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rheem 90 will not stay running

I have a Rheem 90 Imperial plus furnace that is about 16 years old and was in the house when I bought it. Here is my issue. We have had the house for two years and noticed the first winter we were here the furnace would shut off throughout the night for no apparent reason. At first we would just shut off the furnace at the thermostat and turn it back on and it would relight, then the problem became worse and we were restarting numerous times throughout the night. I called a furnace service in the area and they sent out a tech. I went with him to the furnace room and after explaining the problem I watched him take a small tube off of a round metal item which had some sort of diaphragm in it and blow into the tube. After replacing the tube the furnace would relight and the issue seemed to be resolved. Well after several more nights of having to restart the furnace by blowing into the tube myself I called them again. They returned and replaced the metal part with a round black plastic item and said the issue should be resolved. Once again it was night after night of waking up in the cold and restarting the furnace. The returned and after a third service call he replaced the thermostat and it seemed to have solved the issue. Now that fall has arrived and I have once again began the struggle with restarting the furnace by blowing into the small tube coming from the newly replaced part. If you have any answers please let me know.  


  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,565
    edited October 2012
    wrong section

    try to repost this in the controls, or gas section here, as this section is for hot water heating.

    it seems as though you need a new service company to help you with this.--nbc
  • Techman
    Techman Member Posts: 2,144
    edited October 2012
    rheem 90

    Somewhere on the unit is a "condensate" trap that collects the condensed flue gas moisture. The trap is usually black plastic . Shut the off by the emergency switch , remove the trap wearing rubber gloves , and wash out the trap w/plenty of water, lots of "stuff"should come out .If yes then that was ur problem. Do not blow into this trap as the water is acidic.
  • D lux_2
    D lux_2 Member Posts: 230
    Is this a drum type excanger

    If so the flame rectification is done through the hot surface Ing . some times you can brush the HSI off enough to have a good signal if that works replace it . do not break it handle like bone china, If its a tube or clam shell exchanger clean the flame  sensor . it  has  1 wire going to it and looks like a bent pencil lead sets in the flame likely on the left end burner .  next blow in the red tube on the presser  switch to see if its open to the exchanger or the inducer
  • John Mills_5
    John Mills_5 Member Posts: 935

    the model #? 
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