HVAC question.

[Nodpete]

Have you checked the filter ? A dirty filter will restrict the air.

[brownbagg]

if you can get twenty degrees different from outside, you are doing good

[kokonutty]

Do the easy stuff first. Like Nod said, check to see if the filters are clean. Check to see if the registers are open. Check to see if hot air is escaping into a basement or attic due to an open duct. See if any registers, or returns are blocked by furniture. See if uninsulated ductwork runs through an uninsulated area. If you have a big sofa or something up against a return there won't be enough air going through the system. Anyone should be able to figure out the direction of flow from and back to the furnace and then trace where heat is lost just by feeling where it is hot and where it is not.

[JohnnyMack]

REALLY simple stuff first ... What are the outside temps like? Have you closed all the windows for the winter months? Are there drafts ? Go to where the furnace is and listen to it when the flame comes on and when the blower kicks in.

While at the furnace check the filter, depending on YOUR case it should be changed/cleaned every one to six months.

OCCAM'S RAZOR fits in a lot of cases.

How much your bill is doesn't matter much without knowing usage and price per unit.

[miltner]

Originally Posted by brownbagg

if you can get twenty degrees different from outside, you are doing good

Temperature rise is measured using supply air versus return air, outside temperature has nothing to do with it. When heating the temperature rise should be much greater than 20 degrees for a single stage gas furnace. A heat pump can have a temp rise closer to 20 degrees, but again that is supply vs return, not outside air.

[QIS]

Can you actually hear the flames igniting and functioning? If so- try and hear if the burners are cycling on and off.

[gcretro]

I had an issue where the burners would cut off / cycling on-off. Fix was simple DIY, the flame sensor (a thin rod that stick out into the flame) was dirty had some white gunk.

[chet everett]

Originally Posted by miltner

Temperature rise is measured using supply air versus return air, outside temperature has nothing to do with it. When heating the temperature rise should be much greater than 20 degrees for a single stage gas furnace. A heat pump can have a temp rise closer to 20 degrees, but again that is supply vs return, not outside air.

The output in the plenum for many many forced air furnaces is often around 125, depending on airflow / insulation that may drop below 100° by the time it reaches the furtherest ducts.