Geothermal Under The House

monticellohomes

I am new to the site and I build in SW Missouri. I have a client that is wanting a geothermal and after a little research one site briefly said you could put the coil under the house. Anybody have any advice or experience with this? Seems like a cheaper alternative since we will be below the frost line anyway.

playsinmud

I'm not sure of your weather conditions. If you are in a heat dominant area meaning you need to cool the house mostly then it's ok. But if you are in a heat dominant area... bad news.. Essentially what you are doing is freezing that ground. So unless the house is on piles, structural slab etc... The house will shift like it's driving an 18 wheeler. Best to stay away from the house. Is there not enough room for the ground loop or why was this method suggested? Let me know more about this project and I'll try to help you out. I am a geothermal contractor and am familiar with most ways to make a system fit and most of all WORK.

azgardener

Mr playsinmud can you tell me why there are no geothermal systems in the Phx area? I hear there are some in Vegas and I know the local ballpark uses a similar type of principal to cool the Diamondbacks stadium. They pump water from the buildings surrounding the stadium to cool it.

The closest engineer I have found to design a geothermal system is in NoCal and she wants $2500 just to design it. I have also heard the pumps are very expensive although we can't figure out why. Can you shed some light on these questions.

playsinmud

The price of a conventional geothermal sytem is higher for two reasons. Equipment costs are more expensive and you need some sort of ground heat exchanger(closed loop shallow wells, water wells, horizontal slinky loop, horizontal bore, pond/lake loop) In some parts of the states you can you can use an air to air heat pump which works well in some climates.

If you need help designing a system let me know. I've done projects of all sizes and also have contacts who have been around the world and know anything and everything about geo.

I am going to look into phoenix's climate a little more there really seems to be no reason to not use it there. It just has to be designed for it's local conditions.

monticellohomes

Playsinmud, the project we are about to start is a 5700sf home in Bolivar, MO on 4 acres. It is a walkout with 3000up, 2700dn. This is the first geothermal I have even had a customer ask for, we've done some air heat pumps over the last year, so I am not real educated on the systems. I don't know how your would classify our climate, as heat or cool dominant, it is right down the middle. The last year he had a pretty cool winter but that is usually still hovering right around freezing for us with a lot of warm days mixed in. If you would, please help shed more light on these systems for me.

Monticello Homes

azgardener

We are doing a deep 13' basement and I am going to have a 70' trench that starts at 4' deep and ends up at almost 9' deep to bring elt. gas and water to the house and continues to the sewer tap. So I am going to have a lot of open trench and exposed earth in general.

My lot is not very big 75 x 100 heavy clay soil mosty shaded. The house has aprox. 1500 sq ft footprint and is a two story. My lot will be about as cool and damp as would be expected here in Phx. because I am a landscaper and will have a very heavily planted and well watered landscape.

We are using a sip type system for the exterior walls. 8" steel studs with foam in between R-40 or more. The roof is typical wood truss with 6" icelene sprayed insulation. So again best case scenario to keep a home cool here.

I would greatly appreciate yor help with a system design. My father-in-law is a HVAC installer and in general very intellegent and mechanicaly inclined. He is the one who suggested the geothermal system. You can PM me if you lke or I don't mind doing the info exchange through the forum. Thanks in advance for any help you can provide.

polar8989

Why not electric?

playsinmud

Sorry I was away last week and didn't get back to you guys. I'm assuming these are both new construction, if you want I could take a look at the blueprints and get a design going for you guys to install. You can reach me at geo-loop@hotmail.com

Haydin

playsinmud,

I was curious about this scenario?

I'm helping a friend out with a structural metal hangar out at the local airport here. The footprint is 50'x60' and 12' tall walls with a .5 pitch roof. We are only looking for a heat source... no cooling. One of the problems with these hangars is that they have a natural gas heater hung in one corner of the building. This does little to "pre heat" the planes prior to starting in the winter months. Our average low temp Dec-Feb is about 20 degrees. I suggested we do a radiant heat slab with geo-thermal and a couple 300' well holes for the ground loop. That went like a lead balloon with both the city and the airport... no drilling at all! The ground is a few hundred feet of alluvial deposit (the great salt lake bed).
The foundation will be continuous perimeter footings 50'x60' with some spot footings at the corners and mid span. The center of the slab area is free of footings and slab on grade. My thought was to excavate out 30'x40' in the center and bury a sling xx' down under the slab and back fill. Then come in and dig the perimeter footings 48" down with a stem-wall on top and then the slab. I would think that this would eliminate any movement of the building. My thought when I saw this thread was feasability of under slab ground loops.

Thanks,

Karl

KesslerDweller

Curious - how much does a geothermal system typically cost? I know there are a lot of variables. I have heard that they typical lare 1.75 to 2.0x the cost of a "regular" A/C system?