furnace thermostat settings.....while burning wood

jwscarab Posted By jwscarab, Jan 13, 2009 at 5:07 PM

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  1. jwscarab

    jwscarab
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    Dec 5, 2007
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    SE Indiana
    I notice most here dont use their furnace for backups unless it gets real cold. I assume it is for money savings reasons. But if I leave my furnace on 72deg and run my wood stove as much as possible - what else can it hurt, besides the pocketbook??

    I have an outdoor air to air heatpump, with electric backup heat. If my thermostat senses 71, it kicks on. But heat pumps are not efficient if its too cold out - and if the thermostat gets to 70 then the electric heat kicks on.

    But with the woodstove, it may be telling the thermostat to only run the heatpump, assuming it is only down to 71deg but in reality it is way too cold outside for the heatpump to be efficient, and the electric heat needs to kick in like it would if the thermostat got to 70 - but it wont because of the wood stove. Whew - I hope that all made sence!!!!

    Thoughts???
     
  2. torgo

    torgo
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    Dec 27, 2008
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    set your thermostat to emergency heat when the outdoor temp is below 25. emergency heat is all electric heat with no heat pump. your heat pump doesn't do anything but waste electricity when it is that cold outside.
     
  3. Corey

    Corey
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    Nov 19, 2005
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    With electric heat, I think you're correct that the only difference is the pocketbook. I suppose there might be a little more motivation to keep the fire going if you knew the furnace was off versus saying 'oh, I know the electric heat will kick on, if I slip up on the fire, no problem"

    My heat is natural gas - I'm 99% sure that my house is drafty enough that there shouldn't be any flue reversal problems with a load of coals dying off in the stove and the furnace kicking on. But throw in running the clothes dryer, water heater and possibly a bath fan...that is starting to be quite a bit of air flowing out of the house. I just like knowing the furnace and stove won't be running until I want them to, so the furnace is in the 'off' position.
     
  4. Highbeam

    Highbeam
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    Dec 28, 2006
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    I set the stats to 60 and burn wood to stay between 70 and 80. 60 degrees won't freeze pipes and it won't be terribly uncomfortable. Also, motivates you by cold to start a fire vs. motivation by the sound of money burning in your furnace.
     
  5. burntime

    burntime
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    Aug 18, 2006
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    60 during the day, everyone that is home has fur so they can live with it. 65-67 at night. The thermostat is in the living room and the bedrooms stay cooler. By morning the furnace ran 2-5 cycle heating the basment in cold weather... I restock the stove to get back to 72!!!
     
  6. Pagey

    Pagey
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    Nov 2, 2008
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    We have 2 electric heat pumps/central heat/air systems - a smaller unit for the upstairs and a larger unit for the downstairs. After I bank the fire for the night, I set the upstairs for 70F and the downstairs for 65F, as the bedrooms are upstairs. The Endeavor usually loses the battle around 2AM or so, and the electric will kick in until I get up at 5AM and reload. So, rather than running the electric 24/7 in this weather, I find that I'm using it about 4 hours a day. If I had my 'druthers' as they say around here, I'd have enough insulation and a big enough fire box to use wood exclusively, but the pocketbook does feel a bit better with 4 hours vs. 24 hours.
     
  7. mranum

    mranum
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    Aug 20, 2008
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    Wisconsin
    My thermostat has the energy star programs in it so it changes it setting several times a day. I like that when the wood fire dies off at night or in the morning and if it drops the house temp back to 65 the furnace kicks in. During the day(9-5) its set for 62 and in the evening(5-10) it changes to 70. Works for me. I only ever had one issue with smoke coming back in through the stove door and that was in the fall(September I think)firing a cold stove with a real smokey kindling fire and the furnace kicked in. There wasn't enough draft with the cold stove and it sucked the cold air right down the chimney.
     
  8. cgeiger

    cgeiger
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    Nov 22, 2008
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    I have two heat pumps, one smaller for upstairs and a larger one for downstairs (2.5T and 3T for anyone who cares). I leave the therms set at 60 for both, knowing that it will get difficult in the early AM for the stove to keep up and the upstairs rooms will cool off too much without leaving the doors open. With small children this creates a whole other set of problems aside from the issue of firesafety.

    Our heating plan assumes we won't be able to fully satisfy our heating needs with wood due to our layout. Thus we are only shooting for an overall percentage (say 90%). What I would love to be able to do is set the thermostat to only turn on the blower, not the condenser unit when the threshold is reached. Both returns are ideally situated to pull in the warm air created by the fire and distribute it throughout the home via the registers. Does anyone know how to do this, short of turning off the breaker to the condenser motor or something?
     
  9. pgmr

    pgmr
    Feeling the Heat 2.
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    Jan 14, 2006
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    Actually, a modern air-air hp has a coefficient of performance (COP) >1 down to at least 0F. Since electric resistance heat is only a COP of 1 it's certainly not going to cost less to run by itself than the hp at temperatures above 0F. I'd suggest NOT putting it into emergency heat, but let the thermostat call for second stage resistance heat as needed to maintain the set point.

