Hayward H400 shuts down after 10-15 seconds

wysocki

Bronze Supporter
Apr 19, 2015
50
Covina,CA
HELP! I Turned my heater on to get up a few degrees for a pool party and noticed no hot water coming out. Found that the heater did come on properly, but then after 10-15 seconds it turned off ("Heating" light goes out and so does flame). All burners do work for a while. I can then restart the heater, but it again lasts only a few seconds. Any ideas?
 

wysocki

Bronze Supporter
Apr 19, 2015
50
Covina,CA
The unit does not have a display for codes. And I can't find any documentation about this particular unit. There's no blower or pilot light (has electronic ignition). I've looked at the schematics for other H series and it seems like the problem would be one of the limit switches since it fires up great and hot water flows to the pool - for a short time before it shuts down! I assume all these sensors must be under the side panels but I can't find any docs that show me the location of the switches.
Then to diagnose just which one is causing the shutdown, can I just jumper around each one until I find the offender with process of elimination?
20220718_114225.jpg
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
37,896
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60

FSDpool

Gold Supporter
Jul 4, 2022
43
Sandy, UT
Pool Size
24000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
That looks like my old heater! Could be your flow switch (had a tech come out to replace mine in ~2006), not sure what else they did. I replaced mine with a mastertemp400 back in 2010, wasn't too hard. Newer will be more efficient.
 

swamprat69

Well-known member
Mar 30, 2019
690
Las Vegas, NV
1poolman1 is correct in that the most likely cause is the flame not being sensed. It appears that your heater is direct spark ignition ( main burners light off from a generated spark with no pilot ). It may be something as simple as pulling and cleaning the spark ignitor/electrode attached to the burner assembly on the lower left (single wire) and associated grounds. Since it does not use a gray box Fenwal ignition module with a label stating operating parameters it is difficult to tell the exact timing for trial for ignition ( time from when the gas valve is powered until the circuit board makes a go/no go decision based on whether the main burner flame is sensed or not). It could be about 10 sec give or take? Please note that not having the heater cleaned on a regular basis can cause problems that can snowball into much larger problems. I know that getting a competent service tech to work on a "pool heater" can be a very hit and miss situation. At a minimum, burner assembly should be pulled and spark ignitor/elctrode, burners and orifices should be checked/cleaned and heat exchanger visually checked above and below for any obstructions to insure safe/efficient operation.
 

wysocki

Bronze Supporter
Apr 19, 2015
50
Covina,CA
I pulled & cleaned the igniter and all the orifices, problem remains. I believe you may be right about the flame sensor but I'm not sure of where it is! Is this thing at the bottom right of the photo the flame sensor (I believe I've seen it labelled "Temperature Limiter")? For testing, can I disconnect it and insert a jumper there to see if works? My ohm meter says it's open now with no flames, what values should I see from it20220718_114225small.jpg?
 
Last edited:

swamprat69

Well-known member
Mar 30, 2019
690
Las Vegas, NV
The spark ignitor is the part with the single wire leading to it on the bottom left of the burner assembly. It would have 2 metal rods that are angled to sit over one of the burners. The metal rods can be cleaned with a small metal or diamond file, steel wool or sandpaper (but should be wiped off if you use sandpaper as silica "dust" is an insulator). At the same time the grounding surfaces of the spark ignitor leading back to case ground need to be cleaned also (see page 45 of the manual that ajw22 left the link for you). This means the underside of the spark ignitor plate that has the uninsulated ground rod attached, the part of the spark ignitor bracket that the spark ignitor plate attaches to and both sufaces ( on the spark ignitor bracket and the burner assembly ) where it attaches to the heater cabinet via the burner assembly. Hard to see from the photo, but also any metal to metal surfaces from the spark ignitor bracket back to the cabinet ground must also be cleaned. What you are pointing at on the right hand side is the rollout safety that prevents the heater from running if the combustion side of the heat exchanger is partially blocked/blocked.
 

wysocki

Bronze Supporter
Apr 19, 2015
50
Covina,CA
Yes, I already cleaned the igniter, but that had nothing to do with my problem since it does ignite the gas promptly every time. The problem is that the gas shuts down after 10 seconds, long after the igniter does its role. But it's now PROBLEM SOLVED!

Something in the works was either saying "there's no flame" or "there's excessive heat" and shuts it all down. Since I got hot water while it runs, I know nothings really wrong, just mis-reported.
There are 5 limiters in the circuit (and one of them is a manual reset). Actually, my wiring is slightly different than this diagram, but the same effect. I Decided to jumper over all 5 limiters and see what happens: IT RAN for several minutes before I shut it off! Then I narrowed the jumpering down to the one that is the problem: the one Temperature Limiter switch that I referred to in the picture a couple posts back. Right after I shut the thing down, I checked the resistance on the limiters: All were closed except that one was showing open. Everything ran well without that one switch in circuit. Interestingly, after a couple more system tests, I checked that switch again and it was CLOSED! Just a fluke? Now I know that if it fails again, I'll know to replace that switch. Thanks to all that helped me understand what's going on here!

ImageCapture9.jpg
 

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