Installing thermocouple in Williams 3508732 wall furnace

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  #1  
Old 06-15-19, 02:06 PM
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Installing thermocouple in Williams 3508732 wall furnace

Hello:

I was having the classic pilot will not stay lit problem with my Williams wall furnace, so I purchased a replacement thermocouple and went to replace it, but for the life of me, I cannot see how to remove the old one without separating the two halfís of the combustion chamber, which looks like trouble.

I must be wrong, so please help if you have any experience with this wall unit model and thanks.
 
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Old 06-15-19, 02:13 PM
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Looking at the manual..... it states to remove two screws and pull out the burner assembly.
The manual is in the link below. Pictures of your unit are helpful too....... How-to-insert-pictures.

Williams furnace manual (pdf)
 
  #3  
Old 06-20-19, 12:45 PM
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Corrected model number

I finally was able to reach back with a small older phone to take a picture of the mfg tag on the furnace. The model number I provided was wrong; the correct model number is 5507332. I noticed the manual provided did not include that model. I found the manual online but it was no help (contact service rep, etc). As in the other manual, it says to remove the three screws to access the burner assembly. There are no three screws to remove to gain access.. It seems to have an enclosed combustion chamber that is made up of two clamshell pieces with a seal in the middle. Iíve attached photos to make that clear. Iíve looked around the top and bottom and cannot ascertain how you get access to the combustion chamber unless you removes all 6 screws and each of the side panel screws and then crack open the chamber. Iím worried about doing that because I donít know what the seals is made out of and I canít find the seal online to buy.

There is a small, about 3/4Ē access hole with a glass cover to see the liting of the pilot. I can see inside the pilot burner, the electronic ignition wire as well the thermistor wire (looks like the part I purchased to replace). Iím stuck how to proceed.
 
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  #4  
Old 06-21-19, 04:02 AM
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I am confused about the part you are trying to replace. I never worked on your exact furnace model, have been retired for 12 years but will try to help. My questions are; what is the part you are trying to replace, give description and part number? How old is this wall heater. Is it a direct vent as the literature says? What problem are you experiencing? You said "thermocouple", it has a sensor and not a thermocouple. The sensor part number is P271100 as per the manual. And be careful just what you take apart, since this looks like a sealed combustion unit with gaskets on everything, and I doubt that you have to remove the burner to replace the sensor. Post a picture of the part you bought. Pages 46 and 47 of the instruction manual shows the steps to take to trouble shoot pilot problems. These types of units are a pain in the butt to work on so be careful.
 

Last edited by Steamboy; 06-21-19 at 04:22 AM.
  #5  
Old 06-21-19, 03:31 PM
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Ok, so I will try and answer your questions. This wall unit is at my cabin in the local mountains, so I donít have access daily. There are two identical units, installed in 2005; one on each floor of the cabin. When I purchased the cabin, the owner gave me the temperature sensor for this furnace with the receipt from a local HVAC house. He was upfront that he was having trouble getting anyone to make a service call. But when I had a home inspection, the unit worked fine. It worked fine for 2 years and then, every once in a while, is started not starting correctly. I should mention that my father was 40 year heat and air, so I know a little bit how these systems work, just short of wall heater experience (first placed Iíve owner with one, all other properties have central heat).

Initially, I took the unit completely apart and found a nest in the exhaust on the outside. I replaced the screen to keep the pests out and suspected the flow restriction might be causing the problem but it didnít. The problem you ask is, the gas valve opens, the ignition sparks, the pilot lights and 2 or 3 seconds later, the gas valve shuts off the pilot. The system tries to reignite the pilot, but the gas valve does not appear to open and all you get is 30 seconds of ignition attempt that must be the units cycle. Since I have two exact units, I swapped the electronic unit from one to the other and that resulted in the same problem, eliminating that control unit as the issue (I was hoping). Since the temperature sensor is designed to send a micro current to the gas valve and without that current, is designed to shut off the gas to the pilot, it is the most logical component that has failed. But, how do you remove it to replace it. I did call the same HVAC house and gave them by correct units model number. They confirmed I have the correct temperature sensor for the unit.

