The Heating System

The good news is that I finally have a building permit in hand! The bad news is we aren't ready to start yet.

The biggest obstacle is not having decided on what heating system I'm going with. Since one of the options has a below-the-basement heat storing "sand pit", I can't start digging until I decide if I want this hot sand pit below the house.

When I started the project, I knew I wanted radiant in-floor heating with solar panels providing the heat. I didn't know exactly how that was done, but I thought there would be a pretty standard way of doing this and there would be companies who did it. It really isn't as easy as I thought it would be. Innovative Power Systems (IPS) is a Minnesota company that specializes in solar energy. They've done quite a few projects in Minnesota are know as the leader in installing solar and wind energy systems, both commercial and residential, in this area. They did the big PV solar array at my local food co-op. I figured IPS would probably do my solar system. Richard, my "design/builder" architect, installed his own system in his house and studio (much smaller than what I will have). I thought it would be relatively easy for him to recommend a good system and find someone to put it in.


He came to me with one heating proposal, from a guy named Norm, who had supposedly done dozens and dozens of these systems. Norm proposed a closed-loop system with 2 or 3 large (120-200 gallon) hot water storage tanks. He also proposed a 2 foot deep bed of sand with pex tubing under the basement. This sand pit would store heat from the sun all summer and then I would draw it off through the fall and early winter. There would be a heat exchanger which would warm the pex tubing in the floors, and a heat exchanger to warm water for domestic hot water use.


When I first met Norm, I wasn't impressed. There were misspelled words all over his proposal, and the grammar was terrible. It just didn't seem to be a good sign that there were so many errors in the proposal when there can be no errors in installing the system. I would have pex tubing filled with liquid, a third of which will be buried below the basement floor, another third will be embedded in the concrete basement floor, and the last third will be sealed under the first floor hardwood floors. There can't be any mistakes. Once the system is complete, mistakes can't be fixed without ripping up the floors. But Richard was absolutely sold on Norm; he'd have Norm install his heating system if he were building a home.


I told Richard I wanted a bid from IPS. I wasn't going to give a huge hunk of money to some guy named Norm without comparing it to something else. Richard never showed me the bid from IPS, just said it was a "drain back" system that was inferior to Norm's. He also told me that the water going up to the solar panels to get heated up was the same water that came out of my shower, which I didn't exactly like. (It turns out that isn't true, so either I misunderstood him or he misspoke.) We met again with Norm, as I was still having great reservations. Norm had some fancy graphs and flow charts and assured me I'd get 90% of all my heat and hot water needs from this system, it was that efficient. He presented a system that was going to total $45,000, but assured me "it would probably be a lot less." Richard kept pressuring me to go with Norm, because his was the best. No one else could do it. At one point I even said "Do you mean to tell me there is no one else in the Twin Cities who can do a solar heating system in a residential home? I don't believe that."


By this time, Richard's time was being taken up by another project, and he recommended a General Contractor to help me finish. The first time I met Jeffrey Swainhart, he stayed for a meeting we were having with Norm. With all the fancy charts Norm had, he still couldn't explain to me how the system was going to work in terms of the sand pit and storage tanks. I can understand some pretty complex issues, but he totally lost me with his explanations. I became convinced he didn't know how the system worked. Jeffrey wasn't overly impressed, either. That night, I went online and found an article by Bob Ramlo on the very kind of system Norm was proposing. Bob has written a book on soar heat and I had seen the book just a week or two before. The article Bob had written was clear and easy to understand, so I finally understood what Norm had been trying to explain. It wasn't a difficult concept, and I took it as a bad sign that Norm couldn't explain something that was pretty simple.


We asked Norm for references and actual projects he's done, and got the runaround, another really bad sign. Apparently, Norm works with a relative, Tom, on the solar heating project. Tom is the brain behind the business, and actually hooks everything up himself, while Norm makes the sales and does the grunt work of laying the pex tubing out.


Jeffrey got a hold of the bid from IPS, which had been given to Richard in the fall. IPS just bids on the solar energy hookup, they don't install any of the radiant in-floor heating itself. You have to get an HVAC installer to do that. So Norm's bid was about $45K, and the IPS drain back system plus an HVAC bid I had already gotten came out to about $48K. So the prices are close, but there are differences, the main one being how to store the heat. IPS doesn't have a sand pit under the basement (the sand pit raises the cost of excavation and masonry work by $3000 or so).


When I had a chance to look at the IPS bid this weekend, and saw the solar broken out separately from installing the heating tubes and overall heat system, it got me thinking.


Radiant in-floor heating is supposed to be the healthiest (no hot air blowing around, drying the air and spreading germs and dust), warmest, and most energy efficient. I still have to have a boiler for backup, as well as a hot water heater (for backup). The solar will still probably only provide 60-70% of the heat/hot water needs, on the average. When the sun is low and weak during the coldest months in Minnesota, the gas boiler will be on a lot.


It is going to cost about $26,000 to add the solar thermal heat. This includes heat exchangers, heat extractors, very large storage tanks, maybe a sand pit, and nine 4' by 8' solar panels on the roof.


What if I took the $26,000 and bought PV panels and used an electric boiler and tankless electric hot water heater? Shouldn't $26K worth of PV panels power a boiler and DHW heater year around, 100% of the time?


I did some research on that. My house will be incredibly energy-efficient. If I bought a 5kW system of PV panels, it should be enough to power all my electric, including an electric boiler. I could get a 5kW PV array for about $40,000. I get a $2000 rebate from the feds, and a $11,250 rebate from the state. Also, from the state, the $40K worth of PV panels are not part of the assessment for real estate tax So I'd save a few hundred bucks every year in taxes.

So do I want to spend $26K on thermal solar, and all the paraphernalia that goes with it (heat exchangers, 200 gallon storage tanks, etc.), which will provide about 60-70% of my heat and hot water (I'll still be paying for the other 30%), and I'd still be paying all my electricity? Or should I spend $27k ($40K for the PV array minus the rebates equals $27K) and get 100% of my heat, hot water, AND electricity? Unless I'm really missing something, this seems like a no-brainer.

Stay tuned as this gets fleshed out.