Well, not really, yet.
My wife and I moved a house on an island in WA. Or more to the point, bought and cleared land, and contracted someone ELSE to move the house. Raised it up, and put an unfinished daylight basement under it.

We had to trench for a well water line, and for power, so, since the goal was eventually to install a GSHP, we trenched 6' deep, and buried 2 800' 3/4" HDPE pipes. That seemed like a no brainer.

I'm a pretty intensive DIYer, and since I'm on an island, if I couldn't figure out a GSHP, I didn't want one. Getting service calls is at best a challenge. Every contractor of any trade I contacted in this project either disappeared, or added $$$, and wouldn't commit to a timeline. Nothing against contractors, they have to make a living, and everything we've been doing on this house has been improvised and/or custom. That's not a recipe for easy or cheap bids, and I'm cheap, but my lovely wife is cheaper. I really want to do this myself, so I'm thouroughly familiar with all aspects of this install. Having a pro do it wouldn't be as satisfying, and having worked over 10 years in various forms of construction, I know that no matter how good the sales guy is, or reputable the company, some techs are better than others. I'd hate to write a check for more than I take home in 6 months, and then find that I didn't trust the installer. As a DIYer, I'm pretty comfortable blaming myself, and fixing the problem. Life should always be a learning experience.
 
The climate here is pretty much spring and fall. A touch of summer and winter, but not too much. 5199 heating degree days, 121 cooling degree days. Average lows in winter are mid 30's, and summer high's in mid 70's. I did a manual J calc based on anticipated completed stats, and came up with 2.5 tons, but since we're more heat oriented here, I prefer the 3 ton, and I think the 2 stage setup should allow for proper dehumidification by just running stage 1. We have 2 pellet stoves as auxillary heat for those cold snaps.

I've been reading extensively, and this is the BEST site out there for getting actual information.

Now I'd like your help in stopping me from making too many expensive mistakes.

THE PLAN: (so far, and subject to change)

I have the 2 800' 3/4" loops. They go down either side of my driveway. Bring them into the utility room, (part of the daylight basement) header in there. All potential leaks in a room with a floor drain.

Install a 038 climatemaster Tranquility 27 (3 ton) and flowcenter.

Provide ductwork to move that 1400 cfm air throughout the house. I plan on unducted return.

Install 2 standard 30 gal water heaters, one as a buffer, and insulate them and their piping until they are unregognizable.

I'm still up in the air about adding an HVR.

It wasn't until I was reading on this site, and I started checking the resistance figures, for sizing a pump, that I realized I'd made my first (I hope) big mistake. Wow, that's allot of resistance for such a smooth pipe. 9 gal/minute (3 gal/min/ton), through 2 800' 3/4" loops by my math is:
4.5 gallons per minute per loop. So that's 5 ft of head per 100'. 40' of head- each. Plus fittings and heat exchanger, right? With that much resistance, I'm off the charts.

So, clearly, I need more pipes. More pipes means less gallons per minute per pipe, resistance drops, right?

So, we have 5 acres, but it's wooded and hilly, and we like that. So I'm hoping to only install 1 more long loop. I was thinking, if I installed the 3rd loop as 1 1/4" or maybe 1 1/2", most of the flow would go to the larger, lower resistance pipe, but I have no clue how to calculate that.

So, That's where I am currently. Since I just found my first blunder, I thought now would be a good time to ask you good folks to review my grand scheme, before it gets outta hand.

Thanks!

Hi and welcome,
The mistake you think you made is really not a deal breaker. You just need to install a larger flow center set up to meet your head loss. All that means is that the cost of the electric to circulate your loops will be higher than if you had less friction loss. I also recomend diy use a non presurisedflow center as they are more diy freindly, but require periodic inspection for fluid levels lost to evaporation.
hope this helps

What is the actual heat loss in BTU's?
You are possibly making a mistake in sizing heat pump or loops.
joe

A TT026 would match up well with your loop scheme, with minimal pumping costs (1 up26-99). I would forget about adding a 1.25" loop, You need to match the press. drop of each loop to keep flow balanced. If I had pellet stoves for backup I would try to downsize a ton anyway.


What was loss/gain in BTUs

Posted By heatoftheearth on 11 Jun 2010 09:49 AM
A TT026 would match up well with your loop scheme, with minimal pumping costs (1 up26-99). I would forget about adding a 1.25" loop, You need to match the press. drop of each loop to keep flow balanced.

What was loss/gain in BTUs

Reading my mind are you heatoearth?
I'm suspicious that the already demonstrated "bigger is better" mind-set has steered OP away from the obvious conclusion that the loops are fine; the heat pump is wrong.

Posted By riggerjack on 11 Jun 2010 01:22 AM
9 gal/minute (3 gal/min/ton), through 2 800' 3/4" loops by my math is:

4.5 gallons per minute per loop. So that's 5 ft of head per 100'.
40' of head- each. Plus fittings and heat exchanger, right? With
that much resistance, I'm off the charts.

