Sunday, January 3, 2010

Home Again

We've been back from the holidays for a few days now. Our house was just as it should have been upon our return. If we had a programmable thermostat, we would have been able to see how cold or how warm it had gotten when we were gone. I did note that there was water in the overflow tray of the solar storage tank meaning that the water in the tank had gotten so warm that a pressure relief valve had let a little out. If there is a flaw in the system, it is that the two parts, the solar and the propane back-up, work well together when heating our hot water but not when heating the space. To most efficiently heat the space I have to be here to manipulate the system. If I'm not here to press buttons, the benefit of solar heat going into the slab is lost. One problem is that the heat is controlled by thermostat. Since the house is passive solar, on any day that there's solar heat for the slab it's already warmer inside than the temperature set on the thermostat. So at the time when it would be free (no propane use) to add heat to the slab, nothing happens. When I'm home at a time like this, I turn up the thermostat for a few hours and the excess solar heat flows through the concrete. The result is impossible to measure, but imagine, for example, that the 1000 square feet of concrete goes from 65F to 67F in the few hours I'm able to dump heat in. At 3am when it's in the single digits outside, those two degrees are slowly seeping from the slab, keeping the house just a little warmer. As the day lengthens throughout the course of winter, on sunny days there'll be more and more of this excess heat for the slab. By March the days we'll need supplemental heat from the wood stove will be few.

Michelle and the girls are off to Florida soon. My job is to transform as much of the upstairs space as possible when they're gone. Painting, trimming windows, painting the plywood floors. I should be able to put a large dent in it in ten days.

A nor'easter dumped a foot of snow yesterday and last night. Today might be good for building snow forts.

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