Geothermal heat pumps anyone?

[Country Geek]

Getting ready to replace my dual-fuel heat pump and a geothermal system looks like the favorite. I have plenty of land for the water lines so that's a plus, and tax credits make it just a bit more than conventional, seems like a no-brainer.

Would love to hear others' experiences with this type of system.

Do you have backup heat on yours? In NC I'm hearing mixed messages on whether or not that's needed.

How is the air temp that blows out? Comfortable or chilly?

Any other comments on reliability, etc?

 

[doxford jim]

I have a Waterfurnace geo system that is probably 15 years old or more. It does an adequate job but where I am the extremes are pretty severe. Winter temperatures here can go to -35C / -30F and the system uses a lot of electricity to keep the house comfortable in those temperatures. The system was already installed when I bought the property, so I cannot really compare to present day energy costs.
I do have a backup heating system and it is propane heat. It works well but is an older 80% efficiency unit and is only used when the main system is shut down.

Where I live we get maybe two or three power outages each winter, which means no heat ordinarily. However, I have a 12kW backup generator that I fire up at such times. The geo system is a fairly heavy user of electricity and unless an adequate back up power supply is available, the geo system is of no use - for heating or cooling.

NC weather would be much more suited to a geothermal system, however I would definitely recommend an appropriately sized back up generator.

These things break down eventually and are prone to being expensive to fix. Fortunately I use the people who installed the system for parts and they are very helpful with information and any questions I might have regarding repairs.

HTH

It sounds like your situation might be a worthwhile consideration with the tax credits.

 

[tcartwri]

I did quite a bit of research on converting our house to geothermal and what it came down to was that if the ductwork is not designed for it, it will severely limit the life of the pump. so in my case it would have required redoing all the ductwork in the house... which was obviously not going to happen.

 

[Stimw]

I installed a 3 ton in my last house and it was in it when I sold it 20 years later!
I had a well and discharged the water on my lawn or drainage ditch as needed.
The ground water was 65* so it was like heating or cooling at 65* verses a heat pump that works on ambient.
There was no heat strips and the heat vent put out about 20* over room temp and about the same with cooling.
It only drew 23 amps and was on a 30 amp breaker! Do the math on efficiency.

 

[mfreund]

We have a 4 ton capacity geothermal heating and cooling. Much cheaper than the propane we used to have. We have electric resistance for back up heat. That part is not very efficient. We have a desuperheater and that works well. What is that you say? It takes the waste heat from the compressor and puts it in to your domestic hot water. It will make well water up to 90°F.

What would I do differently? Make it a 5 or 6 ton unit. They size the unit to 80% of your heat/cooling load. I would size it to 90%.

 

[BitChin1]

I installed a 3 Ton unit from Bosch when I built my house last year.

Ours is a pump n dump approach (water from well returned to another well)
Unit is very efficient.

We live in SC Kansas and never has trouble keeping up with 100+ nor > ) deg days (although most of our norms are 90's in summer and low 20's in winter.

in my case the installed cost was < for a similar air source HP due to the tax credits (credit is for all necessary costs, plumbing, wells electrical etc)

I find that the air temp from the registers is a bit colder in summer and bit warmer in winter as compared to the HP at my previous house.

My HVAC guy thinks the system will last longer then typical air source due to all equipment inside and less effort required (transferring heat from constant 56deg source vs air source). we'll see but it came with 10yr parts and labor warranty

make sure your house is well insulated/air sealed then don't oversize the unit - doing this and the key issue for summer comfort is handled well by the geo unit (de-humidification)

 

[JimRB]

I have a 3 ton Climatemaster in a 2700 sf house. Basement is conditioned but the vents aren't full open. Anyhow in 17 years I had to replace a coil. Other than that it has run without issue. I think it is also on a 30 amp breaker. No booster heat and it ran a lot when we had those cold snaps last year. 3 ground trenches.

I turn on my hot water heater I guess about 3 months of the year when I am not conditioning the house. Desuperheater works well.

There was a geothermal thread not all that long ago here.

 

[s219]

We've had one about a year (Climate Master brand), and it has been working great. It does have aux heaters, and they came on occasionally when we were having extreme cold snaps this past winter. Usually the aux just comes on temporarily in cases where the desired temp is a lot higher than the incoming air temp and it's real cold outside (for example, we saw aux kick in for a few minutes during extremely cold mornings when the thermostat switched over from overnight to daytime temperature). I don't think I ever saw aux come on when the house was already warn, and certainly not when ambient temperatures were above 20F outside.

One other purpose of aux is to provide backup heat if you ever have a compressor failure in cold temps. The "emergency heat" mode on the thermostat uses only the aux heaters. Obviously that would be expensive, but better than nothing in an emergency situation. It could also possibly let someone operate heat using a smaller backup generator, rather than trying to power the full geo system.

I have a 21kW backup generator (diesel). We haven't had a real good chance to run it under emergency conditions, but it will run the geo system OK. I am thinking it installing a soft-start kit on the geo compressor just to make life easier on the generator.

 

[fordmantpw]

We put one in our house to replace our central air/forced air gas system in summer 2011. We LOVE IT! It is super quiet, keeps our house 3 degrees cooler in the summer, 1 degree warmer in the winter, and costs us less to run than before. Overall, we save about $500/year over the previous system, but our house is much more comfortable now than before.

We have a pellet stove in the basement that we use for supplemental heat. We only use it because of the way the duct work was laid out, the geothermal (nor the previous system) does a good job of heating the basement in the winter.

We are currently building a new house, and it will have a geothermal system as well (it's actually already installed). The overall cost is not much more than a conventional system, and in the long run, the savings will more than cover the cost. We will not have backup heat in our new home other than the heat strips in the unit.

As far as brands, we went with WaterFurnace as their unit seems to be the most efficient, and around here, the WaterFurnace dealer seems to be the most knowledgeable. That last bit is probably the most important part.

One note, for added efficiency, you can have them drill an extra ton of loops for your unit. In other words, if you need a 4 ton unit, have them drill enough holes (or trench, if you go that route...I vote for drilling vertical) for a 5 ton unit. This will give you a bit more efficiency on your unit, and will give you extra in case you have a need for expansion in the future.

 

[dpb800]

We installed a 3 ton Bosch unit 2 years ago and it has been great. It has been much cheaper than propane and more comfortable. We installed it while leaving our original propane furnace in place as a backup. Rebates at the time made it affordable as well.