Geothermal

[RON58]

Any of you have it or know anything about it at your homes? Pro's/Con's ?????

 

[howellhandmade]

Any of you have it or know anything about it at your homes? Pro's/Con's ?????

Don't have it, but a friend in Michigan heats his house with well water (steady 50 degreesF) and a condenser/heat exchanger. He says it works great.

Jack

 

[indiansprings]

I priced it when I built my first house, on that location I would have had to drill multiple wells, they wanted around 16k to install it, I had the electric company do a cost/payout study, it would have taken 19 years to see any pasyback.

Now I live on a place with six springs within 100 yards of the house, it would be more reasonable since I already have a continuous temperature water source.

 

[Rockland Farm]

We have had ours about 7 years.We put it in when we built the house.We have been happy with it so far..People with oil heat in the same size house are definitely paying more to heat than we are.Our unit air conditions the house in the summer as well.Seems to cost me less to cool than to heat.They are very pricey how ever.We got lucky and got in on the tail end of a program that the Power Co. had that paid for part of ours.

 

[Joshlaugh]

For one of my building at work we installed a pond loop system where we used a 2 acre nearby pond for the heat source. We bought two Water Furnace Envision heat pumps. So far so good as they were installed in November 08. Have not seen quite the saving I expected but I hope it will be better throughout the summer.

 

[mtfallsmikey]

It's all in the design and installation. I've heard of both miraculous results, and wailing and gnashing of teeth. The basic concept behind geo is solid.

 

[powerstroke73L]

I'm hoping that once we sell the home we're currently in (not for at least 10 years) and build the home that we'll stay in for the rest of our lives that we can install a geothermal system primarily for A/C in the summer. Geothermal doesn't tend to work that well for heat in climates where it gets REALLY cold, so I would just want to plumb a wood boiler into the system. We probably wouldn't run the geothermal in winter unless we were away for an extended period and couldn't fire the boiler. The geothermal could at least keep the house warm enough to prevent pipes from freezing. The cherry on top would be solar panels as all you need for both the boiler and the geothermal system is electricity to run the pumps.

 

[slowp]

Well, I do live in the middle of a triangle of 3 volcanos, maybe something on a bigger scale would work here.

 

[powerstroke73L]

Well, I do live in the middle of a triangle of 3 volcanos, maybe something on a bigger scale would work here.

You don't need hot water unless you're trying to generate power. Geothermal works on the principle that once you get to a certain point below ground (it varies a bit depending on the region of the country you're in) the soil is a constant 55 degrees F all year round. Basically you're using the earth as a giant heat sink or heat source. In the summer its a heat sink-you pump excess heat from your house into the ground. In the winter you're just running in reverse-you pump the heat from the ground into your house. So essentially if it's 35 degrees outside, you want to try to pull 20 degrees of the 55 degrees of heat energy in the ground out and into your house.

 

[Laird]

I've recently heard that there are some new tax credits for new installations that may reduce the cost enough to really shorten the payback period. I've heard they max out at $2-3k for a federal credit.

 

[Taxmantoo]

Geothermal works on the principle that once you get to a certain point below ground (it varies a bit depending on the region of the country you're in) the soil is a constant 55 degrees F all year round.

Another way of saying it is that down deep, the temp is constant and approximates the average annual surface temperature. If it's 55 degree F, you're someplace warmer than Michigan, for example.

 

[Laird]

So it won't work in permafrost? :jawdrop:

(Not a serious question.)

 

[Wood Scrounge]

so the cost (after installation) is just the electric pump running? how big (wattage) is the typical pump?

 

[Marc]

So essentially if it's 35 degrees outside, you want to try to pull 20 degrees of the 55 degrees of heat energy in the ground out and into your house.

That's a little confusing. It doesn't matter what the temperature is outside, really. Typically a heat pump is employed to move available heat from the ground into your house. You can warm your house to a temperature warmer than the heat source (the ground, at 55 degrees) because you're inputing work energy into the system. Thermodynamically speaking, heat can be moved from a cool reservoir to a warm reservoir (ground to house) with a work input (a variation on the Clausius statement, related to the 2nd law).

So it could be 80 degrees outside, and the heat pump will still work to heat your house if you run it so, even though the ground is colder than the air. The only factor the outside air temperature plays is in determining the rate at which the heat pump must transfer heat to keep the house at a desired temperature.

 

[Marc]

So it won't work in permafrost? :jawdrop:

(Not a serious question.)

A ground source heat pump would work in permafrost. Theoretically, it would work with any temperature reservoir as long as the reservoir is above absolute zero.

Practically speaking, though, the amount of work required to move energy increases proportionally with the temperature difference between the two reservoirs, so the colder the ground the less cost effective the system becomes.

