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Old 01-05-11, 02:03 PM   #1
pachai
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Default Partial DIY GSHP?

I'd like to bounce something off the group.

I am having an addition built on my house.
(Digging started on Tuesday :-)
The builder asked me what kind of heat/cooling I want.

Well, GSHP, of course!

I have been pricing GSHP, and everyone around here says,
there is not enough room for horizontal loops.
(even the one person who seemed quite knowledgable and
thought at first it could be done :-)

So, they say, we drill. That's expensive.
Bedrock is only about 15' down.
We talked about perhaps a Domestic water
well with Pump and dump, etc.
(It would be fun to get DWW and have 30% tax credit :-)
But even with the tax breaks, this is very expensive.
I got two quotes for over $60,000.
I'm still waiting for another one,
but it likely will be more not less.

I have also been following the HomeMade GSHP Manifesto thread, and
have even built a drilling rig, but winter and bulldozer came before
I finished my own tests on it. What tests I did showed me that it
would be a fun project, but I could not possibly do it on the
builder's tight time schedule. He doesn't seem too interested in
helping me. (but his worksite manager has a green streak, did not
have a chance to talk to him :-)

In a parrallel project, my friend has added RF microcontrollers to my
boiler and all my steam radiators, which should make the house more
comfortable, and should save 20% on my gas bill. (I am a beta site)

So I thought, maybe I'll use steam for the addition,
(which should need heat in about 1 month or 2)...
(I can do that, I did for one radiator previously).
and work on DIY GSHP. in the spring/summer/fall/winter etc.


Ideas that have occured to me include
-borrow money and "do it right" (another forum had this idea)
-Have the GSHP installer "start" do the parts that need to be done
before the walls go up, and "finish" after the refinance
-Buy a commercial GSHP and install myself, and pray that I can
put in the Redundant Array of Independent Ground Loops myself

Note, I am convinced that some of my heat can come from Solar
Thermal and GSHP...and I have ideas for cooling the loop water also.
So if my ground loop is shorter than "specified" for a GSHP,
I am not so worried.
(BTW, if I went horizontal, I think I can get at least 140' of
trenches without much hassle).

-Buy a used GSHP on ebay for $600/ton and DIY install as above
-Convert my old Air Conditioners (EER 9 - 10) - A few good ideas
were shown on this forum.
-Have the builder install the wall penetrations at the time of pouring
cement, and even stub out the pipes 5' so that I don't have to dig
near the house when I go to make the ground loop. - He and I
discuessed putting in a dry well (misnomer), so I thought I could
use that as a manifold vault. I could have him stub out 6 pipes
into the dry well, and then do my drilling from there.

(BTW, my friend who is using my house as a beta site, said,
just spray water on the coils of my existing A/C. Not as easy
as it sounds, but do-able).

One concern I have is whether a "homeowner-assembled" heat pump would
impact home value positively or negatively.

And of course, into the whole mix goes my "free time"
which is really. (It will get bigger in a year or two,
as my kid gets old enough to help... :-)

BTW, I signed a contract under 1BOG.org to get solar panels
on the roofs that face 120' and 210', so it's only the 300'
face remains, 18' pitch.

I am thinking I will have a 2'x20' skylight on the 210' face, and make my own solar collector under it - INSIDE the thermal envelope

I would be grateful for your comments, good bad or otherwise. I hope it doesn't sound like a repeat question...at the very least, it is a revision of an old question.

Thanks for your patience

Seth, in NORTHERN NJ


Last edited by pachai; 01-05-11 at 02:13 PM..
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Old 01-06-11, 05:32 PM   #2
AC_Hacker
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Quote:
Originally Posted by pachai View Post
The builder asked me what kind of heat/cooling I want. Well, GSHP, of course!
I hope you are paying at least as much attention to your insulation/infiltration issues as you are to heating issues. That's really where it all starts. Nice thing about insulation is there are no moving parts, and no service calls in the middle of the night. Many people make the mistake of thinking about heating at the expense of insulation, that's really putting the cart before the horse. A BTU saved is cheaper than a BTU made.

