Quote:
Originally Posted by Vlad
...With 3/4" pipe you can not have enough water flow to wash out cuttings...
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I think you're right about that. But another issue I had was that the walls were collapsing in on the drill stem. Initially I was just using water, then I discovered the wonders of mud.
I also came to realize that where I was drilling, there was a hard-pan layer at 17 feet that holds up the water table, and that since the amount of heat I was trying to extract was small, and I could get good heat transfer from the water that was underground, I thought I could get enough heat from sixteen shallow holes.
Vlad, I think it will be a very good idea for you to talk to some local well drillers. They don't get to talk to people much about what they know, and would probably be willing to tell you what the soil formation is likely to be.
I asked local well drillers and got a tremendous amount of information that was very useful to me.
You might even find out what the average bore-hole depth is to achieve a particular amount of heating in your area.
I'm in Portland, Oregon so the heat transfer information is likely to be very similar to what it is in Vancouver, BC. We figure 175 feet to 225 feet of bore-hole-per Ton of AC. I'd guess that deep Vancouver earth is going to be somewhat cooler than here in Portland, so the bore-hole would need to be somewhat deeper (or more of them). But you should ask some well drillers, to find out how much deeper. I'd really like to know what you find out.
Regards,
AC_Hacker