Thermostat Science??

[PAV1]

Ok, so I have heard conflicting theories on the best way to set your thermostat for efficiency... This would apply to any heating appliance..

1)It is better to maintain a reasonable temperature when you are not home, no more than say a 4 degree difference from your desired temp when you are home.. rationale is that it it is more efficient to maintain heat than it is to crank up the system at full bore to raise the temperature 10 degrees when you get home..

2)It is better to drop you temp way down when you are not home so your system will barely run.. rationale is that it is more efficient to barely run system all day and then when you are home crank it up to desired temperature.

So…which is better and why?

Also.. how does everyone set up their pellet thermostats versus their central heating thermostats... For me I have 3 zones on my oil boiler.. 2 upstairs (1 bedroom over garage) (1 for the remaining rooms), and then (1 for the entire first floor). My pellet sits on the first floor in a great room (13ft ceilings) and is in the same room as my 1st floor oil thermostat. I have been setting my pellet stat slightly higher 2 degrees than my oil stat so that the oil does not really kick on... Thoughts? My 2nd floor is a whole diff story..no way around using oil for that place.

 

[Corey]

Seems to come up a couple times a year on here. I think there are two key elements to this:

1) Some appliances (mainly heat pumps) don't do well running long periods and are better in short bursts to maintain heat as opposed to warm up a house. Since we're talking pellet stoves, this probably doesn't apply.

2) The highest heat loss from the house (and highest efficiency for the stove/appliance) occurs at the highest temperature differential.

This means the hotter your house is inside, the faster it looses heat to the outside. Secondly, the cooler your house is inside, the easier it is for the stove to transfer heat and the more efficiently it operates. Given both of these facts, it seems to be more efficient to let the house cool during the day, so you lose less heat to the outside and when you do heat it, the stove is more efficient because it is easier to transfer heat to the cold house.

If you can track your pellet usage, you should be able to prove this one way or the other for your specific condition. Does it take more pounds of pellets to keep the house warm all day long, or give the stove a blast in the evening?

 

[dbjordan]

This is what I have learned from my experience in my house. I use my pellet stove space heater to heat my entire 1800sqft open rancher. The 3 rooms farthest away from the stove are kept closed (gym and quest bedroom unheated, bathroom electric baseboard, programmable stat). I have a skytech 3301p and have used it in both program and thermo mode. Program mode is 68F at night and away 72F when home. I have found in cold weather that I use less pellets in thermo mode at 72F, and it keeps the whole house warmer overall. In the shoulder season the program mode works best. I found that in the cold months it just took too long to get the whole house back to a comfortable temp (for us). It only took about two weeks to tell which worked best for us. If your outside temps are fairly consistent, you should be able to find out quickly yourself. Again this from my experience in my house, your mileage may vary. All the physics, and thermal dynamics in the world will not match real working conditions. Test it yourself and see what works best for you.

 

[dac122]

Setting back your tstat will save. How long you are willing to wait for the temp to recover and timing it is a comfort issue.

 

[exoilburner]

Seems to come up a couple times a year on here. I think there are two key elements to this:

1) Some appliances (mainly heat pumps) don't do well running long periods and are better in short bursts to maintain heat as opposed to warm up a house. Since we're talking pellet stoves, this probably doesn't apply.

2) The highest heat loss from the house (and highest efficiency for the stove/appliance) occurs at the highest temperature differential.

This means the hotter your house is inside, the faster it looses heat to the outside. Secondly, the cooler your house is inside, the easier it is for the stove to transfer heat and the more efficiently it operates. Given both of these facts, it seems to be more efficient to let the house cool during the day, so you lose less heat to the outside and when you do heat it, the stove is more efficient because it is easier to transfer heat to the cold house.

If you can track your pellet usage, you should be able to prove this one way or the other for your specific condition. Does it take more pounds of pellets to keep the house warm all day long, or give the stove a blast in the evening?

Tracking my pellet usage confirms what cozy heat posted. Nice write-up too. My house is not well insulated so the heat loss is significant. I also turn my thermostat down to 60 overnight and shut it down on warm nights.

 

[hossthehermit]

I fill, clean, maintain the stove.
My wife runs the thermostat.
My life is good.

 

[dac122]

1) Some appliances (mainly heat pumps) don't do well running long periods and are better in short bursts to maintain heat as opposed to warm up a house. ...

Hate to nit-pick here, but heat pumps do not do well in short burst. It can take a while for the indoor coil to reach optimal temp. Short bursts are synonymous with short cycling, which wears them out quick.

 

[Jambruins]

My experience is the same as dbjordan. My house is an old farm house/not very well insulated so it takes a long time to get it back to a comfortable temp if I turn the temp way down so I run my stove on high/low and keep the therm set at 70. This is during the colder temps. When it starts to warm up I may drop the temp down when nobody is home.

 

[exoilburner]

My experience is the same as dbjordan. My house is an old farm house/not very well insulated so it takes a long time to get it back to a comfortable temp if I turn the temp way down so I run my stove on high/low and keep the therm set at 70. This is during the colder temps. When it starts to warm up I may drop the temp down when nobody is home.

Jambruins and dbjordan,
What is the actual time to get your house back to a comfortable temp from the pellet burner being off? Another factor may be the max BTU output of the pellet burner. The max BTU of mine is 112,000 and gets my house comfortable in 30-40 minutes. But it also uses hot air ducts to each room for circulation so maybe we are talking "apples and oranges" between a pellet stove and pellet furnace/boiler. I think dbjordan is right "Test it yourself and see what works best for you."

 

[dbjordan]

My experience is the same as dbjordan. My house is an old farm house/not very well insulated so it takes a long time to get it back to a comfortable temp if I turn the temp way down so I run my stove on high/low and keep the therm set at 70. This is during the colder temps. When it starts to warm up I may drop the temp down when nobody is home.

Jambruins and dbjordan,
What is the actual time to get your house back to a comfortable temp from the pellet burner being off? Another factor may be the max BTU output of the pellet burner. The max BTU of mine is 112,000 and gets my house comfortable in 30-40 minutes. But it also uses hot air ducts to each room for circulation so maybe we are talking "apples and oranges" between a pellet stove and pellet furnace/boiler. I think dbjordan is right "Test it yourself and see what works best for you."

44,000 BTU stove. Takes 40min. to an hour to get room were stove is back to temp. 1-2 hours for the rest of the hose to heat back up.

 

[SidecarFlip]

I fill, clean, maintain the stove.
My wife runs the thermostat.
My life is good.

That covers it. Wives rule. Mine will fil it provided I go get the corn from the tank.