Strange Rheem Criterion II furnace problem - http://www.hvacmechanic.com/ Forums
Original message
| jasonw6
 |  "Strange Rheem Criterion II furnace problem"
, posted Wed 5 Nov 15:28  
Hi all, I have a Rheem furnace criterion II that is behaving a bit strange a month ago. When thermostat calls for heat, it will turn on and run its cycle and produce heat, everything seems working fine. However the problem is when furnace stops and within a minute, it will start this cycle again. One time I was watching the furnace (when it starts second time), it will produce flame and then after 20 seconds, flame went out and just fan keep running until it stops. It will NOT do this foreever, sometimes, it will do it one more time, sometimes, twice, and sometimes not at all. I thought it maybe thermostat problem and I replace it with a new one (automatic), but it behave exactly the same so looks like not a thermostat problem. It happens when the room temperature and the target temperature are very close (like 1F or same degree). If there is a big gap of several degrees, it will run continuely for a while (but I did not pay attention whether it will recycle itself after a long run). This is more apperant when I use it in A/C mode, the A/C will cool and stop, and after a minute, start again.
Any help is greatly appreciated.
Jason
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Replies:
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| SAVED
| "Re(1):Strange Rheem Criterion II furnace prob" , posted Sat 8 Nov 23:27:
is it a heat pump
Joe
[this message was edited by SAVED on Sat 8 Nov 23:28] |
| | wingnut_2u
| "Re(3):Strange Rheem Criterion II furnace prob" , posted Tue 11 Nov 21:25:
If the hole behind your thermostat is not plugged the negative pressure in your house will draw outside air from attic through your wall and accross your thermostat effecting your setpoint. :)
also sounds like your stat is close to a heat/cool vent or draft
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Masters Heating & Cooling
Caldwell/Boise Idaho
Always call a certified HVAC Professional when you are unsure on how to do it yourself.
[this message was edited by wingnut_2u on Tue 11 Nov 21:30] |
| | jasonw6
| "Re(4):Strange Rheem Criterion II furnace prob" , posted Wed 12 Nov 09:43
thanks for your reply. I will check into that.
Last night, it did its thing again. this time, I got up and stand next to the thermostat to find out what is going on. when the thermostat calls for heat, the furnace kick in and works fine. However, when the furnace stopped and restarted in about 1 minute, I did not hear the "click" sound from my thermostat, which means that it is NOT the thermostat which cause the furnace to stop and restart. All this time when furnace was recycling, the thermostat is always on (calling for heat, as it was not satisfied with its temp), so it must be something inside furnace that was causing the furnace to stop and right after that, because thermostat is still on, so the furnace starts again. It is doing this over and over until the thermostat is happy with the temp and turned off furnace, then this complete its cycle (this is why it seems no regularity on it as in my first post).
I did a bit reading and saw there is a some kind of limit switch inside furnace which can turn of furnace if it malfunction, and I saw on a book one can adjust its spread, but my furnace is rheem criterion II and there is no adjustment disc on it. All I can see is a small disc (size of quarter) that has two wires leading from it (actually, there three such things).
I am wondering if I can bypass this switch just to diagnosis the problem (i.e. connect the two wires directly, bypass this switch). I am not sure if there are safety issue, but this is only for diagnosis, maybe I have to do it three times (one for each).
Is there a way to clean this thing ? if so, how, just by cleaning cloth ?
thank you very much for the help.
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