Quote:
Originally Posted by cdig
I have an old well on my property that we just recently decomissioned in favor of town water. In the geo_thermal manual you provided at the beginning of this thread there's a section on 'standing column well ground heat exchanger' ... thoughts?
How deep would the well have to be in order to work? The ground water is pretty high around here, so I don't think the well is very deep, but if I can use it instead of drilling a bunch of holes in my yard, why not right?
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The easiest & cheapest way is usually the best way.
However, in my explorations of alternative energy strategies, I am continually confronted by just what a tremendous amount of energy I use habitually without being aware of it. The alternative energy strategies usually involve using energy densities much lower than what is available with fossil fuels.
I got a taste of this when I hooked up my first experimental 400 watt heat pump to a 10 foot ground loop to see how much heat I could extract. Short story is that the loop froze solid in about 25 minutes.
There was heat in that loop, but my little 400 watt compressor was drawing the heat out at a much faster rate than the 10 foot loop could supply it. The ground gives up its heat, but gives up its heat very slowly.
In a few days, I should have the last of my loops completed and I'll have 240 feet of loop for the heat pump to draw heat from. I'm pretty confidant that my little heat pump won't be able to extract heat as fast as the ground can supply it.
cdig, I'm not sure where you live, but some things you'll need to know are:
1. What is the average ground temperature where you live? If you have a state office of energy, they should be able to tell you this. It will be aprox. the temperature at about 25 feet down. The baverage ground temp where I live (Western Oregon) is around 55 degrees F. However, the measurements I have gotten at the bottom of my holes is 53 degrees.
2. What are the heating degree days where you live throughout the year? This is a number that is used to calculate of how much heat will be required in your area.
3. What is the heat load of your house? You can get some computer programs that can give you a pretty close approximation of this for free.
Try something here:
home heat load calculator - Google Search
...here's one that might work for you:
Heat Load Calculator / Refined Home Renovation
You can also figure it pretty close from your heating bill. Look at the bill from the coldest month, convert it to BTUs per hour for that month. and maybe multiply the BTU per hour by 50% to account for energy use peaks.
Last winter, where I live, we had a really cold spell, and for that two week period, I turned off my gas heat and used only electric heaters which had watt meters (Kill-a-Watt) on each one, and I kept detailed records every 4 to 6 hours, so I know with a very high degree of confidence what my energy use baseline is.
4. What is the rate of energy transfer I can expect from my source? In your case, the well you're talking about. If you look through this blog (
http://ecorenovator.org/forum/projec....html#post2787), I site a test that you can do on your own well to determine what the rate of heat out will be.
So you can experimentally determine the heat you can get from your well, divide that into your calculated or measured peak heat load and see what percentage of your heat you'll be able to get from your well.
If it is over 100%, you are indeed in fat city!
If it's somewhat less than 100%, you can use your well as an adjunct to your existing heating setup and save some money.
If it's pretty tiny, like for instance only 5%, then you know that if you had 20 such wells, you'd be back in fat city.
I did exactly this procedure, and my calculations came out to 15.4 holes, so I'm going for 16.
I'm also going for a lot more insulation.
Hope this all helps...
Best Regards,
-AC_Hacker