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 03-05-15, 09:27 AM   #11
MN Renovator
Less usage=Cheaper bills
 
MN Renovator's Avatar
 
Join Date: Nov 2010
Location: Minneapolis, MN
Posts: 934
Thanks: 41
Thanked 114 Times in 88 Posts
Default

Quote:
Originally Posted by theoldwizard1 View Post
If I ever had a GSHP system installed, there would be a "performance" clause in the contract. If my inlet water temp EVER fell below 40F, the installer would have to repair/replace/agument the ground loop. I would try to hold 50% of his installation fee in escrow for at least 1 year.

If you are going to pay the premium of having a GSHP, you want one that is designed and installed for optimal performance !
Do you think there would ever be a contractor willing to provide such a performance clause? ..or allow themselves not to be paid in full for that long? Most contractors can't afford to provide such a guarantee unless their business was more of a sure thing or health related like radon mitigation.

MN Renovator is offline   Reply With Quote
Old 03-05-15, 09:52 AM   #12
theoldwizard1
Apprentice EcoRenovator
 
Join Date: Oct 2014
Location: SE MI
Posts: 105
Thanks: 3
Thanked 12 Times in 9 Posts
Default

Well, I sort of, kind of got the information I was looking for (perhaps I did not phrase the question well to begin with).

First, if you Google around you can find charts similar to this one from www.texas-geology.com/



The important data here is that soil temperature stabilizes at about 30'. I have not found a chart that shows deeper reading, but I am fairly certain the do not shift much (although I would still like to see readings down to say 200' if anyone has access to them !)

This chart is from TX, so the center point is pretty high (70F !).

This map from www.hotspotenergy.com shows the average ground water temperature in different parts of the US. I a pretty certain that these numbers line up with the center of the above graph.





So my conclusion is that GSHP are not as big of a "win" for heating and cooling in far northern and southern areas. This surprised me ! I thought below some reasonable depth (20-30') that all ground water (at least water not heated by some geological "feature") was about 50-60F REGARDLESS of what latitude !

Anecdotal evidence is welcome !
theoldwizard1 is offline   Reply With Quote
Old 03-05-15, 10:32 AM   #13
theoldwizard1
Apprentice EcoRenovator
 
Join Date: Oct 2014
Location: SE MI
Posts: 105
Thanks: 3
Thanked 12 Times in 9 Posts
Default

Quote:
Originally Posted by Mikesolar View Post
You wouldn't have to go that far. Lots of systems have input water temps that low and still perform well. It just has to be designed for it. No problems.

Don't forget, the system has glycol in it so it won't have a freeze problem and it won't hurt the equipment.
From my research, in general, most heat pumps start to loose efficiency around 35-45F. Why not pay a few extra $$$ to have a system that will stay ABOVE that threshold. ?

I understand a extra well hole could be thousands of dollars, but it could mean the difference between sitting comfortably or having to install some kind of secondary heat source !

It is all about trade offs. If that secondary heating system only costs a few hundred to install and $100-$200/month to operate 3-4 months a year. maybe it IS a a more cost effective solution ... short term !
theoldwizard1 is offline   Reply With Quote
Old 03-05-15, 01:33 PM   #14
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 theoldwizard1 View Post
If I ever had a GSHP system installed, there would be a "performance" clause in the contract. If my inlet water temp EVER fell below 40F, the installer would have to repair/replace/agument the ground loop. I would try to hold 50% of his installation fee in escrow for at least 1 year.
I'm pretty sure that you are kidding here... but if you found someone that would agree to that, you would know that you had a fool for a contractor.

Quote:
Originally Posted by theoldwizard1 View Post
If you are going to pay the premium of having a GSHP, you want one that is designed and installed for optimal performance !
"Optimal" by what measure? Yes, it is possible to build a loop field that will do what you are asking for, but it will be expensive... maybe more expensive than you are willing to pay.

Rather than wearing out your keyboard by asking these serious questions of people who have never actually designed a loop field (but are wearing out their keyboards answering you), why don't you read the design and installation manuals that are written by people who actually do design and install loop fields. These manuals are a compilation of theoretical and practical knowledge gathered over half a century, from thousands of jobs, from all over the world, for all manner of applications. This information has been distilled, so as to be organized and accessible to someone like you who wants a working system.

The information is all there for you to design and build a loopfield that will function correctly at the lowest price point, if that is what you want, or you can design and install a loop field that will meet a criteria such as you have set... or anyplace in between.


If you bought every book they have, it would cost you $692, if you joined IGSHPA, it would be cheaper. Then you would have at your disposal more knowledge than anyone you could ever hire.

