Why do you need a GSHP system? I, like most i would assume, do it because they give a rats a s s about the environment, are fed up with rising cost of energy, dont like the inefficient systems currently used. to those comments addressing my question, thank you.

Joe, yeah i think that is one of the few questions I had. I have been in contact with a gentleman here in town who is very experienced setting up systems, testing them, and making any adjustments that need to be made to maximize the efficiency of the system. I asked the question just to get some clarity to make sure there was not a big difference in the trench design. I am going with the 6 pipe design. I guess i could have clarified my question a little more, i wanted to make sure that with the 6 pipe design i wouldnt be "saturating" the trench with to much pipe and cutting down on the amount of transfer.

Welcome back Mark. More foot/foot of pipe in a trench does tend to collect more btu's per foot of trench. Less foot/ft of pipe in a trench tends to collect more btu's/foot of pipe. So the big advantage to more foot/foot is shortening the trench.

I did a quick run on the model and for the same project compared 4 foot raceway (4 foot/ft) , 4 foot/ft slinky and 2 pipe trench. The most pipe required (2940' pipe) is the 4 foot/foot of trench with average depth of five feet. The second most pipe (2860') is the 4 foot/foot slinky, but it is the least amount of trench at 715'. The 2 pipe trench (or 2'/ft loop) called for the least amount of pipe (2040) but the longest trench 1020'.

So yes, the more ft/ft of pipe in a trench, the less btu's you harvest/foot of pipe, but cutting your digging down by about a third in this model so depending on your cost for excavation and the amount of lawn you wish to tear up......

Joe, thanks again for the helpful information. I have heard alot about a 5-51/5 average depth for trenching. Is this mainly because below that grade you run into osha's requirements to shore up the trench? or is it because the cost to dig deeper does not prove to pay off for an additional 1-2 feet? I understand diggin deeper brings on its own set of difficulties, but because i have limited space to trench (a city lot 50x145) i wonder if the six pipe design would harvest more consistently if it was deeper. Could you recommend a book, or software that would help with future decisions like these?

Deeper = shorter.
Climatemaster's website will let you download geodesigner for free.

Posted By joe.ami on 28 Apr 2014 08:37 AM
Welcome back Mark. More foot/foot of pipe in a trench does tend to collect more btu's per foot of trench. Less foot/ft of pipe in a trench tends to collect more btu's/foot of pipe. So the big advantage to more foot/foot is shortening the trench.

I did a quick run on the model and for the same project compared 4 foot raceway (4 foot/ft) , 4 foot/ft slinky and 2 pipe trench. The most pipe required (2940' pipe) is the 4 foot/foot of trench with average depth of five feet. The second most pipe (2860') is the 4 foot/foot slinky, but it is the least amount of trench at 715'. The 2 pipe trench (or 2'/ft loop) called for the least amount of pipe (2040) but the longest trench 1020'.

So yes, the more ft/ft of pipe in a trench, the less btu's you harvest/foot of pipe, but cutting your digging down by about a third in this model so depending on your cost for excavation and the amount of lawn you wish to tear up......

Hey Joe - thanks for doing and share your "quick run." It sure helps put things in perspective.

It also shows that there is no "one size fits all."

Loop design question:

I'm going to need to power a GSHP system using PV (yes, a lot of PV)in an entirely off-grid application. I've been told that overcoming the starting phase of the pumps is the biggest draw and that once the pumps are circulating they consume less/moderate amount of energy. So....my question... I'll be on a hill-side: is there any advantage to horizontal drilling and running flat, or near flat loops into the mountain and back out in an effort to avoid having to pump down and lift up the transfer liquid? I'm thinking just overcoming pressure, and weight of the liquid might require less from the pumps than pushing down and pumping up transfer liquid in vertical bore holes....

Thoughts??

Thx!

CB.

Posted By cbryndal on 02 May 2014 12:51 PM
Loop design question:

I'm going to need to power a GSHP system using PV (yes, a lot of PV)in an entirely off-grid application. I've been told that overcoming the starting phase of the pumps is the biggest draw and that once the pumps are circulating they consume less/moderate amount of energy. So....my question... I'll be on a hill-side: is there any advantage to horizontal drilling and running flat, or near flat loops into the mountain and back out in an effort to avoid having to pump down and lift up the transfer liquid? I'm thinking just overcoming pressure, and weight of the liquid might require less from the pumps than pushing down and pumping up transfer liquid in vertical bore holes....

Thoughts??

Thx!

CB.

Closed systems need only to overcome the friction in the pipe (among a few minor other things), not matter if they go vertical or horizontal. The same weight of the water which pushes it down then pushes it up in the return pipe....Different story for most open systems.
The high startup amperage comes from compressor, when it starts rotating. you can get a soft start kit which reduces the startup amperage.

You could also look at a truely variable unit like the WF 7 series which will take a fraction of the start up amps as a similarly sized 1 or 2 stage.

Thanks, Joe. I'll read about the WF7. Is there a way to run 2-3 smaller units in series for redundancy in case one fails?

CB.

Posted By cbryndal on 07 May 2014 03:39 PM
Thanks, Joe. I'll read about the WF7. Is there a way to run 2-3 smaller units in series for redundancy in case one fails?

CB.

Like most anything, yes you can. It will be expensive and I don't think necessary.......

Posted By joe.ami on 05 May 2014 08:59 AM
You could also look at a truely variable unit like the WF 7 series which will take a fraction of the start up amps as a similarly sized 1 or 2 stage.

You could also have a soft start kit installed which reduces the start up amperage. But nothing beats the 7 series.