What is this cold air thing for?

[duaner]

The other end of this duct goes straight to the outside. Other than brackets which attach this piece to the side of the furnace, it does not interface with anything. It's cold air in an insulated duct straight from outside into the basement, hence the frost. It runs beside the actual cold air intake for the furnace.



So what is this for, other than making our basement cold?

[C_Dave45]

Its your cold air supply for the furnace to breathe/burn. Otherwise it pulls air in through any cracks/holes in the house.

[duaner]

Originally posted by C_Dave45
Its your cold air supply for the furnace to breathe/burn. Otherwise it pulls air in through any cracks/holes in the house.

Even though there is another intake that goes directly into the furnace?

[blitz]

The other intake is for fresh air to be circulated. This one is just for air to be burned in the combustion process. Like the intake for your car.

[ianmcc]

And as you see by the frost it goes straight to the outside.
Replace it with a Hoyme damper.
http://www.hoyme.com/
Closes it off until the furnace kicks in and then it opens up to let air circulate.

[AE92_TreunoSC]

I have a auto damper and I dont know why any house has anything but. Looks super easy to wire in as well.

[ianmcc]

Since it is thermostat activated it is only 24v and yes it is super easy to wire up yourself.

[Darell_n]

Originally posted by duaner

Even though there is another intake that goes directly into the furnace?

How about the hot water tank? If no appliance needed it, no air would be coming out of it. (and no frost) The fresh air supply for circulation should be connected directly to the return air plenum on the furnace and not dumped into the room.

[codetrap]

.

[89s1]

Originally posted by codetrap
I think in a perfect world that would be true, but I'm pretty certain there's a couple of bars pressure difference between outside and inside due to temperature.

You're right. The pressures inside of buildings can be pretty impressive.

I've had sheets of glass jump right out into my hands once the plates holding it in were removed. (being pushed on by nothing other than the air pressure in the building.)

[dirtsniffer]

Holly fuck, a couple bars seems excessive doesn't it?
That's more pressure than most turbos make. If that difference was on temperature alone you would need -73 degrees outside and 327 degrees inside. Assuming density didn't change.

Maybe it would fluctuate 20 mbar?

[codetrap]

.

[ExtraSlow]

Originally posted by dirtsniffer
Holly fuck, a couple bars seems excessive doesn't it?
That's more pressure than most turbos make. If that difference was on temperature alone you would need -73 degrees outside and 327 degrees inside. Assuming density didn't change.

Maybe it would fluctuate 20 mbar?

Don't go bringing math into this place. I was pretty sure beyond was a math free zone.

[89s1]

I should also add I didn't read the "couple bars" part.

There is a difference in pressure, can't say for sure what the actual amount is... But I wouldn't put it at ~30psi

[revelations]

Originally posted by 89s1
I should also add I didn't read the "couple bars" part.

There is a difference in pressure, can't say for sure what the actual amount is... But I wouldn't put it at ~30psi

A 1 psi difference means that a large plate glass window will have many pounds of force pushing it out or in.




I have one of these intakes in the basement as well. Its stupid cold there now, i masked off everything except a 3 square inch and the air just streams right in still - but the basement is MUCH warmer now.

[Fuzzybunnykiller]

Crazy for every 1 cubic foot if natural gas it needs 55 cubic feet of primary air and 5 cubic feet of secondary air for safe complete combustion. That "thing" is called a combustion air pot it is sized for the size of your furnace and by blocking it off you have the potential for reburning the products of combustion ( co2 and water in a perfect world) reburn co2 and what do you get co! Carbon monoxide THE SILENT KILLER. Hvac expert did you get any credentials? Do you trust him with your life? If you want to stop he air put in a high efficient furnace. Or at least the auto damper just make sure you her one that will fail open in the event it fails.

[Darell_n]

The proper way to cure the draft is to build 4 walls and a door around the furnace and water heater. This way the basement will be warmer and can now be a living space.

[codetrap]

.

[Darell_n]

Originally posted by codetrap
I did that. I also put a cold air return in the wall just like I'm supposed to. And it worked perfectly, returning the cold air to fill the entire basement. Before I sealed that sucker off, my basements average temp was 16C, that's with the rest of the house at 23C. Eventually, I might put in a hoyme damper, when I have some spare cash sitting around. However, considering that neither the CO, Ng, or smoke alarms has ever tripped in that small room, I'm not terribly worried.

The return air requirements do not change by building a mechanical room. Ideally, this room should be air tight from the basement space. If you have an air grill simply going through the wall from the mechanical room, board it up and leave all the cold air inside. (with the outdoor air supply still functioning)

[Fuzzybunnykiller]

You should never have a cold air ra in the furnace room. I will come look at your place and give you the whole story and what you need to do to midagate off cycle losses.

Tinman installations 403-454-5597