But after all of that, I still see no way into the chamber to replace it unless I remove all of the screws and break the seal of the unit.

At about $1900 on sale, I might be better off replacing the unit since I can not locate one local business who is even willing to return my phone call, zero response of the three Angie List contractors I called and left messages with.

What would you do?
 
  #6  
Old 06-21-19, 04:36 PM
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First item; the manual PJ indicated is not the correct one, sorry PJ. Instead go to.(williamscomfortprod.com/product/forsaire-furnace) and on the right column of the literature click on-- English manual direct vent under the manuals heading. scroll down to pages 30, 36, 38, and 40. Other pages may apply . On page 38, it looks like that you remove the 2 screws holding items 46 &47 and the pilot tube connection and pull out the pilot assembly. That part has a gasket that may offer some resistence. As I said, I never worked on any Williams heater just heaters similar in construction. Pages 46 and 47 give suggestions on trouble shooting. Also on their home page you can click on "find a rep" who may be able to help find someone that specialises on their heaters. Try it and let me know. It would be great if I was there.
 
  #7  
Old 06-21-19, 08:28 PM
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As I tried to show in the pictures, the entire clamshell combustion chamber unit does not have any parts attach into it with screws, not 2 or 3. The pilot tube, ignition wire, and temperature sensor wire come into the bottom of the clamshell unit and there are no screws or any visible item attaching them to the clamshell, there are just holes with fiber washers to seal the hole around the wires or the tube.

I have the manual for this unit and it has been no help. I will try the rep part to see if I can get someone out.
 
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Old 06-22-19, 02:46 AM
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The next to the bottom picture and the bottom picture show the pilot tubing and a red wire and a small metal plate. That small plate with the 2 holes in it looks as if the 2 retaining screws have been removed. I would see if that small plate will move by trying to insert a small screw driver or putty knife between the case and that small metal piece. Sometimes a sticky substance is used on the gasket or mating surfaces to help seal the access point. That small plate which is probably the pilot mount should be able to be removed for access to the pilot. (My guess) There has to be a way to access, service and replace the pilot and sensor. Lastly I would call the Rep. Good luck
 
  #9  
Old 06-22-19, 03:26 PM
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Whatís weird, is under that plate are two small holes, one for the pilot gas tube and one for the red wire, which is the ignition source. It must be a gasket or seal because when I removed it, it was glued or bounded to the bottom.

I did get lucky and talk to a rep yesterday. He said he doesnít service them. When I reminded him his name was provided by the Williams website, he said, and I quote, ďI mean I donít service those units.Ē

So, Iím still trying to find someone to put eyes on it but Iím losing hope. And remember, this exact unit is available for sale at the local HVAC house.
 
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Old 06-22-19, 03:38 PM
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@ steamboy
First item; the manual PJ indicated is not the correct one, sorry PJ.
That's because the OP originally left the wrong model number.

I've been out on service for two days and haven't got a chance to look up that heater BUT if it only has a gas tube and an igniter wire..... it doesn't have have a thermocouple. It is direct spark ignition. There is basically nothing to replace in there. That's why it's not easy to open.
 

Last edited by PJmax; 06-22-19 at 04:47 PM.
  #11  
Old 06-22-19, 05:02 PM
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Pjmax, it has three items coming into the bottom, the pilot gas tube and igniter (the pic with the alum tube and orange wire) and the temp sensor (the pic with the white wire).
 
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Old 06-22-19, 06:48 PM
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Is there only one aluminum gas line going into the burner ?
I only see one in the pictures.
If yes.... that can't be a pilot line. You would need a pilot line and a main burner line.
 
