Low utility bills with geothermal heat

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 .