In your mild climate, it might be best to design for maximum
efficiency in stage1 (part load). For Tranquility27 series, CM
says that's 7 GPM for TT026 or 8 GPM for TT038. (In either
case, that yields about 3 ftwc pressure drop across the coax.)

Assuming 20% methanol antifreeze, that corresponds to a loop
pressure drop of 3 to 4 ftwc per 100' of pipe, or 24 to 32 ftwc
total -- with Reynolds# comfortably above 3500, in either case.

At worst, you'll need two UP26-99 circ pumps -- but with a
TT026, you might get away with one UP26-99 or UP26-116.

...a little oversized can be a lot expensive,

Looby

Posted By Looby on 11 Jun 2010 11:58 AM
For Tranquility27 series, CM
says that's 7 GPM for TT026 or 8 GPM for TT038. (In either
case, that yields about 3 ftwc pressure drop across the coax.)


Looby

Cant agree with your math here 7 gpm for an 026 is 1gpm more than needed in 2nd stage. A 026 will perform optimally in the 5-6 gpm range. Also the 038 has a significantly higher press. drop across the coax than the 026. It also has a higher drop than the 4 ton and 5 ton Without antifreeze correction factor the 026 and the 038 have drops of 7.2 ft and 13.1 ft respectively

Posted By heatoftheearth on 11 Jun 2010 12:36 PM

Cant agree with your math here 7 gpm for an 026 is 1gpm more than needed in 2nd stage.

"Needed" ain't the same as "optimum." Pages 60 & 62 of the Tranquility27 manual
show 7 gpm and 8 gpm as stage1 optimum flows for the 026 and 038, respectively.
Personally, I'd  tend to design for "optimum" -- and be satisfied if the actual flow
turned out to be a little less.

My bad re: coax pressure drops -- I pulled the wrong numbers out of the tables.
According to CM, the correct values are 9.4 and 10.4 ftwc, respectively @ 30F EWT.

http://www.climatemaster.com/share/...27.pdf

Posted By heatoftheearth on 11 Jun 2010 12:36 PM

Without antifreeze correction factor the 026 and the 038 have drops of 7.2 ft and 13.1 ft respectively

Please, tell me what you can about antifreeze correction factors for coax
pressure drops. I've searched extensively for any mention of the subject
with no success.  Came to the (uncertain) conclusion that viscosity has
little or no effect on p-drop at the extremely high Reynolds numbers such
as those expected in a coax HX.

If you can point me to something authoritative on the subject, please do.

Posted By Looby on 11 Jun 2010 01:56 PM
If you can point me to something authoritative on the subject, please do.

Sure! You can download the pressure drop calculator here.


http://www.climatemaster.com/index/res_software


It has the pressure drop of each unit, correction factors for antifreeze, and pump curves

Posted By heatoftheearth on 11 Jun 2010 02:51 PM

Sure! You can download the pressure drop calculator here.

http://www.climatemaster.com/index/res_software

Thanks for the link, but I'm afraid that I have zero confidence in that
Excel spreadsheet.  For example, it shows only 1% and 3% increase
in p-drop per 100' of pipe for methanol and ethanol, compared to 
water -- rather than 15% and 30%-ish increases found elsewhere. 

http://waterfurnace.ca/Engineer/Mis...ctions.pdf

If the true differences were only 1% to 3%, "antifreeze correction"
would be an exercise in pure silliness.  Who believes ANY of these
guesstimations to +/- 3%?

I'll give the GeoDesigner app a try when I'm on my own computer.

thanks again for the reply,

Looby

Posted By Looby on 11 Jun 2010 11:58 AM

 

In your mild climate, it might be best to design for maximum
efficiency in stage1 (part load). For Tranquility27 series, CM
says that's 7 GPM for TT026 or 8 GPM for TT038. (In either
case, that yields about 3 ftwc pressure drop across the coax.)

Looby

IMHO this project may benefit most from a design around loops available if they are viable.
Sure love to know what the manJ load is.
j

Agree that the cart seems placed before the horse on this thread

well, i did the manual j calc about a year ago. i used the calculator at acdirect.com. Then because all the gshp's are rated by ton, i just converted that over, and spent a bunch of time trying to find loop info for that. sorry, i didn't write down the results after the conversion. the number converted over to a 2.5 ton heat pump, but i figured go 3ton, and keep the ac in stage 1 and all would be well.
the 1600' loop length was based on anectdotal information. finding a few other cases and going with something similar. I actually thought i'd do better with the single long loop, instead of the slinky, or several loops in a field. by going with the single loop, heat could move 360 degrees around the loop, without a neighboring loop also heating/cooling.
the tranquility 038 is fairly set. it arrived today. yeah, my timing could use some work...
as to loops, i have land, and a backhoe, so more loop only costs me time and pipe.
perhaps i'm doing the math wrong for resistance. 2 loops, 800' each. at 4.5 gallons per minute, the chart i looked at showed 5 feet of head for every hundred feet. 5x8x2=80 feet of head, plus the loss for fittings and heat pump, right? that's more than i was showing for a 3/4 hp pump handling. then i started thinking about how much power goes into running that pump, and now i'm here.
so you folks are saying change my math around to 7 gallons per minute, and rerun the numbers? I admit, i got the 3 gpm/ton rule from a waterfurnace manual, but is there that significant a difference between manufaturers of heat pumps with the same rating?

