geothermal questions and possible DIY

[LD1]

Considering putting in a geo system in the house I just purchased. Gotta do something. Only has electric baseboard heat and no AC.

So I called some contractors for some quotes. One came out today. Looking about $9k for air-air or about 18k for geo.

Both include ductwork which the house has none of. And the geo is with ME doing the excavation. $3500 is for ductwork which will be the same either way.

So air to air unit installed for $5500 vs geo for $14,500

Not sure what makes geo units cost so much? They both have compressors, and related parts. The geo adds a water pump and some outdoor plumbing, but $9000 more? Doesn't seem right.

This is just a preliminary quote from him just to get an idea of cost difference between geo and air to air. This is for 4-ton units too.

Just didn't think there would be $9k in material difference. Cause with me doing the digging, labor and ductwork should be nearly a wash in cost difference.

So...those that have made the decision and gotten quotes on geo vs a2a, what was the price spread for the furnace/unit itself?

Also, I know tbn is full of diy'ers. Anyone on here do one of them diy kits? And from where? How did you like it and would you do it again? I am considering this route as well, but not really something to get advise about from an HVAC contractor.

 

[s219]

I believe there is still a 30% federal income tax credit for geothermal. And it's calculated on the total cost of the system, so that would be about $5400 discount based on your $18K cost. In our case, it offset most of the extra cost of geothermal versus heat pumps. So look into that.

Federal Tax Credits for Energy Efficiency : ENERGY STAR

Without the tax credit, geothermal is a tougher sell. We are seeing an estimated 35% reduction in heating/cooling expenses per square foot in our new house with geothermal, compared to our old house with heat pump (and it's more comfortable and more capable). But even then, it would take quite a few years for the savings to offset the higher cost of equipment and installation. So the tax credit is a big deal.

 

[SPIKER]

My understanding of the two is that the A2A uses larger air exchanges & noisier than the geo. The biggest cost is digging wells OR excavation for the in ground tube & antifreeze in the tubes. The heat exchanger for the water to air is smaller than the A2A. Air just does not hold the BTUs of the water. The Vertical lines does not have to have the antifreeze materials in it as it spends most of it's time under ground at depth.

Addition of a wood fired heat exchanger would make it a LOT more efficient. Using burning wood to heat water store the BTUs back in earth to be extracted when fire is out.

Mark

 

[japody]

++ what s219 said. I calculated an 8 year payback period. Make sure you get the desuperheater. It's like getting free hot water. The highest electric bill we had for an all electric house last winter was $138. Also check to see if your state offers any rebates. Virginia only offers incentives for retrofits, not new installations. Good luck.

 

[buckeyefarmer]

I installed 2 units in my house myself. Take a geothermal installer class and you will learn everything you need, including how to fuse the HDPE pipe. Start with manual J calc for your house to determine the size, don't assume. Set yourself up as a business and set up accounts at geo supply house. I used Heatcontroller units, basically same as climatemaster. They come standard with desuperheaters and cu-ni coils. I used the non pressurized pumps, and headered inside. inside header allows you to flush with your loop pump, and it gives you full control over the loops, such as if one ever leaked, it can be turned off.

 

[LD1]

S219: I am aware of the rebate. I allthough it isn't 30%,of everything. Only things specific to geo. IE: duct work don't count.

But I do get an additional $1k from my local electric co.

But I refrained from bringing the rebate into this. Just symply trying to compare the base cost difference in equip/ material needed.

 

[LD1]

Spiker: digging ground loops is what I too thought was the most expensive to hire it done. But the 18k qoute, was me doing the digging. If I hired that out, its $900/ton.

So while I am saving $3600 digging a 4-ton myself. I just cannot believe the equip is 9k more than air to air equip

 

[LD1]

Also, I am not concerned with load calcs. I don't like the size units they end up concluding to. Too small IMO. I want something that will actually keep the house warm without the constant use of backup.

I don't like sizing for ac loads as most contractors like to do.

