Unique forced air furnace

Originally Posted By: lclark
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Today I had an inspection on a limestone ranch, slab foundation. This house has a forced air furnace, all the ductwork is boxed in the attic, with blown insulation over top. There are no registers in the ceiling, the furnace heat’s the boxed area in the attic and then the heat radiates down through ceiling. Has anyone ever seen a set up like this before? The sellers say that it works pretty good. They also said they burn a lot of wood in the fireplace to. I couldn’t get very good photos of the attic, for all the personal items stored there. If anyone knows anything about this type is set up with sure appreciate your input.


Thanks Larry

![](upload://ird6I6eMKNiE6jZtHHByhjn8kur.jpeg)

The boxed in area is in-between the steps and the pink insulation.


--
" Motivation is what gets you started. Habit is what keeps you going."

Originally Posted By: jkormos
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I have seen radiant heat in the ceiling before but not this type of application. Could you expand a bit more, how does a forced air furnace, force air into a “box” and not be vented.


regards

Joe


Originally Posted By: lclark
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To tell you the truth, I don’t know. The whole attic area was boxed, with blown insulation over top. The cold air return was in the boxed area to. So I guess you could say it was a warm air return. This house was built about 50 yrs ago. The builder built two of them next door to each other, one for him and one for his daughter. Here is a photo of the house.


![](upload://74YlhkjyWkQPi3C6uMTx84DpOKQ.jpeg)


--
" Motivation is what gets you started. Habit is what keeps you going."

Originally Posted By: mboyett
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I’m betting the return air was actually separate from the supply air, you just can’t see it for all the insulation. I’ve never seen this type of installation but I guess it does make sense that all of the supply air could be provided to the various rooms via site built chases rather than standard ductwork.



Mike Boyett


Capital City Inspections


Austin, Tx


www.capcityinspections.com

Originally Posted By: dedwards
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Im trying to get my mind around this and picture what you are saying. It sounds like this guy created basically a heated “plenum” out of the entire attic floor, and that the heated air just circulates through the boxed in area and the source of heat is ALL radiant heat. No heated air ever enters the living areas (or leaves it either for that matter). Ive have heard of someone using a plenum system under a house that was all enclosed to cool the spaces, using the naturally cooling ability of earth to basically augment the mechanical system. Ive have never seen or heard of anyone doing what you are saying. I suppose it might work but I am wondering if it is cost effective. Hot air is probably the least effective method or medium when it comes to radiant heating. It very quickly loses efficiency the farther it travels from the source. Radiant floors are so effective due to the medium (usually concrete which absorbs and retains heat for hours) and due to warm air rising to mix the ambient air inside the living quarters. Seems to me the heat in the winter would naturally rise out thru the roof and be wasted. May account for why they have to burn so much wood. Interesting, thanks for sharing it with us. I am going to have to ponder the possibilities of this for a while.


Originally Posted By: Gary Reecher
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Looks like the wooden version of a Lustron home?


These were porcelain enameled steel houses built post World War 2. These were built with a forced air radiant ceiling heating system.

http://members.tripod.com/~Strandlund/index-5.html


--
Gary Reecher, CM
HVAC Service Technician

MechAcc's Carbon Monoxide Site Links

Originally Posted By: lclark
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Doug,


You are on the right track with the plenum system. You explained it better than I did. He may have taken the idea from the Lustron home that Gary is talking about. As far as efficiency I’ll tell my client he may want to check out some past heating bills.


I wonder, would it be possible to put in some registers in the ceiling, or would that mess up the whole works?


--
" Motivation is what gets you started. Habit is what keeps you going."

Originally Posted By: Gary Reecher
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lclark wrote:
Doug,
You are on the right track with the plenum system. You explained it better than I did. He may have taken the idea from the Lustron home that Gary is talking about. As far as efficiency I'll tell my client he may want to check out some past heating bills.

I wonder, would it be possible to put in some registers in the ceiling, or would that mess up the whole works?


Recently saw a Lustron that had been converted from the original Williams Oil O Matic to a 90 percent gas furnace with air conditioning. The existing radiant panel duct was used only for a return. A supply trunk was chased through the ceiling of the radiant panel duct into the attic. Supplies were then run back down into each room. Square decorative ceiling registers were used and located in the center of the square ceiling panel.


--
Gary Reecher, CM
HVAC Service Technician

MechAcc's Carbon Monoxide Site Links

Originally Posted By: lclark
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Gary,


The ceiling is drywall, no porcelain enameled panels in this house. I talked to the realtor a few minutes ago, she told me the sellers had two different HVAC companies come in and give estimates on installing A/C. They both said their was not enough room to run the ductwork. I wonder if she is telling her clients everything she knows.



" Motivation is what gets you started. Habit is what keeps you going."

Originally Posted By: dandersen
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Check out the “Opened Panel” link! icon_eek.gif






And how do your access the inner panel. I looks like only half of the panel is exposed.

As for heating with "Radiant Ceilings", it just isn't efficient.

As for not enough room for ducts?


Originally Posted By: lclark
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Dave


I know what you mean, sounds like they did’nt want to take on a project like that. Can’t blame them, looks like a belly job.



" Motivation is what gets you started. Habit is what keeps you going."