EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 08-13-11, 08:32 PM   #11
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 3,997
Thanks: 303
Thanked 700 Times in 524 Posts
Default

Quote:
Originally Posted by braebyrn View Post
Then would there be any reason to use a metal or pvc casing?
As far as I know, casings are to prevent the sides of the borehole from caving in. If you use drilling mud, it is denser than water and can help form a 'skin' on the walls and help hold the walls back.

Quote:
Originally Posted by braebyrn View Post
Direct contact with the soil and filler material seems like it would have a better heat transfer?
This would be correct. Usually grout is pumped down the hole. The grout serves to prevent cross-aquifer contamination, and to increase thermal transfer.

If you search the 'manifesto' thread, you will find a recipe for "MIX-111" which is an open source borehole grout. I stopped when I hit hard-pan, and didn't drill through multiple aquifers, so I felt that grout was not needed. Also most of the soil I went through was damp to wet sand which had a thermal transfer that was pretty close to MIX-111, so again I decided that grout was not required.

Quote:
Originally Posted by braebyrn View Post
The mud pump from the drilling equipment has the ability to mix a slurry [ bentonite] and pump it in the bore to fill the gaps.
As far as I know, grout is mixed pretty thick.

I think the professional drillers use a grout pump. I have no idea if your rig will be able to handle grout.

Your call...

By the way, the things we are talking about really don't have so much to do with open loop /closed loop advantages, but would be very interesting to someone who wants to do their own GSHP. I think you ought to either start a thread with a title that reflects what you are doing, or else start posting to the manifesto thread (which gets lots of hits).

Your call...

-AC_Hacker

__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...

Last edited by AC_Hacker; 08-13-11 at 08:44 PM..
AC_Hacker is offline   Reply With Quote
Old 02-09-12, 08:11 PM   #12
Plantman
Lurking Renovator
 
Join Date: Feb 2012
Location: Angola, IN
Posts: 24
Thanks: 0
Thanked 3 Times in 3 Posts
Default

The advantage of the open loop is installation cost and efficiency. I have an open loop. There are no drilling costs as I use my existing well. I built a pond in my yard to receive the outflowing water. I plan on raising perch for harvesting. If that overflows, it will just soak into the ground as it is very sandy. I plan on piping overflow to a wetland I am constructing to grow plants. Open loop is also more efficient because the water temperature never changes. In a closed loop, the ground will drop in temperature as it transmits heat to the coil. Efficiency usually drops as winter progresses. The reverse is true for cooling in the summer, the ground temperature gradually increases.
Plantman is offline   Reply With Quote
Old 02-09-12, 10:48 PM   #13
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 3,997
Thanks: 303
Thanked 700 Times in 524 Posts
Default

Quote:
Originally Posted by Plantman View Post
The advantage of the open loop is installation cost and efficiency. I have an open loop. There are no drilling costs as I use my existing well. I built a pond in my yard to receive the outflowing water. I plan on raising perch for harvesting. If that overflows, it will just soak into the ground as it is very sandy. I plan on piping overflow to a wetland I am constructing to grow plants. Open loop is also more efficient because the water temperature never changes. In a closed loop, the ground will drop in temperature as it transmits heat to the coil. Efficiency usually drops as winter progresses. The reverse is true for cooling in the summer, the ground temperature gradually increases.
Have you had any issues with crud building up in the heat exchanger or pump?

-AC_Hacker
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 02-10-12, 09:59 AM   #14
Plantman
Lurking Renovator
 
Join Date: Feb 2012
Location: Angola, IN
Posts: 24
Thanks: 0
Thanked 3 Times in 3 Posts
Default

I am currently in my 3rd heating season and have had no problems. I believe they now make the exchangers out of materials that resist corrosion and mineral buildup. It may also depend on water quality. I haven't had my tested for hardness, but there are not obvious deposits like iron stains etc. I have a 1000 sq ft greenhouse that gets white mineral deposits from watering, possibly calcium carbonates? The water in my pond is currently 9 ft deep and crystal clear. I can see at least 6 ft down.
Plantman is offline   Reply With Quote
Old 02-10-12, 10:57 AM   #15
Plantman
Lurking Renovator
 
Join Date: Feb 2012
Location: Angola, IN
Posts: 24
Thanks: 0
Thanked 3 Times in 3 Posts
Default

Correction: this is my 4th heating season. I also have an inline filter in the water inlet pipe. It is a small cylindrical metal mesh screen slightly smaller than window screen. I have cleaned in a few times, maybe once a year. The thermostat indicates when water flow is too low, usually because the filter needs cleaning.
Plantman is offline   Reply With Quote
Old 02-17-12, 06:35 AM   #16
Plantman
Lurking Renovator
 
Join Date: Feb 2012
Location: Angola, IN
Posts: 24
Thanks: 0
Thanked 3 Times in 3 Posts
Default

I discussed buildup with my service tech. My filter has a slimy coating when I clean it. He said it is iron bacteria. I told him I clean my filter about yearly, but it is never completely plugged. He said I must have good low-iron water and will probably never have a problem. They do occasionally clean exchangers by flushing with acid.

Plantman is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:09 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design