Furnace Mystery - Did I use the wrong valve?


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Old 04-25-18, 07:04 AM
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Furnace Mystery - Did I use the wrong valve?

I have an amana furnace that stopped working. The inducer kicks on, the igniter lights up, then there is no flame and the igniter goes out. After some troubleshooting I assumed that the valve had failed. The control board was sending a voltage, but the valve was not clicking on. I ordered a replacement valve and put the new one in the furnace. The valve is now firing because I can feel/hear it, but the gas is still not lighting.

I've done all the basics like checking to make sure the gas is on and the plumbing/manifold are clear of debris and clean. It's a 7 year old furnace so there was almost no corrosion. I checked the continuity and function of the rollout switches and the pressure switches. I checked all the drain lines and the intake/exhaust of the system. I have another furnace of the same type in a different heating zone and verified that the old valve did not click on when I plugged in the connector from the working furnace, so I'm pretty convinced the original valve is broken.

Back to the new valve troubleshooting. I turned all the other gas appliances off in my house (I have two fireplaces with pilot lights, another furnace and a hot water heater that are all working fine) and turned the furnace on several times to see if the smallest dial on my gas meter moved at all in the few seconds that the valve is open. It did not move after many cycles so I suspect that even though the new valve is firing, for some reason it is not letting the gas through.

The only thing I can think of with the valve is that maybe I was sent the wrong one. The original valve is labelled as "Honeywell P/N: VR9205Q1010 / Goodman 0151M00014". I ordered a replacement that was advertised as "Goodman 0151M00014" and when it arrived the sticker on the valve said "P/N VR9205Q1006". I have not been able to find any specs on Honeywell's numbering scheme to understand what the slight difference in product number means and if it might be significant.

Do I have the wrong new valve? or is there something else going on?

Any help would be greatly appreciated. I am out of ideas.
 
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Old 04-25-18, 09:54 AM
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Welcome to the forums.

I doubt the original valve was bad and the chances of the replacement being bad are almost nil.

Is there a gas shutoff at the furnace..... there should be ?
If the gas valve is getting the 24vac to it when it should light... there is no fault in the furnace.
A few pictures around the furnace would be helpful. How-to-insert-pictures
 
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Old 04-25-18, 10:52 AM
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yes, there is a gas shutoff next to the furnace as well as one farther away. Both are in an open position (inline with the pipe). I know that the gas is flowing to the furnace because I opened the valve for a second to get the air out of the line when I replaced the valve. The original valve was not working on either the furnace at issue here or an exact same version of the furnace in a different zone in the home. The furnace is a AMH950904CXAD.
 
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Old 04-25-18, 11:04 AM
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It should be a three wire valve.
Does that use the W/R or Honeywell gas valve ?
 
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Old 04-25-18, 11:12 AM
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It's the honeywell. Yes, it is a three wire valve.
 
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Old 04-25-18, 11:23 AM
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That is a two stage furnace and should have the front cover(door) pressure switch in the gray wire. You need to verify that is closing when the inducer runs.

Pin 1 - main valve
pin 2 - hi fire
pin 3 - common/ground

You need 24vac on pin 1 and 3 when the gas valve should be open.
 
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Old 04-25-18, 11:30 AM
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I have verified that both pressure switches are closing when the inducer runs by using a multi-meter to check continuity as the furnace is going through its startup cycle.
 
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Old 04-25-18, 11:33 AM
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I'll have to check the 24vac on pins 1 and 3. I think I was measuring 24v voltage across pins 2&3 and I don't think I checked 1 and 3.
 
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Old 04-25-18, 11:37 AM
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Sorry for the many posts in a row. I know that something in the valve is firing because I can feel it when I touch it during startup. After it wasn't working for me I also tested it by disconnecting it from the gas and physically blew through the valve as the furnace was going through startup. When I felt/heard the click air went through it. For some unknown reason the gas just won't go through it.
 
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Old 04-25-18, 12:52 PM
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Another update. I spoke with the gas valve company and they said that I do have the right valve for this furnace. The new valve part number replaced the original.
 
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Old 04-25-18, 03:08 PM
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What is inlet and manifold gas pressure?
 
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Old 04-26-18, 08:08 AM
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I think I may have found the issue. Thank you to PJmax for getting me thinking on the right track. I was measuring 27V across one of the common/valve pin combinations and nothing on the other common/valve pin combination. I then measured what my working furnace was doing and on fire up it was measuring 29V across both common/valve pins. The furnaces have a dual stage valve but are currently configured for single stage operation. I'm thinking that a relay went out on my board and is preventing one of the valves from opening. I've got a new board on order and I'm optimistic it will fix the problem.
 
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Old 04-30-18, 07:58 AM
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Turns out that the control board was the issue and now I'm up and running again.
 
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Old 04-30-18, 09:35 AM
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Good job. Thanks for letting us know the outcome.
 
 

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