Low utility bills with geothermal heat

JackMentink · Nov 4, 2009

I know everybody is into the alternative building types and high tech insulation sytems, but most I've seen are not real cost effective and have very long paybacks.

When I built our new house two years a go I went with 6" stud walls, r-19 blown in cellulose, r-48 blown in celulose in the ceiling, and anderson 200 series low-e windows (lots of them as my wife is a sunshine fanatic. I paid attention to the house wrap to get it sealed on the outside, and put my energies in the heating system.

I installed a ground source heat pump with a open loop system that use my well that supplies water to the home to supply a geothermal source. ( I upsized the well pump to a 2 HP and put a variable speed drive on the pump).

I discharge the geothermal water into two 1500 gallon tanks that I use to irrigate my two acre lawn. The heat pump has a variable speed fan and four zones with four thermostats to keep the house perfectly temperate in all areas. The house is the most comfortable I have ever been in it cost less than conventional system as my electric cooperative gave me a $1700 rebate for the system.

The house is 4400 square feet finished with all of it heated and cooled to 73 year round.
It is about 2800 foot ranch over a full walk out basement. I live in Missouri and we have winter with lows of 0 and summers over 95 for weeks.

The best part is the utility bills. The largest heating portion of the electric bill we have ever had was $45/month, with the largest summer cooling bill of $30/month.

Ground source heat pumps rock

BruceWard · Nov 4, 2009

Great info. I am curious what brand of ground source heat pump are you using?

Also do you know how much water you are pumping out the ground?

I am planning for a closed loop system on a house we are building next year.

JackMentink · Nov 4, 2009

My unit is a Water furnace. As far as how much water it depends on how much the furnace runs. At 3 tons it uses 6 gallons per minute, at 6 tons it uses 12 gallons per minute. On a day where it doesn't run a lot it uses 700 gallons in a day. On a real hot or very cold day it uses about 3000 gallons of water in a day.

Water is very economical to pump, and we have very strong aquifers in this area of Missouri

woodlandfarms · Nov 5, 2009

I am thinking of closed loop as well. What do you do with the remainder of the water? Once pumped I would think they would not allow it to return to down the wellhead.

Also, are you using this system for cooling, like a swamp cooler? Just wondering how the cooling works out for you.

Also, how deep is your well? The water is 55 degrees or are you getting something different?

peterssj4034 · Nov 5, 2009

I have a closed loop, vertical geothermal system using 2, two stage electric heat pumps that heat and cool about 5,000 square feet. I live in Northeast Ohio, so our summers aren't quite as hot, and our winters can be a bit colder (we had numerous days of below zero temps this year). I have an all electric house, built in 2006. My electric bill, for everything, is between $100 (spring/fall) and $225 (coldest months, Jan/Feb).

I have already recouped the additional cost of installing this system in the short time I have lived in my house.

Seth

eepete · Nov 5, 2009

My heat pumps (two 3 ton, one 5 ton) are also Water Furnace. They are closed loop systems with horizontal ground loops. House is insulated with 5" isocyonate (sp?) foam in walls, 7" in ceiling. Tin roof reflects lots of heat. The entire house is enclosed space so the attic is sealed too. Way to expensive 2 pane Anderson argon filed low E windows. Fenestration percentage is about 13.5% with the main room (kitchen/living room) area pushing that up there, most of the other rooms are single window or small windows. We also upped the air duct sizes by 2" over what was recommended for better efficiency and increased the number of output registers in bedrooms so that the noise level was reduced. I could drone on about many other little tweaks that were done.

All of these various energy related things have about an 8 year payback on them. That's all a calculation, so could be 6 to 10. And when electric rates go up it gets better. A common theme dealing with all the energy related trades is that they push things with 3 year paybacks because that's all most people will pay for. This is also what they have been taught. So you really have to fight to spend more money. Since I'm leaving here horizontally some day, a long payback period and doing it right were doable. A starter house is a much more challenging problem, but you can make good decisions and get most of the money back by showing off your low electric bill. Nothing new here- If you're in your 40's or higher, I'll bet your 2nd or 3rd tractor was bigger and cost more than your 1st tractor.

Interesting money numbers example: We did semi-custom cabinets and Corian counter tops. That saved about $35K over full custom cabinets and granite counter tops. That money paid for all the improvements in energy related areas. Much like life, I worry more about feeling good on the inside than looking good on the outside, but then I'm just a butt ugly geek.

Pete

JackMentink · Nov 5, 2009

woodlandfarms said:
I am thinking of closed loop as well. What do you do with the remainder of the water? Once pumped I would think they would not allow it to return to down the wellhead.

Also, are you using this system for cooling, like a swamp cooler? Just wondering how the cooling works out for you.

Also, how deep is your well? The water is 55 degrees or are you getting something different?

As fAR as my system goes the excess water that is placed on my yard just overflowes my irrigation tanks and down a swale on the back of my property.

