daveincorona Posted February 3, 2011 Report Share Posted February 3, 2011 Help - I have a Hayward H400IDL pool heater. It comes on properly, but then every couple of minutes the burners cycle off (the fan continues to operate). After a couple more minutes the burners cycle back on. This cycling continues for as long as the heater is turned on. The end result is that it is taking 2 to 3 times longer than it should to heat the spa. I have replaced the system control board and the thermister, but the problem remains. Any ideas? Thanks for your help. Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 3, 2011 Report Share Posted February 3, 2011 Have you been near the heater when it goes off? Does it make any noise or banging? Maybe even rock back and forth a little? How about he filter? If it is dirty, there will be less flow through the heater, and a hi-limit temp sensor will do what you are describing. Quote Link to comment Share on other sites More sharing options...
daveincorona Posted February 3, 2011 Author Report Share Posted February 3, 2011 Have you been near the heater when it goes off? Does it make any noise or banging? Maybe even rock back and forth a little? How about he filter? If it is dirty, there will be less flow through the heater, and a hi-limit temp sensor will do what you are describing. No noise or banging and I have cleaned the filters to see if that would make a difference. It is acting like a high temp sensor issue. If, in fact, the high temp sensor is shutting down the burners until things cool and then doing so repeatedly might I have a defective high temp sensor, or might I need to make an adjustment somewhere? Thanks for your comments! Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 3, 2011 Report Share Posted February 3, 2011 Does it heat normally say up to 80ish, then begin the cycling? That may be a thermal by-pass. Quote Link to comment Share on other sites More sharing options...
daveincorona Posted February 3, 2011 Author Report Share Posted February 3, 2011 Does it heat normally say up to 80ish, then begin the cycling? That may be a thermal by-pass. Unfortunately - No. The heater starts cycling within a few minutes of being turned on when the water temp is still in the 50's fahrenheit and it does so until the spa is up to temp which in our case is 99 degrees. Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 3, 2011 Report Share Posted February 3, 2011 Diagnosing a heater over the internet is not my favorite. Maybe a intermittent flame rectifier (sometimes called flame proving). Or a blower not quite coming up to speed (you may, or may not be able to hear this). Since heaters a source of liability, you should maybe call a pro. At best i gave you places to take a look at first. Good Luck. Quote Link to comment Share on other sites More sharing options...
daveincorona Posted February 3, 2011 Author Report Share Posted February 3, 2011 Diagnosing a heater over the internet is not my favorite. Maybe a intermittent flame rectifier (sometimes called flame proving). Or a blower not quite coming up to speed (you may, or may not be able to hear this). Since heaters a source of liability, you should maybe call a pro. At best i gave you places to take a look at first. Good Luck. Thank you very much for your help and comments. Very much appreciated. Quote Link to comment Share on other sites More sharing options...
PoolGuyNJ Posted February 4, 2011 Report Share Posted February 4, 2011 It could also be the internal thermal bypass. When they let go, frequently an insufficient flow goes through the heat exchanger, tripping the hi-limit. It's in the inlet/return header. Scott Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 4, 2011 Report Share Posted February 4, 2011 Does it heat normally say up to 80ish, then begin the cycling? That may be a thermal by-pass. I agree with you NJ, but it has been my experience that the heater will run ok for a while, at least till it got out of the 50's. This one is tripping right away. It would be a good idea to check it anyway. Quote Link to comment Share on other sites More sharing options...
daveincorona Posted February 4, 2011 Author Report Share Posted February 4, 2011 It could also be the internal thermal bypass. When they let go, frequently an insufficient flow goes through the heat exchanger, tripping the hi-limit. It's in the inlet/return header. Scott Scott - You say the internal thermal bypass is in the inlet/return header. Is it a part that can be replaced or might the entire header need to be replaced? Not sure what you mean when you say, "When they let go". Thanks - Dave Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 4, 2011 Report Share Posted February 4, 2011 http://www.haywardnet.com/pdfs/replace_pdfs/188-189Hay2009.pdf 23 is the thermal, 25 is the mechanical, they,(the mechanical) can "let go"(malfunction/fall apart) too. Replacement is best left to a pro. Not many of them fail due to natural causes. Usually failure is due to improper water chemistry, low Ph eats them up. Or improper flow (erosion). Quote Link to comment Share on other sites More sharing options...
PoolGuyNJ Posted February 4, 2011 Report Share Posted February 4, 2011 Pool Clown, you might want to re-read the 1st post. Scott Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 5, 2011 Report Share Posted February 5, 2011 So i'm guilty of asking a question that has already been answered. You yourself offered a diagnosis that had already been suggested, so, your point? If you have a problem with the way i diagnose this fellows heater, you should PM me, not hijack the thread with your nit-picking of my posts. If this was not your intension, then i apologize for the heat. Quote Link to comment Share on other sites More sharing options...
PoolGuyNJ Posted February 6, 2011 Report Share Posted February 6, 2011 Sorry buddy. Your right. Scott Quote Link to comment Share on other sites More sharing options...
daveincorona Posted February 6, 2011 Author Report Share Posted February 6, 2011 Scott and PoolClown, I very much appreciate your input. You know much more about this heater than do I. I've gone ahead a purchased another Part#23, thermal sensor, since the part only costs $40 with shipping. If replacing that part doesn't solve the problem I'm afraid I may need a new heat transfer unit which means I might be better to buy an whole heater. Thanks again for your input! - DaveInCorona Quote Link to comment Share on other sites More sharing options...
Pool Clown Posted February 7, 2011 Report Share Posted February 7, 2011 I would at least have a pro come out and look at it before you shell out for a new heater. But don't let on that you are willing to buy a new heater. Otherwise, he will be more inclined to sell you a new one rather than try to diagnose yours. Quote Link to comment Share on other sites More sharing options...
daveincorona Posted February 7, 2011 Author Report Share Posted February 7, 2011 understood - thanks! Quote Link to comment Share on other sites More sharing options...
Buzz83 Posted December 21, 2019 Report Share Posted December 21, 2019 I’m having this issue but, the flame never goes out. So it acts like it’s trying to start again. Adds extra gas then the igniter clicks a few times. It does this 3 times before a Big Bang happens. I’m guessing it’s the extra gas buildup igniting. Any one know what the issue might be?? Quote Link to comment Share on other sites More sharing options...
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