Old fart learnin geothermal ?????

[Mongo and me]

From another post I did in another part of this HUGE web site...........
I figure some one some were will see this and I'll be one smart old fart soon !!!

Well I have a few years left in the trade and its come to pass I need to upload this geothermal stuff now.............. will be doing a change out for a REALLY special friend!! going closed ground loop............

So, I understand water source HP, work on them all the time in ceilings and buildings, have read many post here now and have a better understanding of some of the ground points.............

Few questions to help clear things, how do ya calculate the loop lenth needed?? I see a program out there "Right Loop", but since this will more then likly a one time thing, not wanting to put the money out for ANOTHER program..... Internet is not a place for me to go searching, I'm lucky to find my own house let alone all this stuff on Google !!!

Some info............ Slinky loop laid flat, location, north GA. ground is * hard dirty !!! Like I'm an earth exspert now !! ????

Unit will be 5 ton. name brand not made yet.

I understand the "SAND" lay in thing, as in great contact for the piping, wet it and all that to get the best contact !!! Neat vidio on the net !!!

Defintly using the slinky rig for building loop, ausome vidio too !!!

For now I am figuring we will go with an externall pump station in stead of built into unit, comments on that choice would be good............ Too much crap inside those cabnets already !!!

House has the 5 ton dx split heat pump and does very well, I see mention of duct work issues, is there something I'm missing ??? I figure if ducts are good now, why change, after all, 5 tons is 5 tons.....????

Good news is I patched his leaking evap coil, and the acid test came back clean, so I am going on a bad factorty coil, 7 years old and already a leak, third row back, 1 inch from u bend joint !!! Frigidair ---- need to stick to refrigerators !! So have time to get up to speed on this stuff, just one more thing to add to my memwars !!!


Well there ya have it, questions and what evers, hit me now while I go ponder some................

In advance, I will thank you all for being here, makes an old fart like me feel better knowing I'm not the only one still learning............... be kind !!!

[teeball57]

Dealers have a program they use for loop length by entering heat loss/gain loop type and soil conditions.
An accurate heat load is imperative don't size by existing equipment!
The program will also help size the unit by showing operating cost for different units loop temps and design conditions.
I assume the extended slinky is what your referring to and I feel it is best.
External pump is good for reasons you mentioned.
Heat pumps require more air flow than conventional systems just make sure duct work is adequate well sealed and insulated.
Proper design and installation will will make for a happy customer and save you a lot of headaches.

[Mongo and me]

Thanks, locols reps are not too helpfull on design for loop. The heat pump in place is good, ducts are good, I already had them redi some trunks, given the original installer cut soem corners, new air flow works great, so they say !!!

Exstended slinky, yes way to go..............

I have so far this as a base understanding, 600 feet of plactic pipe per ton, with 3 gpm per ton, ground dept will be at least 6 ft. covered with sand and toped with regular ground removed dirt............

Need to get bettier info on dirt diffrences and depth info..............

at this point it looks like we have the winter to ponder the job.

Thinkin we might drill some holes down and place soem temperature probes and bury them, read them over the winter for brain testign !!!

[teeball57]

Slinky loops are put in a trench around 125ft length for 600ft of pipe (extended slinky). Deeper the better but cost and safety become the issue. The trenches are separated by at least 10ft

Your looking for soil conditions at depth... heavy - lite - damp - dry- ect. Damp is good... dry clay is not and affects your sizing.
Temperature readings are for your amusement only not useful.

Every manufacturer has the software available to dealers if they don't use it I would look elsewhere.

[lemagr67]

We have had all of the calculations done on all of our jobs and we always end up doing the same exact thing every time. We use 600ft of 3/4 geo pipe per ton, 1 1/4 inch supply and return lines to the header, and 5-6 feet deep. I live in Ohio, so this may not be the case everywhere. It is not sandy here, its pretty much clay. We do a min of 100feet on each trench length at 5 feet wide and 10ft in between. We've done quite a few, and they have all worked great.

[teeball57]

I'm curious 5ft wide trench what or how do you dig that @ 5-6ft deep.
Most diggers around have around 40 inch buckets.

[lemagr67]

I ment to type 4 feet, but even that was a wrong number. I double checked and it was 40 inches. We measure from the edge of one ditch to the edge of the next, so there is still a 10 foot spacing. So, if you are looking for a 5 foot bucket, I'm wrong... its a 40 inch bucket.

