have collected on or around the top of the exchanger causing the over temp issue. You would have to disassemble the heater to check for sooting (underside of the exchanger), unless you have a mirror and are comfortable working around the burner tray while it is firing. This is the point where you may want to call a tech.

    If it is inside, make sure that the room has adequate venting (vents cut into the walls) to the outside. Failure due to inadequate venting is something that would not happen overnight or may not present even after 1 season, but over a long period of time, depending on how severe the lack of venting is. Raypaks are extremely forgiving when it comes to failing for this reason. So much that, in some cases the heater will run to a point where the damage is irrecoverable by the time the heater "wont run". This is not to say that the heater will have a catastrophic event and burn the place down, but quite the opposite. It will just quit one day, and not want to run again, and replacement will be more cost effective than a repair.

    A Hi Limit that is operating properly will: Detect high heat, open, shutting the heater down, cool, close, and heater should try to relight. If it is shutting down and not relighting after a few moments, then there may be a problem with the hi limit itself hanging open. Raypak Hi Limits are, for the most part are fairly robust, and don't fail that often.
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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    If you want to replace the unitherm governor, get part 006719F.

    Yes as Pool Clown said, the limits on the Raypak's are pretty robust.
    Paul
    Gastek Pool & Gas Services If you would like to provide a review of the help I provided, please use the following link to leave a review. Gastek Google review,
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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Thanks guys, I appreciate the thoughtful insight.

    Pool Clown - Heater is outside. I did remove the top and pretty thoroughly vacuumed all the leaves and other debris that had collected over the winter when I opened a few weeks ago so I think I am ok there, though I did note some rust.

    I would not attempt to inspect for sooting as you describe, that would be time to call a tech for me.

    This comment however did catch my eye

    Quote Originally Posted by Pool Clown View Post
    A Hi Limit that is operating properly will: Detect high heat, open, shutting the heater down, cool, close, and heater should try to relight. If it is shutting down and not relighting after a few moments, then there may be a problem with the hi limit itself hanging open. Raypak Hi Limits are, for the most part are fairly robust, and don't fail that often.
    My heater has never tried to relight after a high limit fault. I have always had to turn the mode to off and then back to heat pool and then it fires right up.


    Does this in your eyes make the hi limit the prime suspect?

    Again the unitherm governor seemed to be operating properly in that it would fully open and close when exposed to changing temperatures - any thoughts as to whether the mangled gasket could be hindering its proper operation?


    Paul - thank you for the proper part number.
    Dedicated TFPer since 2012 with recommended test kit
    AGP, 30 foot, 21,000 gallons with these homemade islands
    Hayward 150 sq foot cartridge filter, 1HP Waterway pump
    Raypak 400K BTU NG Heater! (Model 406a - installed 2015)
    Pool installed in 2006? (just a guess, pool came with house I purchased in June 2012)

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    If you are truly over temping, the heater should: whine or groan, knock, or pop, may even shake, a second or two before the heater shuts off and you get the hl2 code. If this is the case, look towards limed tubes (improper water chemistry), sooting (gas delivery) or a uni-therm gov. (improper mixing). I don't think the mangled gasket would cause this type of problem. Contribute to? Possibly. But not by itself cause this issue.

    If you don't get any physical symptoms, then it is probably an electrical issue. I would start by removing the Hi Limit 2 from the header (should be yellow wires) and let it hang by the wires, and see if you still get the fault. If you do, remove the other high limit (black wires) and plug it into the yellow wires, and the other hi limit into the black wires (switching them). Let them both hang and check. If you still get HL2, something is up with the board.

    Hope all this makes sense...

    One thing does concern me, with a HL1 or 2, the high limit should reset and re-fire the heater. You say it won't re-fire. Is it possible that the heater does re-fire? If the heater shuts down from an HL1 or 2, It may lock out after three attempts. Could this be happening?
    Factory Warranty Station for:
    Jandy/Zodiac, Pentair, Sta-Rite, Raypak (Rheem, Rudd), Polaris,
    and Paramount pool cleaning systems.

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Thanks. I have not observed those physical symptoms you mentioned, though I am not always nearby when it faults as it generally runs fine for a few hours before faulting.

    I can pretty confidently rule out any chemistry issues (I am a dedicated TFPer after all!) so I am leaning towards an electrical issue. I'll see what happens when I run it this weekend, maybe the removal and cleaning of the unitherm governor fixed it, but if I get the fault again, I will try as you suggest and see where that takes me.
    Dedicated TFPer since 2012 with recommended test kit
    AGP, 30 foot, 21,000 gallons with these homemade islands
    Hayward 150 sq foot cartridge filter, 1HP Waterway pump
    Raypak 400K BTU NG Heater! (Model 406a - installed 2015)
    Pool installed in 2006? (just a guess, pool came with house I purchased in June 2012)

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Weekend observations:

    The heater does actually re-fire on its own after the hi limit fault. In the past I must have been resetting it manually as it was cooling so it seemed like I was restarting it. Also possible that it was faulting and then restarting without me ever knowing.

    I was standing next to it when it faulted twice. Both times it just quietly went off, same as if I turned it off or it reached desired temp, no knocking or groaning. It does sometimes knock after the first few minutes of startup.

    Scaling seems unlikely, 3 seasons I've had the heater, my TA has been 80-100, CH rarely test but I don't have hard water, and don't use any calcium products, it was 100 last I tested in May, Ph has always been 7.2-7.8, usually 7.5 and remains remarkably stable.

    Loss of gas pressure? No idea what might cause this but we did have an extensive remodel of our home this winter so gas lines were turned off, re-routed here and there.

    So, given the above it seems like:

    The high limit is working properly

    Given lack of physical symptoms it is not actually overheating

    As I need a new gasket I'm going to replace the unitherm governor anyway (can't find the gasket separately)

    If that does not solve it, then time to call a tech?

    Did I miss anything obvious or simple that I can evaluate before calling a tech?
    Dedicated TFPer since 2012 with recommended test kit
    AGP, 30 foot, 21,000 gallons with these homemade islands
    Hayward 150 sq foot cartridge filter, 1HP Waterway pump
    Raypak 400K BTU NG Heater! (Model 406a - installed 2015)
    Pool installed in 2006? (just a guess, pool came with house I purchased in June 2012)

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    It's a pain but I would inspect the internal bypass and make sure it is operating correctly.
    Paul
    Gastek Pool & Gas Services If you would like to provide a review of the help I provided, please use the following link to leave a review. Gastek Google review,
    Check out some videos on my YouTube channel - Gastekservices on YouTube

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Hmmm, if it is a pain to you that may be a sign that I should not attempt.

    But, I just watched your video on replacing it for a hayward and looks doable, though perhaps tedious.

    So, if I try this, how am I testing the bypass valve to see if it is working properly?
    Dedicated TFPer since 2012 with recommended test kit
    AGP, 30 foot, 21,000 gallons with these homemade islands
    Hayward 150 sq foot cartridge filter, 1HP Waterway pump
    Raypak 400K BTU NG Heater! (Model 406a - installed 2015)
    Pool installed in 2006? (just a guess, pool came with house I purchased in June 2012)

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    Re: Raypak - High 2 limit fault - checked unitherm governor, now what?

    Check the spring and make sure the bypass is moveable. Just make sure you have lube to put on the oring when you put it back together.
    Paul
    Gastek Pool & Gas Services If you would like to provide a review of the help I provided, please use the following link to leave a review. Gastek Google review,
    Check out some videos on my YouTube channel - Gastekservices on YouTube

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