Why waste your time with fantasies of escrow, when you can take full responsibility, and become the very best designer?

Best,

-AC
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...
AC_Hacker is offline   Reply With Quote
Old 03-05-15, 02:03 PM   #15
theoldwizard1
Apprentice EcoRenovator
 
Join Date: Oct 2014
Location: SE MI
Posts: 105
Thanks: 3
Thanked 12 Times in 9 Posts
Default

Quote:
Originally Posted by AC_Hacker View Post
"Optimal" by what measure? Yes, it is possible to build a loop field that will do what you are asking for, but it will be expensive... maybe more expensive than you are willing to pay.
If the specs on my GSHP showed CoP falling off below 4C, I would surely want a field that could produce above 4C !

Quote:
Originally Posted by AC_Hacker View Post
The information is all there for you to design and build a loopfield that will function correctly at the lowest price point, if that is what you want, or you can design and install a loop field that will meet a criteria such as you have set... or anyplace in between.


If you bought every book they have, it would cost you $692, if you joined IGSHPA, it would be cheaper. Then you would have at your disposal more knowledge than anyone you could ever hire.

Why waste your time with fantasies of escrow, when you can take full responsibility, and become the very best designer?

Best,

-AC
Thank you !

Although I would likely never install a loop field, I would rather PAY for ACCURATE knowledge then what people with a keyboard (and too much time on their hands) espouse as "truth".



This (and my other recent thread) all started because a person on another forum was complaining about poor heating performance of his GSHP. He finally admitted that is inlet water was -10C and he felt that was "typical" in winter in the midwest US.
theoldwizard1 is offline   Reply With Quote
Old 03-05-15, 02:53 PM   #16
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 COP with More Good Picture

Quote:
Originally Posted by theoldwizard1 View Post
If the specs on my GSHP showed CoP falling off below 4C, I would surely want a field that could produce above 4C !
Dear Wiz,

If someone gave you the impression that COP falls off (like a buffalo falling off a cliff) at some particular temperature, they have seriously misled you.

The truth is that in a heat pump situation, COP depends on the temperature of the SOURCE, no matter if it is air, or water, or concrete.

When the temperature of the source declines to any extent, so does the COP.

EDIT: I went to the Carnot Efficiency page of Wikipedia, and generated a graph that will best indicate what I am trying to say... the legends are bogus, but the shape is right.



When your source temperature goes down at all, so does your COP, and it will continue to do so at an increasing rate.

The actual problem is really an economic issue, because there will be a point when the electricity to run the unit, is worth more in watts of heat than your heat pump can deliver.

Now, it is possible that you could build a loop field so vast, that you would no longer be able to notice any temperature drop (and COP decrease)... and that is because you are old and your eyes are not those of an Olympian god so you would not be able to see it.

-AC
Attached Thumbnails
Click image for larger version

Name:	COP.jpg
Views:	686
Size:	12.3 KB
ID:	5037  
__________________
I'm not an HVAC technician. In fact, I'm barely even a hacker...

Last edited by AC_Hacker; 03-05-15 at 03:17 PM.. Reason: More Good Picture
AC_Hacker is offline   Reply With Quote
Old 03-05-15, 03:41 PM   #17
ChrisJ
Lurking Renovator
 
Join Date: Jan 2014
Location: Rhode Island
Posts: 5
Thanks: 0
Thanked 1 Time in 1 Post
Default

Most GSHP's have performance charts which rate them at x BTU's at -1*C (30*F) for heating and 32*C (90*F) cooling.

A well designed loop (performance and cost) will get down to -1*C by the end of the heating season. To gain 1* or 2* can cost 75% to 100% more in upfront costs, not to mention the additional pumping costs for the life of the loop.

-10*C is not typical, most are only freeze protected to -9*C.

CJ
ChrisJ is offline   Reply With Quote
Old 03-05-15, 09:13 PM   #18
where2
DIY Geek
 
Join Date: Apr 2013
Location: Sunny Florida
Posts: 397
Thanks: 69
Thanked 83 Times in 73 Posts
Default

Quote:
Originally Posted by theoldwizard1 View Post
This surprised me ! I thought below some reasonable depth (20-30') that all ground water (at least water not heated by some geological "feature") was about 50-60F REGARDLESS of what latitude !
North Florida spring water is typically 72F when it comes out of the ground. If I could pull 72F water out of the ground in Maine with a simple pump, I'd be a millionaire.

Nice map, btw. I needed that info.

where2 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 03:24 AM.


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