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Ruud rgfg

BillspagBillspag Member Posts: 2
Does anyone know if a ruud rgfg has a post purge . Recently installed furnace with single stage tstat run for a minute at hi fan speed at the end of the call for heat.both the fan and draft motor do this .


  • furnacefigher15furnacefigher15 Member Posts: 502
    This is normal

    Almost every gas furnace has a post purge
  • John MillsJohn Mills Member Posts: 747

    One of the best furnaces on the market with modulating up & down is crippled by a single stage stat? 
  • alotlikeearlalotlikeearl Member Posts: 68

    The single stage T'stat certainly limits functionality but I'm not sure it "cripples" the furnace.  You still get three stages of operation; 40% for 5 minutes, 65% for the next 7 minutes and 100% therafter.  As Adam Sandler would say, "not too shabby."

  • John MillsJohn Mills Member Posts: 747

    The Rheem mod with 13 stages of heat that will stage up and down (at least 1 brand won't stage down) nearly perfectly can follow the heat loss of a house if properly sized. Yes, you get 3 stages, 2 briefly, with a single stage stat but since you time up to high and stay there, you lose most of the comfort advantages of that furnace.

    Look at it this way: in your car on a cold day, do you constantly play with the controls or find a gentle setting and leave it alone once the car is warmed up? Well, most will find a nice low setting and leave it alone. If you have auto climate control, that is done for you. The mod with proper control is like that too. It may sit at 40% capacity all day long. Perfectly even heat, usually inaudible. Like hydronic heat!

    But with single stage stat, you quickly pass 40%, 65% and sit on high til the stat satisfies. Then the house gets cooler and the cycle starts again. Over & over. Do you turn your heat in car completely off only to turn back on in a few minutes on a cold day? No. Why not? It's not comfortable. Same with the house. And frequent cycles aren't as efficient.

    I never had people rave about a furnace until this one. All mine went out with the matching stat.
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