balky water heater

Old-Biscuit wrote:


Clean spark electrode with some emery cloth
Check that high voltage wire to spark electrode connection is clean/tight both at electrode and at circuit board
Check that spark electrode has good clean/tight ground connection
Check that ceramic on electrode is not cracked allowing trace to ground

Install a new spark electrode.

All but your last suggestion has been done. Methinks it's time to try a new igniter. Thanks

I had the exact same problem, only w/ the fridge. Thru it all, I found the igniter/sensor gap to be quite critical. Increasing the gap to about 3/16" fixed it. This was after installing a new sensor/igniter.

noplace2 wrote:
I'll try this one more time. I mistyped in the first place, and subsequently. In the mean time, I've removed and properly gapped the igniter electrode, burnished the contacts and centered the igniter in the tube.

What I did not make clear originally, is that the unit fires immediately with a strong flame but shuts down after a few seconds (it appears that the gas valve is shutting down). Only on the 4th or 5th try will it remain on. Hopefully that explanation will lead to a better diagnosis. Thanks again in advance.

OK main flame is lighting off but is not staying lit.

Main flame needs to engulf the spark electrode when it lites off.
Then thru 'flame ionization' a milivolt signal is generated. This milivolt goes back to circuit board to 'prove' main flame is burning.
If circuit board doesn't get this signal it drops DC power to gas valve and closes it.

So main flame lighting off...milivolt signal is getting dropped, shorting out to ground, not being generated etc.

Clean spark electrode with some emery cloth
Check that high voltage wire to spark electrode connection is clean/tight both at electrode and at circuit board
Check that spark electrode has good clean/tight ground connection
Check that ceramic on electrode is not cracked allowing trace to ground

Install a new spark electrode.

bump

I'll try this one more time. I mistyped in the first place, and subsequently. In the mean time, I've removed and properly gapped the igniter electrode, burnished the contacts and centered the igniter in the tube.

What I did not make clear originally, is that the unit fires immediately with a strong flame but shuts down after a few seconds (it appears that the gas valve is shutting down). Only on the 4th or 5th try will it remain on. Hopefully that explanation will lead to a better diagnosis. Thanks again in advance.

Old-Biscuit wrote:
Spark electrode gap to ground is 1/8"

Gas valve is only open for 6 seconds or so WHILE voltage is sent to spark electrode.
IF main flame does not light off and PROVE voltage is dropped from gas valve and another ignition sequence is attempted.

IF Spark Electrode gap is too wide/narrow.....tough to generate enough 'heat' to light propane
IF Spark Electrode is not directly in path of propane.......harder to get it to light
IF Spark Electrode ceramic is cracked......voltage can jump to ground in wrong area

Have you WATCHED it while attempting to light?
Good Strong Spark?
No false tracking.....jumping to ground?
DO you hear gas solenoids click when energized?
Does main flame light then go off? Or not light at all until several attemts?

I knew this was going to get complicated :)

Yes, I have observed it while it is attempting to light. Strong spark. In those first 3 attempts it can vary between 1-3 seconds before it goes to the next cycle. Attempt 4 or 5? As it should be.

Spark electrode gap to ground is 1/8"

Gas valve is only open for 6 seconds or so WHILE voltage is sent to spark electrode.
IF main flame does not light off and PROVE voltage is dropped from gas valve and another ignition sequence is attempted.

IF Spark Electrode gap is too wide/narrow.....tough to generate enough 'heat' to light propane
IF Spark Electrode is not directly in path of propane.......harder to get it to light
IF Spark Electrode ceramic is cracked......voltage can jump to ground in wrong area

Have you WATCHED it while attempting to light?
Good Strong Spark?
No false tracking.....jumping to ground?
DO you hear gas solenoids click when energized?
Does main flame light then go off? Or not light at all until several attemts?

Old-Biscuit wrote:
Are you using other propane appliances?

IF YES>>>>>>>
LP System valved in service then propane lines are pressurized so NO there isn't air in line.

If using system and water heater is stubborn then spark electrode might not be properly positioned or proper gap. Needs to be centered and directly in path of main flame.

I'll try to check that although I'm not sure what size gap I'm looking for. That still doesn't explain (to me) why it consistently is either 4 or 5 (not 3 or 6) firing attempts before it stays on. And the only other propane we use is the stove, many times/day. Furnace in season but not for several months and there was no problem with it firing while the water heater problem was extant then as well. Thanks for your help.

Are you using other propane appliances?

IF YES>>>>>>>
LP System valved in service then propane lines are pressurized so NO there isn't air in line.

IF NO>>>>>>>
Then LP System needs to have a demand placed on regulator which then has to open allowing propane to flow.
Pressure has to be sufficient enough to force propane thru orifice and get proper air/fuel ratio before propane can be ignited.


If using system and water heater is stubborn then spark electrode might not be properly positioned or proper gap. Needs to be centered and directly in path of main flame.