How low can you go?

[sweetsncheese]

I'm heating a 2200sq two story Colonial with a Quadra-Fire MT. VERNON AE Insert. My question is for the programmable thermostat folks.

I like the second floor to be 68°F from 6:00am-8:00am and the first floor to be 70°F between 5:00pm-10m. Overnight and during the day I'm fine with the house at 60°F. Using the oil furnace I would lead these times by about an hour to make sure they would be up before I needed them to be. The pellet stove seems to need more like 3 hours of lead time. So, do I still save on pellets by operating the stove in this manner? Would it be more efficient to only drop the temps to 65°F so that the stove can recover quicker or is maintaining those extra 5°F going to cost just as much? I tried starting a log of pellet usage but with varying temperatures outdoors and a small set of data points it's hard to get anything conclusive. Has someone already done a similar study for me?

The morning setting is a tough one. It seems I need to get the first floor pretty warm for the second floor to reach 70°F. I'm pretty sure the second floor zone of the oil furnace is the only efficient way to heat a second floor for 2 hours (3 hours including lead time).

Regardless, those that aren't home during the day or drop temps during the night, I'm curious what you've found to be efficient settings and recovery times.

 

[trogers]

I have found that I am better off leaving the stove going all night long. It actually seems like I use less pellets this way. To get my house up to 70 I have to turn the stove way up and it sucks down the pellets. I have been told by my heating guy that it's more efficient to not let the outside walls cool down too much over night. He claims that the cold walls suck up the heat. Good luck.

 

[jtakeman]

Good question. But it seems every install is very different. How your air moves and so forth. You seemed to have the lead time figured out pretty well. Some say its better to switch to low when its cold and try to maintain the temp than let it drop. In other words use the Hi/Lo feature on the stove with the stat set up. Once temp is reached stove goes to an Idle and tries to maintain the heat or at least reduce the drop.

I tried this Hi/Lo setting for 4 days and averaged a bag a day. I am on the first day of the Auto/ Off setting. Still need to run a few more days to get the average. But I can say the house felt warmer in Hi/lo mode. There isn't the 2 to 3 degree swing and the temp drop I did get was more gradual. House had an overall warmer feel. Plus the lag time is also reduce because the stove is warm and not having to recover from a cold start up.

So I guess you would really need to play to answer the question. If the stove does not have Hi/Lo. Just try to let the stove plug along and maintain the heat for a few days and compare the pellet usage. But also comepare the house feel. Include the other family members too!

With the Auto/Off setting it takes an hour or so depending on temp to raise my temp by 1ºF. So in the average cold I see 4 hours to go from 68ºF to 72ºF. In HI/Lo it was taking 4 hours to drop my house temp by 1ºF and 2 hour to return it to normal temp of 72ºF(8 hours away and with a 2 hour recovery time). On a warmer day above 36ºF my house would still raise in temp even on lowest setting. So I have to go to Auto/Off mode.

Just my 2 Hope it helps a little anyway.
jay

 

[Mr.Goodfella]

I have been lurking the forums since I installed my Summers heat 55 SHPAH so take the noob's advice for what it's worth. I have a full electric house and I didn't want to have the huge electric bill in the winter. Since it has been cold I have had my stove running 24/7. About 1800 ft total for the house, 800 downstairs, 1000 upstairs and the bedrooms are above the garage. I run the stove at night on 3(fuel) 4(blower) and the downstairs is about 80-85 and the upstairs is 70-73. During the day I run it on 2-2 and the temps stay the same. I have found if I shut it down it takes forever to get the area (downstairs) back up to temp because I have to re-heat the basement completely in order to move heat upstairs. To move the heat upstairs I just put a box fan at the base of the stairs and blow it straight up the stairwell and let the ceiling fan in the entryway do the rest. So far it has worked out very good because I haven't heard the thermostats click on in the bedrooms. As for pellet use, I go through around 1/2-3/4 a bag per day and it has been 14-35 F outside.

 

[Gweeper64]

sweetsncheese,
I have not done an extensive test like that either. But, I have my mid-day and overnight temps programmed only 1 to 2 degrees lower than my morning "wake up" and evening hours. I have my lead time set about about a half hour before I want it. But, I am also only heating a single level ranch of about 1500sf too. Heating 2 levels like you are will definitely be tougher. Do you have any circulation fans set up? My gut feeling is to try not lowering your temperature so much during the day or night. Try keeping it a little more constant and see how it goes. I think you are right that heating the second floor off your oil burner in the morning might be more economical, especially if you have a separate zone on the second floor.

 

[imacman]

IMO, if the Quad will run on Hi-Lo, and the room(s) that you're trying to re-heat in the morning are relatively small, and heat up quickly normally anyway, then I'd say keep the stat set low and let the stove just idle all night.

However, if it's a relatively large & open area (like the great room in my home w/ 16' ceilings), I think it makes more sense to leave the stat set higher. The stove has already spent most of the day getting the room nice & toasty, why let all that go to waste.....I leave the stat at 66 at night.....only takes a few hours to recover back to 70.

 

[sweetsncheese]

Do you have any circulation fans set up?

I have a Tjernlund room to room fan (http://www.tjernlund.com/retail/aireshare.htm?gclid=CI6ZjfSz0Z4CFYJx5QodFy7jqQ) in the header above the door of the room where my stove is located which is controlled with a Lux Win100 fan thermostat (http://www.amazon.com/dp/B000E7NYY8...e=asn&creative=380341&creativeASIN=B000E7NYY8).

 

[Gweeper64]

IMO, if the Quad will run on Hi-Lo, and the room(s) that you're trying to re-heat in the morning are relatively small, and heat up quickly normally anyway, then I'd say keep the stat set low and let the stove just idle all night.

