Hayward heater F400FDN problem

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Kylecramm

Member
Nov 26, 2022
11
Montgomery Texas
Pool Size
29000
Surface
Plaster
Chlorine
Liquid Chlorine
I have been having trouble with my pool/spa
Hayward H400FDN heater the past few months. It started out as an intermittent problem but has progressed to complete fail somewhere. When I turn the heater on the fan activates and heater fires and seems to lite but goes out within 3-4 seconds. No codes are showing. I have replaced the flame sensor and the board but still having the issue. It is very difficult to find anyone to come out and work on Hayward products in my area. I am pretty handy when it comes to testing components if anyone has any ideas. I am completely stumped on what to do next. I have a video of the cycle but not sure how to post it. [/YOUTUBE]
 
Kylecramm said:
Click to expand...
It acts like you 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 (below, about $5.00) 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.

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The manifold was loose enough to rotate it back enough to remove the orifice s. They are all completely clean.
I did have a home generator installed installed last year and they teed off of the line to my pool heater I’m pretty sure. I wonder if that is effecting anything
 
Kylecramm said:
The manifold was loose enough to rotate it back enough to remove the orifice s. They are all completely clean.
I did have a home generator installed installed last year and they teed off of the line to my pool heater I’m pretty sure. I wonder if that is effecting anything
Click to expand...

When was the heater last run successfully?

Check the gas pressures at the gas valve with a manometer.
 

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I think the plumber was reading it wrong somehow. The technician today said the pressure was a little bit low but said it was within specs. I haven’t had a chance to talk to him a get the exact pressure yet but I will in the next day or so.
I think the original plumber didn’t know what he was talking about when I came to testing gas pressure is what I comes down to. 🥺
 
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