 

[AKKAMAAN]

My friend in Sweden is building a new house this summer, and he says it is most cost effective for him today to put money into insulation....18+2" in ceiling, 10+2" in floor, 8+2" in walls, vented crawl space in foundation, a plastic moist barrier in the walls, floor and ceiling, the 2" part of insulation inside the moist barrieer, 2 or 3?? glass xenon windows...then a two way electric ventilation system (no heat pump) and then electric waterheater with water radiator heating.....
with his 6 months winters plus 32F to minus 32F his electric bill will be less than 20000 kWh. his new house will be a one story 2500ft^2 plus garage...

His last house, 2 story 3000ft^2, he built at 1980 had a woodburner 5-8 cords a years, 80ft culvert to house, and still 15000kwh. That house had only 65% of this new house insulation

Last 25 years everybody have used heatpumps, earth and geo thermal systems, but now this is (insulation) what is most economical....

Pros with insulation....no maintenance, dont have to be replaced after 10-15 years like a heatpump.....

 

[blis]

My friend in Sweden is building a new house this summer, and he says it is most cost effective for him today to put money into insulation....18+2" in ceiling, 10+2" in floor, 8+2" in walls, vented crawl space in foundation, a plastic moist barrier in the walls, floor and ceiling, the 2" part of insulation inside the moist barrieer, 2 or 3?? glass xenon windows...then a two way electric ventilation system (no heat pump) and then electric waterheater with water radiator heating.....
with his 6 months winters plus 32F to minus 32F his electric bill will be less than 20000 kWh. his new house will be a one story 2500ft^2 plus garage...

His last house, 2 story 3000ft^2, he built at 1980 had a woodburner 5-8 cords a years, 80ft culvert to house, and still 15000kwh. That house had only 65% of this new house insulation

Last 25 years everybody have used heatpumps, earth and geo thermal systems, but now this is (insulation) what is most economical....

Pros with insulation....no maintenance, dont have to be replaced after 10-15 years like a heatpump.....

We built a new house us last year and it is heated by big wood oven and also we cook 90% on woodstove, the heat is then used to warm all water (domestic and floor heat) with airheatpump (it takes heat from air and uses it to heat)... 250mm insulation on floor, 200mm in walls, ~500mm in attic... Also has 3 layer windows (been a standard here for couple decades allready), House itself is ~95m^2 and also has a ~50m^2 garace with floor heat... Yearly electric consumption is around 11 000kwh.

Extra insulation might cut a bit off the bill but insulation is quite expensive so i doubt it would ever pay itself...

 

[AKKAMAAN]

It doesn't matter what the temperature is outside, really.

Correct...It is hard to understand, and the Fahrenheit temp scale doesnt make it easier....

like you can store heat energy in some liquid or solid mass, even gas or air, you can also take the same energy from it to use for heating....

talking heat energy, there is nothing like cold and warm....everything is heat....molecular moition....that motion stops at minus 273.15 deg C, or minus 459.67 deg F, which is zero 0 deg K in the Kelvin, K, temperatur scale, which is used in science to calculate all these things....The Kelvin scale dont have a "minus" part, just zero and plus....
+273.15 deg K is the same temperature as 0 deg C or 32 deg F...
so it is theoretically possible to heat a house from a temperatur just above the zero K temperature, like +1 deg K, but practically science havent got that far yet....

BTW...if a conductor, like Copper, can be cooled down to 0 K, all resistans the copper will be eliminated....it is called "Supra conductor"....scientists are working on making supra conductive materials.....

 

[Moss Man]

I just completed an energy auditing couse and alot can be done with new and old homes to air seal and insulate. Build smaller homes and build them right and energy becomes much less of an issure. In new construction, I would be looking very hard at passive solar if you have the right land for it.

I am not downplaying geothermal, it is taking off here right now and there are some numbers to back it up. I met a guy that used it today and he has the drilled well type. When you factor in the fact that this style supplies you potable water, eliminates the need for a conventional furnace and is a 30% direct write off on your taxes.......it looks pretty sweet to the right people.

 

[Marc]

I just completed an energy auditing couse and alot can be done with new and old homes to air seal and insulate. Build smaller homes and build them right and energy becomes much less of an issure. In new construction, I would be looking very hard at passive solar if you have the right land for it.

I am not downplaying geothermal, it is taking off here right now and there are some numbers to back it up. I met a guy that used it today and he has the drilled well type. When you factor in the fact that this style supplies you potable water, eliminates the need for a conventional furnace and is a 30% direct write off on your taxes.......it looks pretty sweet to the right people.

I believe some utilities will also give you a break on your electric bill as well. Mass Electric used to, not sure if they still do since being swallowed by National Grid.

I love the idea of passive solar... probably not the kind you mean... just big arse south, east and west facing windows.

Unfortunately, and hopefully without getting too political here, the $1500 tax credit, which one can get for replacement windows, stipulates a solar heat gain coefficient of 0.30 or less... no matter where you are in the country. A low SHGC is great if you spend the majority of the time cooling. Unfortunately, for this small part of the country (y'know, the entire northern half) the primary heats and doesn't even have AC, save for maybe a window unit... maximizing SHGC while minimizing U-factor makes the most sense. Looks like I'll be getting my $1500 on the new boiler, and not on windows.