[ahuangsolo]

I want to replace my upstairs furnace gas valve. After looking through cross references the part number I need is White Rodgers 36H33-412. So out of curiosity I compared that to my downstairs furnace and that part number after cross references is 36J24-214. But I believe the two furnaces are the same model. Why the different part numbers, what's the difference between 36H vs 36J? Are they interchangeable?
Thank you all!

 

[roughneck]

What’s wrong with the current valve?
Just a side note, but when you change the valve you’ll have to set the gas pressure with a manometer. They do not come preset, as everyone’s input gas pressure isn’t the same.

 

[ahuangsolo]

Thank you roughneck,
The furnace locked out and gave me error code 21. This I think is a bad board or gas valve. I reset the furnace then worked for a couple days then stopped working, it would give me a hum, then pause and then hum again. So I assume this is the ignitor glowing and trying to ignite. So I reset the furnace again and then it works. I hear the hum, then the click, then the flames/furnace going. So it's been working for the past week but obviously don't want it to go out again.
How do I know what pressure to set it at?

 

[user_12345a]

what's the model of the furnace?

What did you reset?

Gas valve replacement is not for most diy'ers to do.

 

[roughneck]

It doesn’t sound like it’s anything to do with the gas valve.
Most residential natural gas furnaces run at 3.5” manifold pressure.
Sounds like you need to do some investigating with your meter. Whatever you do, don’t start throwing parts a the problem without diagnosis. You’ll wind up out the money for the parts and still have a broken furnace.
To diagnose a faulty valve we will need voltage readings to the coil, and both input and manifold gas pressure readings.

 

[ahuangsolo]

Sorry for the confusion guys.
1)Yes my upstairs and downstairs furnace are different models. Upstairs is a Carrier 56Bravo70-12 and downstairs is a Carrier 58Bravo95-16. So thus the different gas valve models, duh. Thanks for making me check user_12345a.
2)roughneck, when I meant "hum" of the furnace, I meant the inducer starting before the click ignition. So the inducer I think is just running and stopping repeatedly.

 

[ahuangsolo]

-So maybe a bad inducer? Is there a way to check for that as well? But if it's working then my meter won't give me a diagnosis because it's working. Don't I have to wait for it to fail?
-Also when the furnace is off. I do smell gas near the manifold. Is that normal?

 

[roughneck]

Yes, you’d have to check with your meter when the furnace was failing to operate.
There is no one part we can say is at fault until some diagnosis is done.
You may have to sit in front of the furnace and jumper it on and off until it screws up, then you can start checking with your meter.

 

[ahuangsolo]

Hi all,
So I got around to replacing the gas valve. I smelled gas coming from the manifold area, checked with a gas detector, and decided to just replace it. After replacing it, I do have a question about the wiring. See photo. The common wire (green) splits to the board and to the furnace. The gas valve itself has a place to hook up a ground at the corner of it. Is it okay to leave it the way I have it now or should I not have the common wire split like that? Thus have a separate ground wire from the valve to the frame?
BTW I did run the furnace and adjusted the gas pressure to 3.5. Everything seems to be running fine. The model of the gas valve is 36J24-214.
Thank you

 

[yuri]

The board and secondary side of the transformer are grounded so you can leave it the way it is. You don't need to ground the valve it is just there for convenience.

The board is grounded on it's mounting plate or nearby.

Carrier and W/R for some weird reason change a few digits in the model # of the gas valve every time there is a different batch of furnaces made or series change but there are only 3 types of valves.

Quick open, slow open and step open. Carrier only uses quick open.

However I use Universal ones sometimes and they are quick open and cross reference to all brands.

IMO it is to try gt you to buy OEM Carrier parts.

Lennox and every one else uses the generic Honeywell or W/R part numbers.

 

[ahuangsolo]

My furnace is Carrier model number 58RAV070-12. After looking everywhere I thought the W/R 36j24-214 was the right valve. It’s a slow open but Yuri you state Carriers are fast open. Did I buy the wrong type of valve?

 

[yuri]

RAV I belive is reverseflow or counterflow. Is your fan above the furnace and blowing air down under the floor?

If it is then it may be slow opening. I rarely see them.

Point is Carrier seems to change the part # with each series and W/R follows suit as they make them in large batches.

In your case as long as you got it from Carrier or someone cross referenced the part # you should be OK.

The upflow furnaces all seem to use fast opening.

 

[ahuangsolo]

Thanks yuri, yes I think my model is a reverse flow after looking at other diagrams of other furnaces. The blower is above the heat exchanger blowing the heat down.