 

[dragoneggs]

Interesting thread... good luck LD. I have almost no experience but am eager to learn. Keep posting the design and build!

 

[s219]

S219: I am aware of the rebate. I allthough it isn't 30%,of everything. Only things specific to geo. IE: duct work don't count.

I don't know how it works for your situation, but for new construction, the 30% came off the top of the entire HVAC bill. They didn't itemize on the final invoice we got with the tax form, nor did the gov't ask me to itemize the individual costs when I did the paperwork with my taxes the following year (not sure how I would have even done it at that point). You can see the most recent tax form here:

http://www.irs.gov/pub/irs-pdf/f5695.pdf

Still looks like it covers the full system cost. Our total HVAC system cost included the geo unit, the well drilling, all interior ducting/dampers/etc, the de-superheater option, the hot water heater to go along with that, installation/labor, and a few other things. If I remember right, it was going to be $16-17K for dual heat pumps, or $27K for the geo-system. With 30% rebate, that came down to $19K, and was a reasonable leap. We have probably already recovered 60% of the price premium for geothermal by now.

So just because you're breaking costs down now, don't assume that's how the rebate works. If your house doesn't have pre-existing ducting and it's required for the forced air geo system, then that cost is most certainly part of the system. Same for trenching/drilling/installation.

Our HVAC installer, and the sub he used for geo drilling/installation, were both very knowledgeable about the tax rebate, and had gov't brochures and tax forms to share with me up front, when we were talking over the numbers. They use the rebate as a selling point for geo systems, otherwise far fewer people would buy them. So talk to the installer -- he should know the routine very well if he has done a lot of systems.

 

[mfreund]

Also, I am not concerned with load calcs. I don't like the size units they end up concluding to. Too small IMO. I want something that will actually keep the house warm without the constant use of backup.

I don't like sizing for ac loads as most contractors like to do.

I vote for oversize too. Ours is a 4 ton unit with drilled wells for the ground loop. Wish it was 5 ton.

 

[Pixguy]

I am starting to look into geothermal for my next home and trying to understand how it works and understanding the technology.

Another challenge is learning if the forced air is similar to traditional forced hot air systems that are cold and hot, cold and hot and drying out the mrs's eyes and contacts.

Good luck, I'll be watching this thread closely.

 

[JimRB]

I do not have backup heat unit in my house. It has gotten down below zero F and the house has stayed warm. Fairly well insulated house, thermopane windows, 1,100 sf daylight basement, 1,100 sf 9 foot ceiling first floor and 600 sf two bedrooms on second floor. Not the most energy efficient home construction from a floor space and design perspective. 3 ton unit with slinky ground loops.

I have 17 years of electric bills on a spreadsheet. I do know that my neighbors pay a lot more to heat or cool their houses.

My power co-op did the manual J calculation, I think it was manual J, off the blueprints. I believe they calculated 2.5 tons. Seat of the pants and rule of thumb is not a good way to size a unit. If you have a house with plaster walls and no insulation in the cavities is going to figure out different from a house with fiberglass insulation, or one with cellulose insulation, or one with sprayed closed cell insulation.

When you compare apples to apples remember that there are inexpensive air to air and expensive air to air. I do not know if there are inexpensive geothermal units. Two of my neighbors replaced their air to air units when they were less than 10 years old. My geothermal is 17 years old and is chugging along. Yes I had to have the coil replaced as it started leaking but I gather all coils did that back when my unit was made. If you shared the specs, brand and model of the air to air and the geothermal then someone might be able to make a more educated guess. It may be that your contractor is just tossing out ballpark numbers to a tire kicker.

As mentioned in a few articles, a geothermal tech will have another day or two of training over a regular tech. An air to air may take a half day to set up. A geothermal may take a day.

If you do some research you will see horror stories of loops not deep enough and freezing, leaks, improperly sized. I have been rather satisfied with my unit and installer. My house is not humid in the summer. It does not have hot or cold spots. My electric bill is not outrageous.

