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Community and Q&A

Options for Replacing an Oil-Burning Boiler

jekeddy | Posted in General Questions on


Looking for advice on options to replace an oil boiler with tankless coil for DHW.

We are a family of 4 in Halifax, NS and in a 2 story home with finished basement (total square footage is around 2000). Minisplits meet the majority of our heating needs for the top 2 levels, but we do require oil back up heat on cold days for those and the oil is the primary heat source in the basement – no minisplit down there. We only spend a couple of hours each day in the basement and when we are not down there we tend to keep the thermostat at 58-60F.

We continue to spend a considerable amount on oil despite it being our back up heat due to it also being our supply of hot water.

I have received quotes for propane combi boilers and have also thought about an electric boiler with an electric hot water heater, but what else could be appropriate for my situation? Having to use the system for back up heat on two levels and primary heat on another seems to not be ideal.

Appreciate any direction and if needed I’ll try to provide additional info as required.

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  1. walta100 | | #1

    Consider moving your domestic hot water to an heat pump water heater and keeping the oil burner for use on the few very cold days a year when the heat pump cant keep up. Seems like that would cut almost all of your oil bill.


  2. user-6623302 | | #2

    Is your boiler failing or are you just trying to cut your oil bill?

  3. Expert Member
    BILL WICHERS | | #3

    I agree with Walter here: getting your hot water off that boiler will probably help a lot. Even an electric resistance tank-type water heater will probably be cheaper to run than an oil fired heater, and it will be significantly cheaper to buy compared to a heat pump water heater.

    If you only use the basement ocassionally, it might make the most sense to just install some electric resistance heaters down there. Electric resistance isn't that expensive to run compared to oil with current oil prices if you're in an area with cheap electric rates, which I'm guessing you probably are. Electric resistance is the cheapest to install by far though, so it's great for places that need relatively small amounts of heat for relatively small amounts of time. Keep the boiler ready to fire up for extremely cold days, but use the water heater and electric heaters for the rest of the time.


  4. monkeyman9 | | #4

    I'm about at a similar point to you. I have a 25-year-old oil boiler with a newer veissman indirect hot water tank. I have a ducted mini split going in the second floor this spring. The other floor and above garage room have mini splits.

    We do need the oil boiler on the real cold nights. But it seems silly to keep the boiler going for the current indirect tank otherwise. Been debating a new properly sized buderus boiler or milking the one I have and using a heat pump water heater. Only problem is my oil boiler is old enough I don't want to let it go down to room temperature when I don't need it and chance leaks.

  5. nynick | | #5

    I have a similar oil furnace that has to run all summer just to supply our hot water. I hate it.

    I have a propane tankless combi-heater in my detached garage that heats the garage, the apartment above it and supplies all the hot water upon demand. I love it.

  6. gusfhb | | #6

    While propane could allow you to use a more efficient device, it is usually very very much more expensive than heating oil. 100k btu per gallon vs 140k

    Your old oil boiler is probably setup to maintain temperature which means it fires up every so often no matter what. That is probably where a lot of your oil is going.
    If your electricity is cheap hydro, perhaps resistance electric is an option[would not be where I live!]
    I second the HPWH, definitely cheaper to run than oil

    If it somehow made sense to stay with oil, some newer boilers are designed to be 'cold start' meaning with an indirect tank, the furnace would only fire when called for heat or hot water. This would save a significant amount of oil, but it is hard to imagine a brand new oil boiler for this limited use makes financial sense.
    Solar panels would probably be a better investment

  7. Expert Member
    Akos | | #7

    Unless your hydro is silly, Canadian oil prices are pretty close to the same as heating with electric resistance heat. Getting the hot water off your oil fired boiler is the first step. Keeping that fired the whole year is a huge waste of energy, I would guess heating hot water off resistance tank would probably cost less than 1/2.

    A heat pump water heater is definitely more efficient, they tend to be pretty pricey up here in the great white north. If you have room for solar, you better bet is to add more solar panels and use a resistance tank instead of paying for a HPWH.

    For supplement heat, I would keep the boiler until it dies. Once it does you can look at electric resistance or heat pump options. Propane is cheaper than oil but still costs more than a heat pump option. Plus it is expensive to install.

    You can get a lot of your heat load reduced by adding a hyper heat slim ducted mini split in the basement. Even if it is just ducted locally (that is mount in the utility room and have a return and supply to the adjacent space), it will can provide a lot of the heat load for the main floor so the oil is only needed to even things out. A warm basement is also a more comfortable basement, plus it will help with keeping the floor on the main floor warmer. This way if the boiler dies, you can also now have the option to run ducts from the main floor to this air handler and eliminate the boiler.

    1. monkeyman9 | | #8

      My boiler is WAY oversized. Like 2x. But it appears I use 100 gallons of oil from mid April to start of Sept just to keep the boiler warm and heat the indirect tank. That's a lot of money these days!

      Do the heat pumps water heaters make your basement noticeably? Mine isn't finished and the walls are not insulated.

  8. Expert Member
    PETER Engle | | #9

    You could install a heat pump water heater and just use it in the summer. In winter, keeping the boiler warm to heat DHW is also heating the basement just by heat leaking from the boiler. With the cost of oil and resistance heat being similar, neither one is saving you money in winter. Your big loss is using the boiler in summer. Once the boiler dies, or if/when oil stabilizes at a very high price, you can install a minisplit to heat the basement.

    A HPWH will make your basement noticeably cooler and dryer. That's nice in summer, but it will make the basement uncomfortably chilly in winter. If you switch basement heat to a minisplit system, the HPWH just acts like a two-stage heat pump - the first is the minisplit and the second is the HPWH. The combination is still more efficient than resistance for DHW, even in all but the coldest climates.

    1. monkeyman9 | | #10

      That's def something I could do. My electric company has a $500 rebate for a heat pump water heater too which softens the blow.

      1. iwatson | | #11

        Alternatively, EfficiencyNS offers a $650 rebate on the Giant three-element resistance heaters. It basically covers the cost of install. I ran the math and determined it made more sense than a heat pump water heater. I've been very happy with mine.

  9. charlie_sullivan | | #12

    If you get a heat-pump water heater, you can run it as a heat pump in the summer, and get the benefit of basement dehumidification and very low energy use. Then in the winter, you can switch over to resistance heat, using the same unit--no need to buy something different for that.

    Then for keeping the basement warmer, insulating and air sealing the walls might be the first step. Then spend a winter or two with that setup and see how much oil you use, and what temperatures you need the oil heat, and come back to discuss what to add to stop using oil for those scenarios.

  10. bestbigboi | | #13

    It seems weird no one is addressing the real issue. You need to keep the baseboard supplied with hot water for cold days and as backup to the heat pumps. I am inthe same situation as you in Halifax with an old oil conventional boiler but heatpumps throughout the house and dont care about basement heat. I see two paths but don't know which is best.

    1/ get a modern combi boiler to suply hot water on demand for both the radiators and the domestic hot water line. Downside is cant over demand with multiple showers and taps drawing hot water, upside is lower electricity bill.
    2/ get an electric system boiler with a cylinder to store hot water for instant use.

    both require me to upgrade my panel to 200amp ($2700) and feed a high gauge wire down to the basement.

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