Low utility bills with geothermal heat

[Redneck in training]

Curious - How do you isolate the heating portion of the electric bill from the rest? Separate wiring and meters?

That is how we have it. Two separate meters and two different rates in the heating season. Normal rate in our area is 11c/kWh while heating rate is 4.2c/kWh. We heat little less than 4000 sqft including 1800 sqft of the garage. Our highest heating bill was around 100 dollars. I compared the cost with a colleague of mine who has few years old 2400 sqft house on natural gas. His bill was 350 dollars for the same time period.

 

[eepete]

On the topic of years to recover the extra install expense: When we built our house, we decided that any 6-10 year pay back period for "better" was OK. That decision affected the HVAC, windows, and insulation. The HVAV payback was at 10 years, but we also did a lot of different stuff with the duct work and dampers for zones.

The payback time decision also put on a metal roof, put in hard gutter drains, and better electrical system. And there were a few things that were hard to measure, such as having the garage floor at 1st floor level (big fill project). How do you put a price on being able to stay in the house a few more years near the end of it all? In general, this house has much more $$s hidden in things you can't see than things you can. I suspect this is typical for a latter in life house as compared to a starter or 1st home. Much like people and tractor implements, as the years go on the finish gets a little rough but the true inner value really shines.

Sometime next year I'll have all the automation stuff going and be able to read the 24 odd current transformers that I put in. Then I can get more objective data on costs. I know that we had 6000 sq feet with just the HVAC going during construction (getting the floor wood acclimated) and our August bill was $200, the September bill was $180, and the October bill was $120 in North Carolina at 10 cents per kilowatt hour.

Hope these datapoints add to this discussion.

Pete

 

[Believer]

I have a spring on a property I plan to build. It flows out of a limesstone escarpment at about 10-20 gal/min. Could I put that to use?

 

[Zick]

We just build a new house this summer and put in a Geothermal (vertical wells) in our 2800sqft house. We went with a Waterfurnace Synergy 3d cause it will do both Air & Water (radiant floor) heating plus a desuperheater.

We compared the price of a Geo unit to a High efficiency Boiler and it was around 30% higher cost. We almost went to a boiler due to the extra cost of Geo but then the new 30% tax credit came into effect that lifted the original $2000 cap to unlimited.
Now after taxes returns our Geo will have costed roughtly the same as the Boiler but with greater efficiency.

 

[Tig]

I have a spring on a property I plan to build. It flows out of a limesstone escarpment at about 10-20 gal/min. Could I put that to use?

Flow rate seems good enough from what I remember. Temperature of the water in winter and summer is also important.

 

[SpringHollow]

I have a spring on a property I plan to build. It flows out of a limesstone escarpment at about 10-20 gal/min. Could I put that to use?

If you have enough height drop on your property, generate electricity with it. These micro hydro setups can be impressive

Ken

 

[JackMentink]

On the topic of payback on the system, the nice thing is that my unit has a zero year pay back. I priced high efficiency 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.

I did use a open loop system that I pump the water onto my 2 acre lawn that looks great 9 months out of the year.

So it started paying for itself from day one. I estimate that it saves me about 2000-2500 per year at today's 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 estimate my electric costs off of the no heat or cool months and what my base electric bill is during those months. I heat and cool my 4400 square foot of house for no more than $50 per month.

 

[buckeyefarmer]

my system is currently open loop

Thats a 3 ton unit, with a 2 ton unit behind it out of sight.
don't know if I'll get it installed before winter.

 

[neilly2]

A few posts back someone noted to not believe everything we read -- talking about open loop systems decreasing the life of the heat pump.

I sell heat pumps for the leading manufacturer of water source heat pumps (Climatemaster -- wasn't going to mention the name but Water Furnace has been mentioned numerous times). So the suggestion that i only believe what i read is ridiculous.

I get calls by the boatload for replacement of old units. 98% of water source heat pumps that have to be replaced with less than 15 years of service is due to a bad refrigerant to water coil (the heat exchanger) from an open loop system.

As a salesman for heat pumps, logically i would want them to fail so i could sell more, but we try to do right by our customers and STRONGLY AND REPEATEDLY suggest that they consider a closed loop to make sure the heat pump gives them the 20 to 25 years of service we routinely see.

