Furnace & Heat Question

[brucebanner]

Just wondering if anyone would have a reason as to why some vents in my house blow cool air and why others blow warm (like they should be). For instance, last night the house was nice and toasty, so I had to turn the heat down a little bit, but as a woke up this morning, it was a bit on the chilly side, and I definitely did not change the heat that much.

So if anyone has any ideas/explanation, I would appreciate it.

[lint]

Does your furnace have an option to continuously circulate the air even when it's not heating?

[Cos]

+1 check that your fan is on Auto not On

[brucebanner]

Yeah, I guess I should have mentioned that as well. I do have that option, but I leave it on "auto".

[Cos]

So I just re-read your first post. Do you mean that the same vent sometimes blows cold air and sometimes blows hot? or do you mean that certain vents blow hot and certain vents blow cold?

[brucebanner]

This.

Originally posted by Cos
that certain vents blow hot and certain vents blow cold?

However, I just went and cycled the power to the furnace again and it seems that everything is working normal.

I notice it most often from the living room to the half bath. It will be blowing cool in the living room, but be the opposite in the bathroom. Both rooms are on the same level and close to one another. So it doesnt make much sense to why it would happen that way.

[Cos]

So do they always blow cold? it doesnt sound like it but I just want to check.

How big is the house? Do you have two furnaces?

[masoncgy]

How old is the house? Is this a high efficiency furnace?

It could be a ducting issue. Sometimes the placement of the furance vs the length of ducts to certain portions of the house result in certain areas being 'too far' from the heat source & blower, resulting in some places getting more direct heat than others.

I had this issue in my last house... the right side of the house, closest to the furnace always had the warmer heat... the left side was cooler & had far less air movement coming from the registers.

[Kloubek]

Is it possible that you're noticing the blowing air before the furnace has a chance to heat it? When mine first turns on, the air blowing out is cool.... then after several seconds it gets warmer.

I'm wondering if this is impatience on your part as opposed to a faulty HVAC system...

[Ven]

My house does this too. By the time with warm air has made it to the farthest outreaching vents it's lost so much heat through and into the pipes, it feels almost cool. Our furnace is HE and size spec'd for the house, and I've even checked the pressure delta across all vents (+/- 5%). I insulated just one of the pipes and it totally solved the heating problem in the room it lead too. I'll be doing the rest of the system on my up coming days off. The ducting insulation was fairly cheap at Lowes too, I can see it paying for itself in within the season.

[alloroc]

What were you doing last night.

Perhaps the house was just warm from normal activities cooking or many people which would bring the temperature above the set-point and overnight the temp. dropped to what the thermostat set-point actually is.

[brucebanner]

So since I have made this post, I haven't noticed an issue anymore. I would think there is (was) a problem though, the air was definitely cool and blowing strong so it wouldn't be the ducting. The house isn't big by no means, 1200sq/ft between both levels and it also only has the one furnace. Also, it was built in '05 so everything is fairly new.

Whatever the issue is, it has gone away for now. I can have the dial set on a normal temp and everything is working just as it should.

[alloroc]

Some houses have a current sensor so that when you are using a high current device like a vacuume or microwave the furnace fan will run to ventilate.