Hi Scott, Yes, drilling holes to extract geothermal heat is very expensive. The water sort can be open or closed loop, they can draw water from the bottom of a lake or river then return it when the heat or cold is extracted from it or they can be closed loop, water or other virulant is run through closed pipe in a water bath like a lake.
Rather than drilling holes though you can dig a trench 8 to 10 feet deep depending on your frost line, possibly a little shallower and lay a closed loop system into it. That is much cheaper than dropping it down a hole. To answer your other question, closed combustion units draw combustion air from the outside into a closed chamber where it is burned and then blown back out. Usually two 3 inch PVC pipes are used, there are limits to the distance you can run them, up here we usually push them out through the rim joist but the exhaust must be some distance from a window or other opening just to keep carbon monoxide out. There is a fan which comes on to clear any residual gasses from the system after which an igniter starts a pilot then the main fuel. Fuel is circulated along with the exhaust gasses back through the combustion chamber in ways to burn any incompletely combusted fuel and the lot recirculated until what comes out of the exhaust is about body temperature along with a load of water which is drained off the bottom of the unit. The better gas units or propane units claim something like 98% efficiency but I understand that there are fuel oil versions these days which are pretty darn good to, a little more carbon to get rid of I suppose. The real advantage is not just the efficiency but you are not burning already heated room air and you don't have an open flue constantly withdrawing heat up the chimney. Usually finding a place for an inlet and outlet pipe is easy no chimney and very cool. I expect you could go Propane but it will cost to have a tank, similarly fuel oil. If you have enough soil though, a back hoe up here costs about 50 bucks an hour last time I hired one and they shift a load of dirt in an hour if you want to consider geothermal. It won't be cheap to instal but it will give you efficiency similar to what you might expect with outdoor temperatures at a constant 55 or so degrees F. There is the additional cost of running the circulating pump but that is minimal. I have a gas closed combustion furnace in my basement, don't remember the capacity. I am now having a little trouble with reliability, it is now 16 seasons old. There are a number of sequencing things which have to happen, little vacuum sensors and such which detect that all the cycles complete before heat comes through each demand cycle and we have been having a little trouble recently with it. I took it apart last week and found some crap in the tip of one of the rubber tubes I think washed down the exhaust vent with water, it looked to me like a shard of the PVC when a pipe was cut, probably washed down over time with condensation. There are a lot of parts though which could fail. Hope this information is helpful. Dale Leavens, Cochrane Ontario Canada [EMAIL PROTECTED] Skype DaleLeavens Come and meet Aurora, Nakita and Nanook at our polar bear habitat. ----- Original Message ----- From: "Scott Howell" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Saturday, February 17, 2007 3:42 PM Subject: Re: [BlindHandyMan] what to know about replacing your central unit > Now water to air sound really interesting. Gee, wish I had known > about these when I was getting a new system. I looked into one of the > geothermal systems and they could install, but I'd need a 400 foot > hole drilled and man that would have cost some serious cash so I had > to scrap that plan. Drilling into the ground here wouldn't be easy > since we sit on a great deal of rock. > > > Scott > [EMAIL PROTECTED] > > > > To listen to the show archives go to link > http://acbradio.org/handyman.html > or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > The Pod Cast address for the Cooking In The Dark Show is. > http://www.gcast.com/u/cookingindark/main.xml > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/handyman/ > > Visit the new archives page at the following address > http://www.mail-archive.com/[email protected]/ > For a complete list of email commands pertaining to the Blind Handy Man > list just send a blank message to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.412 / Virus Database: 268.18.1/690 - Release Date: 16/02/2007 > > To listen to the show archives go to link http://acbradio.org/handyman.html or ftp://ftp.acbradio.org/acbradio-archives/handyman/ The Pod Cast address for the Blind Handy Man Show is. http://www.acbradio.org/news/xml/podcast.php?pgm=saturday The Pod Cast address for the Cooking In The Dark Show is. http://www.gcast.com/u/cookingindark/main.xml Visit The Blind Handy Man Files Page To Review Contributions From Various List Members At The Following address: http://www.jaws-users.com/handyman/ Visit the new archives page at the following address http://www.mail-archive.com/[email protected]/ For a complete list of email commands pertaining to the Blind Handy Man list just send a blank message to: [EMAIL PROTECTED] Yahoo! 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