Reducing Our Electric Bill: Thermostat Replacement

Developmental Blogology. 2014 January 3

Reducing Our Electric Bill: Thermostat Replacement

Abstract:
Replacing analog dial thermostats with digital programmable and non-programmable models for electric baseboard heat increased subjective comfort, but did not show major energy savings to offset initial investment in replacement thermostats in a well insulated 1980's contructed duplex in State College, PA.

Introduction:
The house we're currently renting was built in the early 1980's, and has electric baseboard heat, an electric stove, and hookups for an electic dryer.  Each room was already zoned independently, and hooked up to these ghastly things:

Pros: Came with the rental Cons: "On-or-Off" Loud Wide temperature range

The Mears 602 thermostats have temperature marks on them, but they aren't very accurate.  Turning the heat to 65ºF resulted in the heat fluxating from the 50's to the 80's.  The relay in these thermometers is quite loud, and when the set point is reached you hear a loud "click".  The issue with older thermostats is that they are either "on" or "off", and by the time the register has warmed up enough to heat the room, it's well over the set point at the heat source, and just getting warmer at the thermostat.  The long cycle times and extreme temperatures the registers were reaching also resulted in a lot of noise coming from the registers with each heating cycle "click click click, ting ting ting, etc" and hot spots in the room followed by drastic cooling before the next heating cycle began.

Methods:
I decided to install a programmable thermostat in the main living area right after we moved in.  The major advantage to programmable thermostats is that you can set them to turn off whenever you're away, or when you're asleep, and warm back up before you get home, or before you wake up, so you don't notice the changes (except when you open your electric bill!)   I decided to buy the Honeywell TL8230A thermostat after reading several reviews, and trying to find what would work best for us.  The NEST thermostats looked pretty neat in that you can control them remotely, and that they learn based on activity,  but the price tag ($250 pays for a lot of electricity), the need for multiple units, and the fact it isn't compatible with high voltage electric baseboard heat disqualified it.  Installation of our first Honeywell TL8230A was quite easy  despite several trips to and from the breaker box (DANGER: ALWAYS remember to turn off the circuit breaker, and VERIFY the electricity is off when working with electric baseboard heat - 240V, 15 Amps can kill you, unlike the low voltage systems you typically find on heat pumps and other heating/cooling systems, and had I not read the instructions, I would not have realized this until I removed the existing unit from the wall and seen the Romex wiring).  The controls are straight forward, and the thermostat has a nice simple clean appearance with the side panels closed.  The thermostat is silent in operation, requires no batteries, defaults to a safe temperature in the event of an extended power outage, and the best feature is the "Proportional Integral Adaptive Control" which regulates the time the thermostat is energized, keeping temperatures very close to the set point.

Pros: Excellent design Easy installation "Proportional Integral Adaptive Control" ensures even consistent temperatures Programmable for additional savings Backlit display Cons: Still expensive compared with programmable heat pump controllers Need a separate unit for each zone

After installing the first unit in the living area, it performed fine until the warm spring weather eliminated the need for it.  We turned it off, and didn't worry about it until fall.  Once we started using the heat again, I realized the bedroom thermostats suffered from the same issues, and I'd go to bed freezing cold, only to wake up with an 80ºF room.  Knowing we had a baby on the way, I thought we should equally equip his room, since baby's ideal temperature is 70ºF, and I typically prefer a colder (and cheaper!) room around 62ºF.  Since these rooms are used only for sleeping, I figured a programmable thermostat might be overkill.  After doing some reading, I decided to go with two more Honeywell units, this time the RLV3120A units, which were cheaper, particularly with a promotion Amazon was running.  There were cheaper "dial" based thermostats, but I liked the design and the idea of having a set number displayed rather than the guesswork I was experiencing with the old Mears units, and thought the "Proportional Integral Adaptive Control" feature was worth sticking with. Again, installation was simple (although I had to do some experimentation with the wiring in the baby's room, as the master bedroom line was spliced in this junction box), and once installed the units worked just as well (and quietly!) as the one installed in our living area, and a fraction the cost.

Pros: Cheaper than a programmable model Digital display Easy installation "Proportional Integral Adaptive Control" ensures even consistent temperatures Cons: Not programmable Dated design Display not backlit

There are still 4 more Mears thermostats in the house, but I haven't been able to justify replacing those.  I only occasionally use the heat in my office, and the bathroom doesn't require precision control, and the kitchen and storage rooms get ample afternoon sun and are adjacent to other heated rooms.

Results:
The total cost of installing these thermostats was near $100. Based on our very minimal electric usage (~10kwh/day), and inexpensive power locally (5.76 cents/kwh, plus distribution and customer charges), it's unlikely we will recover the investment in the thermostats in the time we'll live here, but it has increased our comfort and control despite the cold weather outside.  I've installed smart/programmable thermostats in every place I've lived since I started living off campus in college.  While I saw instant savings in heating costs in a poorly insulated building with a gas furnace and in another poorly insulated home with a heat pump, it is unlikely we would see as drastic a change here.