Nightly setback

Doug_7

Nighttime Thermostat setback will save you money if your house actually cools down during the 7 hour setback period.

The cost savings is due to the lower heat-loss from a cooler house during this period. Heat loss from a house at 56 degrees is much lower that from a house at 67 degrees. The important question is - how long was your house actually at the lower temperature ?

There is energy used heating back up, but this is offset by the energy saved while cooling down. The cost savings is all in the length of time you are at a cooler temperature.

If your house cools down quickly you will save a lot of money (10 - 15%) but you should look at upgrading your insulation.

If your house cools down very slowly, congratulations - you have good insulation, so you won't save as much on nighttime setback.

If you go away for a week and setback you will save about 15% if it is zero degrees outside.

Doug

Jerry Withers

nightly setback

I currently have our thermostat set to 67 during the day and between 11:30pm and 6:30am to rollback to 56 degreees. Is that to large of a rollback? I live in the fingerlakes region in New York and it gets pretty cold here at times.

I am just wondering if that much of a rollback may be costing me more that it is saving.

Kara

depending on how long it takes for your radiators to heat up.
Honeywell thermostats have a function called "recovery". if it takes 2 hours for your tstat to reach its desired temp, then assume the system to start cranking no at 4:30am, just so you can wake up to 67 degrees at 6:30am.
Being that it is so cold out, your system may even crank on earlier than that...

not a steam pro, just a home owner that share the same experience. I set mine back to 62 degree during night hours and 67 when i wake. the recovery kicks in about 45 mins prior to the set time to get temp at right setting...

Jerry Withers

Hm... my thermostat does not actually kick in until the time I have it set at. It does not do a warm-up phase like you describe.

It seems that when I get up in the morning the thermostat is often still in the low 60's so the major parts of the house may actually never get to 56.

The ballroom however freezes over, but that is another issue....

Unknown

If your thermostat (in other words boiler) doesn't kick in until recovery begins there has been no savings as all else equal the fuel you saved as the temp went down is exactly offset by the fuel consumed to bring the temp back up.

In the real world and with a non-modulating boiler there are some slight savings possible from cycle-induced loss when the boiler kicks in during the setback period, but there is also the very real possibility that allowing the temp to "free fall" all night long causes you to keep the daytime temp higher than required for the same degree of comfort if you had used less setback.

While the "ideal" amount of setback varies with the structure AND the weather, 5-6 degrees is a good starting point for a reasonably insulated residence.

Try reducing your daytime tempeature by 1 or better 2 degrees and limiting setback to 5-6. Very good chance that you won't notice any comfort difference and that you'll save some energy.