Thanks, Will. Ten degrees several times during the winter sounds about right. Sometimes I forget just how cold it gets here. We are in the city itself. I keep the thermostat around 68 degrees. On a cold day outside when it's 68 in the front of the house, it's about 63 in the back (ie, the new addition). Thank you for framing it in terms of heat deficit vs. distribution. The ducts are basically vented to the front half of the house; partly because two were taken offline in the process of building the addition. And partly because it's awkward to run them to the furthest part of the new addition without getting in the way. (Thus the reason why we're in this predicament of considering a fireplace). We had a blower door test done - house is circulating 30% of its air each hour. And we did have a heat load calculation done - that's how we arrived at the 75K figure. But it would be great if the current furnace could handle the whole load. So all of this is to say, I'm still curious to know what size fireplace we might install. I'm guessing it wouldn't have to be very big. Anyone want to estimate what we would need?

Hey guys finally got the HVAC plans to our builders AC guy. They ran a j-calc and did cost comparisons for the units we specified. The calc shows that we need 3.88 tons including ventilation air. first, we looked at conventional units. Between 14 and 16 seer, there is a $2200 difference in equipment cost. 14 SEER = $10893 & 16 SEER = $13,100 b/c they buy so many 15 seer trane systems, they get the 15 seer system at the same price as a 14seer. For our home, there is only a $90/year difference in operating cost between 15seer and 16seer. so the payback would be 6.7 years to go from 15 to 16 seer. we would pick the 15 seer unit in this comparisson. Air source heat pump in the same range isn't even worth looking at. it only saves an additional $10/month. Again, not a big jump from 15 seer conventional gas. however, the dealer did mention that we would probably have to install a fresh air system if we go with gas heat -- this is due to foam spray in our attic and the corners of our house. we may need to rethingk a few things if we go with gas. this is where it gets interesting. we looked at geothermal. 1. the dealer sells all types of systems and manufactureres -- geothermal, air source heat pump, conventional ac... carrier, trane, frigidaire, water furnace... etc etc. 2. he assured me that he has hundreds of units in each system type installed in the local area. 3. there are two other geothermal companies in town, so should he and their whole company get hit by a bus tomorrow, there is still knowledgable geothermal service in the area. 4. I was initially interested in a closed loop system, but we do have a potable water well on site. a/c guy swears that in over 20 years he has not had a problem with open loop geothermal units on a potable water well in our area. local water quality is very high compared to other states where they have installed them. also says that the temperature in a closed loop varies b/c ground temp changes. says open loop is his preference due to consistent water temp from ground well. 5. top of the line Envision system from Water Furnace is $21,495 but the tax rebate is $6,449. 6. geothermal costs half as much to operate. operating cost for the three units is as follows... 15 seer unit = $142/month = $1708 per year 16 seer unit = $134/month = $1610 per year Geothermal = $ 61/month = $ 732 per year 7. we then put the units into a 6.5% interest loan scenario VS the monthly savings to calculate the investment payoff. Pay off for geothermal VS 15 seer is 4.1 years. Pay off for geothermal VS 16 seer is 3.8 years. 8. an installation tech showed us the geothermal loop piping. they use an iron to fusion weld the piping to the fittings. makes for a solid and thick joint. 9. hot water biproduct from geothermal can be used for hot water in our home. all comments are welcome. please shoot holes in all of this. thanks again!!!

