Geothermal?

[jaed]

I recently got Tesla solar and power walls installed but I found that my older 5 ton 10 seer and 4 ton 12 seer AC use a Ton (don't mind the pun) of power and drain the 4 power walls quickly. So I am looking into getting a new AC system but in my exploration I came by Geothermal and it looks interesting.
Has anyone priced out / installed a Geothermal system? If so any advice or experience?

 

[shs1]

I have a WaterFurmace Synergy 3D 5-ton unit that heats and cools air and heats domestic water. it works fine with my 2 Powerwalls using their soft start thing. I also pre-cool the house so that I don't use any energy from the grid during peak or partial peak times.

 

[SSedan]

There is a lot of room for improvement there without going to geothermal.

How high and low do your temps go?

Drilling for the underground loops cost a lot. If you have a pond sometimes that can be used for the geothermal loop.
Here near Green Bay where an average year swings from -15f to low 90s my primary heating and cooling is air source Fujitsu mini-splits. If it sustains -15f or lower we do turn on some old electric baseboard. Point being air source has come a long long way.

 

[jaed]

True I am in the CA Bay Area so the weather is nice maybe low of 30 and high of 105 on the extremes.
I am just in the process of pricing out systems and seeing what I am in for and Geo Thermal was an option.

The other option is a dual fuel heat pump normal AC / heating units. Would like to get close to 20 SEER.
I am interested in what Elon is going to come out with so I might just wait. Normally my solar makes more than a need on a given day other than the really hot days so far.

 

[lavalamp425]

Geothermal (ground-source) heat pumps are great, but the expense of the ground loops (whether drilled vertically, or excavated if you have enough space) makes them generally non-competitive with air-source heat pumps for most installations.

First thing I'd do is confirm whether you really need 9 tons of cooling; that is a lot. If you can downsize the units, that along with newer and more efficient equipment would reduce your load quite a bit.

 

[MorrisonHiker]

True I am in the CA Bay Area so the weather is nice maybe low of 30 and high of 105 on the extremes.
I am just in the process of pricing out systems and seeing what I am in for and Geo Thermal was an option.

The other option is a dual fuel heat pump normal AC / heating units. Would like to get close to 20 SEER.
I am interested in what Elon is going to come out with so I might just wait. Normally my solar makes more than a need on a given day other than the really hot days so far.

You might also look into evaporative coolers. While they do use water, they hardly use any energy. Some of the better ones, such as Breezair, have very good warranties and can do a great job lowering the indoor temperature by 20 to 30 degrees vs. outdoor termperature.

 

[shs1]

Just FYI, my geothermal system uses a pond loop.

 

[shs1]

I know that there are Federal tax incentives for ground source heat pumps that I don't believe apply to air source. That should make ground source more competitive.

 

[jaed]

Yea I think I do need the two AC units with the house being almost 4200 sq feet. Thanks everyone for the input.

 

[m3-pw2]

I have a WaterFurmace Synergy 3D 5-ton unit

Out of curiosity, how much power does this ground-source heat pump use when it is running? Is it the same whether it is heating or cooling?

 

[wjgjr]

I know that there are Federal tax incentives for ground source heat pumps that I don't believe apply to air source. That should make ground source more competitive.

Geothermal heat pumps are covered under the same ITC credit as solar - so 26% this year. There may also be other incentives (our state has them.)

 

[nwdiver]

While they do use water, they hardly use any energy.

I guess it depends on your location. Here in NM it's A LOT easier to make energy than water.

To some extent it's a bit of a catch-22. If water is abundant then so is humidity => evaporative cooling isn't as effective. If humidity is low then water is probably a bit more scarce and you'll be better off adding a few solar panels and going with a mini-split.

Individually evaporative cooling might seem like a good idea but IMHO the last thing we need as average temperatures rise is water supply issues if too many people are relying on evaporative cooling....

 

[strider]

Geothermal (ground-source) heat pumps are great, but the expense of the ground loops (whether drilled vertically, or excavated if you have enough space) makes them generally non-competitive with air-source heat pumps for most installations.

First thing I'd do is confirm whether you really need 9 tons of cooling; that is a lot. If you can downsize the units, that along with newer and more efficient equipment would reduce your load quite a bit.

We installed a 5 ton ClimateMaster unit a couple years ago. We replaced 2 air sourced units (one 3-ton and one 4-ton). We did spray foam in the attic which allowed us to be able to cool the whole house (3,200 sq ft) with the 5-ton unit in a 2 zone config.

Installed price after tax credits was 28$k (this included redoing all of the ducts, moving some returns, etc), which was almost exactly the quote I got to replace the air source units.

Bottom line, the tax credit pretty much covers the cost of the ground loops.

 

[shs1]

Out of curiosity, how much power does this ground-source heat pump use when it is running? Is it the same whether it is heating or cooling?

From the Tesla app, it seems that unit uses either 5 or 9 kW when running. When it kicks in, it runs for not too many minutes before turning off. Also FYI, my home is about 4000 sq ft, but made with SIP panels and so very well insulated. My 5-ton unit heats and cools our house, no problem.

 

[animorph]

I kind of liked the Trane XV19 conventional heat pump. It has a variable speed compressor, so no soft-start is required when powering with solar, and it runs continuously instead of on/off. It's also more compact and quieter than average, which is nice in our application. SEER is around 19. I don't currently need a new system, so I don't know what similar options are available from other companies.

While I have kept an eye on geothermal, it hasn't seemed cost effective.

 

[jaed]

Anyone with heat pumps feel like they should have dual fuel? An HVAC guy was telling me you need gas when it is to cold. I live in the Bay Area and it gets around 30 deg + or -

 

[bkp_duke]

There is a lot of room for improvement there without going to geothermal.

How high and low do your temps go?

Drilling for the underground loops cost a lot. If you have a pond sometimes that can be used for the geothermal loop.
Here near Green Bay where an average year swings from -15f to low 90s my primary heating and cooling is air source Fujitsu mini-splits. If it sustains -15f or lower we do turn on some old electric baseboard. Point being air source has come a long long way.

I've only done a "little" research on geothermal, but . . . could you use a large swimming pool as the heatsink. You mentioned a pond . . . and that got me thinking.

 

[nwdiver]

Anyone with heat pumps feel like they should have dual fuel? An HVAC guy was telling me you need gas when it is to cold. I live in the Bay Area and it gets around 30 deg + or -

I really hate ~99% of HVAC techs. For some reason most of them think VFDs are witchcraft, ductless systems are the work of the devil and if you need a coat then it's too cold for a heat pump to work. They set my sisters heat pump system to swap to propane at 40F.... 40F!!! WTF is wrong with these morons?! My sister manually set it to 23F and guess what... works just fine at 23F.

I think some tribal knowledge got stuck in their heads ~30 years ago and it's become gospel. You can ignore pretty much everything they tell you as nonsense.

 

[jboy210]

Anyone with heat pumps feel like they should have dual fuel? An HVAC guy was telling me you need gas when it is to cold. I live in the Bay Area and it gets around 30 deg + or -

When we had a heat pump in Virginia we often used the "Emergency Heating" switch because the house was not heating. It was just blowing out air at 74 when I set the temp to 78.0. After that experience, we have never again wanted a heat pump for heating.

 

[nwdiver]

When we had a heat pump in Virginia we often used the "Emergency Heating" switch because the house was not heating. It was just blowing out air at 74 when I set the temp to 78.0. After that experience, we have never again wanted a heat pump for heating.

How old was the heat pump?