Rheem Furnace gas valve clicks on/off crazy


  #1  
Old 01-25-08, 08:49 PM
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Rheem Furnace gas valve clicks on/off crazy

Hi all.

this is a 1986 vintage Rheem gas furnace, model is
RGDD-06NC-ER

The ignition module is a Robertshaw SP715A

The gas valve is a Robertshaw 711 DER-SC

The problem: When heat is called for, often it works normally, but often the gas valve will click, the pilot comes on (electric spark ignition), and the burner will fire, then the gas valve starts clicking on and off, very fast, randomly (no cadence), and the unit will shut down.

Or, it starts clicking madly as soon as the pilot lights, and the burner will not fire. Or some variation of this, but always the gas valve is clicking madly.

I removed the flame sensor and cleaned it, but no difference. I also cleaned up the thermostat connections and contacts, no joy.

Is there a way to test the flame sensor?

Any other sensors that might be bad.

Any help diagnosing this problem is greatly appreciated.

I do have some electronic skills and diagnostic tools.

thanks
 
  #2  
Old 01-25-08, 08:59 PM
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do you have a meter to see if for sure the t-stat isn't dropping out on you?

If you do have a meter, take a reading on R and W, and see if that power is steady. If turns out it's steady, then take a reading as the gas valve, and see if power is steady. if it's on and off as you said, then it's the control. But if the power is steady, then it's the gas valve itself.
 
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Old 12-27-08, 01:45 AM
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just a followup

I forgot to post a follow up on this issue back then when I tried your suggestions, Jay, so here it is.

I did as you suggested, the problem turned out to be the ignition control module. I opened it up, and just cleaned the relay contacts and replaced it. It's been fine since then.

thanks for your assistance, I really appreciate it.
 
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Old 12-27-08, 08:22 AM
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Wow, almost a year later you came back.

Thanks for the update.
 
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Old 12-27-08, 01:45 PM
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Yes Jay, I did forget! I am a die-hard DIY'er, and I seek out professional help on various forums whenever I think I need it. I usually try and figure things out myself, sometimes that works, sometimes it doesn't. In the case of a furnace, I felt it would be more prudent to ask questions first! :-)

Anyway, I just wanted to thank you again for your assistance. I had asked the same question on another forum, and got a response that inferred that I shouldn't be messing with my furnace, I may poison my family with CO, and I really should just call in a professional. Of course, that forum is mostly HVAC techs. A rich source of info, but unwilling to share it.

Your forum was 180 opposite. You were helpful from the get-go.

Thanks again for your help.



Dana
 
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Old 12-08-10, 01:06 PM
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Me too

I found this thread searching for gas valves. Mine is clacking and chattering same as the above described, also the furnace will fire up sometimes, and sometimes not. I thought it was the gas valve, the tech who was just here did too, but he wants $910 to put in another one. I also asked him to check the input command to the valve to make sure it wasn't getting an erratic input, but he only had a digital meter, which will not show millisecond-long glitches. I'm going to check it with my old analog meter. I also have a DMM but this calls for the visual indication of an analog.

After reading the above post I wonder if my problem isn't the same. I have a 6 year old Rheem system. Seems a little premature to fail.

Any help is appreciated! If it is the valve, I can get one for $221. All I really need to know is what type of tape is that around the pipes going in and out of the valve? I have teflon but seem to remember when I put in my gas stove another material is required.

Thanks!
Bob
 
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Old 12-10-10, 12:17 PM
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Reem gas valve clicks

I have similar case. furnace is working first cycle or two, and then valve start going crazy until gas shuts from safety and try to restart, but does thru same thing.
I have two furnaces like that, so I swapped all possible sensors, they all good. What's left its the board, or the valve itself. I will swap the board today and see.
I just do not understand - did the original poster opened actual relay on the board to clean contacts?? I dont think on newer board will you could do that. but i'm sure I could buy new board for like $150. I just hope its not the valve, cause I would not want to deal with gas piping to replace it.
Could you please update me what happen in your case?
 
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Old 12-10-10, 07:03 PM
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And you cleaned the flame rod?
 
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Old 12-11-10, 06:04 AM
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if you see a constant 24V on the top of that valve and its dropping out the coil is weak within it change the valve..i
 
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Old 12-12-10, 03:58 PM
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All set now

I finally found an HVAC guy who knew what he was doing, he was the third I tried. He cleaned out the burners - said they were really dirty and a lot of corrosion and crud came out. Once he did that, the third burner fired up relilably rather than sporadically. Then he cleaned the flame rod since its output had been low.

What was happening - the last burner (the one with the flame rod) wasn't getting enough gas flow. That along with the dirty flame detector was intermittently shutting down the gas valve, hence the clicking and clacking and shutting down. So the furnace is fixed without having to replace any parts. $216 and done.

Unfortunately I paid the guy before him $346 and it got me nothing. He claimed to have cleaned the burners but apparently he didn't do very well. In fact, he said they weren't that dirty. The last guy said they were packed with crud - he must have been right based on results. Also, the old guy was the one who said I needed a gas valve and it would be $910. Glad I didn't let him at it - I'd be at well over a grand and still have a bad furnace! It was then I wanted a second opinion. Glad I got one. It's nice and toasty in here now.

BTW, the new guy did a lot of testing the first didn't - he measured gas pressures, voltages, singals, safety sensors. That's how he knew for sure what is was. The other guy was just guessing, at a cost to me of $910. What' sworse, the gas valve has three push-on color-coded wires and two gas fittings. The part was $221. He was charging $689 labor for what amounts to a 15 minute job? Yikes, you gotta really watch these guys. A lesson learned.

Whew!
 
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Old 12-12-10, 04:06 PM
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Send the first guy a copy of the second guy's invoice, which presumably described what he did.

Ask to have your money refunded since he didn't do a competent job of diagnosing the problem or cleaning the burners.

Heh, heh! I'd LOVE to see you appear on Judge Judy with this case...
 
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Old 12-12-10, 04:10 PM
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This is a good example of why it's usually a mistake to revive old threads because "the problem is the same." The problem is usually NOT the same, and it causes confusion to have multiple posts on one thread.
 
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Old 12-12-10, 07:14 PM
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Sounds like you found a good tech! Keep his number for next time down the road!
 
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Old 12-12-10, 09:15 PM
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classares,


Heh, heh! You are a BAD BOY for not telling us one of the burners wasn't lighting reliably! That was very important information you apparently noticed but didn't post.


Had that been posted, we would have been zeroing in on the burners like a duck on a Junebug!
 
 

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