No ductwork??

[Michael Roberson]

I recently inspected a very intricately designed 1980 home with Geo Thermal. The house has a main floor and a full basement built with engineered floor trusses. (high tec for 1980?) I pulled up a floor register on a hardwood floor to discover no duct work. I at first I thought it was a cold air return. I found out that this is the heat source. The owner/designer has charged the entire floor cavity with warm air. (Keep in mind this is geo thermal, so no risk of overheating, fire or even carbon monoxide) Where ever he wanted heat, he simply cut a register into the floor or ceiling. He says this works well, and keeps his floors warm too.

This is the first time running into this configuration, and it took me a minute to wrap my head around it. Have anyone else seen this or have anything to add?

[James H. Bushart]

Originally Posted by mroberson

I recently inspected a very intricately designed 1980 home with Geo Thermal. The house has a main floor and a full basement built with engineered floor trusses. (high tec for 1980?) I pulled up a floor register on a hardwood floor to discover no duct work. I at first I thought it was a cold air return. I found out that this is the heat source. The owner/designer has charged the entire floor cavity with warm air. (Keep in mind this is geo thermal, so no risk of overheating, fire or even carbon monoxide) Where ever he wanted heat, he simply cut a register into the floor or ceiling. He says this works well, and keeps his floors warm too.

This is the first time running into this configuration, and it took me a minute to wrap my head around it. Have anyone else seen this or have anything to add?

"Geothermal" simply explains the heat source and has nothing to do with heat distribution.

What would be your thoughts if this were a standard air source heat pump supplying heat to the air handler with this configuration?

[Jeffrey R. Pope]

Sounds pretty inefficient to me, but I've never actually seen a geothermal system. Was there a heat pump incorporated into the system, or was it simply a radiant transfer of the earths heat to the residence?

[Michael Roberson]

What would be your thoughts if this were a standard air source heat pump supplying heat to the air handler with this configuration?

I would call this out IF this had a standard gas fired forced air system. I would think this would be less efficient. Also anytime you remove part of the ceiling, you will basically depressurize the heat system.
I cant see any reason why this is dangerous, Im curious what YOU have to say about it Jim.

[Michael Roberson]

Jeff: This was a "Pump and Dump" style geothermal, that looked like a large stainless furnace. It has a internal heat "Extractor" and a forced air blower. It used about 10 gallons per minute.

[Jeffrey R. Pope]

With that type of distribution, ducts would certainly be more efficient and I would likely recommend that as an upgrade to the system.

[Roy D. Cooke, Sr]

Houses years ago had a big old wood stove and that heated the first floor and opening let the air get to the second .
With this system the floors would always be warm and warm floors make MOMMA happy with her warm feet .

[Michael Roberson]

Originally Posted by jpope

With that type of distribution, ducts would certainly be more efficient and I would likely recommend that as an upgrade to the system.

The blower simply blew into the floor cavity, roughly 125 degree air (I didn't actually measure the air temp, but the plenum above the furnace was nice and warm) It had a natural cold air return through the stairwell and open balcony. Almost all the doors an the house were Louvered to improve air flow.

This was very quiet, (and once the floors are warm) I would think a very even heat. I could also see moisture as less of an issue in the floor cavity.

I guess Sunny Southern CA don't install these much Jeff?

[Jeffrey R. Pope]

Originally Posted by mroberson

I guess Sunny Southern CA don't install these much Jeff?

No, we don't. The only thing I've seen that might be similar, was a "solar room."

This hillside home had a dedicated room with rounded glass (1/4 round essentially) running the length of the home facing south. The room was roughly 10'WX10'HX40'L. At the top of the interior wall, there were thermostatically controlled dampers, which allowed heated air to flow beneath the house through an 18" (non-partitioned) finished crawl space. The solar room had two blowers, one at each end of the room. Throughout the house, there were floor registers that opened directly into the crawlspace.

The biggest "issue," according to the homeowner, was the temperature difference of the conditioned air by the time it reached the opposite end of the home. I imagine a ducted system would have helped solve (or at least reduce) that problem.

[Michael Roberson]

Hows's this for a description? Comments?

No ducting present. Furnace blows warm air into the Floor cavity, and then subsequently out of the registers. Cold air return is natural though the louvered doors, stairwell, and balcony. This is an irregular but not necessarily an unsafe method of heat distribution considering the heat is geo-thermal. Installing ductwork would help improve the efficiency of the air flow system, but would change the "warm floor" feeling.

[Jeffrey R. Pope]

Again, I am not familiar with these systems, but that sounds like what I would suggest. I would change "irregular" to "unconventional."

Was there a return air duct at least, or does the system draw air from the outdoors?

[Robert Ernst]

How does he get the heat to travel across the joist bays? I guess any heat that is loss downward enters the basement. The rim should be sealed and insulated well to prevent heat loss that way. Also any wire or pipe homes would need sealing to prevent the air blowing up the wall cavity and into the attic. It's a interesting to say the least.

[Michael Roberson]

Originally Posted by rernst1

How does he get the heat to travel across the joist bays? I guess any heat that is loss downward enters the basement. The rim should be sealed and insulated well to prevent heat loss that way. Also any wire or pipe homes would need sealing to prevent the air blowing up the wall cavity and into the attic. It's a interesting to say the least.

Very good point Robert, I obviously couldn't see all the rim joists, but they were insulated where I could see. These were engineered floor joists, about 24" thick and made of criss-crossing 2x4's. Heat would flow just fine sideways.
A shot from below the floor through a heat duct.

[Michael Roberson]

Was there a return air duct at least, or does the system draw air from the outdoors?

The Cold air return system was a natural flow, through the Louvered doors, down the stairwell or balcony, and into the utility room.

[James H. Bushart]

A very similar and grossly inefficient system is commonly found in mobile homes. I can't believe somebody would put this in a real house. What an incredible waste.

Is this an exceptionally small home ... 1000 sf or less?