Photograph via snooOG

A reddit focused on geothermal energy and geothermal electricity. All civil discussions aren't just welcome but wanted.

The Geothermal Reddit

Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. The Geothermal energy of the Earth's crust originates from the original formation of the planet (20%) and from radioactive decay of minerals (80%). The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface. The adjective geothermal originates from the Greek roots γη (ge), meaning earth, and θερμος (thermos), meaning hot.

Wikipedia: geothermal energy

Geothermal electricity is electricity generated from geothermal energy. Technologies in use include dry steam power plants, flash steam power plants and binary cycle power plants. Geothermal electricity generation is currently used in 24 countries, while geothermal heating is in use in 70 countries

Wikipedia: geothermal electricity

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Can I power hydronic radiant floor heat with geothermal waterfurnace 7 series?

I currently have geothermal heating/cooling with Waterfurnace 7 series.

Thinking of adding hydronic radiant floor heat for main floor - tubing would be under subfloor between joists.

Does anyone know how this might work with my 7 series? Or, would I need a separate boiler for the radiant heat?

17:12 UTC


Geothermal HVAC 10 years of Frustration

Good morning folks.

I am getting to the point of sheer frustration with my system.

First a little back story..

Built this house 10 years ago... Geo system , climatemaster tranquility 22, with a Honeywell HZ432 controller.

Almost every year for the first 6-7 its mostly worked ok. The drain vale (due to our water) clogs up once or twice a summer, and I clean it out and off we go.

This year however has been an absolute nightmare.

  1. Had a local company come out to fix the cooling. Did some stuff and said the coolant was low, and the coils needed to be cleaned... Fine.. whatever... 1000$
  2. Didnt fix the issue. Comes back, notices the coolant has dropped a bit more (i think hes scamming me at this point). Puts in some anti leak stuff, whatever.. 500$.
  3. Didnt fix the issue. Over the next week I figured out the issue was dampers. Most of the were seized. One basement zone damper was open, so the basement was staying SUPER cold (67) and the upstairs was 75. He came back out, quoted $2500 to replace all four of them. I bought them online for 800$ and did it myself... Ill never work with that company again.

Fast forward about a month to today. Im not getting this thing to stay on for the life of me.

Its showing all green on the panel. If I reset it, it cools (fans blow etc) for a few minutes and shuts off. Flipping the breakers, waiting a few minutes, resulted in the same behavior.

So it just keeps shutting off and not cooling.

Any clue as to what could be happening? Just super frustrated... This year alone im in over $3k in repairs for a system that was supposed to save me money.


15:29 UTC


Combo geo and mini-splits?!

Do any of you have combinations of both geothermal and air-source mini splits? The price of geo for our whole house is too expensive. This involves a new geo air handler in both attic and basement with new duct work in the basement. However, if we only did a new geo air handler in the attic, and for the basement instead install two mini splits, the final cost would effectively be very similar to the whole house air source quotes I’ve gotten. Is this idea reasonable?!

00:40 UTC


Code of practise for deep geothermal wells

Hello good people,

Is it possible to find this code https://www.standards.govt.nz/shop/nzs-24032015/ anywhere online for free, or if somebody can maybe email the pdf version?

Thank you!

1 Comment
21:22 UTC


Geothermal system coming in soon. Any ideas to reduce electricity usage?

We have a solar PV system. Generates more than 100% of need before geo system. How has a geo system impacted your electricity usage and how do you minimize it?

16:11 UTC


Geothermal in South eastern Virginia

Anybody have any recommendations? I’m converting an oil furnace. Shopping around for options between a heat pump and geothermal.

18:27 UTC


Lower Temp at Night?

I know, I know, ground source heat pumps are meant to be set at 21C (or whatever) and left for the year.

But our house is like a church in design and the bedroom is a loft 16ft up, where it is obviously much warmer. I'm wondering about setting up a system where it's 21C from 7am-9pm, and then maybe set it to 16C at night.

Are the only downsides that the furnace might take a while to bring it up to 21C? If so, I don't really care if the mornings are a bit chilly - I can always set it at 5am start for exaple.

Putting that aside, wouldn't my furnace be more efficient running for 2-3h at a time? Right now it runs for only about 30-40 minutes at a time, which seems inefficient.

If it matters: I have 6, 600ft loops burred 5.5ft down in a very clay-soil. I have a 2-stage Hydron 5-ton furnace. Our climate is Southwestern Ontario (winters down to -25C occasionally but mostly -15C, and summers +30C).

