[Christian Nelson]

A slightly different approach I am considering is to use the heat pump to extract heat from the water storage tank down to a point that would prevent the tank from freezing, in my area. Then the heat pump would switch to ground source heat extraction, until solar energy brought the storage tank up to some desirable temperature. This plan would have the advantage that the heat pump would chill the water that was flowing through the solar heat collector, giving the collector a larger delta-T, which will result in higher collector efficiency. The water-source switching can be done with electrically controlled water valves, which are used in the hydronics industry.

My tests indicate that the water-source temperature has a direct, positive effect on COP... the higher the temperature, the higher the COP. But only up to a point. If the feed temperature gets too high, it can boil the refrigerant prematurely and mess up the evaporation/condensation cycle.

Interesting, I never really thought about this.. Then I wouldn't have to dig any trenches, and I would be able to run the system as one, instead of splitting it. I will have to do some serious thinking about this!

So there's still work to do. BTW, I went to a local solar equipment trade show a couple of years ago and I told them about my idea of a heatpump-assisted solar collector, and everybody I spoke to got really excited... always a good sign.

It is an exciting possibility. How hot is too hot though? I am fairly certain that most solar systems shouldn't get above 150, mine will probably never see north of 120, except for summertime.

I actually tried this before I build the fuser. I used a heavy duty electric heat gun, that was capable of soldering copper water pipe. Using the heat gun carefully, I was able to heat the poly pipe to the point where they would bend, but I was not able to get a smooth bend without the poly pipe collapsing. I also tried using a bending jig, but was not able to prevent the collapsing problem. I never did try filling the pipe with sand or salt before the bending... might work.

OK, even with a jig, it was collapsing, must be thinner walled than I was thinking.

I can tell you that the fusing process is really pretty easy, and is incredibly strong. But as I learned, you need to be able to test every weld... very important.



I came across a page somewhere on the net that described some of the early ground-source work, and it turns out that the early efforts were with PVC, but that type of plastic was abandoned because polyethylene is more flexible and tougher, and the welding thing is not rocket science... it's not as simple as gluing PVC, but it can be learned by a mere mortal.

Yeah, to me, there should be no reason you couldn't use PVC. I've seen it used for under ground water stuff all the time around here. As long as it isn't exposed to solar radiation all the time, it is pretty robust stuff. But that goes for many polymers.

Oh, so you have one of the oldies-but-goodies too! I think there are several of us here at ecorenovator who are working in the same way on their old houses.

Yeah, 2 reasons (I may be wrong of course) I don't like people moving out, buying small chunks of land from a farmer, and building up a bunch of houses around here. Bugs me everytime I see another development spring up, or another McMansion being built in a cornfield. So, I decided to just buy an old farm. Place was built in 1908, has an old barn, that needs work, and some other out buildings originally on 40 acres, but I ended up with only 15. Couldn't afford the whole property right off, and when I was set to buy it, some city guy bought the rest and built a gigantic place out behind me, it has since been foreclosed, and sat empty for several months now. Really regret not being able to buy the whole 40 acres. But, I didn't have much choice. So, now I get to look at this gigantic house, and stupendously big horse barn (with indoor arena) right behind me that made my property taxes go up. The town folks figure that if my neighbor could afford to build a $700k house, I must be rich too I guess.. Anyhow, the other reason was, I was getting married, and I wasn't gonna make my wife live in a tent while we build our dream home..

I really want to hear about the foam injection scheme...

Have you figured what the cost per cubic foot is?

Do you have any info as to the R-value of the foam?

Yeah, it's standard slow rise kits, around $700 for 600 board feet shipped to your door. tigerfoam.com is one there are others that sell these kits. It's VERY expensive, but it fills the wall solid, R6 per inch is the claim. I don't have to tear out my lathe and plaster walls, I just drill some holes every stud space, every 3 feet high, pull the trigger for 15 seconds, plug the hole, and go to the next. Plug the hole is very important if you don't want to see the playdough noodle factory flying out of your walls. I've been slowly doing this every year, one 600 board foot set. I have actual 2x4 walls, so 4 inches should give me R24, give or take. BIggest benefit I have found is ZERO air infiltration. I have also been doing rigid foam in my basement walls. Almost done there. 2 inches. I plan on reroofing this summer, with steel panels, and I am going to put the fanfold insulation under the roof, and according to the foam people, if I spray foam directly to the inner roof of my attic, I don't need to vent the attic space, I then plan on majorly insulationg the nonsense out of the underside of the roof, and making the attic into useable storage. I have never understood why we spend so much time and effort trying to keep the elements out of our houses, then punch holes in the roof to vent our attics. Then we pile a ton of insulation on the floor of the attic, so you can't even use that space! We will see if I have a mold problem. I plan on checking that.

My method of using slabs of EPS foam layered up in the wall is working, but it is a fearful lot of work.

Yeah, not to mention trying to figure out where to put all that lathe and plaster (with lead paint) and breathing all that dust while you are tearing it out (did I mention lead paint getting kicked up?) I like to leave dead dogs lie, the walls are in good shape, not crumbling, I want to leave them as intact as possible, so I don't have to deal with the disposal of that stuff.

Good luck on your project! Please feel free to ask any questions and share any discoveries you have along the way. And in case you haven't noticed, there are loads of people tuning into this kind of thing.

We're all in turn: scientists, grunt workers, pirates and a revolutionaries.

This is exciting stuff.

Best Regards,

-AC_Hacker

I am less scientist, more techie (that makes tons of mistakes, but tries to learn along the way) but yeah, this is exciting! I am thankful that there are people out there who do the stuff I do, but take the time to document and make sure things are accurate, unlike my off the cuff approximations, and hand wavy calculations