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Correcting a mistake I made 25 years ago.

I would like to correct a heating and air conditioning error I made 25 years ago.
My wife and I built our home here in Kentucky 25 years ago. I was a lot smarter then, but not smart enough.

I was the general contractor. I made some mistakes, but for the most part, we have a beautiful, comfortable home.

The mistake I would like to correct is this: The home is built on a slab and I did not have any ducts placed under the slab for heating. We contracted for a geothermal heat system and the contractor put the cold air returns through the walls and placed the grills near the floor, and he put the warm air ducts in the ceilings. That (I am smart enough to figure this out) is contrary to good heating practice since warm air rises. But, he told me that it would be sufficient and that it would work. I trusted him.

Over the years my heating bill has been much higher than I would have expected with geothermal system. So here's my big sixty four thousand dollar question:

Can this be reversed? Can sheet metal ducts be made and inserted between the walls in the current cold air return spots, and cold air return reversed to use the existing registers (grills) in the ceilings? Is it possible, plausible, and within my financial means? (MEANING IF IT COST THE SIXTY FOUR THOUSAND, I CAN'T AFFORD IT !!)

I'd be glad to have a "This Old House" contractor come out and do the work if it can be done. I'm planning on replacing the furnace unit in the near future and would like to correct this dastardly error while I'm in that process.

Thanks, anyone, for your response !!

Don Yarber
Morganfield, KYH

Re: Correcting a mistake I made 25 years ago.


The answer is yes and no.

Yes, it can be done.

No, it won't cost that much.

Go for it.

A. Spruce
Re: Correcting a mistake I made 25 years ago.
A. Spruce

I don't think that you'll get the return you're hoping for, making the modification a needless expense. Here on the west coast, everything since the mid 60's has been built on slab with HVAC ducting put in the walls and ceilings. While you may not like how your system is ducted through the ceiling, that doesn't make it wrong.

What may be far more beneficial is to have a thermal efficiency evaluation done on your home, odds are you've got cracks and leaks that are allowing your conditioned air to escape.

Re: Correcting a mistake I made 25 years ago.

If you had the ductwork put under the slab 25 years ago, you would have even higher heating and cooling bills and you would be asking if there was anyway to fix those leaky, uninsulated ducts under the slab. I've lived in quite a few houses with heater vents in the ceiling and they have never been a problem. The floor, if a slab, gets cold, but then so do slabs with the ducts under them. Slabs get cold.

I would expect that you have a heat exchanger outside for the geothermal part and a heat exchange in the house to heat and cool the house. The return registers through the walls would be through the walls to the closet where the inside heat exchange is. If the system was designed properly, the ceiling vents should be located mostly above windows. If the registers have movable directors, the directors should be set to direct warm air in the winter to go straight down to the floor in front of the window. From there it spreads out and returns up to the ceiling in the center of the room, spreads out to all the walls and back down again.

In the summer, you change the directors in the register to spread the cold air along the ceiling. Twice a year, you need to adjust the directors in the registers, if they are the adjustable type. Many times they just kinda spread the air so it sorta works all year.

You can spend a lot of money messing around with your ductwork and you will still be disappointed with your utility bills. In my opinion, you should make sure your existing ducts are well sealed and well insulated. That will give you the biggest bang for the buck. Don't expect massive returns for this, but it will be cost effective, if your expectations go beyond this, you will be disappointed. I don't think you other plan is either feasible or effective.

BTW, every new technology tends to be oversold and that leads to a lot of disappointment. Personally I still like geothermal, but I don't have one simply because each time I needed a new HVAC system, there hasn't been an installer in my area. Maybe next time, I think there is one now.

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