18:23 UTC


Replacing pump, but keeping heat extractor coils?

Hi - just moved to a house in the UK. Built c. 2005 - has an older Water Furnace Series E heat pump, which is failing. Water Furnace have since withdrawn from the UK market, so very tough to service, get parts etc.

Annoyingly, we have no plans for size of heat extractor coils / lengths etc - but assume it is a horizontal install.

We would like to replace the pump with a different brand of unit, but keep the coils.

E.g. replace the entire heat pump unit, reconnecting the new one to the existing ground water loop (Vs getting an air pump - seems a shame to waste the work that's gone into putting the coils in.)

How practical is this? What are our options?

Sorry, complete newbie to this field, so grateful of any and all advice! Thanks folks.

** Edits for clarity **

21:56 UTC


Community proposal for shared ground arrays - pricing and modelling

21:08 UTC


Cold water is hot!!

We have a newly installed (June) geothermal system in Manitoba, Canada.

In summer, it was on "cool" setting. Last night we switched to "heat" and this morning, our cold water ran hot for about 10 minutes before cooling down.

This happened a few times for shorter duration (2-3 minutes).

The installer said he didn't really know why this was happening in summer, but we shouldn't be concerned.

However, this felt extreme to me.

Can anyone explain to me layperson's terms what might be happening, so I can have an intelligent conversation with the installer?

I believe we do have a "superheater" connected to our hot water tank in some fashion...

12:21 UTC


Is it worth it?

Our furnace needs major repairs, and our AC is on its last legs. We're currently looking at $15k to replace both. Since that's a pretty big investment, we're researching whether geothermal would make long term sense for us.

A highly rated local company is advertising horizontal closed loop systems for $20-25k, which after tax rebates, would be similar to the cost of traditional systems. But will it actually save us money long term? My concerns are:

  1. How are maintenance costs? I know the loop should be good for 50 years, but in your experience is that accurate? I'm also worried that we'll have far fewer options for repair and annual maintenance, since not many companies are familiar with geothermal, so costs could be inflated compared to traditional systems.

  2. How much land do we need for horizonal loops? Vertical are likely beyond our current budget. We have 3/4 acres and our backyard is huge, flat, and only has a handful of trees.

  3. Will our utilities actually go down? We have a 2500 square foot (plus basement), well insulated 90s house. Our average utility bill over the last 12 months was $185. Our worst winter and summer bills were $230, but our AC at least will already improve, because our old system was a 13 seer on its last legs, and the new quote is for a 16 seer. Our current furnace is gas, and we are on city gas lines. It seems like many people in this sub started from far more expensive propane or oil systems.

Google brings up tons of ads trying to convince us to go geothermal, but very little for first hand experience. Is it worth it for people with lower heating and cooling costs?

15:46 UTC


No aux heat wire on panel

I have water furnace open loop system, that uses premier intellizone 17p519a01 panel. When I looked at it while replacing my thermostat I noticed there is no port for auxiliary heat on the zones but there is one on the panel itself. Does it mean thermostat can’t request aux heat ?

1 Comment
23:47 UTC


Geothermal vs Air Source Heat Pump Specification Comparison

I've been researching geothermal to replace my oil burning furnace in southern Maine. I recently reviewed the performance data for a geothermal heat pump and an air source heat pump. For my location where the average groundwater temperature is ~42 F there is minimal efficiency gain from geothermal.

The geothermal heat pump is a Miami Heat Pump HPX036. With a 40 F source water temperature the input power is 2.48 kW and total heat capacity is 28,890 btu/H for an air temperature of 68 F. The air source heat pump is a MRCOOL MDU18024. At 17 F air temperature the unit will consume 2.9 kW and total heat capacity is 24,000 btu/H of heat. At 32 F the unit will consume 2.3 kW and total heat capacity is 24,000 btu/H.

Is anyone able to provide additional specifications that provide substantial efficiency gain from geothermal in a cold northern climate to support the increased cost of the ground source loop?

Please review the tables below for comparison:



01:06 UTC


I and someone else wants to learn more about teneeeble energy sources that is less known. How and where should we start to learn?