I use the system for cooling but the water is just what is circulated over my coils , the same way as an Air to Air heat pump does with air cooling the coils. Mine just uses 55-57 degree water as my fluid instead of air. Stiill a totally sealed system with freon.

My well is about 370 feet deep with the pump set at about 220' and my sttic water level is about at 100'

The nice thing is that my unit has a zero year pay back. I priced high effeicency gas heat with high efficiency cooling and it was the same price as my ground source unit. I had to up size my well (2 hp) and put a variable frequency drive on the pump and all that cost about $2000 extra, but I got a $1700 rebate from my cooperative for installing the ground source heat pump.

So it started paying for itself from day one. I estimate that it saves me about 2000-2500 per year at todays electric prices (7 cent a KW). That will increase as time goes on. The other thing is that the blower on the furnace is on a variable freq drive so it slowly ramps up and down and only speeds up to the speed it needs. It also has a loop that pre heats my hot water when it is in cooling mode.

I have to say that the house is the most comfortable, even, draft free home we have ever lived in. And it is economical also.

Geothermal Heat pump is the way to go.

woodlandfarms · Nov 6, 2009

Given the politics of washington state, I am sure that they would not allow open loop. In a state that rains so much, the water seems pretty precious (I don't mind as I am a bit of a tree hugger).

Carl

slan · Nov 6, 2009

Most states either have or WILL be banning open loop systems and for GOOD reason if you think about it.
IMHO

I have a closed loop system in my lake. If my neighbor was pumping water out of OUR water source I would be having a talk with him directly but I would,t need to because it is illegal to do it here.
Sorry, not a tree hugger but you got to think about what your doing as fresh water will be like oil in another 20 years.

Geothermo systems are great, I just dont like anyone promoting the open loop system because they are cheaper.

dave1949 · Nov 6, 2009

slan said:
Most states either have or WILL be banning open loop systems and for GOOD reason if you think about it.
IMHO.

Like a 100 house subdivision each with open loop geothermal? That would be problematic.
Dave.

eepete · Nov 6, 2009

@slan: When we 1st did the geothermal, we had one loop in a field and one in a pond to save money digging trenches. The pond wasn't big enough for the whole house. During January, I did some measurements of the water temperature from the pond vs. the ground, and the temperature at the registers. The ground water was 58 degrees and the pond water was 40 degrees. And guess what- the air temperatures out of the registers was about as many degrees cooler as the differences in the two water loop temperatures. So while the heat pump on the ground loop was putting out 98 degree air, the heat pump on the ponds was putting out 78 degree air. This translated into a bit difference in the run time of the units when we tried to do the morning warm-up from 62 to 68 degrees.

So we dug up the ground and put everything on earth based loops. The pond loop is now a standby system. The guy who did the system had done many systems and had never measured the performance. The pond still does much better than an air to air heat pump, but the saving in the installation cost of pond vs. earth are a pay me now - pay me later scenario. Certainly if the delta cost means no geothermal, go with the pond. But if you can swing it, go in the ground. I suspect this is also a completely different story in rocky areas as opposed to North Carolina clay (with just a few rocks).

Close loop also don't have long term problems with the heat exchanger if there is anything funky with the local water (either PH or hardness). The also keep working in drought when wells have their output drop or go dry.

Just one more data point from stuff that happened to me.

Pete

gpflepsen · Nov 6, 2009

It's tough to judge a use figure by a dollar amount of a bill, please give the kWhr consumed.

I've been in a 2000 sqft house w/ 6" fiberglass walls and ~R50 ceiling with a full basement for about a yr now. Floor slab and basement walls have 2" extruded polystyrene. I put in a 4 ton Climatemaster Tranquility 27 with a seer 27 rating w/ 4 vertical loops down to 200'. We are 75 in winter or summer, with 0 to 100 outside. Our usage is 1300 kWhr summer high and 2700 kwhr winter. The winter is skewed high because the mrs still insist on using those **** 1.5 kW plug in heaters which are multiple times less efficient, but that's like beating a dead horse to convince her otherwise. She thinks fans will cool also, but that's another... fiasco.

Our winter rates run about 8.5 cents/kWhr.

slan · Nov 7, 2009

I guess the point I was trying to get across was the long term cost to the environment not the pocketbook.
It makes sense to anyone that an open loop is far more efficient and cheaper to put in.

Think about driving buy someone in your neighborhood that has their garden hose running out on the street 24 hours a day and you realize, hey wait a minute, we all share the same well!

In about twenty years from now the kids will be looking at videos to their disbelief of someone hosing down their driveway with drinking water.

Not a tree hugger but anyone that doesnt think there is a problem with pumping 1.5 to 3 million gallons of drinking water each year out of the local aquifer to save on heating bills might want to think about that before getting thier neighbors to start doing the same thing.

Be a sad day in August when the water starts to get contaminated. Look at Florida where they once had lots of water.

