Ruud Furnace Won't Fire

jasonckcmo

I have aprox. 15yr old Ruud model UGDG 07EAUER furnace that won't fire. Replaced the blower motor 2yrs ago. New thermostat. When call for heat, the draft inducer starts up. I can here the pressure switch do its thing. The hot ignition lights up very bright. Then I hear the gas valve click, and most of the time(almost everytime) the burners don't fire. When it clicks and doesn't fire, the click is louder than when it clicks and does fire. But it seldom will fire. It has a Homeywell gas valve VR8205H. Can anyone explain in detail what terminals to connect a multimeter to in order to do some troubleshooting. I'm guessing the control board is going bad, but I suppose it could also be the gas valve not opening. I have tried tapping it with hammer handle.

SKIP4661

If the valve is clicking and not opening the main valve it is probably the gas valve.

HvacWiz

Check for 24v at valve when you hear it click, if you have 24v, you will need to replace the valve.

jasonckcmo

How do I check for 24V? Do I turn my multimeter to AC Volt, ground the black and put the red on one of the two terminals going to gas valve or what? I think I need to go get a new meter too. Don't think this one is working anymore.

yuri

Check for 24 volts from R to C on the circuit board to verify that your meter works. If not buy a new one. Then check for 24 volts across the 2 wires on the gas valve while the igniter is glowing.

jasonckcmo

ok, I'll do that as soon as it quits again. I just went down and pulled some connectors off and put them back on and the furnace fired this time. Gonna get this house warmed up first. (62 F.) Thanks for all the help, will keep posting.

jasonckcmo

Ok, had to go buy a new meter. So now I checked to Volts at the valve and it shows 00.1 while the furnace is going through its startup cycle. When the valve clicks, it jumps to 5.x and 7.x once. It then did fire up, and read 26.x but that was after several trys. Does anyone have any ideas?

har199

sounds like your gas valve is on its last leg. a replacement valve is probably needed soon especially if its the original valve.

JohnH1

Normally at 5 or 7 vlt the valve wont click. Since it clicks it sounds like the valve is trying to open. But if you are trully only getting 5 to 7 volts you may have a bad board.

jasonckcmo

I think its the board. I can jump a wire from 24v on the board up to the gas valve when it is ready to fire up and it does. If i hold that wire there for awhile, then take it off, it will usually run on its own, but not everytime. It will usually quit in the middle of the night. Then sometimes when I remove the jumper, the gas valve just closes.

frankie3s

Check all the wire connections on the board and make sure that your grounds are OK. In some of the other posts, people have mentioned that the some PC boards have had bad solder joints and/or lose molex connectors.

hallwayhouse

I am about to replace the valve on my Ruud furnace. It's the same age as yours and having the same symptoms. I have replaced these kinds of parts on other units over the years and believe it's time to replace the valve. I am wondering if you ended up replacing the board too. thanks!

frankie3s

I had a Lennox furnace that had the same issue and in the end replaced the gas regulator and the problem has since been resolved (did this last winter).

What I think caused the regulator to fail in the first place (beside normal wear and tear issues) was that the Honeywell thermostat that I was using was too sensitive. The furnace would stop and then come back on 5 to 6 minutes after. I replaced the thermostat with a Lux one that I bought at Costco for $50 CDN and it is working exactly as it should. Not coming on more that 3 or 4 times an hour (I remember reading somewhere that the furnace should not be coming on more than 6 times and hour. In my previous case it was like 10!).

hallwayhouse

frankie... thanks for the response... my situation is exactly like the orginal post here. The thermostat calls for heat, the draft inducer kicks in, the glow plug lights for about a minute, then you hear a click from the valve, (usually this is when the valve opens to let the gas through) instead, the glow plug turns off and the furnace blower continues to run. What do you mean by "gas regulator" do you mean the valve? I am happy to also replace the thermostat. It's 15 years old too and a cheap one.

A couple years ago I had a similar problem with another Ruud furnace, and replaced the glow plug, valve, and the circuit board. Nothing worked and I replaced the furnace.

frankie3s

Yup, I mean the valve. The one the op had quoted "Honeywell gas valve VR8205H" is known to have a lot of issues and Honeywell had discontinued some of them and had replaced it with something newer. If you have cleaned the flame sensor and the above problem is still happening then it might be time to replace the valve.

Click here to find out if your gas valve has been discontinued and what the replacement would be,
http://customer.honeywell.com/Honeywell/CatalogNavigator.aspx?Definition=ObsSearch&Catalog =&ChannelID={03E741AF-5630-4558-8935-E56D3759DC16}&SearchFrame=ALL&ReturnUrl=http://customer.honeywell.com/honeywell/UI/Templates/CMSTemplates/ProductXRef.aspx?NRMODE=Published%26NRNODEGUID={07 6DF614-2EDB-481E-8A9A-4DE159079029}%26NRORIGINALURL=/Business/Cultures/en-US/Products/Cross+Reference/%26NRCACHEHINT=Guest



I hope this helps!