13:32 UTC


Vertical closed loop system

Hi all,

we are planning to build a home in Ireland and we are wanting to get underfloor heating. we are looking at a geo-thermal system. there is an existing well on site which was only used for washing vehicles etc and will not be used for drinking use as there is a private scheme in that area.

would it be worth getting an open loop system using this existing well in stead of a horizontal system? and what costs would we be looking at?

thanks in advance

10:41 UTC


WaterFurnace Quote

My dad’s 20 year old system went kaput, and this is the quote he received for about 27k. From the model number I can’t even tell if it’s a series 5 or 7. Since it’s 2 stage not 100% variable it’s more likely a series 5?The lack of detail makes me question things a bit but curious on any thoughts for this?

WATRFURNACE GEOTHERMAL SYSTEM NDV064K111CTL0AA 5 ton 2 stage Geothermal unit. Unit pad, 15kw heat, 2" filter, Hose kit, Intelastart Pro1 IAQ T855 Programmable 3H/2C thermostat WARRANTY 10 year parts and labor allowance Install Material Freight Supply Transition Material Return Air transition Labor Flush loop system Labor Quote to replace the GEO thermal unit with a Waterfurance 5 ton 2 stage unit. Includes hot water regeneration, soft start for the compressor and a 10 year parts and labor allowance warranty. This will be installed on he existing ductwork and ground loop. The existing loop pump will be used. Complete loop flush is included.

23:08 UTC


DSH to Hot Tub?

This may be a dumb idea, but I’m an homeowner with two Water Furnace 7 series. Both have desuperheaters with one hooked up to the water heater buffer tank and the other not hooked up to anything. There is also a 1,500 gallon swim spa ~10 feet away (it’s sunken into the floor above, so the tub, pumps, etc are on a platform in the mechanical room). My harebrained idea is to make a loop with the free DSH to a heat exchanger which would then be connected to the hot tub (since it seems like a bad idea to run pool water through the DSH). I’m just trying to get some initial thoughts as to feasibility, potential issues, etc. Thanks!

16:47 UTC


Green Building Advisor: Geothermal Heat Pumps: Reputation vs. Reality

Geothermal Heat Pumps: Reputation vs. Reality - GreenBuildingAdvisor

I'm a fairly regular reader of GBA. They put out some good material on building science.

Article calls into question the benefits of geothermal, showing the measured ground temperature increasing after the first year. There is a seasonal lag where the outdoor air temperature is actually a better heat sink than the ground.

Is this just and improper installation, or are geothermal users seeing decreased efficiency thoughout the heating and cooling seasons, once the ground absorbs the heat from the house?

19:30 UTC


Estimating Electricity Usage

Does anyone know of any reliable tools or data for estimating the electricity consumption of geothermal units? I have our square footage and a proposed geothermal system, so I’m hoping to calculate based on that. Alternatively, our home is currently on oil, so I know our annual oil consumption — if there are ways to estimate based on that, that would also work. Thanks so much in advance for any guidance!

13:30 UTC


Considering geothermal cooling system for summer - is it this easy?

I have a large property (>50 acres) and have recently heard about geothermal cooling.

I'm very naive so starting here to get some pointers.

As I understand you can build a simple system by laying PVC pipe underground (1m or so) and pumping air through it and you should get cool air (13 - 15c or so) coming out the other end.

I am thinking of dedicating about 1 acre to lay the pipe - I have my own excavators and other equipment so I'd do all the work myself (so cost will be time and diesel + PVC).

On a hot 40c day I expect I can circulate our house air through this crude system and get 13 - 20c air out the other end to cool our home?

Am I on the right track?

13:30 UTC


Geothermal Utilisation in Canada's NWT

Nearly 98% of our planet is hot enough to boil water. Hot enough to boil anything! Geothermal heat is there waiting for us to bore. Countless people have expressed interest in harvesting earth's subterranean thermal-treasure. However, we have not invested enough effort in getting it. The high cost and political reticence of establishing geothermal systems seems to be the only couple of gates in the way.

The people of the North West Territories mostly live in the south-west of the territory. It is also one of the most promising regions of Canada for accessing near surface geothermal heat. This is not a new finding and those folks in the region know more about the technology and potential than I do. In fact a series of governments have shown interest, but not enough! And in this rare case it was the grass roots governments that were most reluctant. But there was not enough action and follow-through from the top either!

A geologist told me that bore drilling for assaying the viability of mining an area is terrifically expensive, partly because of the usual failure of finding a vein or commercially viable deposit in many of the bore holes. "Eating countless oysters at a ritzy restaurant in the hope of finding a gemstone quality pearl." One in one million. Give or take a pearl. The geologist added that they knew with great certainty that whatever they wanted was down there; Just a daunting deal of hit and miss with too much of the latter.