More 'myths': ----------------------------- dazureus claimed: " Geothermal is a stand alone installation for both heating and cooling. " Really? You go on to say that it requires continual electricity consumption to run the system. How is that 'stand alone'? ------------------------------------------------------ "It is important to note that geothermal systems do have a back up heat source, but it's only used in a situation where the ground loops aren't providing the required temperature for the process stated above. A well designed system shouldn't encounter this issue." Few, if any, geothermal systems can operate without supplemental oil or gas or electrical energy sources despite what the salesmen tell you. If they could, we would have a 'perpetual motion device' that could operate indefinitely without ANY energy consumption to keep the system going. But, alas, there are no such things except for those whom of PT Barnum said: "There is a sucker born every minute!" ----------------------------------------------------------- " Besides these facts, we're installing a 6 well, 6 ton geothermal (ground source heat pump) for our 5000 sq ft ICF new construction in SE Michigan. Due to our tight building envelope, our ROV will be much longer than a conventional stick built house, but it will still be realized during the life of our build since it's our final house. Also remember that geothermal systems run off electricity so the future operating costs are decoupled from fossil fuel technology. Whatever technologies become more cost effective in the future for providing electrical energy, the cost to run geothermal systems will stay fairly stable." Ultimately you only tell us less than half the story. You do not tell us how much it is costing you to install your geothermal system and you have absolutely NO experience in operating your system to tell any of us IF it really will work as the salesmen told you it should! The fact that you are building with extremely expensive materials ( ICF construction) and extremely expensive heating and cooling technology (geothermal) only serves to tell us that you "think" you "might" one day see your house pay for itself over the rest of your lifetime, and only then, perhaps, see some energy savings! I can tell you with my broad experience that a conventionally built stick home, well insulated for your region, sealed against air infiltration, and heated and cooled with conventional methods will pay for itself much sooner at a lower initial investment... and save you more on energy costs over the long term than your ICF house will with geothermal! Too many simply fall for the gimmicks, the ploys, and the technological mumbo-jumbo they do not understand, without understanding how that technology works or whether or not it truly economical or can deliver as promised. ------------------------------------------------------ A friend of mine installed 6 240kva solar panels on her roof in her all electric home with the promise of the salesman she would reduce her electric bills immensely. Unfortunately, she never asked my advice. She paid $13,000 for the system. A system that does not provide enough electricity on good days to even run her toaster...and on most days does not produce enough electricity to light 2 light bulbs. Not to mention a system that doesn't work at night. The only one who is happy with her system is the salesman who duped her out of her $13,000 (plus interest) Oh yeah. Are you rolling your geothermal system and ICF technologies into your mortgage? If so, then rest assured, you will likely NEVER pay them off during your lifetime, or will have paid 2-3 times MORE for them had you paid cash, and immensely more for these 'systems' than if you built using conventional framing, insulation, heating and cooling technologies! So where are the 'energy' savings? There are ABSOLUTELY NONE! ZIP! NADA! You simply are paying the geothermal manufacturer and installer and mortgage lender rather than the energy company...and paying each of them considerably MORE! -------------------------------------------------------- Bottom line: CAVEAT EMPTOR! (BUYER BEWARE!) Newer does not necessarily mean 'better'. If geothermal systems REALLY worked and were the best bang for the buck, EVERYONE would have one! BUYER BEWARE!

"Setbacks are not necessarily more efficient with geothermal as they are with fossil fuel" People say that about fossil fueled, variable output equipment and it is true. There is no real contrast to be made with heat pumps of any kind. Zealots in the mod con boiler world are unhappy if their boiler cycles any time between September and May in a heating intensive climate. They'll tell you that a properly sized and set up system should only modulate up and down. Even with these systems, set backs may be more energy efficient. There are too many variables to make blanket statements and the calculations to determine that are beyond the patience or capabilities of most people. People say that about all kinds of equipment. Urban legends abound for decades starting when it was obviously false. I think it started with early heat pumps with dumb thermostats hitting the electrical resistance heat inappropriately. That got fixed pretty quickly, yet the legend grows. As far as I can see, saying setbacks are not always more efficient is only appropriate in situations with variable output equipment only. With single output, "bang bang" equipment, setbacks are always more efficient. The added efficiency may be significant, or it may be insignificant but it will be there. It is difficult for installers to take lifestyle of the homeowners into consideration when installing HVAC equipment. Clearly what works best for one person or family won't work best for another.