Intermittent ignition failures on Hayward 400FDN heater

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cptkirk

cptkirk

0
Jul 29, 2018
229
FL Panhandle
Most of the time, the heater fires up like it should. But often when we have significant rainfall or conditions are very damp, I'll get the IF code. From the sound of things, the flame comes on momentarily but then immediately goes out. When things dry out, it will work normally again. What can I do so that the heater fires up reliably? It's a bit over three years old, so out of warranty now. Thanks for any help you can provide.
 
Thanks for your reply, it's very helpful. The ground connections inside the heater all look good, but the connection between the bond wire and the chassis is significantly corroded, to the point that the set screw holding the wire in place to the bracket that connects to the chassis won't budge. I cleaned it off to the best of my ability and the heater fired up like it should.
 
Doesn't look like the Hayward H400FDN uses the Fenwal, but I suppose the flame sensing principles are the same so the article is helpful. I ran supplementary wires between the burner, flame sensor, and controller ground, and it appears I have good continuity from all those points to the bond wire. However, the heater still fails to fire intermittently. Something appears to still be on the edge. I ordered a replacement flame sensor since the part is relatively inexpensive. Does it make sense to also order a new igniter?
 
I do not see why you would need a new ignitor as it at least fires up for a short time before it shuts down. Looking at the wiring diagram on page 29 of https://images.inyopools.com/cloud/...s-asme-heater-service-installation-manual.pdf , it is difficult to tell exactly where the ground is connected in the system. There is no labeled ground on the 24V transformer secondary. I do see a "G" connection at E10 on the control module and there may be a physical ground connection on the fuse circuit board at P6 "G andG" and possibly at P5 "C/GY" to E13 "C/GY" on the control module. Where exactly did you connect these supplementary wires and how? Photos would be nice. The bonding wire is not a ground it equalizes the potential differences in voltage between different parts of your pool equipment ( most of which are or potentially can be in contact with your pool water). Also, is there any moisture inside the control compartment(s) when it rains as this can effect the electronics?
 
Thanks for the link to the service manual, did not have that doc. Referring to the picture on page 31 (the one in the middle is the most similar to my model), I ran a wire from the top left screw of the gas manifold to beneath the triangular plate that secures the flame sensor, and then another wire from that point to a ground screw that is wired into one of the boards. I'll take a closer look at where that ground screw is wired tomorrow and post some pictures.

There did not appear to be any standing moisture inside the control compartment, but there is some corrosion visible on many of the interior screws.
 
Below are a couple of pics. The first shows the first ground wire (black) I installed from the gas manifold to the flame sensor plate. The second shows where the second ground wire (white) from the flame sensor plate connects to the chassis ground wire that goes to P6 on the fuse board. The control module ground on E10 is connected to the adjacent connection on the P6 fuse board connector (the control module is not separately grounded to the chassis).

ground1.jpgground2.jpg
 

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You do not need the ground wire under the flame sensor. The flame current passes from the sensor through the flame to ground. That is why the sensor has a ceramic insulator and you may be shifting its position by putting the wire under the sensor mounting plate. The current is "rectified" by passing through the flame to ground because the surface area of the sensor is much smaller than the surface area of the ground (burner) which makes it easier for the current to flow in one direction than the other. If the sensor is dirty it makes it very difficult for the current to pass and if ground area (burner) is dirty/corroded it reduces the surface area ratio making it difficult to read as DC current. I am still curious as to where the ground is attached to the circuit boards.
 
So I should have a wire then between the gas manifold and the circuit board ground only? I can rewire that tomorrow to see if I get better results. I did inspect the flame sensor, it seemed to be in pretty good shape. The four screws that attach the gas manifold to the air box are all a bit corroded like the one in the first picture. Maybe it's worthwhile to replace them?

The green ground wire in the second picture goes to P6 on the fuse board, as depicted in the wiring diagram. Next to that connection point, another green ground wire runs from P6 on the fuse board to E10 on the control board. There are no other ground connections that I can see.
 
That green wire in the second photo looks like a good cabinet ground as long as the heater itself has a good ground to the electrical panel. Is a separate ground (green wire) run from the panel to the heater and are those connections clean. I would expect the 24V "C" (common) connection at P5 to be grounded and am wondering if there is a trace connection on the board between P5 "C" and P6 "G&G" on the fuse circuit board.
 
Mine has done that a few times and what seems to fix mine is taking the burner cover off and blowing air and cleaning it out. It is frustrating because you decide to go out and use it and it won’t light for nothing.
 
One thing I have been doing is to run the heater for 15 minutes once a week year round. Previously it was kind of a pain because with Hayward Omnilogic, when the water temp drops below 65 you had to manually turn the heater on and off (because that's the lowest temp setting and you could not turn the heater on/off on a scheduled basis, only adjust the temp). With their latest firmware however, now it will turn the heater on during the scheduled interval if it is not already on, so I don't have to remember to do it. Unfortunately, there is no direct feedback from the heater to tell you it has actually fired (the application says "heating" if it has commanded the heater to fire). The only way to tell is to either go outside to check or to look at the chlorinator diagnostics to see the cell temp. Would be nice if it would send an alarm.
 
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cptkirk said:
One thing I have been doing is to run the heater for 15 minutes once a week year round. Previously it was kind of a pain because with Hayward Omnilogic, when the water temp drops below 65 you had to manually turn the heater on and off (because that's the lowest temp setting and you could not turn the heater on/off on a scheduled basis, only adjust the temp). With their latest firmware however, now it will turn the heater on during the scheduled interval if it is not already on, so I don't have to remember to do it. Unfortunately, there is no direct feedback from the heater to tell you it has actually fired (the application says "heating" if it has commanded the heater to fire). The only way to tell is to either go outside to check or to look at the chlorinator diagnostics to see the cell temp. Would be nice if it would send an alarm.
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I think that helps, I do try and run mine every couple months for an hour. Nothing more frustrating then having your kid show up to get in the hot tub with a couple friends and it won't lite!
 
Looked at the connections to the heater from the panel, they look OK. I used a meter to check for continuity between the ground from the panel at the junction box on the side of the heater to the ground connection to the fuse board, it seems fine. I changed the supplementary wiring to run a single wire from the right top gas manifold screw to the ground screw near the fuse board. Didn't make a difference, still can't get the heater to fire successfully.

I've never taken the burners out to inspect them, seems like a fairly major operation. Is it easier than it looks?
 
I can’t remember exactly, been a few years but seems like removed a cover and blasted mine with compressed air mainly around the pilot lite area. If you don’t have a air compressor can buy canned air in the PC area of Walmart or amazon

Falcon Dust, Off Compressed Gas (152a) Disposable Cleaning Duster, 1, Count, 3.5 oz Can (DPSJB),Black https://www.amazon.com/dp/B0000AE67M/ref=cm_sw_r_cp_api_glt_fabc_WM28VTR22M8Q5SQDCA03
 

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