Feeling the Heat

thermostat 1219

The first Dusty-built house we invited ourselves over to tour was a straw-bale house owned by Nancy and Bryan, featuring a concrete floor with in-floor heat. Not only did the concrete (perhaps it was adobe) radiate the heat from the pex tubing woven throughout; it also absorbed the heat of the sun coming from the south-facing windows.

While I don’t remember his exact words, Bryan told me about the importance of anticipation, such as opening the windows first thing on summer mornings, before the floor picked up heat and made it unbearable in the house. (We here in Gunnison overheat a lot quicker — we’re quite happy at 70 F — than most of the rest of you, at least in the summer.)

By the time we invited ourselves to the Bennetts’ Dusty-built house, we were looking at stick-built with a crawlspace featuring under-floor heat. Similar concept; far less mass. When I asked about the temperature, Carol looked a bit startled, like it was something she didn’t give thought to, and this turned out to be the case: “We just set the thermostat at 68 and don’t worry about it,” she said.

Coming from a lifetime of forced-air furnaces, and over a crawlspace that still needs to “tune” for another several months, I am still trying to decipher the rhythms of our under-floor system.

Not that we’ve had a lot of need for the heat yet, not really much at all before this month. There were a couple of really cold days in October, but it was warm enough to reclaim screens well into November, which meant it got quite hot in our new house. This is probably largely due to the large amount of glass on our south side — way too much glass for Dusty, who informed us we aren’t practicing “passive solar” at all.

Really, we are, just not in the manner of the experts. In a truly passive solar house, I guess, the house would heat to a comfortable temperature, and then a mass — either the concrete/adobe floor or a giant concrete wall — that had soaked up sun all day would slowly release it at night.

Here we heat up — or we did, back in the days when we had sun — to a temperature that reads 75 at the north end of the house, so probably close to 80 in the full sun at the south. Although so far, when temperatures really haven’t gone below zero, that heat holds several hours post-sun.

But I’m still trying to figure out a good pattern. During the packing process I found a spare programmable thermostat, which I brought to the new house and Ben the plumber installed in the Good Room. Had I been thinking, I should have requested he install it on the west side of the house.

And I really shouldn’t have to think (as I often don’t), because I have replaced several thermostats both at home and work, so I ought to be able to swap the two thermostats. But I hesitate, because maybe it is better to leave a programmable option in the Good Room.

For the east “wing” of the house, I took Carol Bennett’s advice and just set the thermostat to 68, or in this case, 69. Lynn, who keeps insisting she would be quite happy to lead a seasonless existence in a place like Hawaii, gets cold easily and often. So that part of the house is always 69, and this seems to make her happy, although not as happy as if it were 80 with a light tropical breeze.

(She says this is my biggest fault, that I lived in Colorado rather than Hawaii when she moved from Wisconsin. I can live with this fault and apparently, so can she.)

I am liking underfloor heat. It’s very nice to wander around on a warm floor in your bare feet, and it’s rare (so far) that I feel the need for a sweatshirt in this house, where I wore one often in our old house.

But I can’t go the 68-all-the-time route in the west wing. The other night I forgot to turn my thermostat down, and kept waking up to kick blankets off and stick my feet completely out from under them.

So far I’m not working much of a range, setting it to 63 rather than 60 at night, and then only turning it to 66 for the day, but those three degrees apparently make the difference between being able to sleep and not.

And I am pleased to announce that while I no longer can hear my heat registers hum as air blows through them, there are lots of little knocks and dings as the glycol or whatever is in the pex tubing starts heating up and moving. It’s still a sound of heat, and it’s warm and comforting to me.

Today I pushed the temperature up around 6 a.m., and two hours later the temperature is still showing 63 degrees — but the floor is warm, which is really all that matters.

Which takes care of both side of the house. Now it’s just the middle I need to figure out.

Right now I have the programmable thermostat set to go from 60 to 68 about 15 minutes before Lynn gets up at 4:30 (who does that?), but based on this morning’s informed study, it’s probably still 60 when she leaves for work. By the time I get up and look at the thermostat, say around 8, it’s at 68 and the floors are still putting out heat.

But then I leave it set at 68 all day, and I wonder about that. I don’t know what the sun could do on its own if the floors were cooling down (assuming, again, that the sun ever feels like shining again); perhaps it would be best to not ask the floor to do any work while the sun is shining in.

But I’m leaving it at 68 until 6 p.m., at which point I have the program reverting to 60. This is early even in this household, where everyone is under a blanket somewhere by 9:30, but it also gives Lynn a chance to use her gas fireplace that is taking up so much space it certainly ought to be used. (I’m still quite happy with our three-sided choice, rather than something installed in a wall.)

Whether it’s better financially to use the in-floor heat or the gas fireplace, which I was assured costs literal pennies to operate, I don’t know, and whether in-floor would work more efficiently if the temperature isn’t constantly going up and down I don’t know, and whether this model will work into January I don’t know.

So there’s a lot I don’t know, as if you didn’t already know that. I guess we’ll just have to figure it out with a lot of unscientific experiment.

 

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