I don’t know how much interest there will be in this, but in response to this post I thought I’d put myself out there & answer questions about this project.
So, a couple years ago we decided to install a geothermal heating and cooling system at our house. We needed to replace both of the original systems anyway, which were as old as the house (about 30 years) and limping along. It was expensive and messy, but for the most part we’re glad we did it.
So… ask me anything. I’ll be radio silent until Tuesday morning some time.
Start by describing the system, the installation, what climate you are in, and how it is performing. Sorry, that’s not a question. Can you describe all of that anyway?
Sure. We live in central NJ and previously had an A/C compressor and a forced hot air furnace/blower, gas powered in our 2-story house. It was inefficient and noisy (compressor) and expensive, although as I’ve since learned, maybe pretty standard cost-wise for the house and region.
We decided to go geothermal and got a Waterfurnace unit in the basement, which looks just like a traditional forced air furnace. However, all the fun happened outside. They had to run a trench outside the house from the end wall of the house across the front yard, and they bored two wells, each about 450’ deep and one foot in diameter. The trench connected each of the wells to the house, and they bored two holes in the exterior basement wall in line with the trench. A pipe- basically PVC- ran from inside the house, along the trench, down & up each well, and back to the house. The pipe was cemented into the wells before they filled them and the trench with soil.
The digging and trenching completely tore up our front and side yards. We had a drilling rig and front end loader parked in the yard for a few weeks, with some other support vehicles coming & going every day. The drilling of course hit some underground water, which would spray up out of the holes and flood the yard. We have a lot of clay in our soil so the front of the house was covered in red dust until I had an opportunity to pressure wash it a few months later. I also had to hire a landscaping crew to grade, rake & seed the yard when the project was finished. I can’t stress this enough- it was a huge mess. And according to our tree guy (but disputed by the drilling company), the trenching also damaged 65’ silver maple in our front yard to the point where we had to have it cut down last month. So there was some collateral damage.
Inside the house, the pipes were filled with the antifreeze solution and hooked up to the furnace. They also installed a new programmable thermostat and advised us that, as with most systems, it’s most efficient to just keep the house at one temperature all the time. We were accustomed to turning down the 'stat at night in the winter, for instance, but they told us that to run at peak efficiency, it wants to maintain a single temperature.
On a day to day basis, it performs beautifully. The house is much more even temperature-wise between upstairs & downstairs. We never touch the thermostat so we rarely even think about temperature.
As mentioned above, each well was 450’ deep; it’s a closed system.
Total price for the project was just over $36,000. New Jersey gives a $3,000 rebate for this job which comes off the top, and when we filed our taxes for that year we were eligible for a tax credit which saved us about $10,000. We also received a ten year, 0% interest loan for $10,000, so actual out of pocket cost was about $13,000. Our monthly savings on gas & electric is greater than the $83/month we pay on the loan, so we’re coming out ahead there.
Before geothermal, we were paying over $400/month for heat and A/C in the winter and summer; now we pay just under $300/month in the coldest months and around $100 for A/C in the summer. If you deduct the cost of what we would have spent on a traditional replacement HVAC system, our payoff period is probably around the 8 year mark.
We’re actually saving more than we think, because we now keep the house a couple degrees warmer in the winter and cooler in the summer since it’s less expensive to do so. As a result, it’s hard to compare apples to apples when checking our monthly cost each month now to the pre-geothermal days, over the course of the year.
Of course, and I can’t tell you that. You’ll know when it happens.
beowulff: It’s a well (or wells, actually) in the sense that it’s deep enough to hit water, and then some, but the system doesn’t need water to work. Once you go down about 50 feet or so, the ground temperature is a consistent 45-50 degrees throughout the year. In fact, after the pipe is inserted into the wells and trench, the water is pumped out and is replaced with a slurry of wet cement. Some geothermal systems can take advantage of a body of water on the premises, but most just use the steady temperature underground.
The antifreeze solution in the pipes removes heat from the house in the summer and cools as it circulates through the pipes, and is then pumped back into the house. Inside it runs through an evaporator coil where a blower pushes air past it, and the cooled air flows through the ducts. In the winter the same thing happens, but it goes through a condenser coil to raise the temperature of the fluid, and the warm air is circulated through the ducts.
The system operates off of electricity, but less of it is necessary to run the pump, condenser/evaporator and blower fan than is necessary to run a traditional A/C or heat furnace.
How big is your house that you were previously spending $400 a month in the most extreme months?
Why did they have to go 450 feet down when, as you say, temperature levels off at maybe 50 feet? Just to increase the surface area for the anti-freeze to dissipate/absorb heat?
How big a mess (that is, how much of the yard was temporarily ruined, in approximate square footage)?
another method is tubes zig-zagged in trenches below the frost depth or into a pond. as long as you can make enough surface contact with soil/water of suitable temperature then you are good.
We have a 4 bedroom colonial, about 2600 sf. I compared notes with a couple friends & relatives about heat & A/C costs for similarly sized homes and we were actually spending less than they do.
Yes- surface area. The longer the antifreeze is surrounded by the steady temperature as it circulates through the loop, the more stable the temp will be when it gets back to the house. The original plan was 3 wells at 300’ each, but they revised it somewhere along the way.
We have one acre, maybe 1/3 of which is in the front yard. So there was an area of about 120’ x 30’ that needed repair.
Sure, but each new well requires the drilling rig to be repositioned, which means it drives forward & back a few times to get it into the right spot, tearing up more of the yard. Plus, the wells have to go at least 50’ or so to hit the constant temperature, so it makes more sense to position it once or twice and just go deep.
Right- I believe that’s what they do when there is a body of water on the property.
One thing I forgot to mention earlier- of the $36,000, about 1/2 of that was the cost of the drilling. A local HVAC company was the project leader, and they handled everything inside the house- new furnace, charging the system with antifreeze, all paperwork for rebates and credits, the loan, etc. They hooked us up with the drilling company and we contracted with them separately. We would have paid a markup/admin fee if we had the HVAC company deal with them. The drillers handled all exterior work. The drillers were surprised how much water they hit when drilling, and were trying to convince us to have them drill for a water well while they were there- it would have cost practically nothing since the rig was in place already- and not have to pay for public water anymore. I wasn’t as interested as they hoped I would be.
I want to make the point that this is not geothermal heating or cooling (although it is often described that way). What it is a heat pump that pumps heat up during the winter and down during the summer. True geothermal heating would require going down thousands of feet at least. At least in most places (including New Jersey).
That said, it is much more efficient than any other form of heating or cooling. I have contemplated it, but right now the price is not right. I imagine that after the providers have enough experience, prices will fall.
Have you been through a really hot Summer with that system yet? I ask because my brother and SIL had one of these put into their new home a couple years ago and every time I have been over to their place on a really hot day it just doesn’t really feel like the unit is doing a very good job of removing the humidity from the air inside the house. They would set their thermostat to like 72 degrees and the system didn’t ever seem to be able to get the temperature below 74.
Also: is there a sight gauge or something whereby you can monitor your antifreeze level? If you have some ground shift and one of your PVC pipes cracks or breaks, is the only way to repair that to pull up the piping and replace it all? How could anyone tell where the leak would even be given the depth of the piping and the fact that it’s encased in concrete?
Where does your Brother live?
I can’t get the house to 70 when it is 90 outside in Central Arkansas.
If he loses antifreeze, the pump that moves it around will let him know.
I imagine the wells are capped off with concrete; OTOH, I have a concrete fish pool that holds water.
The wikipedia article on this topic says it’s only about 20 feet. But whatever. I guess the engineers still figured 450 feet twice was cheaper than 165 feet 6 times.
