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Boiler Efficiency W/Programmable Thermostat

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I'm just wondering about a couple things. I currently have an old Fuel oil boiler and I will be changing that out this summer. That is beside the point though. I have been thinking about a programmable thermostat rather than my regular mechanical style. When it comes to setting a thermostat will less energy (fuel oil right now) be used if I leave it/program it a few degrees lower during the day and then turn it up at night or is it better to leave it constant so it doesn't have to bring it back up to temp.

Also, are there any recommendations for a WiFi thermostat for boilers that may also be able to control a ductless mini split A/C unit.

Thanks for the help

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,433
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    That's one of those discussions. Which goes on and on... and the answer is, it depends. There is sort of a general consensus that you may save a tiny amount of fuel for steam and hot water systems with turndowns during the night of a few degrees. Turning up in the morning, down again during the day, then back up in the evening... unlikely to save significantly, if at all. Turning down at night more than a few degrees. Also unlikely to save.

    Radiant floors etc. you won't save anything at all -- it may cost you. Forced air you can use larger turndowns and turndowns during the day, but some would say comfort suffers unless the turned up temperature is higher, at which point...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    SuperTechCanucker
  • isaacleonard1
    isaacleonard1 Member Posts: 21
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    That's one of those discussions. Which goes on and on... and the answer is, it depends. There is sort of a general consensus that you may save a tiny amount of fuel for steam and hot water systems with turndowns during the night of a few degrees. Turning up in the morning, down again during the day, then back up in the evening... unlikely to save significantly, if at all. Turning down at night more than a few degrees. Also unlikely to save.

    Radiant floors etc. you won't save anything at all -- it may cost you. Forced air you can use larger turndowns and turndowns during the day, but some would say comfort suffers unless the turned up temperature is higher, at which point...

    Understood, anyone have smart thermostat reccomendations to work with both of my systems?
  • HVACNUT
    HVACNUT Member Posts: 5,863
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    Is the ductless system controller hardwired or are you using a remote?
  • isaacleonard1
    isaacleonard1 Member Posts: 21
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    HVACNUT said:

    Is the ductless system controller hardwired or are you using a remote?

    When I bought the house i received a remote control. It is a Mitsubishi.
  • Gordy
    Gordy Member Posts: 9,546
    edited February 2020
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    Depends how much energy your envelope can lose in a program period.

    It also depends on how well the boiler, and it’s emitters are sized for the load coming out of a set back program.

    It also depends on how much comfort you are willing to sacrifice. Mass always lags setpoint. Which leads to lack of comfort.
    Canucker
  • isaacleonard1
    isaacleonard1 Member Posts: 21
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    Gordy said:

    Depends how much energy your envelope can lose in a program period.

    It also depends on how well the boiler, and it’s emitters are sized for the load coming out of a set back program.

    It also depends on how much comfort you are willing to sacrifice. Mass always lags setpoint. Which leads to lack of comfort.

    Yes it is subjective, I was just curious what was generally seen.
  • pecmsg
    pecmsg Member Posts: 4,883
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    Set backs are more for comfort then savings. The savings come over long periods, 24, 48, 72 hours. 4 or 8 hours you probably cant measure the difference.
  • isaacleonard1
    isaacleonard1 Member Posts: 21
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    Ok, thanks for the info guys. Any reccomendations on thermostats?? ^
  • SuperTech
    SuperTech Member Posts: 2,186
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    I think you are stuck with either the remote or possibly a wired thermostat that will work with the Mitsubishi only.
  • unclejohn
    unclejohn Member Posts: 1,833
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    If you are getting a new boiler get a high eff. wall hung and forget the night setback and use outdoor reset.
  • isaacleonard1
    isaacleonard1 Member Posts: 21
    edited February 2020
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    unclejohn said:

    If you are getting a new boiler get a high eff. wall hung and forget the night setback and use outdoor reset.

    How many BTU can you get a high efficiency wall hung in? I'm not versed on boilers all that much yet..
  • Gordy
    Gordy Member Posts: 9,546
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    pecmsg said:

    Set backs are more for comfort then savings. The savings come over long periods, 24, 48, 72 hours. 4 or 8 hours you probably cant measure the difference.


    I think it’s debatable. Some can probably save on daily setbacks while away. However if you are saving dollars by daily setback schedules, I would say the envelope is pretty bad.
    Canucker
  • jimna01
    jimna01 Member Posts: 35
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    Consumer comment. Never mind the energy savings, I like a cool bedroom at night . Like 60 degrees. Big down comforter . Hence my use of setback thermostats. I only heat to 67 degrees during the day. In southern New England, 1600 sqft house I burn 550 gallons of oil per year including DHW. Heating is copper finned tube baseboard installed before the House was insulated so it warms up pretty quick