[AC_Hacker]

Christian Nelson,

Thanks for your excellent report.

Originally Posted by Christian Nelson

New here, I have a propane boiler I installed myself this past year. I also installed my hydronic heating system, used slant fin's heat loss estimator, and sized my system. I have a combination of infloor radiant, and baseboards, using hot water. I sized the radiators to run at 140 degrees, so a bit large, but I was making the runs with PEX instead of copper, so I didn't want to run any hotter than 170, plus I wanted to augment with solar, so I wanted it to be as forgiving as possible.

So, where did you get your copy of Slant Fin heat loss estimator? I'm assuming you're referring to the Hydronic Explorer program.

Now that your into the thick of winter, what is your assessment of your combo-hydronic system? Is it delivering heat to your home as you had hoped it would? What kinds of things would you do different? What did you do that was really right?

Do you know what the 'degree days' are in your area?

How well is your place insulated?

Can you share details regarding your hydronic floor layout? Did you use a 'wet system' or a 'dry system'?

More details of the radiators?

The reason I'm so curious is that I'm about to put one in my place in a few weeks, and I'd appreciate any advice you have.

Originally Posted by Christian Nelson

Anyhow, I have had no end of fits dealing with HVAC people, the boiler I got, I bought from PEXsupply.com, and it needed to be fine tuned for optimum efficiency, and I don't have a meter. Well, I got the answer form almost every HVAC person "you bought it on the internet, have the internet adjust it for ya" and they wouldn't come out to do it.. So, I am buying a meter myself I guess.

Yeah, doing it on your own forces you to be a combination of scientist, a grunt worker, a pirate and a revolutionary.

Originally Posted by Christian Nelson

Anyhow, pretty happy with the system so far, and hoping to set up the solar shed with under ground storage tanks this summer. I found this DIY VERY interesting, and was thinking of maybe using a heat pump to keep my storage tank warm in the cloudy days of winter when the solar isn't helping much, and at best not using the propane boiler much.

Well, using a heat pump as a secondary heat source makes pretty good sense. If your are using a commercial air-source heat pump, you should be able to geat a COP of around 2.5 or better. I haven't to build an air source heat pump so I'm not so sure what a DIY could achieve... most likely 2.5 or a bit less. My experiments with water-source heat pumps indicate that a COP of 3.5 is a reasonable expectation. Anyway, if you pencil the conversions out, you'll see that either approach should be more efficient than propane.

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.

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.

Originally Posted by Christian Nelson

My question is about the deep well drilling loops, I noticed you made about 4 fusion welds to make the "U" to come back up, and was wondering why you didn't heat them up and bend them into a "U" instead. Maybe drill the hole a wee bit bigger.

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.

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.

Originally Posted by Christian Nelson

Or, I was looking at SC80 PVC, and simply putting "U" fittings and gluing them at the bottom I would think would work. We use PVC for sewer pipe, and other things under ground, why not this? Electricians have a sort of blanket they use for heating up PVC conduit (SC80) and you can make a fairly tight 180 once it is warmed up without kinking the things. Would this poly pipe you are using be similar?

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.

Originally Posted by Christian Nelson

Also, I very much agree with the insulate the nonsense out of your house thing.

I've been slowly injecting slow rise foam in my walls, zero insulation in them before.

I live in Wisconsin, with the frost line of 34" house built in 1908.

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.

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?

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

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