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 11-17-15, 05:30 PM   #1791
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,002
Thanks: 303
Thanked 707 Times in 529 Posts
Default

Quote:
Originally Posted by superlen View Post
I seem to recall that you can't fuse pex so I would be left with a mechanical connection that most likely will cause some issue sometime in the future. I thought about bringing the 3/4" up nearer the surface (18-20") at the connection point to the supply/return and making that connection in a box so that I could easily inspect/repair if necessary. 95% of the loops would still be at 6' of course. This would require 5 boxes and a small portion of the supply/return lines to be at 20" depth. I would then drop back to 6' deep on the 200' way out and back to the loop field from the house to pick up whatever additional heat transfer I could gain in transit. That amount of heat exchange might be small due to laminar flow in the larger pipe.
That's right, can't fuse PEX. I even tried... will not work.

So that leaves you some kind of physical connections. Whatever you use will most likely go inside of the piece(s) of PEX so you don't want to reduce the diameter any more than needed. I've seen brass barbed connectors that might do it. The more acidic your soil, the faster the corrosion, so if you know the pH it could help. Also, if it is possible to obtain (make) stainless steel barbed connectors, that would give you a chance. I used some stainless steel hose clamps on some very wet-duty applications, and the clamp itself was resistant to corrosion, but the screw was the problem. If you can get 100% SS hose clamps you might be OK.

As to the rest, it looks like you did your homework, so your guess will be an educated one.

-AC

__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 11-18-15, 01:27 PM   #1792
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,372
Thanks: 390
Thanked 601 Times in 503 Posts
Send a message via Yahoo to jeff5may
Default

Please flog me if I am wrong, but this would seem to be a good fit for shark bite fittings. They are not as cheap as irrigation-style clamp or crimp fittings, but they are dead easy to install and come in either plastic or brass. The connection is repairable if it leaks.
jeff5may is offline   Reply With Quote
Old 11-18-15, 10:33 PM   #1793
superlen
Helper EcoRenovator
 
Join Date: Nov 2015
Location: NW Arkansas
Posts: 37
Thanks: 5
Thanked 7 Times in 7 Posts
Default

Jeff,

If I made the connections inside the access boxes I think sharkbites would be fine, although I'd probably still just use typical crimp rings. If I opt to bury I think sharkbites would bite it. (I don't know if they are underground rated, but I suppose they could be)

Truthfully I'm a bit leery of any connection 6' underground. The hassle to dig up and repair is just too much risk. I'd much rather just bring them up to the near surface at those 5 locations and make the connections there. I do like how easy sharkbites are to replace/repair.

Len
superlen is offline   Reply With Quote
Old 11-23-15, 07:06 PM   #1794
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,002
Thanks: 303
Thanked 707 Times in 529 Posts
Default

Other than the fact that PEX is not a thermoplastic (weldable) like HDPE is, it's great for Ground loops.

It might more expensive than PEX, but PEX actually starts out life as HDPE.

Regarding shark bite vs. barbs & rings, I have tried barbs and rings, both compression copper rings, and stainless steel 'clinch' rings. I think the clinch rings are superior in every way... even to corrosion.

-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 11-23-15, 07:38 PM   #1795
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,372
Thanks: 390
Thanked 601 Times in 503 Posts
Send a message via Yahoo to jeff5may
Default

Quote:
Originally Posted by AC_Hacker View Post
Other than the fact that PEX is not a thermoplastic (weldable) like HDPE is, it's great for Ground loops.

It might more expensive than PEX, but PEX actually starts out life as HDPE.

Regarding shark bite vs. barbs & rings, I have tried barbs and rings, both compression copper rings, and stainless steel 'clinch' rings. I think the clinch rings are superior in every way... even to corrosion.

-AC
I agree. The stainless "pinch or cinch clamps" are much stronger than the copper crimp rings. If a pipe freezes, the stainless clamps are strong enough that the fitting will pop open and leak before the clamped end. With the copper rings are used, a lot of times the ends leak when the pipe thaws out. However, It's not a good idea to use the stainless clamps with plastic fittings. They tend to squeeze hard enough on the fittings to deform them.
jeff5may is offline   Reply With Quote
Old 11-23-15, 09:41 PM   #1796
rvCharlie
Lurking Renovator
 
Join Date: Jul 2013
Location: central MS
Posts: 21
Thanks: 1
Thanked 2 Times in 2 Posts
Default

I've never tried it for a PEX application, but electrical workers have several solutions for permanent protection of buried electrical joints. There's liquid that's painted on, but I have no idea about whether it will adhere to PEX. There are also tapes that seal to typical insulation used on direct burial cable.

