I recently replaced the heat exchanger in my pool heater due to it leaking, easy replacement. After getting the unit back together, I fired it up, it started fine, but would shut down after seconds, sometimes 10 seconds, sometimes 35 seconds, it fluctuated, but it would start back up on its own after about 30 seconds. It did this over and over with no trouble code ever coming up on the display. I had a pool guy come after I could not figure out the problem, he thought it was the flame sensor so he replaced it, still have the exact same problem. His next suggestion is to try and replace the main circuit board but has no idea if this is the problem or not. I do not want to keep spending money on things that don’t fix the problem. The unit was working fine even with the leak prior to the heat exchanger replacement. Any suggestions as to what the problem could be?
Hayward H400FDN starts but shuts down after a few seconds
- Thread starter RDeeJ
- Start date
- Jul 21, 2013
- 65,298
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Welcome to TFP.
www.troublefreepool.com
Suggestion #1...
If the heat goes out within a few seconds of coming on you can have a clogged orifice, very left hand one, at the ignition and flame sense area. Spiders seem to like that orifice. Turn gas off at the external gas valve. Remove the gas pipe to the main valve, remove the 4 screws holding the manifold in place, examine all the orifices.
If you see a clog, remove the orifice (3/8" or 7/16" wrench, depending on what Hayward installed) and push the clog backward out of the orifice. If you don't remove the orifice the clog will just move to another area.
These are the easiest manifolds to remove and replace. While it is easier if you remove the wires from the main valve, you don't have to if you are careful. If you do, take a cell-phone picture first to put them back where the belong.
Be sure to use a bit of thread sealant when reassembling the gas line EXCEPT on the union. Make that very tight. Do not tighten the pipe into the main valve beyond where the old sealant shows, you can crack that valve if you overtighten. Use some soapy water to check for leaks. If not comfortable working on gas plumbing, hire a pro.
Suggestion #2...
As a test only, jumper each sensor one at a time and see if you find one that keep the heater running.
Suggestion #3....
Check the gas pressures using a manometer.
Hayward H-Series Heaters - Further Reading
www.troublefreepool.com
Suggestion #1...
If the heat goes out within a few seconds of coming on you can have a clogged orifice, very left hand one, at the ignition and flame sense area. Spiders seem to like that orifice. Turn gas off at the external gas valve. Remove the gas pipe to the main valve, remove the 4 screws holding the manifold in place, examine all the orifices.
If you see a clog, remove the orifice (3/8" or 7/16" wrench, depending on what Hayward installed) and push the clog backward out of the orifice. If you don't remove the orifice the clog will just move to another area.
These are the easiest manifolds to remove and replace. While it is easier if you remove the wires from the main valve, you don't have to if you are careful. If you do, take a cell-phone picture first to put them back where the belong.
Be sure to use a bit of thread sealant when reassembling the gas line EXCEPT on the union. Make that very tight. Do not tighten the pipe into the main valve beyond where the old sealant shows, you can crack that valve if you overtighten. Use some soapy water to check for leaks. If not comfortable working on gas plumbing, hire a pro.
Suggestion #2...
As a test only, jumper each sensor one at a time and see if you find one that keep the heater running.
Suggestion #3....
Check the gas pressures using a manometer.
ajw22 I greatly appreciate your suggestions but felt like my issue was caused by the heat exchanger replacement since the unit was working great prior to this. It turns out that I ended up calling a company that was recommended on the Nextdoor app, got lucky and a knowledgeable, honest tech came out today and asked if when the heater would light and run for a few seconds was I seeing alot of steam, which I was, said most likely that was fooling the temp sensor and it was shutting the unit down. His remedy was to cover the air intake 1/2 way with a credit card just long enough for the heat exchanger cavity to dry out and no steam coming out of the top, he removed the credit card and the unit has worked fine since! I guess when we lifted the heat exchanger enough water went into the cavity from the coils (and probably from the leak) that the interior got extremely wet. Anyway, fixed and running and learned a new trick! Hope this will help someone else!