I would take out the new stat and return it.Just because it was new doesn't mean it didn't have a factory defect. I see this all of the time buying a/c and Heater parts that I have to return for credit.
Good Luck, Shastalaker7
PS It sounds to me like you know whats up.Sincerely, Shastalaker7
Hi, This is frustrating for you I know as I went through this on a wall furnace to where after the stat was replaced it would be fine for a few days and repeat itself again. The stat gets is power from the pilot generator or thermopile 750va generator. Pull the cover off of both and you should see a high limit switch at the top, It has a wire terminated on one side and out the other, same wire and it goes down to the gas valve. Check this disc type High Limit switch for signs of heat damage and wire damage from the heat rising.These wall heaters are milivolt heaters and if you have any problems with wiring from the thermostat back to valve, limit switch, or the 2 wire on the generator, you will have this problem. It is difficult to trouble shoot this kind of problem as it works when you replace the stat? so, If you have to pull out the 2 wire Gen. and replace the limit, do this. If you were to remove one of the stats from the wall and expose the 2 wires, touch them together and I bet the unit will start! This indicates the stat is bad, but its not. If you continue to touch the wires together on off/on/off several times, see if it will finally stop.Replace the limits and pilot gen., after checking all low voltage wiring. This should take care of both of them.Let me know what you find. I dont believe you have problems with the gas vale coils. We will see.
Shastalaker7
PS These parts are very inexpensive. Think about the problem, they work fine for a few days after you replace the stat. Then stops? It has to be the wiring, as in control wiring, generator, high limit at top inside furnace cover. The generator supplies the voltage when the bulb is heated , physics.
Shastalaker7
Hi there, the repairman is incorrect about the thermostat saying it was wrong. Even though the t-stat is for a 24 volt unit, they are also used on millivolt wall heaters also. Yes the Limit switch that I told you about located above all else is a safety device to shut everything down if the stat were to go haywire and keep running.By bypassing this limit if it is a problem, it should fire up and work. You can also test the stat again just by jumping the 2 wires together. If the heater starts up, the stat is faulty.I have seen this problem over and over again on these gas wall furnaces. The last thing that I did to repair and keep the unit on-line, was to change out the gas valve it self. It has something to do with the thermopile generator not putting out just the right amount of voltage to keep it up and running.The coil on the gas valve may be weak. I am sure this is frustrating for you as it is to me, but try and replace the gas valve, and the 2 wires coming from the pilot generator, look at the schematic with the valve and make sure you have the 2 wires, red and white in the right place. It will work in either position, but if they are wrong, it will cause this problem.Try switching them now, before you decide whether you will change the valve or not. Please let me no as I will look into this continuing problem for a lot of folks.Sincerely,
Shastalaker7
Hi, I just saw the generous rating you gave me and I am delighted!! I hope I was of help to you as I have been through this time and time again on the wall units. I have contacted one of the manufacturer's and told them about this re-occurring problem. I am a licensed contractor in this field, # C-20 and I want to know if there has been a recall or if they have made any kind of changes we should no about. I am still waiting for a reply wouldn't you know, LOL. I wanted to wish you and you're family a Merry Christmas and Happy New year, and hope you will continue to use us here at Fix-YA as we are here to help in any way we can.
Sincerely, Shastalaker7
×
Part no 84166 is a 'blocked flue switch' and it's job is to make sure you are venting exhaust gases properly through your vent pipe system. IT IS EXTREMELY DANGEROUS to bypass this switch to make your furnace work. If for some reason the exhaust gases going up your vent pipe slow down due to blockage (speed based on heat,convection air flow) the temperature in the draft diverter area will rise (84166 is rated to open @ 350 degrees). I usu see this part show high resistance when cool. It's just a temp controlled on/off switch and if it has higher than a few ohms internal resistance when cool, should be replaced w/proper substitute.Again, for your own safety, you should never bypass any type of safety device on your furnace. P.S. If you burn your house down this way, I wonder if your insurance would cover it if they found out what you did.
I have exactly the same problem with my Cozy. Usually poking at the switch connections makes it start up, but I'm not sure if it's the connections themselves or the switch that has something hinky inside. Just called a local parts place who quoted me $26, which is completely insane for this tiny thermo switch (Cozy part 84166).
I'm going to bypass the switch for a week or so and make certain it's the switch before I try to find a better parts solution, but I agree that it's a design fault. That switch and its wires and connections take an awful lot of heat, and I suspect the tiny voltage from the thermocouple just isn't enough to overcome hinky connections. (my last effort was to coat the lugs with solder, so that the connectors would have a good ohmic connection to bite into the soft solder, but it doesn't seem to have helped.)
3,307 views
Usually answered in minutes!
I have the same problem with both of the W355F I have in my home. I have replaced the thermostat on one heater three time and twice on the other but the problem reoccurs.
Follow to the problem above:
I had a heating guy come out to look at the heaters and there were two problems that once resolved cured the heaters.
First, the thermostat needs to be of the correct voltage. Apparently using a generic therm that does both heating and cooling will burn out over time. I don't know if I believe this (because the problems started while using the original OEM therms.)
Second, the placement and quality of a switch that is located where the thermostat and heater meet (higher up on the heater, not near the pilot) is suspect and tends to "go bad" easily because of it's placement. Once we by passed the switch (while waiting for a replacement to arrive) the heater went back to normal operation.
Thanks for you prior suggestion.
×