Our Armstron (magic Chief) oil furnace keeps shutting on and off during the heating cycle.
I will try to help, but a little more info would be great, when you say it shuts off, it is important to determine if it is the burner or the blower that is shutting off.
If the burner is shutting off and coming back on, the safety "fan and limit" control is getting to hot,,
If what I have listed above, there are several things that can cause it;
1. The first step is to make sure that the air filters are clean, the return air grills are clear, no objects covering them.
2. This part needs to be approached with care, Turning off power to the furnace is a must; then clean the blower area, and if it is a belt driven blower setup, inspect the belt, looking for cracks on the surface that makes contact with the pulleys. If the belt is old, it may be stretched and slipping on the pulleys, reducing the air that is being blown across the furnaces firebox, this will cause the furnaces safety "fan and limit" control to over heat and shut off till it cools off, then it will turn back on.
If the blower is the one that is shutting on and off, you would notice this at the supply registers in each room, air blows, then stops. This usually caused by really cold air blowing across the firebox, like after the house has been cold - over night, and usually will start operating more along the normal side of things as the home warms up.
Either the blower is moving to much air, blowing strongly in each room, or the furnace has been reducein it's firing rate - derated - a smaller nozzle being installed would be the main cause.... this is the first thing to check,,, if that doesn't do it, it would be highly recommended to have a experienced repair person look at it.
Remember when working in the blower area, please turn off the power to the furnace to save the fingers.
I hope this will give you a game plan.
Have a great evening.
Mar 30, 2010 |