The Case for Geothermal Heating and Cooling

New house, old oil furnace.

Back in 2017 we bought a house with a 30+ year old oil furnace with a large oil tank in the basement. After one winter of dealing with the smell and the cost of oil truck deliveries, I knew we would have to do something.

We have gas in the house for the stove and hot water, so that was a consideration.

Being new home owners, we received several flyers in the mail from our existing energy providers reminding that their particular energy source was by FAR the cheapest and best solution, hands down.

So who to believe?

That is a tough question and one that you won’t find a clear answer to online. It’s not because people are dodging the questions, it’s because there is a lot involved.

How far from the equator are you? How close to the ocean? How much snow do you get? Humidity? Are there trees blocking the sun around your house? Basement? How much insulation do your walls have? How good are your windows? How old is the house? etc. etc. etc.

There are a lot of factors that determine your heating load. Separately, a lot of factors determine your cooling load. These two things are determined separately and are often measured in “tonnage”. Local contractors generally have a good finger to the wind for this and are pretty good at estimating how large of a system you need.

In some cases I’m sure oil heating is the cheapest and best solution. Given the current rates for gas however (pushed down a lot by fracking…so keep that in mind), it’s a strong contender. I think gas is MUCH cheaper at the moment, at least for my location.

What about a Heat Pump

Heat Pumps complicate things even further. Depending on who you ask, you’ll be told that heat pumps are either the best of all 3 or the worst. Part of the problem here is that historically heat pumps were pretty expensive for a lot of, mostly colder, climates. But they continue to get better and are now a strong contender for 1st place in many areas.

So where does Geothermal come in?

When you look at the negatives around heat pumps, it pretty much boils down to their lack of efficiency in really cold (~14 degrees F) and really hot (~95 degrees F) temperatures. Traditional heat pumps use the outside air and exchange heat, either moving it into the house or moving it out. So when it’s very cold, it has trouble extracting heat from that air. Same (but opposite) for hot.

1-1/4" Tubing for our Geothermal wells

Traditional heat pumps are “air source”. Meaning, they heat exchange with a large volume of air. This is where that large compressor outside your house comes into play.

Truck that drilled our wells

Geothermal heat pumps are “ground source”. Meaning, they heat exchange using the ground. When you go down a couple of feet, the ground is ~55 degrees F all year round. It never changes. As a result, the heat pump doesn’t have to work as hard and can be VERY efficient.

Wells are put in, but not tied into the house yet

Geothermal is so good, that in just about any climate it out performs all other heating/cooling sources. There is some research that suggests it is also a better deal in the long run than adding solar to your roof. Some more reading

Trenching to connect the wells to the house

Given that we needed to replace are aging oil furnace anyway, we decided this was the best investment for us.

Starting to connect the 1st well to the 2nd

So whats the problem with Geothermal?

It has a high up front cost and you need the space to install it.

The way geothermal heat pumps do their heat exchange with the ground is by running piping underground and moving a fluid through those pipes. This means either trenching (need a LOT of open land) or by drilling one or more wells.

Connecting the two wells to each other and back to the house

For my property, the only option was well drilling. This is more expensive, but also performs better.

There are numerous federal, state, and local tax credits and other support that make it cheaper. After all of those credits, the cost for us has been ~$15K for a 4 ton system in Maryland. By contrast, a new gas furnace would have cost ~$9K. So definitely more expensive, but the credits have kept it in range for us. The pay off period should be somewhere between 2-7 years for us.

Finishing up and hiding everything underground

We have now lived with the system for almost 2 years and are very happy. It is much quieter in the house not hearing a compressor kick on and off. The grass has grown back and you’d never know anything is there. I have compiled some numbers for the cost/benefit analysis, but I will save those for another post.

Edward Romano Written by:

I dabble in, and occasionally obsess over, technology and problems that bug me