New Build in 2018: Geothermal vs NG/conventional AC

Dadnatron · Feb 9, 2018

I am building a new home, roughly 3000sqft higher end home this year. (or at least planning stage with architect).

Location is Lexington KY area. I have access to and will run Natural Gas to the house for range and fireplaces. The run will be long, likely 1/2mile at least across my land.

I am soon to be 50yo and I'm planning on another 30 at least. But I am trying to be pragmatic, not pie in the sky.

My question, to you who have gone there and have more knowledge: would you add a Geothermal Heat pump or conventional Nat Gas/AC system to this house in my situation? While $$$ is an issue, I'd like to know your thoughts on the 'intangibles' as well such as 'down time, noise, comfort, install (new home) etc. ' and would you personally, do it in my situation?

I am ambivalent. I'd like the 'green-ness' of the geothermal just as I'd like it for Solar, however, I don't believe Solar is a wise investment at this point, and I don't know about geothermal.

What are your knowlegable thoughts about it in my situation? Why WOULD YOU or WOULDN'T YOU?

We will be putting in 2 horse barns, well away from the house and will have about 1/2mile of driveway as well. Just to add some info if that brings up any thoughts.

Sigarms · Feb 9, 2018

Can't answer until I know what you're being charged for geo or natural gas AC system.

If the Geo system is cheaper than the gas ac system, geo would be a no brainer.

japody · Feb 9, 2018

We've had the geo system for almost 6 years. Very pleased. It's a Bosch ground sourced unit. Calculated pay back period at 8 years. Looks like it will come in under that, even though we keep the thermostat at 74 year round. Go for it if you can swing it.

Larry Caldwell · Feb 9, 2018

If you are installing central AC, you are installing a heat pump, so you may as well heat with it too.

Air source heat pumps work well in mild temps, and are inexpensive to install. The current crop is about 300% efficient down to where they start to ice up, about 35 degrees. Below that a ground source heat pump will keep right on chugging, though heating with natural gas is not that expensive either. Air source heat pumps will work well below freezing, but the energy efficiency drops off.

For summer use, compare Summer Energy Efficiency Ratings (SEER) on the options. A middle of the road air source pump is about 16 SEER nowadays, a top of the line is about 18 SEER. I have no idea what the rating of geothermal pumps is.

A comment on the natural gas: check with the gas company to make sure you have adequate supply at the end of a half mile line. I once installed a generator system on the end of a quarter mile pipe, run by a Ford V8, and it refused to run until we installed a bigger pipe. If your gas line is high pressure, you probably won't have that problem, but be aware that a whole house natural gas generator takes way more gas than a furnace, and the supply pressure is more critical.

RNeumann · Feb 9, 2018

I’ve never seen a geothermal system that penciled. The up front cost takes too long to recover. Do your own math- not the geothermal salesman math! Factor in upkeep, the pumps etc. I think you are in a fairly mild climate so the pay off is even longer.

Most gain the most with burning wood or pellets. But it’s obviously work. Solar is regional and wind is a waste.

Go to the building science website and trip around. You will gain a ton with some good insulation methods and proper house seal/wrap methods.

FreedomFamilyFarms · Feb 9, 2018

We built in 2016, the last year of the big geo tax credit. I’m impressed with the efficiency. The A/C is excellent. Heat blows warm air, not hot like NG. My HVAC guy was saying the air source heat pumps are getting more efficient all the time. In your climate you’ll probably spend more on cooling than heating so the geo has an edge there but it might take a long time to recover the difference. With the tax credit we installed geo for about the same as NG & A/C. Not sure about prices now. Water furnace is made right here in Northeast Indiana!

prichard · Feb 9, 2018

I've been looking at the same options except we only have l.p. no n.g.

So far I haven't seen anything that would indicate enough pay off over air exchange heat pump in our mild climate.

s219 · Feb 9, 2018

One thing I like about our geo system is that it's very quiet -- no outdoor units making noise like you get with a traditional air-source heat pump. That can be an annoyance depending on where they are located, if they are near windows, if you spend a lot of time outdoors on a porch/patio, etc...