  #13  
Old 06-22-19, 09:15 PM
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Looking at the unit, the main gas line penetrates the bottom clamshell in the left, rear section. The penetration has a fiber seal around the line and the hole; a very tight looking fit.
 
  #14  
Old 06-23-19, 04:57 AM
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Steve; in your #9 post you said that It must be a gasket or seal because when I removed it, it was glued or bounded to the bottom. So , were you able to get the pilot out of the unit and if so did the sensor come out with it? Oh, and sorry PJ about the statement of the wrong booklet. I did not know that you still worked. I thought you were "retired" like me and I had to jab you. Steve, you could also go to the trouble shooting area of the book and try some of their tests. The problem may just be a partially plugged pilot , air of gas side, that needs to be cleaned.
 
  #15  
Old 06-23-19, 08:35 AM
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Steam boy, when you remove that ďcoverĒ, there is no access. What it seems like, is the internals of the combustion chamber were built and the clam shell was sealed behind it, making any maintenance only possible by reversing that process. Thatís all I want to hear from a technician and then I want to know what the seal of the two halfís are made from so I can proceed. If a technician can get that material, so can I.

Ive done all of the diagnostics on this; itís the flame sensor. Or itís a faulty gas valve, but thatís very unlikely. Does anyone know anyone who may have the true service manual for this unit? I couldnít find one on the internet. Iíve also asked Williamsif they have one, would someone be so kind as to scan the pages for me. Who knows, it may work lol.
 
  #16  
Old 06-24-19, 02:33 AM
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Did you try the web site I listed in my #6 post--williamscomfortprod.com/product/forsaire-furnace) . and on the right column of the literature click on-- English manual direct vent under the manuals heading. scroll down to pages 30, 36, 38, and 40. Other pages may apply . This is as close to what you describe that I can find. I would call the rep again and ask him for the name of a service company that can help you. There has to be someone. Also ask him if the mfg has a direct phone number that you can call. If they do, call and ask to speak with one of their service people. They sold the unit, there has to be someone that can help. Lastly, on page 38 the gasket shown is item #48 and page 40 lists a gasket part #P101600.
 
  #17  
Old 06-24-19, 02:23 PM
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So, I finally got through to someone who could help. It was the local HVAC co. that sells these units. The owner of the company called me and told me how to fix it over the phone. If you look at the exploded illustration of the furnace, the entire combustion chamber and flute are one part, with the bottom ďbowlĒ as he called, is attached with 6 sheet metal screws and that gasket. He said that gasket, after a very short use, welds itself to the seal and is very difficult to remove the bottom bowl from the rest of the assembly. He said thatís why no one will return my call. He also quizzed me on the issue and agreed, itís exhibiting classic flame sensor malfunction.

So, I ordered the gasket and will await it. Iíll try to take pictures and make notes to post later as a ďhow to fixĒ on this type of model. He told me itís one of their best sellers and they typically have maintenance free issues (with the natural gas units), but I had that nest restricting gas low, so he thought that could have caused the problem.

So, wish me luck. If I break it, it goes from a $30 repair to a $1900 repair. Lol.
 
  #18  
Old 07-04-19, 08:16 AM
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Problem solved.

Ok, let me explain. As the pictures try to illustrate, the problem was not as obvious as I expected. As you know, I set out to replace the temp sensor or the flame sensor on the unit, requiring the complete removal of the combustion chamber and stack. While I was removing the items attached to that, I had to remove that black cover you see in the pic. That allows you to uncouple that piece from the exhaust pipe. When I did, I discovered the nest in the second picture. To say the pipe was stuffed with that debris doesnít come close. It was difficult to remove because I was so full. After I did, I decided to test it and of course, it worked fine.

So now I have a flame sensor and combustion chamber gasket in case someone needs them. Thank you to you guys and the HVAC dudes at Redlands & Henry Bush Plumbing, Heating and Air Conditioning.

Now Iíve got to redo the exhaust pipe vent cover to keep whatever built that nest out.
 
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