[sbilja]

Hi all,

I found this forum full of helpful answers, so I'm hoping will be able to get some ideas on what could be wrong with my heating system.

Iam using forced air furnace, that was working fine last year blowing hot air. However, this fall soon after turning it on, cycle starts but blowing the cold air first for like few minutes, and then heats up blowing more warm to hot air. Once I turn it off, fan is still working for few minutes, again blowing cooler air before it stops.

Also, the following is still puzzle to me, since Im not familiar with the whole Heating/AC system, there are two vents in two different rooms that hot air is coming from, and one seem to be blowing in full force, while another one is mild almost no air coming out, although when you put your hand in it, you can feel the warm air. Also, there is vent toward the outdoors (balcony) that seems to be blowing hot air at the same time, way stronger that I can get in this room.

Any ideas as to what could it be, and what parts might need inspection?

Thanks for all your advices,
S-Bilja

[letmetellu]

I will go through the cycle of a heating cycle of your furnace. The thermostat feels that it is cool in the house, it tells the furnace to bring on the heat, (I am assuming it is a gas furnace) the furnace then lights and burns for maybe 30 to 45 seconds and then a motor comes on that blows the hot air out of the furnace into the ducts. The ducts are full of cool air so the first air that comes out will be cool followed by the hot air that the furnace has heated. The warm air reaches the thermostat and it tells the furnace to turn off the burners of the furnace, the blower continues to blow for another minute or so to blow all of the heat out of the furnace and then it cuts off. That is one complete cycle.

Now about the two grills in one room, it may be that this a large room and the builder felt it needed two grills to supply the heat needed for that room. The reason that you don't feel the same amount of hot air coming out of each one is that the one with the lesser air may be closed or at least partially closed. Check to see if you can see that it is completely open. You also may want to close the vent that is blowing so much towards the balcony.

[labman]

Modern furnaces have timers meant to prevent the problem. I am having trouble figuring out why it isn't working like it did last year. If a bunch of crud built up inside the heat exchanger over the cooling season, the same timed delay that worked last year, may not be enough this year. I am not sure the inside of modern heat exchangers is easy to see, let alone clean. If it is crudded up, you may have a nasty shock when your heating bill comes.

If the vents were always that way, you might look for dampers in the ducts.

[sbilja]

Thank you so much for your answers.

If there is a problem with build up crud, would there be some professional maintenance solution to it, or I would have to go for replacement? I have no separate gas bill, as we all pain monthly maintenance fee in the building. However, that does not mean I do not care for keeping gas usage/cost at its minimum. On contrary.

And you were probably right about warm air how it is distributed between the rooms, as one is double size than the other. It is the only thing that balcony exhaust blows more warm air that I can get in my bedroom, and I have no access to that one since it is behind the cabinet (heating system). I can only see it or feel the air when on the balcony, behind the metal screen. Building itself is 12 years old, so I wouldn't know does it fit into modern category :) but thanks for sharing your thoughts and ideas.

S-bilja

[NorthEastSolutions]

No one answered her question! I have the same problem, The indoor fan comes on first, then the draft inducer motor, then the gas fire! My furnace is a Goodman GMT-070-3 and I replaced the igniter last year, then the inducer motor this year... then I saw the funky startup sequence... I will look in to this issue more and tell you what I found. All fingers point to the control circuit or the "make one furnace act like two" control---:) I bet is I change the thermostat the fan would not come on before the gas fire...

[bkspero]

No one answered her question! I have the same problem, The indoor fan comes on first, then the draft inducer motor, then the gas fire! My furnace is a Goodman GMT-070-3 and I replaced the igniter last year, then the inducer motor this year... then I saw the funky startup sequence.... I will look in to this issue more and tell you what I found. All fingers point to the control circuit or the "make one furnace act like two" control---:) I bet is I change the thermostat the fan would not come on before the gas fire....

If your indoor blower is going on before the exhaust inducer fan, it is almost certainly a problem with the control board (can't think of another cause, but hedged because nothing is absolute). I had one fail in a way that caused the indoor blower to go through a cold cycle without randomly when the thermostat was not calling for heat and without triggering any other portion of the heating cycle. On a Goodman GMP-075-3 furnace. Replaced the control board and it has been working normally for some months.

[pieceagle]

Some circuit boards have delay controls. One to delay the fan on startup and one to delay fan on shut down check the settings. Manual should let you know the settings

[rdube60]

Handler on the second floor the coil in side is cold pump is running in the basement and is hot not reaching second floor?