Sorry, rant over.

neilly2 · Nov 7, 2009

I agree with Slan 100% about draining the aquifer, but there is another drawback and that is flowing untreated groundwater through the units heat exchanger. You are taking years off the life of the heat pump. And the heat pump will decrease in efficiency as the minerals in the water accumulate in the exchanger.

You can install chemical treatment, but then you are pumping that to the outdoors, not to mention the additional chemical feed equipment, and the continuous consumption of chemical treatment.

MotorSeven · Nov 7, 2009

slan said:
I guess the point I was trying to get across was the long term cost to the environment not the pocketbook.
It makes sense to anyone that an open loop is far more efficient and cheaper to put in.

Think about driving buy someone in your neighborhood that has their garden hose running out on the street 24 hours a day and you realize, hey wait a minute, we all share the same well!

In about twenty years from now the kids will be looking at videos to their disbelief of someone hosing down their driveway with drinking water.

Not a tree hugger but anyone that doesnt think there is a problem with pumping 1.5 to 3 million gallons of drinking water each year out of the local aquifer to save on heating bills might want to think about that before getting thier neighbors to start doing the same thing.

Be a sad day in August when the water starts to get contaminated. Look at Florida where they once had lots of water.

Sorry, rant over.

Slan, that's not a rant....it's common sense

Excellent post!

RD

whistlepig · Nov 7, 2009

neilly2 said:
I agree with Slan 100% about draining the aquifer, but there is another drawback and that is flowing untreated groundwater through the units heat exchanger. You are taking years off the life of the heat pump. And the heat pump will decrease in efficiency as the minerals in the water accumulate in the exchanger.

You can install chemical treatment, but then you are pumping that to the outdoors, not to mention the additional chemical feed equipment, and the continuous consumption of chemical treatment.

We have a closed loop system. We have had it serviced twice. I asked the serviceman if geothermal was high maintenance. He said only on the open loop systems. He said the hard water and lime deposits on open loop systems wrecks the pumps and pipes every couple of years. The energy savings of geothermal is unbelievable. For us it is free heat and air conditioning from where we lived before. And this house twice the size. It's one of those things that seems too good to be true that really is.

irvingj · Nov 8, 2009

Interesting how terminology changes over the years... When I built my house in 1986, it was called a "water-source" heat pump.... Originally it was planned as a "pump & dump" system, but when a (closed) loop became available I jumped at it. It's now been ticking away for 23 years, supplying heating, cooling, and DHW. It has both a desuperheater and a dedicated DHW coil; it's capable of taking house heat (during A/C) and putting it directly into DHW.

Wasn't sorry I did it then, and have been loving it ever since. Nice to see a good idea finally catching on!

I'm looking, too, at Water Furnace for an eventual replacement.

Whatswrong · Nov 8, 2009

I have been a fan of geothermal ever since I first new of it ,passed up gas with the dream of a heat pump .I don,t know the layout of your farm but I can't imagine not putting in a well to return the water to the ground and avoid the swamp,iceberg and mosquitoes it must generate,as well as save the water.

JackMentink · Nov 8, 2009

I appreciate some peoples stances on the open loops, and there are a lot of locations where they couldn't be used, I E densely populated areas.

I am in a different situation, here in Missouri. I am located on a 4 acre tract and there are large 30 acre + parcels around me. Also our aquifers are abundant and not dropping in water level. I have a gauge on my well and I monitor its water level. no droop at all in the three years of use.

Unfortunately a lot of people have been fed the environmental Al Gore spin on everything, and don't really understand that a lot of the stuff is totally unfounded and not scientifically proven. Global warming is a perfect example. Totally unproven and not scientifically justifiable, but a few people have pumped it heavy, and all of a sudden every body is on the bandwagon. Enough of that rant!

In regards to my open loop heat pump, out aquifers are being replenished adequately by surface moisture, and we are not experiencing a drop in our levels. That is not the case in all locations, and open loop is not suited for all locations.

Nine months out of the year, I use my water that travels through my Heat pump, to water my lawn, and I have a wonderful lawn because of it.

Also I have not had a problem with mineral build up in the coils. I specifically questioned the installer if they had ever problems. He has had them in for 15 years and said that they install about half open loops, and they have never done a chemical treatment on one of them and they have not had any issues.

It makes sense, as people only have problems with hardness (calcium carbonate) depositing on things when its temperature is raised significantly (like in a water heater).
Calcium Corbonate hardness is much less soluble in hot water.

In the coils the water does not see high temperatures so there is not issues. My discharging water is only heated or cooled about 20 degrees so it never gets above 80 degrees. No issue with minerals.

Even if it would become an issue it would only take running dilute hydrochloric acid through the unit to remove the minerals. Not a big deal. They make a kit that can be installed to run the HCL through the unit, but because of my installers positive experience, I decided I would put it in later if it becomes a problem in 15-20 years.

Don't always believe what you hear, as sometimes fables get proported that are not always true.

My unit works great, and I feel comfortable that I am not desecrating the environment .