    If one's backup heat is a gas furnace, then there may be an economic set point where it becomes cheaper and/or more comfortable to use the gas below a certain temperature.

    See Wikipedia article for more info about heat pumps.
     
  10. mikeathens

    mikeathens
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    Jan 25, 2007
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    I keep mine at 63. It will run as a heat pump down pretty low (<10). When it can't keep up, the auxillary heat runs in tandem with the heat pump as needed. The stove definitely keeps the heat pump running as a heat pump to lower temps.
     
  11. struggle

    struggle
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    Oct 24, 2006
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    Ours is off all the time. The only thing that might be a problem is if an emergency would come up and we could not get back to the house within two days, but we have neighbors that have a key to the house so they could turn the furnace on.
     
  12. n3pro

    n3pro
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    Aug 24, 2008
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    I keep mine at 60 during the day and 70 at night, I hit the snooze a few too many times and didn't get the stove loaded up early enough for the wife to get her shower, didn't appreciate showering at 60 degrees. I have propane, when the stove was still new I ran the furnace to see if there was any issues and have not had any.
     
  13. jwscarab

    jwscarab
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    Dec 5, 2007
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    SE Indiana
    Thats awesome response!! Thanks all!!

    I learned some about my heat pump too - like it works in colder temps than I thought. Also learned I may just keep doing what I am doing.

    I keep my furnace at 72 24/7. I think a heat pump/back up electric coil system uses more energy to catch the house back up to temp than to just keep it there all the time. This is due to the backup electric turning on and really using up energy when you try to catch up.

    So I may just keep it at 72, and the more the wood stove runs - the less the furnace runs!!!!
     
  14. MikeC

    MikeC
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    Dec 3, 2008
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    I have my thermostat set at 69 during the day(while home) The thermostat is set at 64 while at work and night time.
    I try to use the insert during the weekends and evenings. Wife will start up the insert when she is off.
     
  15. mike1234

    mike1234
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    Dec 5, 2008
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    If I turn my thermostat down at night I get a much longer burn, 2, 3 even 4 hours longer.
     
  16. Jimxj2000

    Jimxj2000
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    Aug 14, 2008
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    Loc:
    SE NH
    4 heating zones...two of the thermostats have been removed for various home improvement projects and haven't be put back yet - keeps the heat from accidentally coming on.
    One zone is a programmable thermostat that we have turned off. It kept turning the heat on at the same time I would get the stove going in the morning. It was installed by a previous owner who didn't leave the manual. I haven't bother to learn who to reprogram it. Last zone (kids bedrooms) we leave at 64ish during the day and 58 at night.

    If we leave for a couple days I set the two working zones at 55.
     
  17. begreen

    begreen
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    Nov 18, 2005
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    There's a wide range of efficiencies in heat pumps. Some can squeeze out heat from an ice cube. Ours is new 2 stage unit and is set to 25 degrees for the aux heaters to kick in. However, I left it at the scheduled temps and during the Dec cold snap was surprised that at 23 outside, it was still running off the compressor and doing its job, albeit working harder than at 40 degrees. With the woodstove burning, if the house is warmer than the setpoint of the thermostat, then the wood stove is doing it's job. If not, the heat pump is doing it's job. They work in tandem as a team and a pretty good one at that.
     
  18. jadm

    jadm
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    Dec 31, 2007
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    Basement set at 50*. Rarely, if ever comes on during the winter unless we have a really cold spell (20* or below for several days). (No comment from all of you arctic dwellers on what 'really' cold is.... :shut: )

    Upstairs 58*. I turn heat up to 64*-66* for a couple of hours in the morning if it is colder than usual to heat the kids' bedrooms before they get up.

    Heat from insert doesn't reach back of the house and temps. there are usually around 55-60*. Daughter's room is the coldest - Northern exposure and gets no direct sun all winter....She still dresses like it's summer....
     
  19. Lumber-Jack

    Lumber-Jack
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    Dec 29, 2008
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    This is our first winter in this newly renovated house, and both our wood stove and furnace system are newly installed. We also have a air source heat pump (electric backup), we leave the thermostat set at 70 F., but because the wood stove does such a great job of heating the whole house it almost never gets a chance to kick in. A couple days ago when I deliberately let the fire burn out and the stove cool right down, so I could remove the baffle plates and clean the chimney, there was enough residual heat in the house that the heat pump still didn't get a chance to kick in. Outside temperature was just above freezing. I guess all that extra insulation and new windows and doors really pays off.
    We have one small fan that blows the hot air, from the ceiling of the room with the wood stove, down towards the steps going up to the second floor and one of the central cold air return ducts, and we run the furnace fan on circulate 24/7 which of course helps to moderate the temperature throughout the house.
     
  20. firefighterjake

    firefighterjake
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    Jul 22, 2008
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    I'm like Highbeam . . . all thermostats are left on at 60 degrees. While I didn't think my woodstove would be able to heat the entire house it has been able to do just that . . . although it is taxed when the temps dip into the negative numbers. In general the oil boiler only comes on in the early morning hours if myself or my wife haven't kept the fire going through the night. I haven't had to worry about pressure variances since the boiler is a direct vent system.
     
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