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Keeping the thermostat low - costing me money?

We recently purchased a very large, old summer home and are in the process of renovating it. We will be making attempts at winterizing it, but as we're only a few weeks in this stuff doesn't happen overnight!

In the meantime it's winter in New England and my oil burner is cackling as it burns dollar bills.

Situation: 100 year old home with no insulation, 4,600 sqft. It's been a mild December so far and we've kept the thermostat at 50 degrees. The house is heated with steam radiators and an oil boiler that burns a whopping 3.5GPH.

Nevertheless, I estimate we've burned through 1/4 of the oil we purchased 2 weeks ago - $250! At 50 degrees with an average temperature outside of low 40s/high 30s.

What's even crazier to me is my boiler is almost never running. However, I have noticed that every few hours it turns on, runs for a few minutes, I hear my radiators whistle, then it stops. They never really even get warm. This happens when the room temperature is hovering around the 50 degrees we have it set to.

I feel like I'm burning fuel for next to no heat. The question:

Am I wasting fuel keeping the house at 50? Would I be better off letting it burn for an hour straight, get the radiators nice a hot, then turning it all the way off for a few hours?

And yes, we're bringing in new insulation and working on new heating options, but in the meantime I'd like to optimize what we have.

Thank you!


  • hot_rod
    hot_rod Member Posts: 22,141
    No insulation? So yes, heating the great outdoors is going to cost some energy. If you are not living in the home, consider winterizing it instead of maintaining 50.
    insulation will make a huge difference, but even insulated it could cost 1/2 gallon per hour or more the keep that size home heated. A heat load calculation with the proposed insulation 
    Package will show you what to expect.
    Finding the oil company that supplied the home could give you any idea if the pre insulation oil consumption.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • bburd
    bburd Member Posts: 912
    edited December 2020
    To answer the original question: Longer heat cycles would almost certainly cost you more fuel. With outdoor temperatures so mild it just doesn’t take much steam to keep the house at 50°.

    Most people in the heating industry  would recommend a setting of 55° at least, to give you some leeway for freeze protection if the power should fail; but that is less of a concern until the weather gets well below freezing.

    Oil burners need to be cleaned and tuned annually, and the burner adjusted by a knowledgeable technician with combustion test instruments. If that hasn’t been done, it will be money well spent for both economy and reliability.

    There’s a good possibility that your steam main vents are too small, and your system  would run more economically if they were replaced with correctly sized vents; but if you are thinking of removing the steam system, you may not want to invest money in it. Most people here would recommend keeping the steam, because it will heat the place more comfortably than most more modern options and is far less vulnerable to freezing damage than a hot water system.

    If your steam mains are not insulated, that is another obvious way to save fuel. 1” fiberglass is recommended. Big box stores tend not to carry it, so you may need to get it online.

  • Jamie Hall
    Jamie Hall Member Posts: 23,286
    Let's see. a quarter of the oil purchased for $250 -- let's say that works out to 25 gallons in two weeks. That works out to about an average of 10,000 BTUh, assuming 100% efficiency -- which that oil burner probably doesn't have. 10,000 BTUh is about what two 1500 watt space heaters produces. And you are heating 4600 square feet for that?

    Um... I think you have just collided with the reality of heating a large, uninsulated structure to a temperature differential of around 15 degrees (50 to 35).

    It does make a difference what you keep the thermostat at -- the lower it is, the less fuel you will burn and the less it will cost you. As @bburd said, the recommendation is 55, just to give you some time if things get crazy.

    Further, while you may gain when you get that big burner properly adjusted and tuned (I wonder how long it has been?), you will not gain by switching to another heat source. Not in the winter time. In terms of the heating system, your best bang for the buck is going to get that system properly tuned, properly vented, good insulation on the pipes -- the usual things.

    In terms of overall bang for the buck, your best return is going to be tightening up the house -- fix draughts, get good storm windows put on, get good insulation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • baldcoliumbian
    baldcoliumbian Member Posts: 2
    Thank you all for these replies!

    Jamie, your calc is a bit off as I have 500 gallon tank so we burned ~125 gallons. Oil is 'cheap' right now.

    Yes, the radiator pipes themselves are insulated (possibly the only thing in the house). It has been a while since the system was tuned and we have someone scheduled to come in January.

    Unfortunately no real comps available for normal winter usage - the prior owners simply did not use the place in the winter. Drained the house out and closed it down.

    We are moving ahead with insulating, bringing in a few contractors next week - just trying to get through the next couple months while we get everything sorted.

    In the meantime we'll put that plastic wrap over the windows and close down the upper levels of the house until we can get things sorted.

    One more question: Is there a large 'spin up' cost to a steam boiler kicking back on? E.g. does it take more energy to get it rolling from a cold start than it does to keep it going once the water is hot? You know, like old cars it burned more to start & stop than to idle.

  • Jamie Hall
    Jamie Hall Member Posts: 23,286
    There is, as you put it, a spin up cost to any boiler -- steam or hot water -- from a cold start. How bad that is is a matter of some debate... probably not all that bad (we're talking dimes here) but on the whole if the boiler is nice and warm when it starts up again, it's going to be less.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • clammy
    clammy Member Posts: 3,111
    My dad used to always say big house big bills they go hand and hand . It s very common for owner of old large homes to shut the heat off and winterize the home for the winter usually because the fuel bills are so high . It’s extremely common I used to service a old semi famous development where many weathly folks would summers-and vacation time ,things really changed after the first stock market crash so even removed the third floors to lower taxes and fuel bills and then a lot of people w these giant homes just bailed durning the first opec oil embargo and dumped there homes or just went into foreclosure for pennies on the dollar just could not afford the fuel To heat the homes . I still this to this day vision of grandeur buying some old home then the first winter comes w a 1500 to 2 g fuel bill a month to keep the home 50 , the the fun of a big old home and everything that goes w it . After over 35 years of doing this I still get to see it a few times every winter and I still love it and also think of the flightless Dodo bird and all it glory it’s all relevant . I always ask my self is all the extras really required we all lived in a cave less the 2000 years ago. I think people need a bit more reality and a lot less excess but that’s me . I always remember the more you want the more you get but don’t be surprised if what you get and have fades w time as w all wants and desires . Peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • ChrisJ
    ChrisJ Member Posts: 15,676
    "Spin up time" depends.
    If the boiler is losing heat into a conditioned space, or a basement below a conditioned space, then the heat it's loosing cooling down isn't being "wasted" so to speak.

    I don't know if anyone else mentioned it but vents shouldn't be whistling either. To me, that means you're severely under vented. Likely both main vents, and radiator vents.

    Pictures of the boiler and it's piping, as well as any main vents, radiator vents etc would be helpful.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    JUGHNE Member Posts: 11,061
    What type of thermostat do you have on the boiler?

    You said the boiler runs just a few minutes every few hours.
    I wonder is the "spin up" term is in play, because in just a few minutes you may not be making much steam for distribution, rather just heating up the boiler.
  • Jellis
    Jellis Member Posts: 228
    Agree with others its no surprise you are burning that much oil
    if you want to reduce your oil consumption then...
    1. insulate and seal the house well. (have professionals help you with this, they can perform leakage rate tests to find out where you are loosing heat and such.
    2. have your heating system inspected by a professional. utilize the find a contractor tool on this site. My guess is a good tech can likely down-fire that monster for you and achieve some longer run times and greater efficiency

    JUGHNE Member Posts: 11,061
    The tstat could be short cycling the system, perhaps?
  • neilc
    neilc Member Posts: 2,703
    don't insulate before you find all your air leakage and seal that first.

    what type of insulation?
    known to beat dead horses