Hello. I am looking for advice again. Let me frame out the system I have and what it does for me and then I will pose my problem and question.
I live in the northern upper peninsula of Michigan and the heating season spans from late September through late April. My main house is approximately 3200 ft.² plus another thousand square feet of heated basement. The house is south facing and has 46 m² of triple pane Glass facing south and west. The house layout is such that it captures very well. The sun when it is at low angles in the winter and reflects it well in the summer when the sun is at high angles. The house was built in 2016 and is exceptionally well insulated. Besides the main house, I have a summer kitchen off my garage that is kept at 65° via in floor heat and one way or another. My garage is partially heated and maintains a temperature of 38° minimum at all times. I honestly have no idea where the heat source for that is. I did not build the house.it is not leak through the walls for sure. I also have a separate 30‘ x 60‘ single-story building that houses my wood boiler and my workshop.
My heating system consists of a Garn 2000 gasification wood boiler with 2000 gallons of thermal storage and a WM Eco 110 propane boiler as back up. I also have a kitchen queen woodstove in my kitchen and another in my summer kitchen for principally shoulder season heating . Heat units output into hydronic radiators that are all individually controlled by thermostatic radiator valves. At least the ones that work :-(. None of the supply lines to the radiators are insulated and run right up under the floors, giving me de facto in floor heat. That is part of the problem that I will lay out shortly. The system also heats my domestic hot water. There is a loop off the wood boiler to my greenhouse, but I never use that. So that is the system.
The system works very well during the cold winter months. There are a few times when we get several days in a row below zero with high winds that I fire up the kitchen stove, but that’s rare. I don’t think I burn a cord in that all year. my principal heat comes from the GARN, and I burn about 10 cords of seasoned hardwood a year. I also burn about 1200 gallons of propane a year, presumably with the propane boiler, kicking on when the wood boiler temp gets low ( The setpoint water temperature for the boiler is 90° to kick on. My rough estimate for heating needs on an average winter day is between 35 and 45,000 BTUs per hour based on the boiler water temperature profile.
Now for the problem. As I said, the system works great in the depths of winter. If it was winter all year long and not just 50 weeks of the year
I would not be writing. However, in the shoulder seasons, when the sun is either still a bit high or rising on the horizon all of my glass area really soaks up the heat and most of the glass is in a two-story open area so the heat spreads quite well. Even with the thermostatic radiator valves, shutting off when, the temperature inside starts to rise, the water still circulates through the lines and they continue to radiate heat. The end result is the house gets very hot. Yesterday with lots of sun and the temperature outside of almost 50 it was 78° in the house. Obviously I can’t turn the boiler off because the water is already hot. I make two fires per day and keep the tank temperature between 145° and 180°. Aside from the basement floor and the summer kitchen in floor heat there are no other thermostats in the house. so there is nothing that will automatically shut off. I ultimately unplugged the circulating pump to the house supply lines yesterday and the house temperature drifted down to 72° by this morning with an outside temperature of 22°. That solution works, but it’s a pain in the butt to run up and down the stairs every time, I need to cool the house down. Besides, I don’t want to cut split and stack wood just to overheat my house. This seems like probably a question with an obvious answer, but I am no HVAC person. In fact, I didn’t know anything about all the stuff before I bought this house. What I’m thinking is to do one of two things: first, I could switch the receptacle that the circulating pump to the main house manifold plugs into and put the switch up on the first floor. Then, when it starts to get too warm, flip the switch. That requires more human input than it seems like it should. On the other hand, if I could somehow place a thermostat on the main floor that controlled the electrical supply to the circulating pump, then I could have it turned off when the main house temperature was above a certain point and on below a certain point. Since the hot water would be still circulating from the wood boiler tank to the house, there wouldn’t be a lot of lag time to get the radiators heated back up again.
I’m sorry this is such a long post, but I wanted to answer all questions. You might have ahead of time. The attached picture is the inside system. Very interested in your thoughts on the best solution to my overheating problem. Thanks.
I live in the northern upper peninsula of Michigan and the heating season spans from late September through late April. My main house is approximately 3200 ft.² plus another thousand square feet of heated basement. The house is south facing and has 46 m² of triple pane Glass facing south and west. The house layout is such that it captures very well. The sun when it is at low angles in the winter and reflects it well in the summer when the sun is at high angles. The house was built in 2016 and is exceptionally well insulated. Besides the main house, I have a summer kitchen off my garage that is kept at 65° via in floor heat and one way or another. My garage is partially heated and maintains a temperature of 38° minimum at all times. I honestly have no idea where the heat source for that is. I did not build the house.it is not leak through the walls for sure. I also have a separate 30‘ x 60‘ single-story building that houses my wood boiler and my workshop.
My heating system consists of a Garn 2000 gasification wood boiler with 2000 gallons of thermal storage and a WM Eco 110 propane boiler as back up. I also have a kitchen queen woodstove in my kitchen and another in my summer kitchen for principally shoulder season heating . Heat units output into hydronic radiators that are all individually controlled by thermostatic radiator valves. At least the ones that work :-(. None of the supply lines to the radiators are insulated and run right up under the floors, giving me de facto in floor heat. That is part of the problem that I will lay out shortly. The system also heats my domestic hot water. There is a loop off the wood boiler to my greenhouse, but I never use that. So that is the system.
The system works very well during the cold winter months. There are a few times when we get several days in a row below zero with high winds that I fire up the kitchen stove, but that’s rare. I don’t think I burn a cord in that all year. my principal heat comes from the GARN, and I burn about 10 cords of seasoned hardwood a year. I also burn about 1200 gallons of propane a year, presumably with the propane boiler, kicking on when the wood boiler temp gets low ( The setpoint water temperature for the boiler is 90° to kick on. My rough estimate for heating needs on an average winter day is between 35 and 45,000 BTUs per hour based on the boiler water temperature profile.
Now for the problem. As I said, the system works great in the depths of winter. If it was winter all year long and not just 50 weeks of the year

I’m sorry this is such a long post, but I wanted to answer all questions. You might have ahead of time. The attached picture is the inside system. Very interested in your thoughts on the best solution to my overheating problem. Thanks.