[ga-hvac-tech]

Sounds like a fun project... drop me an Email... John

[farbeondriven]

maybe best for you to sub out the ground work if you don't have a fushion tool, flush cart ect. these are 2 very pricey items over 2000. We have one local excavator that does geo all the time and use him during our busiest season to help us keep up. Here in NE Pa we do 800 ft of 3/4 pipe @ 100 ft long per ton and 10-15 ft in between trenches about 5-6 ft deep. we avoid using sand and use cracker dust in its place cause that's what our rep suggest to maintain better contact through the expansion and contraction of the piping (valid? I don't know. we just do it). I wish you well on your endevor but it will require a investment of tools and training along with certs to do it properly.

[Mongo and me]

OK, now I'm cookin !!! First thing is I need a bigger pot !!! Sooooo much stuff to this dirt cooling !!!

Fusion (if needed) will be subbed out I am not lookin to be doing more then a few fingered handfull. I am waiting for more from the site down the road from this project location. Thing is I am over 100 miles form site, so its going to be a head full, I am working on getting the customer to slow down and let me get my ducts (or pipes) in order !!

So far things are only on the plannign stage, he wants to move before end of year for tx credits. He has the trench digging stuff, so cost will be low, finding pipe wil be an issue !!!

Thanks all for imnput, keep it commin !!

I truley do appreciate the help.........

[teeball57]

Pardon my ignorance but.... just what is "cracker dust"?

[farbeondriven]

no problem tee. Its like the filings from drilling mud. more course than sand.

[dc-v tech]

I just went to a dealer training on loop sizing and installation, and they said that slinky loops are mostly pointless, and you'd be saving a lot of time, money, and effort by just installing either a vertical or horizontal straight loop.

[teeball57]

I just went to a dealer training on loop sizing and installation, and they said that slinky loops are mostly pointless, and you'd be saving a lot of time, money, and effort by just installing either a vertical or horizontal straight loop.

That's the problem with this industry too much misinformation and opinions.
The best loop for any installation depends on location survey and soil conditions.
If sized and installed properly all loops will work equally well.
May I suggest your next class from IGSHPA.

[ga-hvac-tech]

That's the problem with this industry too much misinformation and opinions.
The best loop for any installation depends on location survey and soil conditions.
If sized and installed properly all loops will work equally well.
May I suggest your next class from IGSHPA.

Even though I have little experience with geo; this makes sense!

Just a side comment; seems to me the 'slinky' method would work better in a very loose soil... one that could find its way between the loops of the slinky for better contact and thus better thermal Xfer. The one geo install I watched (was int involved) was a slinky; they buried about a foot of sand, then the slinky, and another foot of sand on top. Compacted it and filled with the dirt removed. This was in N VA in the late 1980's, do not remember the type of soil.

[teeball57]

The whole point is proper backfill for good heat Xfer. You wouldn't put in a vertical loop without grouting to get heat Xfer.
IGSHPA wrote the book on loops not the manufacturers.

[dc-v tech]

The arguement behind avoiding slinkies was that pipe spacing is very critical on that kind of loop, and you have to be much more careful how you install them when compared to a standard horizontal loop. And in lake loop installs, the slinky is supposed to be much more likely to be damaged by boat traffic than a standard straight loop flat on the bottom of the lake.

I'm sure that both systems work equally well, but the advantages of a slinky aren't supposed to be worth it when compared to the amount of effort installing them vs standard horizontals.

The guy who was running the course had about 30 years experience installing GSHPs and loops, and I'd defer to his experience because I'm still rather new to the industry.

[crash11]

I did the slinky method for my install. Cost me a little more in pipe, but it installed way faster. If you have really sandy soil conditions like me it works out great.

[farbeondriven]

A slinky always ends up being cheaper than vertical even considering the extra pipe and excavation. Drilling around here runs from 5-10 a foot. I have noticed that vertical wells seem to hold better temp thru the seasons, being into the water table and so much deeper into the earth. I prefer wells because its allot less work.

[dc-v tech]

Sure any horizontal install is cheaper than vertical.

We have a lot of rocky soil here in Ontario and soil conditions are often difficult for geo installs. This could have been why we were recommended to avoid them up here.