In reality i don't care what system its attached to -- boiler/tower, ground source (vertical or horizontal, open or closed), surface water, etc. I do know what the units react to and what is best for them.

What i think people shouldn't believe is a contractor who says "i've been doing it this way for XXX years". What does that prove? He could be doing wrong for 15 years and in the 16th year the crap might hit the fan. And are people calling him back 6 and 7 years later when problems crop up? They're probably going elsewhere.

The shocking thing -- any mechanical contractor that knows anything, knows as a rule of thumb, pumping untreated water (or air) into any plumbing or HVAC system requires special consideration. They may not know exactly what to do, but they at least know they have to go find an answer on how to properly deal with it.

And back to the issue of the heat exchanger -- i am sure you are aware that the water coil is a tightly coiled copper loop , and i am sure you know that when you pump into a coil like that the fluid friction loss is greatest on the outside edge of the tube wall, and that the minerals (there is more than just calcium) will abrade the tube walls.

I just replaced an open loop system unit a few months back -- it was 6 years old and there were holes forming in the copper loop.

I could go on all night about various systems, efficiencies, geographical differences/considerations but i was trying to be brief in my previous post.

I will state finally and emphatically --- an open loop system will decrease the operating life of the unit. (efficiencies, though are a different story)

 

[Tig]

I don't get the "water abrades the copper pipe" statement. All the water that goes into the geothermal unit probably passes a copper elbow or two on the way. They don't abrade? Is there a big difference in the copper?
My open loop unit worked fine for 18 years. Pretty good life span for a furnace. It's waiting to be reinstalled.
Dozens of units in my old neighbourhood. Running out of water was the only fatal problem I ever heard of.

Edit; I think dissolving copper pipes can be explained by this page.

 

[neilly2]

Tube wall thickness on a pipe fitting is greater than that of the copper tubing. Copper coil is trying to exchange energy with the refrigerant tubing, so it is much thinner.

I said the open loop will decrease the life, i didn't say it would die at 5, 10 or 15 years, just that it will be less than with a closed loop.

 

[whistlepig]

We do fight the well water in the country. The iron deposits, sulfide, calcium deposits, and hard water all come with a well. But we prefer well water to drink for us and for our livestock because we know where it has been and where it has come from. We have spent a considerable amount of money on a water treatment system that takes care of most of the problems of well water. It works very well. Untreated well water coming in to a house can be rough on everything that water runs through. That would be my concern with an open loop system.

 

[neilly2]

the bug in my bonnet was about being accused of believing only what i read, because i differed with someone.

To be fair the open loop system is more efficient than the closed loop. There are so many variables you can't say any one way is better about any of this. (especially with vertical or horizontal wells). You might check the water quality in your area realize it is so good that the increase in efficiency is worth a shorter equipment life span.

I didn't even take the time to read people's energy analysis. They really are not transferable unless the same system, in the same climate, with similar parameters are used.

 

[JackMentink]

A few posts back someone noted to not believe everything we read -- talking about open loop systems decreasing the life of the heat pump.

I sell heat pumps for the leading manufacturer of water source heat pumps (Climatemaster -- wasn't going to mention the name but Water Furnace has been mentioned numerous times). So the suggestion that i only believe what i read is ridiculous.

I get calls by the boatload for replacement of old units. 98% of water source heat pumps that have to be replaced with less than 15 years of service is due to a bad refrigerant to water coil (the heat exchanger) from an open loop system.

As a salesman for heat pumps, logically i would want them to fail so i could sell more, but we try to do right by our customers and STRONGLY AND REPEATEDLY suggest that they consider a closed loop to make sure the heat pump gives them the 20 to 25 years of service we routinely see.

In reality i don't care what system its attached to -- boiler/tower, ground source (vertical or horizontal, open or closed), surface water, etc. I do know what the units react to and what is best for them.

What i think people shouldn't believe is a contractor who says "i've been doing it this way for XXX years". What does that prove? He could be doing wrong for 15 years and in the 16th year the crap might hit the fan. And are people calling him back 6 and 7 years later when problems crop up? They're probably going elsewhere.

