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Replacing 105k BTU oil boiler with 27.3k BTU electric boiler + wood stove - am I crazy?

woodelec Member Posts: 2
edited September 2017 in THE MAIN WALL
Sorry for the long explanation, I'm trying to see how crazy I am with this idea.

I currently have a 30 year old 105k BTU (80k net) oil boiler. It previously had a DHW coil, which may explain the large sizing. House is 1200sqft, slab, single floor, one side has siding+cinderblock walls+2x4 studs (was a converted garage) other side is siding+2x4. ~150ft of 3/4" hydronic baseboard.

I put in a 28k BTU wood stove 2 years ago, and last year I used maybe 30 gallons of oil, I was simply filling 5 gallon cans from the service station because the delivery companies want to bring 150+ at once. I keep the house at 55-60 and use the wood stove when home. If it's super cold, I'll put a 1500W space heater where I am if the wood stove isn't running.

I've replaced a ton of parts on this boiler as needed over the last 8 years, and it does work well. On the coldest days it will lose prime and I have to put a suction tool on the line to get it going again (which is a PITA to come home to a cold house late at night after a night out and having to do that before bed). That happens twice a year, the Firomatic valve is the last thing I haven't checked/resealed/replaced. Outside of that, I have it fitted with a computerized aquastat with low water cutoff and outdoor reset (I haven't seen it go above 120-130F even on the 1% days), a CleanCut pump along with ProTek nozzle and spin-on filter with 2-pipe system, new transformer and burner motor. It comes on and shuts down cleanly.

I'm looking at an Argo 27,300 BTU electric boiler. It can also be fitted with an outdoor reset which I want. Am I crazy for thinking this could be a workable solution? Or even their 20,500 BTU boiler. No losing of prime, no dirty yearly maintenance (drain and refill, if that?), I gain a ton of space removing the old boiler and chimney, and for what? $25-50 more in electric costs vs oil costs per year?

If I decided to do anything larger in the future it would be propane, and I'd get a condensing unit I can vent with PVC so the chimney isn't needed even in that case.

At 60F, if I use the 1% DB temperature for my area (15F) I get 22744 heating BTU loss on loadcalc.net. Even if I missed a ton in my calculation, the electric should be able to keep up on the coldest day without the wood. If I bump it up to the lowest average temperature from ASHRAE's website, I'm at 14657 BTU's. The 20,500 BTU couldn't keep up during the 1% time, but outside of that even that may be workable. And still, this is without the wood stove in the equation (28k BTU).

TL;DR: Want to replace aging oil boiler with small electric boiler and small wood stove: crazy or not?


  • Ironman
    Ironman Member Posts: 7,221
    What's heating your domestic and how much hot water do you use per day. If you don't know, tell us how many folks live there and their ages and we can estimate it.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,644
    edited September 2017
    How many feet of baseboard do you have? What is your electric rate? A boiler that size would be 8kW so you would need a 50a breaker for the 33amp load.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    EBEBRATT-Ed Member Posts: 14,495
    He stated 150 feet of baseboard so 150x550=82500 btu baseboard is good for.

    B4 you do anything crazy, use Slant fin program and do an accurate heat loss with a 70 deg indoor temp and your design outdoor temp.

    You going to sell the place someday. Don't you want a heating system that everyone won't run from???
  • hot_rod
    hot_rod Member Posts: 20,725
    I enjoy firing up a small wood stove in our living room, a few thoughts if you go that route

    Make sure that your area doesn't have and restrictions on burn days.
    Check with your insurance agent
    Make sure the clearances and flue for the stove are properly sized and installed.
    Combustion air for the stove.
    A top quality, low level CO detector in the room with the stove.
    Gather and dry the wood so it burns clean and hot.

    Enjoy the heat.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • woodelec
    woodelec Member Posts: 2
    edited September 2017
    @Ironman DHW is a heat pump water heater. It does gain a bit of heat from the boiler mass in the winter (both are in an unconditioned room) but it works fine even when the boiler is cold.

    @EBEBRATT-Ed I'll check out the app, this is a good idea, thanks. I've installed it but it's a bit wonky how it drills down to each item on a different screen the last I used it. I've thought about the selling part, I would install a propane one by then.

    @hot rod Check on all. It's in place. I was a bit peeved that the inspector simply asked "did you get your clearances right?" when doing the approval instead of actually checking. No burn restrictions, insurance was asked point blank about _any_ restrictions or increase in premium and they didn't care. But that's a good point, maybe I can get a reduction by removing the oil tank.

    Thanks all for the help so far.