This
http://www.permatex.com/products-2/p...ne-tape-detail
might be an option to apply over whatever connector/crimp is used for the splice. The tape would only serve to keep ground water away from the outside of the joint. (There are lots of other brands; I just picked this link because Permatex has a good reputation for their other products, in my experience.)

I even wonder if a pvc compression splice would fit over the crimp rings of a standard PEX splice. Almost 20 years ago, I trenched through a 1/2" plastic (polyethylene) medium pressure natural gas line (that fed my gas meter). The service guy for the tiny community gas company showed up (without any tools or supplies) and asked if I had a plastic PVC splice. I did; he installed it; it's still in the ground, about 20 feet from my gas meter.

Last, those direct burial polyethylene natural gas lines have their own connectors, too. Link to one source:
https://www.gastite.com/us/products/...nd/couplings/#

FWIW....

Charlie

edit: I'd probably still bring the splices to somewhere near the surface, but I have little risk of freezing where I live. Perhaps a 90 degree splice would make the rise & fall easier.
rvCharlie is offline   Reply With Quote
Old 11-24-15, 03:32 AM   #1797
AC_Hacker
Supreme EcoRenovator
 
AC_Hacker's Avatar
 
Join Date: Mar 2009
Location: Portland, OR
Posts: 4,002
Thanks: 303
Thanked 707 Times in 529 Posts
Default

All of these considerations are reminders of the wisdom of using weldable HDPE for Ground Loops.

-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
The Following User Says Thank You to AC_Hacker For This Useful Post:
jeff5may (11-24-15)
Old 11-24-15, 02:17 PM   #1798
superlen
Helper EcoRenovator
 
Join Date: Nov 2015
Location: NW Arkansas
Posts: 37
Thanks: 5
Thanked 7 Times in 7 Posts
Default

Quote:
Originally Posted by AC_Hacker View Post
All of these considerations are reminders of the wisdom of using weldable HDPE for Ground Loops.

-AC
Give me a backhoe and some free time & wisdom goes out the window.

If I had started the project, 6 months later I would have been golden. About 6 months after I finished my system, I started manufacturing the control electronics (day job) for the pipe fusion equipment manufacturer, McElroy. When I met with their engineers to start the project, I starting telling them about my homebrew system (& in particular the pex/pvc setup). They shook their heads and laughed. I believe the comment was something like "keep the backhoe handy".

Len
superlen is offline   Reply With Quote
Old 11-25-15, 08:25 AM   #1799
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,372
Thanks: 390
Thanked 601 Times in 503 Posts
Send a message via Yahoo to jeff5may
Default

Some engineers just don't like to think out of the box. I live there.

On that bombshell, let me plug my latest thread:

http://ecorenovator.org/forum/geothe...onversion.html

Dirt cheap and recycled as usual. Guaranteed to work when it wants to.

Last edited by jeff5may; 03-14-16 at 08:25 PM.. Reason: deleted unfocused wording
jeff5may is offline   Reply With Quote
Old 11-25-15, 09:28 AM   #1800
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
Thanks: 241
Thanked 165 Times in 123 Posts
Default

Jeff, - how about "some" engineers don't think out of the box and "some" engineers want to pull things inside the box . . . .

I often point to the Apollo project and engineers who not only thought out of the box, but thought out of this world. Simple mission statement in 1963; go to the moon, pick up some rocks and return to earth. No technology to do this, but physics that dictated limits. Six years later (1969), this mission was accomplished - all done by engineers.

All that said, there are a LOT of middle level engineers who can't/won't think. Upper level engineer types have to constantly pry them out of complacency and comfort.

One modern company that does think out of the box - GE.

OK AC, you can now delete these posts as they do not follow your thread . . . .

Steve

__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
Reply


Tags
air conditioner, diy, gshp, heat pump, homemade

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 04:55 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design