Ben's <$1000 solar hot water system

[Daox]

I think thats the rule when you're putting something large up into the air. However, for your relatively short ground mount you could probably get away with an 8" auger which will make a slightly larger hole.

[bennelson]

I've done a little work here and there the last couple days.



To start with, I planned to dig a test hole. I was talking with my Dad on the phone, and he said that I really didn't know what I was going to hit when I started digging. Which is true. I have really high ground water, and very unusual soils that all meet in my yard.

If anyone is familiar with Wisconsin geology, you might be aware of how the glaciers of the last ice age define our modern landscape. Well, the glacier stopped in my yard. Seriously.... I talked with a university geologist once.

Anyways, that darn glacier means my yard varies from gravel to clay to, and I am not making this up, "glacial ooze". (That's actually the scientifically correct term!)

So, I borrowed a hand post hole digger and a long digging bar and set to work to dig a hole 6" in diameter, and as deep as I could get it.

I dug down 12" before I hit the first road-block - a 4" diameter root - exactly across the dead center of my hole. I moved over 3", and started digging down again. I made it to 32" before I hit water.

In my area, what you always hear about footings, foundations, and digging holes that will survive the winter is "dig down four feet". Well, that's not really an option here. It doesn't make sense to dig deep enough to put my 4x4 post into water, just to let it rot.



My thought was that I would leave the hole overnight, and see how much more water seeps in. In the mean time, I decided to start digging the other holes. Since I now knew I wouldn't be going that deep, I would just dig them by hand, no tool rental needed.

I dug holes where two of the other posts will go, but was able to dig just a tad deeper than the first hole. Then it got dark, so I'd have to wait to do that last post hole.

The next day, I could see that the test hole had filled in a bit with water. My plan at this point was to fill in the bottom of the hole with gravel to get above the water line, then put the post on top of that and fill around it with gravel and stamp that down.

Later in the day it rained, and has been wet weather since then. My holes now only have 18" from the ground level to the water line.

I also borrowed a hammer-drill and 14" long masonry bit. Crawling to the deep underbelly of my house, I measured 6' from the end of the foundation, and started drilling holes through the cinder blocks, as close as I could to the concrete floor. The idea there being that on the south side of the house, there's lots of exposed foundation. I wanted to get my solar pipes buried underground if possible.

Outside, I dug a couple of shovels full away from the foundation. While drilling from the inside, when I did put the bit all the way through, I did see daylight. Yea! I measured correctly!

I drilled a series of holes and then started smacking the concrete with a chisel and hammer, to break pieces away.



By now, it was dark. I still didn't have a finished hole yet, but the wife frowns on using hammer drills directly under the nursery after the baby's bed-time!

So, right now, I have three gopher holes in the ground, half filled with water, and a hole in the side of my house. I stuffed some foam into the hole in the foundation, just to keep the cold and the wind out, and maybe even animals...

I WAS planning to put a 4" PVC pipe through the foundation. It would act as a conduit for the plumbing, pump power wires, and thermal reading wires. Foundation cinder blocks are 8"x8"x16", the but hollows in the middle of them are NOT 4", they are curved and end up being a bit smaller than that.

Also, when I was out and about yesterday, I stopped at the building supply store and picked up just a few "test sample" pieces of plumbing and insulation. Here's two photos of 1/2 pipe with closed-cell foam rubber insulation over the top of it. Two of these side-by-side come to about 3" across. (One send line, one return line.)





That foam rubber insulation is pretty nice. It's marked as "UV-Resistant" and is self-sealing along the slit AND has a self-sealing flap that folds over the top of the seam as well. I'm not sure how much better the R-value is on this stuff compared to the plain, cheap pipe insulation, but it sure seals up nice!

I know that any exposed pipe insulation outdoors needs to be protected from both sun and animals. Part of it should be protected by the 4" PVC, but I'm not exactly sure what to do for the individual pipes going to the two far ends of the panel.

Going back to that hole in my foundation. Maybe I can find some 3" PVC that will fit in there. Otherwise, making a 4" hole in there may be challenging. We'll see. I need some better weather and time during daylight hours to keep working on it.

[Daox]

If you're worried about rotting wood, it was suggested to me to put metal in the concrete and then bolt wood to that bracket. That keeps the wood out of the the ground and away from the water.

Nice update!

[bennelson]

Wood keeps it all simpler though.

I need to make everything 18" - 24" inches above ground, just to make room for winter snow (including the EXTRA that slides off the panel.)

By using wood posts, I can leave them extra-long, then cut them off level with each other. With any concrete work, I now need to make concrete posts AND still have wooden posts coming off of that. At that point, I would also need cross-bracing, etc. Seems like it starts getting a bit complicated.

[Daox]

I mean just pour the concrete in the ground and put the bracket on top then bolt the wood to that. You don't need a concrete post sticking out of the ground or anything. Xringer posted this image in my solar hot water thread. This type of bracket simply lifts your wood a little bit off the ground away from moisture. You could still mount the posts and cut them to even heights and I don't think you'd need cross bracing.

[bennelson]

Oh yeah, THOSE brackety things.

Would that give much advantage over just having gravel in the bottom of the hole?

The gravel would get the post above the water line AND allow water to drain away.

[Daox]

Concrete will always absorb moisture and keep your wood damp. Having it out of the ground is most ideal. I wanted to do this but convenience got in my way. I'm sure its not a huge deal either way, just throwing out the option.

[AC_Hacker]

Originally Posted by bennelson

The next day, I could see that the test hole had filled in a bit with water.

bennelson,

Sounds to me like you have some real potential for GSHP action.

Wet dirt has really good thermal transfer potential.

How deep is the frost line where you live?

-AC_Hacker

[zick]

Ben, I know what you mean about WI ground. We live in a flood plain and the year we built our house we hit water at just 12" down. Also have clay, dirt, gravel, clay, gravel, etc...

I've also been planning to put up some hot water solar panels on a ground mount system but the area where I'd like to put it has our Geo lines running right under there.

So I've been thinking about a different approach which may work for you as well. Unless someone can give me reasons why it wouldn't work.

Instead of digging holes and putting down post and supports. Why not just pour a concrete pad?
Just dig down 8" to level it out and put down some gravel base and pour a top pad. It should have enough weight as to hinder any wind resistance.
You could also sink in some bolts or those post adapters shown earlier right in during the pour.
Only downside I can think of is that it might be more expensive but hopefully by not too much.

[zick]

Originally Posted by AC_Hacker

bennelson,

Sounds to me like you have some real potential for GSHP action.

Wet dirt has really good thermal transfer potential.

How deep is the frost line where you live?

-AC_Hacker

This is one reason we put in the Geo, our ground is always wet which should be more efficient.

Around here the frost line is 42" from what I've read but everyone says to go 4'.