Programmable Thermostat Energy and Cost Savings

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by Tim Fulton on March 1, 2010

A few months ago we installed the Trane thermostat you see above in a house that previously had an old manual thermostat. Since then, we have been monitoring the energy usage and are now reporting back on the energy savings from the thermostat.

The thermostat was installed in early November. Thankfully, the billing period for that month started right at the beginning of the month too, so using the utility bill as a measuring stick should be quite accurate. Anyway, here are the numbers:

Heating degree days – 626
Gas usage (therms) – 388
Gas usage per heating degree day – .358

Heating Degree Days – 858
Gas usage (therms) – 405
Gas usage per heating degree day – .289

Heating Degree Days – 1638
Gas Usage (therms) – 422
Gas usage per heating degree day – .307

So, with a little bit of math we can see that the thermostat reduced energy usage around 20% in November. We can also see that as it gets colder out, the house becomes less efficient at staying warm. This is quite normal. Even still with it being over twice as cold out, the new thermostat is still providing a 15% savings in December. That is a really huge savings for one simple install that you can do yourself (and if you think you can’t, join our forums and we’d gladly walk you through it).

All said and done, this thermostat has already saved the home owner almost $150 in heating costs (using 20% and 15% respectively on the bills). That is pretty incredible for only having two months of usage under its belt. To keep this in a bit of perspective, this is an old house (over 100 years) and the energy usage is on the high side. So, the cost savings might be a bit high, but the energy savings as a percentage are likely quite accurate.

So, how can you get your hands on a Trane XL800 thermostat? There is a locate a Trane dealer feature on their site. Just plug in your zip code and it finds the nearest dealer. It also looks like they float around on ebay a bit, so you could snag one there. Lastly, Trane was kind enough to give us an extra thermostat to give away to our readers. More details on that in a few days.

{ 1 comment }

1 Ron April 13, 2010 at 12:53 pm

Hello energy savers
These set back programmable thermostats work great on oil fired/ gas units but be careful on heat pumps. Most heat pumps are set to bring on the electric resistance assist heat (read big bucks!!) when the set or asked for temp is more that a couple of degrees more than the room temp. This is so that if its really cold and the heat pump can’t keep the temp up by itself the elec heat comes on to help or if its cold enough, the heat pump switches off and leaves you on elec heat only.
Soooo when your program thermostat calls for the set temp to go from 60 at nite to 70 for your am shower most of the programmable thermostats do it in one jump and bring on the elec heat til the gap is closed to a degree or so. This may well eat up more than you save!
Does anyone know of a programmable thermo that does it in small early moves up so it defeats the elect heat??

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