Gas Valve Issue? (UPDATE: Yes, probably, but now what?)

AndrewHH

Hi All,

Immediately after some severe rain and some light backyard flooding I heard our furnace humming--the thermostat was off (we live in the desert, so no need for heat right now), which was odd. I have turned the thermostat fan to "On" and air did blow, and then I turned on the heat, but only cold air returned from the vents. I went to the thermostat, took off the panel, I saw some light grey smoke emanating from the C3 port of the (Honeywell) gas valve. I immediately switched off the furnace. I smell no gas. I'm going to get my hands on a multimeter to investigate further, but in the meantime, I'm curious to understand just what happened to my furnace? Any explainations or thoughts are much appreciated. Thank you!

Jamie Hall

If it got under water -- or even if it got wet -- it's done. No ifs, ands, or buts. At least in my book. Simply replace everything that got wet.

AndrewHH

Thank you, Jamie. From what I can tell it did not get wet (it's in a closet on the side of the house (part of the house), and elevated a few feet from the ground). It is curious, though, that I noticed the furnace issue on the same day as the rain.

JUGHNE

Could rain water entered the furnace thru the flue/chimney pipe?

mikeg2015

Wind driven rain comming in down the intake pipe or even extreme humidity could have run into the furnace and dripped onto the gas valve . It’s almost directly under the intake in some cases.

Otherwise, maybe a spade connector came loose and arced to the opposite terminal.

Or the valve just shorted out internally. However, surprised you saw smoke rather than it blowing a fuse. Maybe internal coil winding shorted out.

AndrewHH

Well, it certainly seems like the issue is the gas valve, particularly the Line Voltage Connector. The evidence: (1)inducer motor not turning on despite 120v coming into wire receptacle plugged into the Line Voltage Connector from control board, and (2) apparently damaged Line Voltage Connector (Inability to fully unplug connector receptacle--pulled and it did come loose, but looks like it took some of the control board with it--and it's burnt, black, and cracked). A look online finds only replacement gas valves (Honeywell single stage gas control valve SV9541), but I'm wondering if I might single find a control board and just replace that instead of the whole component--I'm assuming there's a control board there, I don't have the tamper-proof bit to remove the value cover to take a look. Will I be able to luck out and single replace the board, or does the whole valve need to go? Thanks!

ratio

The whole gas valve. Internal parts won't be available individually.