Gas and Oil Home Heating Furnaces - gas fired furnace/cold air
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11-26-00, 11:17 PM
Blower on gas fired furnace comes on after burners come on, too soon. Sometimes, blower does not shut off when room thermostat temp. is reached and when burner shuts off...continues to blow and air gets cold.
I can manually switch the blower fan off at the unit. What is wrong when I turn blower back on and it still runs? It is not supposed to come on until the temp. is right inside the heat chamber, after the burner comes on, right? Is it the limit switch and what adjustments can I make on it? This does not happen all the time, but is sporadic.
thanks, please advise.
I can manually switch the blower fan off at the unit. What is wrong when I turn blower back on and it still runs? It is not supposed to come on until the temp. is right inside the heat chamber, after the burner comes on, right? Is it the limit switch and what adjustments can I make on it? This does not happen all the time, but is sporadic.
thanks, please advise.
PDF
11-27-00, 07:55 AM
SOUNDS LIKE THE FAN LIMIT SWITCH TO ME.IF YOU HAVE NEVER TOUCHED OR ADJUSTED IT,IT'S TIME FOR A NEW ONE.REMOVE THE COVER CYCLE THE HEAT ON AND WATCH THE DIAL.IT SHOULD ROTATE AS THE UNIT HEATS UP,HIT A TAB AROUND 140 DEGREES AND CYCLE THE BLOWER ON.TURN THE UNIT OF,THE DIAL SHOULD ROTATE THE OPPOSITE POSITION SHUTTING THE BLOWER OFF.IF IT DOES NOT,GENTLY ROTATE IT IN THE DIRECTION IT WAS GOING AND SEE IF SHUTS THE BLOWER DOWN.PDF
11-28-00, 05:18 PM
Turned out to be the a breaker.
The blower was running but no burner. I turned it off manually, but when I turned the switch back on it would run again even though the t.stat was not calling for heat and there was no "fire".
It has a reset button on the blower which was depressed and would not reset. I left it off all night, the next morning I turned the blower switch on and this time it stayed off as it should. Then, I turnedthe t.stat up but the burner did not light. The pilot was lit.
I thought it might be a bad transformer or bad t.stat.
I finally turned the main breaker to the house off....and then on again. This time the burners lit and the blower came on everything worked fine.
so, where was the problem? the breaker? When I thought the t.stat was defective, was it just no power to it? How would I have been able to detect that problem or determine if it were the transformer?
The limit switch is a fan time delay switch on the unit with a tiny screw to adjust, no visable dial turning as the heat rises or falls.
The blower was running but no burner. I turned it off manually, but when I turned the switch back on it would run again even though the t.stat was not calling for heat and there was no "fire".
It has a reset button on the blower which was depressed and would not reset. I left it off all night, the next morning I turned the blower switch on and this time it stayed off as it should. Then, I turnedthe t.stat up but the burner did not light. The pilot was lit.
I thought it might be a bad transformer or bad t.stat.
I finally turned the main breaker to the house off....and then on again. This time the burners lit and the blower came on everything worked fine.
so, where was the problem? the breaker? When I thought the t.stat was defective, was it just no power to it? How would I have been able to detect that problem or determine if it were the transformer?
The limit switch is a fan time delay switch on the unit with a tiny screw to adjust, no visable dial turning as the heat rises or falls.