The shocking thing -- any mechanical contractor that knows anything, knows as a rule of thumb, pumping untreated water (or air) into any plumbing or HVAC system requires special consideration. They may not know exactly what to do, but they at least know they have to go find an answer on how to properly deal with it.

And back to the issue of the heat exchanger -- i am sure you are aware that the water coil is a tightly coiled copper loop , and i am sure you know that when you pump into a coil like that the fluid friction loss is greatest on the outside edge of the tube wall, and that the minerals (there is more than just calcium) will abrade the tube walls.

I just replaced an open loop system unit a few months back -- it was 6 years old and there were holes forming in the copper loop.

I could go on all night about various systems, efficiencies, geographical differences/considerations but i was trying to be brief in my previous post.

I will state finally and emphatically --- an open loop system will decrease the operating life of the unit. (efficiencies, though are a different story)

Very interesting statements from some one who obviously has a lot of experience with replacement of units.

I'm not sure I understand the statement of pumping untreated water through the unit causing premature failures. In our part of the country, all water is well water. All public and private water supplies are from rock (limestone) wells. All of it is relatively hard. The only difference in some of the public water supplies are chlorinated. None of our water is treated. If you would use water as your fluid in your closed loop you would be pumping the same water through the exchanger, regardless of closed or open loop.

Personally I am using the same water I am drinking to go through my heat exchanger, and it is clean and pure, but hard, and is never exposed to open air until it is discharged from my system.

I guess only time will tell whether us open loop people will have a problem.

I wonder if some of the units you have replaced were using well water or were they using some source that was open to the environment and had some possibility to be contaminated.

I do appreciate someone sharing their experiences, as it is always good to hear from people that have varied experience.

 

[jenkinsph]

I have to agree with the closed loop systems lasting longer than open loop systems. In a closed loop system you limit the amount of deposits that would be available to clog the system. Further in a closed system you can use a variety of treatments and or additives that will limit the corrosion. So with cleaner pipes the transfer of heat thru the tubing remains higher. I would suspect the open loop system would start out being more efficient but with time could wind up being less efficient.

As a plumbing and heating contractor (thats what the ph is from in my signature) I am still leary of selling highly elaborate systems to my customers. The reason being that beyond the initial high cost of the equipment which dealers such as myself can make a larger profit on is the higher maintenance costs. There is so much more equipment to fail and it will fail. The plumber/heating contractor becomes a member of the family.

Now after years of electronics and mechanical contracting I would rather do something different like landscaping and playing with my tractors.


Steve

 

[SpringHollow]

In a closed loop heating systems we install (not geothermal), we mix RO water with the well water and add anti-corrosion treatments. Years later, the pipes and heat exchangers still look practically brand new. Treating like that is not an option in an open loop. Also, even if one did not do that, there is only so much mineral in the water in a closed loop system. In an open loop system, you have a continuous supply. There are no absolutes but i normally would recommend closed loop for a multitude of reasons.

Ken

 

[ShenandoahJoe]

I'm appreciating all the useful information here. If I may, I'd like to ask a related question I've been wondering about.

Water is always trying to sneak into my basement in town. I have a hard-working sump pump that flushes tens of gallons of cold, clear water out of the house every few hours. The outlet from the sump is about five feet away from the heat exchanger of my air conditioning unit. Does anybody make an auxiliary heat exchanger that I can stick into the sump, so I don't have to watch all that coolness run down to the storm drains all summer?

 

[Redneck in training]

I'm appreciating all the useful information here. If I may, I'd like to ask a related question I've been wondering about.

Water is always trying to sneak into my basement in town. I have a hard-working sump pump that flushes tens of gallons of cold, clear water out of the house every few hours. The outlet from the sump is about five feet away from the heat exchanger of my air conditioning unit. Does anybody make an auxiliary heat exchanger that I can stick into the sump, so I don't have to watch all that coolness run down to the storm drains all summer?

Put a few gallon tank on the top of the unit and then let the water drip on the heat exchager just to keep it wet when the unit is running. The evaporation should keep it cooler. The efficiency will vary with humidity.