March 01, 2013

Life Hack: Electric Heat and Digital Thermostats

When I purchased my condo in the lovely city of New Britain, one of my big concerns was the heating system - specifically, electric baseboard heat. I've been living with gas heat for years - hot water baseboard in Waterbury, forced air in Hartford. I was concerned about comfort, of course, but mostly I've heard much about the high cost of electric heat.


Balancing the cost issues, electric heat brings one big  benefit - it's inherently zoned. Which means, instead of one thermostat for the whole condo, or at best two (upstairs / downstairs) I have seven thermostats in the place: living room, kitchen, master bedroom, spare bedroom (my yoga room), two bathrooms, and the basement. So there's a lot of possibility for fine tuning the heat - to heat just the spaces I commonly use, and perhaps save some money.

When I moved in, all of the thermostats in the place were old-school electro-mechanical devices. There was no visible thermostat or feedback, the rotary dial was exceptionally coarse (with a resolution of 10ºF) , the calibration was highly suspect, and the heat control was simply ON / OFF. If the temperature dropped below a set point, the device turned on 100%, the space heated, and the device eventually turned off.

So my first thought was: Digital Thermostat. I found these Honeywell Thermostats at Lowes for about $25 a shot (cheap!) and replaced five of the seven thermostats (I left the bathroom thermostats in place, they are permanently switched off).

An aphorism I picked up in the corporate quality world was "If you measure something, it gets better" and the digital thermostats have a thermometer on them. So instead of simply "feeling cold" I can look and see the actual temperature. It's amazing how much things like my own health / energy / activity, as well as the ambient humidity and outdoor light level, affects my perception of temperature. So with a digital thermostat, I can now see that the room temp is 65 F (my usual occupied setting) and put on a sweater or sweatshirt. I think a lot of "heat creep" in electric systems comes from this lack of feedback.

In addition, the digital thermostats have a much finer resolution (1ºF) which means even if I decide to "crank the heat" I can restrict that to a few degrees. Finally, the digital thermostats use proportionate triac controls - which means that the heat is not simply ON / OFF, but appears to have four setting: ON / LOW / MEDIUM / HIGH. So as the temperature drops, the heat turns on LOW - and if that's enough to warm the space, it never gets past that. So the heat is a lot more even and therefore comfortable.

The electrical installation was pretty simple - easier than changing a light switch IMHO. The only complexity is that the older thermostats are DPST (Double Pole, Single Throw) - which is to say they break both lines (in my case, the heat is 240 VAC, two hot lines). The digital device is SPST - so one of the lines needs to be connected directly.

Now, simply adding digital thermostats still leaves a lot of room for energy waste - if I forget to turn the thermostats down. In addition, when I turn the thermostats down at night, I wake to a cold home. So I added programmable thermostats to key areas: the living room, the master bedroom, and the basement (where I have my office). This device is a bit more expensive: $50 at Loews. It has the same general functions as the digital thermostat, but adds a programmable function. This particular device permits four different timed settings (typically WAKE / LEAVE / RETURN / SLEEP) and can be programmed differently for weekdays (Mon-Fri) and weekends (Sat-Sun).

So I drop the house down to 58ºF at night (I tend to like a cool house to sleep; flannel sheets, blankets, and a bed dog keep me warm) and just prior to my normal wake-up, I heat the house up to 65ºF. During the day, I drop things down to 62ºF (I'm either in the basement working, teaching yoga, or out and about). I pop it back to 65ºF in the late afternoon, and back down at bed time. If I want it a little warmer, or happen to be hanging in the living spaces during the day, I bump the thermostat up confident that it will reset at the next timed change.

In hindsite, I'm retrofitting all the digital thermostats with programmable ones - I often leave the kitchen up at 65ºF by accident, and on more than one occasion, I've heated up the yoga room to 80ºF (for a warmer practice) and left it on for a day or more. So now the yoga room is permanently set to 55ºF and if I accidentally leave the temperature up, it will reset within a few hours. I'm transferring the old digital thermostats to the bathrooms.

Does it work? I think so. My electric bills (which include dryer, hot water, and range, as well as lights and heat) range from $80 (summer) to $250 (winter) - which is not too bad, especially considering there is no gas or oil bill coming. The total retrofit costs ($250 to go 100% programmable digital) - minimal really and I'm guessing the energy savings have covered that in a single heating season. And with electric heat, I do not need to maintain (and consider replacing) a much more finicky gas or oil furnace, fan, pumps, etc.   

The downside - need to program the thermostats (not really that difficult, as compared to the timer on my front door light) and maintain the clocks (daylight savings time). But so far no real issues with power outages causing resets - I guess these things have some internal capacitor or battery backup, or store the program in non-volatile memory.  

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