I started this post to bring attention to the great opportunity of really doing something with immense benefit for the fragile north's ecology and environment. Currently, in Canada's north, electrical production, home and building heating comes almost exclusively by way of burning diesel and heavy oil.

These sub- and arctic regions are far more sensitive to harmful pollutants -- ecologically -- than it is for the bottom half of the nation. One of the reasons is the slow hand of Mother Nature in cleaning up any mess. Things move slowly up there, save for the Huskies and SNOWMOBILES.....and effective action on implementing geothermal technology! Diesel might be great for a European motorcar but not for the environment of northern Canada.

I am in a sub, sub arctic region of Canada --- note that Canada's capital is in the far south of the country and yet the city is the second coldest capital city of any capital city of a nation on this mostly boiling hot planet. Heat pumps are widely used but I believe that geothermal potential for bigger things (electricity production) warrants more focus, effort and of course money. Picture a Martian chattin with his buddy," Look at them down there, splitting atoms to boil water! Can't they look down below their bipedal protrusions?"

22:11 UTC


Insulating geothermal pipe that runs through the attic?

I have some uninsulated geothermal pipe that runs through my attic for about 30 feet. Considering that my attic can get to over 115F during the summer (Texas), I thought it might be a good idea to insulate the cold water pipe. However, it's an odd size. 1.3" OD. I've found foam and rubber pipe insulation in 1.25" and 1.5". Would it be better to go bigger, having a small gap between the pipe and insulation, or slightly too small not allowing the insulation to close completely around the pipe?


16:20 UTC


Geothermal units, trench depth

Hi there r/geothermal!

I have determined that geothermal is the solution for my situation. I have a large gas heating bill and air source pumps, while operable in low temps, lose their efficiency, need a supplemental heat source, and supposedly have less life span.

I see temps as low as -10 sometimes. I live in climate zone 4, and the temperature of the earth @ 40in deep is about 72.

My question: What are the most efficient consumer-reputable 5 ton units, and how deep should horizontal loop trenches be in this scenario? 6 feet deep? Going to pay an excavation crew to dig and then install the pipe and unit myself.

Thank you!

19:11 UTC


Just bought a home with an existing geothermal system. It's about 12 years old. What continuing maintenance do I need to do?

15:18 UTC


New construction geothermal

I am building a house in Maine, and I got a quote for a Waterfurnace 5 series dual capacity 15 kw (4.26 tons), 2 zones, vertical closed loop, two bore hole 280’. Does not include excavation and electrical.

I talked to the installer and he expects the electrical to be 5k and excavation is unknown until the well drillers go do it.

Quote = 43k (equipment and install) + 8k (duct work) + 5k (electrical) + ? (Excavation costs)

= 56k ++

All of this is before any incentives (30% fed and 3k from Maine).

From my experience everything is priced high in Maine, but this seems crazy based on some other posts I’ve seen (a lot of Massachusetts people getting geothermal).

I asked him to quote just air source heat pumps (w/ducts) too and he was very confident that the difference wouldn’t be that much. He specifically said he’d expect a 5 year payback for the geo vs air source.

This is my first experience with geothermal, I’m very new to doing research into this subject. Any thoughts?

12:56 UTC


Hot roof when geothermal installed?

My geothermal installer says I should have a hot roof when I install a water-source heat pump. A hot roof has a full 7" of spray foam insulation in the rafters. The attic is then sealed off from the outside air.

There is a trapped moisture issue, and for me, the house has integrated gutters on the roof (aka Yankee gutters). A hot roof is more prone to ice dams.

I'm going to see the installer tomorrow. And I will question him over this. But why would he be making such a recommendation?

15:41 UTC


Geothermal in south east mass

Hi all

Looking to get geothermal in my bed home in MA. Any suggestions?

1 Comment
00:09 UTC


My oil boiler died and I want to switch to Geothermal. I'm currently talking to a company called The Geothermal Group and can't find any reviews. Has anyone worked with them?

This is their website


My oil boiler is dead and I really don't want to replace it with another one. But I also don't want to blindly use any company to do geothermal for me. Does anyone either have experience with them or can actually find a review on them?

14:54 UTC


Metal screws for waterfurnace legend

I have a 2012 waterfurnace legend. I've lost the screws for the panels. Anybody have any clue what they are? Metric?

15:53 UTC

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