Geothermal Heat Pump Costs: Pros and Cons | QualitySmith
Cost of a Geothermal Heating System: Geothermal Heat vs. HVAC

 

[dodge man]

I just had geo installed. We already had duct work. Our cost was 20k installed. It also included a new hot water heater and a tank that preheats from the geo. A regular furnace depending on efficiency was 6 to 9k.

We will receive about 5k back in a tax rebate and $500 from the power company. We also get the power at 8 cents a kWh instead of 12. They calculated our pay back in three years on power savings. Even if they were just trying to make a sale, I figure the payback at 5 years or less. Our old system was LP which is pretty costly to heat with these days.

We have a 1900 sq ft house in west central Illinois. Our estimate for power including hot water will be about $1000 per year. Of that 300 is for hot water. The number that impresses me is the AC cost. $100 for the entire year.

How does it work? I think it heats more evenly as far as different room temps go. Less cold and hot spots. I think this is due to the fact it runs more but uses less power when running. It's also best not to change the temp by much. If you turn up the temp more than 1 ot 2 degrees the electric back up kicks in using more power.

They install took just three or four days. They directional bored the tubing in and shot it into our basement.
Hope the info helps.

 

[JimRB]

One problem with oversized units at least in the summer is dehumidification. My house is comfortable in the summer and winter without huge temperature swings when the unit is running or not. The delta T of the discharge air is enough to warm or cool the house but not enough to freeze or boil you if you happen to be close to a supply vent.

 

[Country Geek]

I've got another thread going on my geo install, no DIY on mine. In NC, there is a 35% state credit on top of the federal tax credit. Kinds of makes it a no-brainer, IMO. Of course judging from prices quoted here we pay more so some of the extra rebate is probably just going to the installers. I'm looking at about $31K for a 5 ton system with a propane furnace backup. The propane backup is likely not needed but I want to be able to heat my house with a generator during ice storms that take the power out. The ground loop subcontractor also said that he thought my ground loop was very overengineered.

 

[LD1]

One problem with oversized units at least in the summer is dehumidification.

Same thing the contractors always try to push.

To size the unit for proper dehumidification, makes the unit too small to heat in the winter without back-up heat anytime the temps drop much below 30. Of course you probably dont see much of that in GA, and down there AC is probably more important than heat. Up here Heat is the primary goal.

As far as being too big to dehumidify....well right now the house has no AC at all. So a unit that is too big is still going to dehumidify the house more-so than it is right now.

 

[mfreund]

One problem with oversized units at least in the summer is dehumidification. My house is comfortable in the summer and winter without huge temperature swings when the unit is running or not. The delta T of the discharge air is enough to warm or cool the house but not enough to freeze or boil you if you happen to be close to a supply vent.

Ours is too dry in the summer. You almost need to turn on the humidifer. Yes we needed to add a humidifer our installer said that it was not needed, but we do in the winter because of the back up heat.

 

[Stimw]

I have installed 2 in two different properties. They were both FHP Units. (Florida Heat Pump)
I used ground water (65*) discharged on lawn or drainage ditch as needed.
They are VERY efficient! I checked register temp with room at 70* and heated air coming out of vent was 20* warmer.
The last unit was a 3 ton and was rated at 23 amp and on a 30 amp breaker. Water pump was on a separate breaker, 8 amp 220 V.
Duct work isn't hard if you have sheet metal experience. Duct board isn't bad to work with either. Both are easier with the special tools.

 

[71bronco]

Our installer said an oversized unit was as bad as an undersized one. I turn the breakers for the backup heat off so they can't turn on. Set the thermostat at 70 and it stays at 70 even with last winters -15 temps.
We had our pipes linebored with one extra run than usual for our size unit. This way there's hardly any mess, only a 12' ditch where the pipes go into a manifold and a small spot to go thru the basement wall. Our lines are actually under our septic system around 20' deep.
We really like ours and have had it around 3 yrs.

Jeff