However, if it's a relatively large & open area (like the great room in my home w/ 16' ceilings), I think it makes more sense to leave the stat set higher. The stove has already spent most of the day getting the room nice & toasty, why let all that go to waste.....I leave the stat at 66 at night.....only takes a few hours to recover back to 70.

I'm not exactly familiar with the Hi/Lo setting some of you guys have mentioned on your stoves. If I understand what you described, the "Automatic" setting of the AE might be a cross between Hi/Lo and Auto/Off. When on "automatic", the AE will lower the heat output setting the closer it gets to the set thermostat temperature. When it is within about 2 degrees of the setting, it will be running on "Low" heat. If it still reaches the set temperature, it shuts down. In "manual" mode, you set the heat level on one of 5 settings (low<->high) and it will keep the heat output constant until it reaches the set temperature, then shut down. There really isn't any setting that will keep it on constantly. It would shut itself down every few hours for the autoclean cycle anyway.

 

[sweetsncheese]

I'm not exactly familiar with the Hi/Lo setting some of you guys have mentioned on your stoves. If I understand what you described, the "Automatic" setting of the AE might be a cross between Hi/Lo and Auto/Off. When on "automatic", the AE will lower the heat output setting the closer it gets to the set thermostat temperature. When it is within about 2 degrees of the setting, it will be running on "Low" heat. If it still reaches the set temperature, it shuts down. In "manual" mode, you set the heat level on one of 5 settings (low<->high) and it will keep the heat output constant until it reaches the set temperature, then shut down. There really isn't any setting that will keep it on constantly. It would shut itself down every few hours for the autoclean cycle anyway.

I've tried the automatic setting several times and don't really like the operation.
1. The settings are too conservative. The stove starts downgrading the multiple settings between Hi and Low with several degrees in temperature remaining. I overcome this by setting the stove to 72°F when I want the house at 70°F.
2. The stove runs continuously on Low until Autoclean then works hard to recover from the 1°F or 2°F temperature drop suffered during cleaing.
3. I'm not convinced running all the time is the best way to get years of service out of the stove.
4. The thermostat controlled circulating fan I'm using doesn't cycle off when the room remains warm on automatic. In manual it turns on when the stove room reaches 74°F then cycles off when it drops below that temperature. The quiet moments when the stove and circulating fan are off are surprisingly peaceful.

 

[sweetsncheese]

Quick update:

Currently running the stove at 70°F from 2:00pm till 10:00pm at which time it automatically drops to 65°F until the cycle begins again. I also reduced the heat output setting from 5 (Hi) to 2 (MLo). Pellet consumption is down considerably (currently just over a bag a day) and it does recover in time with the 3 hour lead time. The oil furnace comes on to raise the second floor zone to 68°F from 5:30am till 7:30am. Unfortunately measuring oil consumption isn't as easy as pellet bags.

Although I have the through wall circulating fan, I still can't get the heat out of the room where the stove is quick enough. That's why I decreased the heat output setting as there was no reason to heat the room up quickly if I was distributing the heat slowly. I will be looking at insulated ducting in the future to distribute more heat since that's appears to be my remaining inefficiency.

Thanks for all the advice!

 

[ablejoy]

I have a home with 16’ ceilings living room, dinning room, and kitchen all open space about 1100 sq ft the house is 2100 sq ft.
We bought a Quad Castille last year heats these three rooms to 72 degree when temperature are in low 20's. The stove cost $4,300.00 installed in Sept 08 in the living room. We saved 240 gallons of propane from Sept 08 - Dec 08. and this year saved 400 gallons. The stove should pay for its self in a couple years. The furnace has ran a total of 12 hours since Oct 1st this year. Propane was $ 2.98 a gallon in Sept 08, its now sitting at $2.10 a gallon. We have only one regret should have bought bigger. Burning a bag a day stove on low all night and medium during the day runs about 16 hrs. Stove on low 68 degrees from 11 pm till 6 am, Medium 72-73 degrees from 6 am till 11 am and from 7 pm to around 10 pm. The stove will cycle on medium. Using a bag a day lucky I got 2 tons pellets at @ 2.00 a bag April of this year.

 

[mainegeek]

You will burn more energy (in this case pellets) having such a huge temp. difference. The stove will have to work harder and longer to bring your house back up that additional 10 degrees then it would to maintain the temperature.

Personally, my pellet stove thermostat is programmable and it is set to the same temp all day long. My oil thermostats are also programmable and they are set to the same all day as well.

If you want to turn the stove down during the day then you shouldn't vary the temp no more then 2 to 4 degrees.

 

[dbjordan]

I have found as I think most here have, to use on/off when in shoulder season, and hi/low when it gets stays cold. I use a programmable, and only swing about 4 degrees. I'm heating 1800 sqft on a single floor, and over all hi/low keeps the entire house warmer, with only a slight increase in pellets used. To get the same overall heat for the entire house on on/off you would get cooked out of the room the stove is in. The differentials your talking about, in different parts of the house seems like a lot to me. Good luck finding the "sweet spot" for your setup.

 

[sweetsncheese]

We have only one regret should have bought bigger.

My home layout has a living room at one end and a family room at the other. The stove is in the living room so the family room (over the garage) is typically 3°F cooler than the rest of the downstairs.

Since they're "space heaters" I think two smaller stoves at opposite ends of the house would have been a better option. Pellet consumption wouldn't increase much but the benefit would be more consistent temperatures throughout the lower level. The cost of the first stove is easy to recover with the savings in oil consumption but the second stove is far harder to justify. I have a small electric space heater in the family room now and it probably increases my electric bill by $20/month. Dividing the cost of a second stove by the savings of $20/month doesn't look promising.