And of course, if your heat loss can be reduced, so can the size of your heat pump and those electric bills. Best part is you will be able to reduce the size of your loop field. The rules-of-thumb for estimating the size of your heat pump and the size of your loop field are based on the square footage of your house. You should go the max ('do it right' as you put it) and then have a professional analyze the heat load, and use that as your starting point.

So there's a great manual that was posted on the manifesto thread, and it is loaded with techniques to retain the heat you have paid for. I strongly reccomend it.

I don't know if you mentioned where it is you live, because that could influence your decision as to the best choice. GSHP is not the hands-down winner in all cases. If you live in a very mild climate, you'd be better off with mini-splits. Their COP is getting really high.

If you live in a harsh climate, Ground Source is the way to go.

Quote:
Originally Posted by pachai View Post
I have also been following the HomeMade GSHP Manifesto thread, and have even built a drilling rig, but winter and bulldozer came before I finished my own tests on it. What tests I did showed me that it would be a fun project, but I could not possibly do it on the builder's tight time schedule.
Yeah, that's really the 'gotcha'...

Quote:
Originally Posted by pachai View Post
One concern I have is whether a "homeowner-assembled" heat pump would
impact home value positively or negatively.
I assume you are not talking about building your own heatpump, but rather assuming responsibility for getting the HP system assembled and working. Even that is a lot of work, almost a crusade.

If you're considering some serious DIY options, buying a minisplit to heat some of or most of the house will buy you time. The intrusion hole is not too big, and you could sell it or keep it in place as a backup.

Something else to consider is the wife part. Trying to DIY something as fundamental as heat can be very trying.

-AC_Hacker

Last edited by AC_Hacker; 01-06-11 at 06:17 PM..
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Old 01-06-11, 06:19 PM   #3
pachai
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AC Hacker,
Thanks for your additional thoughts.
You are right, I meant "Integrate-it-yourself" not build-from-scratch.

I am in Northern NJ, where Outside temp is 21' now.

I am paying attention to the the thermal envelope.
The current house has cellulose.
I replaced all the 1st floor windows - not 3pane, but good ones.
This week, a door was added between foyer and mudroom,
and a window upstairs that was installed wrong was replaced.
(that's eligible for 30% back :-)

My friend is getting a demo of a thermal imaging camera,
commercial grade. He thinks that's even more effective
than a blower test.

Meanwhile, the contractor found the old oil tank.
I thought it had been removed, but now I see the fine print
says it was decommissioned. Oh Well, NOW it has been
removed. He may have to stop work for the EPA et al
to come out here, in which case I can do a few more test
drilling, (but now I am 10' below grade:-)

The Contractor asked the Excavator man if he would be
interested in helping me with the loops, and he was
interested. I mean Intere$ted.

I need to review the Heat Loss/Gain info I have
on my house.

My assumption is that my current boiler might work
as a backup. In fact, we could wire it as a backup
heat source for the ground loop. Not very efficient,
but emergency heat in the winter is....good to have.
(A/C failure in the summer is not usually an emergency.)


Thanks
Seth
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Old 01-06-11, 07:11 PM   #4
Ryland
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Quote:
Originally Posted by pachai View Post
My friend is getting a demo of a thermal imaging camera,
commercial grade. He thinks that's even more effective
than a blower test.
It's a two part test, the blower door tests should use a thermal imaging camera, otherwise you never see where drafts come from as the thermal imaging camera lets you see the cold air moving inside the walls, not just it's exit point.

I agree that insulation should be your prime focus, if you can afford to lay tubes for a ground source heat pump then do it, but if your choice is to lay ground source heat pump tubes or add 4" of foam to your foundation walls then I say insulate and seal as you can never have to much insulation.

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