Suburban H2O Heater

[buzzard616]

Subject: approx 10 year old 10 gal gas/elec water heater.

Has worked fine up til now. After operating on electric for a week tried to switch to gas. Switch works fine; solenoids and igniter also check OK.
Igniter starts, gas flows, and lights. When igniter shuts off after a few seconds, the gas shuts off also. Module makes its three attempts and gives up. Ignition sequence sounds and looks normal, but the valves are only open when the igniter is firing.
Given there are only three components in the gas system; control module, burner valves, and igniter; and two out of three work, I'm leaning toward a failed control module.
It appears to be 'glued' to the top of the tank.
Am I correct in blaming the module and if so how hard is it to change?

[mchero]

Should not have to walk out to your HWH and blow/clean the ignitor every time the humidity gets high or it rains. Sounds to me Old Buscuit nailed it on the head.

[edatlanta]

I have a similar problem occasionally especially when humidity is high or after or during heavy rain. To fix mine I blow off the igniter/thermocouple area with high pressure air from my compressor. It has always fixed the issue.

[Old-Biscuit]

Sound more like bad spark electrode...........

WHEN main flame lites off it generates a milivolt signal via flame ionization that goes back to control module 'proving' main flame. No signal----control module drops DC voltage to gas valve solenoids

YES you can get a good strong spark from electrode but not get the return 'milivolt' signal due to cracked ceramic, dirty/sooted electrode, electrode not directly in main flame, high tension wire connections dirty/loose at electrode or control module


Doubt it is control module