Second thing I like is that the geo system makes a good amount of free hot water year round, significantly reducing how much electricity we use for the hot water heater. Unless it's mild weather and heat/AC are turned off, the geo system hot water generator (aka, "de-superheater") does most of the work.

Final thing I like is that the geo system is a lot better dealing with extreme cold than a traditional air-source heat pump. We can run without any aux heat as low as about 12-15F, although I will fiddle with the staging schedule to use a little aux to avoid freezing the ground loop if we have extended cold. Now, when we had abnormal -10F temps recently, the geo system couldn't keep up without running aux heat extensively, but at that point I think our house was losing heat faster than the system could possibly keep up (that was one of those times we regretted having so many windows).

I believe when we were building, it was going to cost $19K for a traditional air-source heat pump, one for each zone, plus backup propane heat. Geo (and no propane backup) was about $35K -- single unit with zone controls, duct dampers, and variable speed fan. I think I got $10K back in a tax credit, so in the end geo was $6K more.

The downside to geo in my opinion is that there is a lot of complexity, and that scares me -- a lot of it is stuff I can't easily fix. I was more comfortable about the traditional equipment at our old house. It broke down a couple times, but it was all stuff I could diagnose and fix, with parts readily available. I can fix certain issues with the geo system at our new house, but for much of it I will be dependent on our HVAC contractor (who has been pretty good so far). I do plan to purchase spares for all the capacitors, and the blower motor, since those are things I can fix and they tend to be common failures.

I just spent $440 to buy the diagnostic tool for our geo unit, so that I can get better data, monitor performance, check fault codes, etc. It's basically a small computer that plugs into the main control board, giving me access to the various sensors and data as well as letting me program the unit. I never needed anything like that with the traditional system at my old house.

Dadnatron · Feb 9, 2018

With the new 2 year budget our illustrious Congress just stuck us with, the Geothermal tax break was reinstalled.

While I am completely against this bloated deficit budget, given it is there... it makes Geothermal at least a little more plausible.

I have not contacted anyone nor have I yet spoken with the architect about it as of yet. I wanted to have a bit more knowledge before I ventured into the morass. My feeling is that over 30 years, I would have to replace a furnace/AC system at least once essentially doubling the cost. However, if there are issues with the Geothermal... I've heard they are incredibly expensive. And over the course of 30yrs, I would plan on at least one 'major' issue and a few minor issues at a minimum.

So that comes down to monthly costs... and as of yet, I don't know where they pan out. I am hesitant to believe that all involved, a geothermal heat pump in my area will be cash + or at least the overall benefits will be neutral or +. But, Ih have no personal experience with them. Just what I've read. I like the idea... but a high efficiency furnace and a newer, better furnace 15yrs from now is awful tempting. My heart says Geothermal... my brain and accountant is preliminarily leaning towards NG conventional.

Japody... we are likely to have similar climates. We are about 5deg cooler than you most of the year. When you installed... how did you choose and why Bosch? Most things I read is to 'go Water Furnace'.

Old Red · Feb 9, 2018

I'm in Kentucky. I came from a house with Nat Gas traditional furnace, then I installed a dual fuel. Here is my recommendation. DO NOT go with natural gas. You get hit with a lot of fees just for being a customer. This fee continues to climb and I believe it is around 15 bucks a month right now. I would go with an all electric home. I would do DUAL FUEL heat pump and run the aux heat off propane. Propane is 99 cents a gallon in some places in KY...or at least it was this summer. Guess how much propane companies charge you per month for being a customer? $0.00. You can rent a 500 gallon tank for $38 per year or you can buy one. I would take the cost of running the gas line and invest in a propane tank and go all electric except for your aux heat. My new house is all electric and it is nice not to have to pay atmos energy 15 bucks a month for just being a customer whether I used any gas or not. And if you do get propane for 99 cents a gallon you can choose to run your aux heat full time and will probably be cheaper than running a heat pump. My last electric bill was $358 and I have 2 hot water heaters, a 5 ton heat pump, and a 2.5 ton heat pump. This was during the cold snap. Had I not had heat strips kick in and had propane to run my aux heat my bill would have been a lot less. When I have to replace my HVAC in the future I will get dual fuel with propane as my aux heat. When you factor in what the utility companies charge as their baseline meter charges and what not I think you are better off going the direction I recommend.