Old house duct question

Old 12-15-02, 09:07 PM
duct tape pro
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Old house duct question

Hi to All... I'm glad I found this website tonight!
I am renovating an 1880 farmhouse, and in 1996 I had a Rheem Criterion gas forced air furnace installed to replace the old system which was also GFA. My question is: How necessary are cold air return ducts?
There are no cold air returns anywhere in this 7 room house! The house is on a crawl space, and the furnace sits in the laundry room off of my kitchen. The ductwork only services the first floor of the house and is mostly inaccessable from the crawlspace.
The man who installed the furnace/CA system told me not to block the draft from my back porch door which is about 3 feet from the furnace and my computer desk. Is this really adequate? I'm freezing back here!
Old 12-16-02, 03:44 AM
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The situation you are in is very common. The draft you are talking about, that the furnace man advised you not to block.....I take it is your only means of gettting air back to the furnace for recirculation. This similiar to the older gravity type furnaces, where the cold fell and the hot air rose.
RETURN AIR is very important in any F/A system, especially on the A/C side. The more return air (from different parts fo the residence)that can be sent back the to the blower the more even the HT & A/C will be. The lower the utility bills will be. Returns in my opinion are a must.
With no or very little return air to the blower/furnace, this can over stress the heat exchanger and cut it's life short
Old 12-16-02, 05:10 AM
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duct tape pro:

If the door to your office is only three feet from the furnace then there should be enough return to get adequate air flow.

Proper returns maximise the efficiency of your system as bugsmeso says but what you have could likely be made to work.

A simple test to ensure the furnace is getting a reasonable amount of return is to feel the suction on the blower compartment door.
Open the door slightly when the fan is running and see how hard the door tries to snap closed.
Warning: Watch your fingers, you could pinch them if the door pulls back too quickly.
If there is little suction felt then you may be ok.

You don't say if this problem is new, started with the new furnace or started recently.

This furnace is six years old, do you have an a/c coil that could be plugged?

Mobile homes do not have ra ductwork and come in lengths of up to 80 feet long.
They have doors inside that are cut to about 2 1/2 inches from the floor and that seems to work ok.

Try the furnace door thing and give us more details on your house.

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Old 12-16-02, 06:29 AM
duct tape pro
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RE: Old House Question

Thank you for your timely answers! I had questioned the cold air return back in 1996 when the furnace was replaced. We had a vent in the top of the wall between the laundry room and the living room which was the only return at the time. My husband drywalled over this vent, hence the need for the back door draft.
Old 12-16-02, 06:38 AM
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Unhappy RE: Old House Question

Darn, I hit the wrong button on that last post... what I was going to add is that this is not a new problem, but now that I had to move my computer desk to the laundry room it has become uncomfortable. I sit with my back approx. 4 feet from the front of the furnace, the back door sits 2 or 3 feet to my left, and the cold air pours over my tootsies! I wanted to have cold air returns installed, but the house inspector told me that my crawlspace is a honeycomb of concrete tunnels with very little or no access to ductwork, mud sill, etc. I need to try to come up with some type of alternative, my husband had said that we didn't need the return vents, so I posted the original question.
Any ideas for a balloon framed house with fire stops? I should mention that the wood is petrified, a hammer will bounce right back at ya!
Old 12-16-02, 08:05 AM
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I'm not an expert at this

At least the furnace part of it.. but I do live in a big, somewhat drafty old farmhouse in a cold area (Vermont).

When reading your post I thought, could you build something AROUND the part where your desk is? Like from the floor up a few feet, to block the drafts from hitting you? If you didn't want to actually close it in? At least on the side(s) where the drafts are coming from?

Don't know what your floor is like, but it might also help to build a slightly raised "sub floor", maybe with insulation under it.

If you were going to put in cold air ducts, the materials and doing this would probably be a lot less (money and trouble).

If it were me, in your place, I'd probably get a big old quilt or rug and lay it along the bottom of the door, or beside where the desk is. I think there would still be enough "draft" for the furnace.

I don't know anything about cold air ducts for furnaces, (we already have some in our floors) but seems like one could be run FROM an outside wall of the house, TO wherever it was needed by the furnace? That way the cold hair would go where it's supposed to go (furnace) and you would be able to close off the drafts, elsewhere.

Just things I thought of while reading your post. Not really "tech" stuff...

Reminds me, I'm sitting here in my barefeet and have to put on some warm socks (LOL)

~ Carrie
Old 12-16-02, 10:57 AM
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Well no wonder you are cold!

This is a secret, so don't let anyone else know!
I have a wood furnace in my bsmt that has a door to an outside woodbox.
I have a rolled up jacket there to keep the cold air out.
Not good for someone that dispenses advice is it?

Move your desk, , or install weatherstripping on the door.

Your problem I think is that to put your desk in a porch, goes against the purpose of a porch in the first place.
A porch was a space in a home that was a barrier between the warmer living space and the cold drafty doors that were the norm when your house was built.

If you intend to use this space as you are, you will have to bring the insulation, door quality and weatherstripping up to today's standards.

You still may have some return air issues, but I think that what I just described will go a long way to making this area useable.

As I said, if return air ducting is not feasible, you could easily change a few things to help with the return.

Things you can do would mimic a mobile home which normally doesn't have a return duct system.
Things like undercutting doors to increase air flow under the door and installing grills between some areas.

Heating supply companies have nice looking door grills for this purpose.
Maybe take a look at some new mobiles to see what they do.

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