Posted By engineer on 11 Jun 2010 10:20 PM
Agree that the cart seems placed before the horse on this thread

This could be the theme for my whole house! learning has been what this was all about. before i started this, i thought this would be no big deal. i've done concrete, framing, remodeling, electrical, and cabling. i had most of the bases covered, right?
there's nothing like really taking on a big project to find out how much you don't know.
this is another case of thinking "sure, i can do that", and jumping in. although everything i read said a gshp wasn't a diy project, i thought i'd give it a go anyway. i've found that the hardest part has been finding out what i need to know. once i know what to look for, the internet usually has an answer out there somewhere.
you just don't know what you don't know...

Posted By riggerjack on 12 Jun 2010 01:01 AM
... perhaps i'm doing the math wrong for resistance. 2 loops, 800' each.
at 4.5 gallons per minute, the chart i looked at showed 5 feet of head for
every hundred feet. 5x8x2=80 feet of head, plus the loss for fittings and
heat pump, right?

Incorrect. Since the loops are in parallel, it's 5x8x1 = 40 feet of head,
plus the loss for the manifold, interior piping, fittings, and heat pump.

With 20% methanol at 8 gpm total, it's more like 4x8x1 = 32 feet of head,
plus yada, yada, yada ....

i got the 3 gpm/ton rule from a waterfurnace manual, but is there that
significant a difference between manufaturers of heat pumps with the
same rating?

CM Tranquility27 and WF Envision are very similar, and the recommended
flow rates for maximum efficiency are identical:

- 026 stage1: 7 gpm, stage2: 8 gpm
- 038 stage1: 8 gpm, stage2: 9 gpm

IMO, 7 gpm would be cutting it mighty thin as a design target for a TT038,
since the spec calls for a minimum of 6.8 gpm for closed loop applications.
Designing for 8 gpm would give you a more reasonable margin of error.

You told us before the load was about 2.5 tons yet you chose a 3. I was looking for BTU's.
If for example the load was 30,000 btus (2.5 tons) a 2 ton heat pump would satisfy ~ 98% of your heating requirements with auxiliary coil making up the difference. It would be cheaper to purchase, cheaper to operate, use a smaller duct system and use the existing loops. Geo is all about right sizing not throwing in a little more to be sure.
Geo can be a DIY project and I'm sure yours will work fine in the end, but it will be cheaper to get answers to questions before you make purchases.
Good Luck,
J

ok, so i can add extra loops without adding resistance? that seems weird.

i'm more comfortable with electrical than plumbing, so i thought of this like a simple dc curcuit.
so 2 parallel 10 ohm resisters result in a circuit resistance of 5 ohms.
but in this case, resistance is determined by flow, and the decreased flow has already been accounted for with the rate of 4 gpm.

so if i added another 800' 3/4" loop, i would recalculate resistance with a flow of 2.66 gpm, and add the results, right?

Posted By riggerjack on 12 Jun 2010 09:53 AM
ok, so i can add extra loops without adding resistance? so if i added another 800' 3/4" loop, i would recalculate resistance with a flow of 2.66 gpm, and add the results, right?

Yes another 800' loop would work well with a 038,especially since you already own it. Although I would design for 3gpm/ton and be happy with slightly less. This probably will require a 26-116.

Looby, I have used that spreadsheet for all my climatemaster installs, about 15 and counting. It has been dead on every time, verified with a flow meter.

I saw what you mean about the AF correction factor. Didnt seem right to me either. So the first thing I did was run the same #'s for various AF's through some software that I actually paid for. The resistance for the loops came out virtually the same as the spreadsheet. Still being baffled,I pulled out my IGSPHA manual,dusted it off, and ran the #'s again, the old fashion way. I got the same result.

After further investigation I found that the spreadsheet applies a base pumping penalty for all closed loop systems , than adds the AF correction factor for E,M,PG.

Posted By Looby on 12 Jun 2010 02:13 AM CM Tranquility27 and WF Envision are very similar, and the recommended
flow rates for maximum efficiency are identical:

- 026 stage1: 7 gpm, stage2: 8 gpm
- 038 stage1: 8 gpm, stage2: 9 gpm

Again, I dont think the recommended flow rate for the 026 are 7 and 8 gpm. IMO its is 6gpm. Although you might squeek out 3 hundreths of a COP(I mean is that silly or what)out of the heat pump. 99.9% of the time,you will loss that in the pumping costs to required to get you there. Then again I could be wrong