Looking for a solar thermal expert to layout custom system NW CO

[MoCoNative]

I'm in Craig, NW Colorado. I planned on integrating solar thermal heating to my home when I built it. We've been in the home nearly two years now and I want to finish this aspect of the project. I got a screaming deal on a used, large, 500 gallon open stainless steel storage tank, and five 4x10 collectors. I already have an 80 gallon electric hot water tank with a double walled solar coil in it. I also have infloor heat in the basement slab running off an instant electric boiler. The electric bill has been a tad high. We really want to get some free energy pumping in here. I'd also like to add a couple staple up loops under the kitchen/dining and bathrooms that only pull from the solar heat. The rest of the home is heated by a pellet stove.

I can do a lot of the work, but I have very little experience in all the possible ways to lay this out. The storage tank will need some heat coils. The collectors will have to use antifreeze, they are going to be ground mount, so no drain back possible. I would like to circulate the collectors with a solar pump. I would like to feed the existing in floor heat, domestic hot water and the extra loops under the above mentioned rooms from the stored solar tank. I'd like to do this as simple as possible with minimal pumps and such. System will most likely need a heat dump. I'm thinking baseboard heater section outside for this, or even dumping it in a seasonal hot tub. Again, more stuff to design.

I do not have a good grasp on what we will need for controllers, or pumping schemes. I envision some of this can be done with mechanical mixing valves, but obviously optimal control is realized with electronic controls. I also would need help with the calculations, at least getting down the right path. The collectors need serviced, this system was scrapped out and originally installed in the 80's. The panels look okay, but I have not started really inspecting them or pressure testing them. They are large and heavy, so that is a project I have not jumped into yet.

I'm looking for someone to bounce some ideas off, help design it, even do a site visit and lay it out with me. Big thing is figuring out a parts list with the proper controllers, pumps and fittings needed. I can look at stuff all day, but hate to guess on a fitting or controller, that does not do what you need it to. I would be willing to pay of course for help, as long as you don't laugh too much, and are willing to piece together a custom system like this.

Anyone game in the area?

Thanks, Graham

 

[MoCoNative]

Wow, no solar folks out there interested.

One of the panels was ruptured internally, even looks like it was repaired at one point in time. Looks like it froze and broke. I'm getting the impression this was all orginally a drainback system I bought and it froze up and was scrapped from an empty home perhaps. However, looks as though I can get new absorber plates from the manufacturer for the panels.

Seriously hit me up if you have any experience at all with a solar thermal system.

 

[alia176]

Sorry I didn't see your post until now, I could've helped you with ideas. What did you end up doing finally?

 

[MoCoNative]

I kind of forgot about this thread too. This project turned into a major odyssey. I had planned on having the system up and running in the fall of 2015, I worked hard at that goal and ran into some problems. By then it was late February, and I had to pull off of it. Put my time and efforts into getting ready for Cruise Moab 2016. I finally got it all working and running around the end of October I guess. So far it is doing pretty good.

I sourced five 4x10 panels and a 4 foot square stainless steel tank for $1000 bucks, so overall I thought that was a good deal, for the tank alone. The five panels were AET Solar brand. They all had bad internals, cracked. Luckily AET still builds that panel, so I ordered 5 new guts and a 6th new panel. Big job cleaning up the old ones and rebuilding them, worst part was carefully lifting off the glass and moving it around. Had the panels stacked up and did one at a time and them restacked them in the other garage bay. They are installed on the slope below my walkout basement on a ground mount, set at roughly 65 degrees. I hope this angle will benefit me the most in winter and provide some passive heat reduction in summer. I ran the piping, all 1" copper from the mount, buried over to the house and across the floor trusses to my tank. Buried lines are in 1" K-Flex and a 2" DOW board coffin. So far I think heat loss has been very, very minimal.

The tank, was a two part, bolt together custom fab deal, 4 foot square. The problem I ran into, was that there were 6 overall fittings in the walls of the tank. Four of those were 1" stainless nipples, welded right into the wall. I cleaned the tank all up, and everything seemed good. When I hooked everything up last January, I pressure tested the system with air of course. I had a persistent leak that I could not track down. Turns out the first leak I found, I thought was the threads on the copper adapter to the stainless nipple. About 6 new fittings and trys later, I found figured out the nipple itself was cracked within the threads. That pretty much shut me down at that point. I had already assembled the tank, and didn't want to separate it and remake that gasket. I ended up cutting off the bad section, which was on the outside of the tank, and stickwelding a portion of a new nipple on to it. Luckily I had a subpanel in the basement that I could hotwire the old Lincoln buzz box into. So jump ahead a bit, we are finally all assembled, thought I had the leaks done, we still are getting a pressure loss. The other lower fitting was cracked too, so I had to haul the welder back down, disconnect all the lines etc... Finally I had all my setbacks fixed and could finally charge it and get it going.

The system is comprised of the 6 panels. About 200 feet of line, and a 100 foot coil of copper in the bottom of the large tank. I made the coil such that it stands, coils apart about as tall as the middle of the tank. Tank holds roughly 450 gallons of water or so. I used a Taco 011 pump with integrated solar controller. The system has a diverting valve so glycol can go to the large tank, or to the DHW tank as needed, solar controller handles that. I put a second 100 foot coil of copper in the top half of the tank that is a simple extension of the return line from the basement floor loops. It gathers heat quite well, and goes through a mixing valve to temper it down a bit and back into an electric miniboiler and pump and back to the floor. Despite the extra 100 feet of line, the pump is handling the floor heating loop just fine.

I had a few hiccups on startup, I had misinterpreted the operation of the three-way valve and had glycol going to the wrong tank, as far as the controller was concerned. I also soon found out, that most of the demand was falling on the DHW tank, and I wasn't getting any heat in the space heating tank, which is where I really want it in the winter of course. So with a second external relay and two three-way switches, I can tell the controller to swap the primary and secondary tank designations through the thermistors, and the external output of the solar controller, that is supposed to activate the valve can work both ways too. So I have two switches, each labeled winter/summer. This lets me make the space heating tank the primary tank in winter, and the DHW tank primary in summer. We'll see how that works for summer, but so far I just keep heating the space heating tank.

On sunny days, which we have had a lot of cloudy days the past month, I get upwards 160F off the panels or better. I'm seeing about a 25-30 degree drop across the solar loop into the big tank, so that is decent heat transfer. On good days we can get the big tank up to 130-150 or more in a day of heating. In November we were seeing even better temps than that. We'll see what warmer sun in the spring brings. At that temp I get at least one good heating cycle in the floor at night, and the boiler does not come on or modulate until the last third of the cycle as the temp decreases in the tank. Tank typically bottoms out in the 90's. I've got the floor loop running at about 115, and mixing valve set just above that. The basement loses very little heat, so the floor only cycles about 1-4 times a day. So I'm getting 1/3 to 1/2 my heat from the stored solar heat thus far. Time will tell of course. I have a few pics, I'll see if I can post those over the holiday.

 

[alia176]

Sounds like an experience, wow! Congrats on the system working. Some day i'll build a drain back system with a DIY 500 gallon insulated tank with three coils for three systems. Some day, it'll become a reality........