Replacing Oil Boiler with Electric Boiler and Heat Pump
Hi,
Our house was built in 1890 and is located in southeast VT (zone 5a, I think). Currently it has an oil boiler to supply hot water and heat via hot water radiators. The engineer from the oil distributor and service company says we need a higher powered circulator pump for the system. This makes sense because the heat is very unevenly distributed and apparently the previous owner installed additional radiators without upgrading. He said to actually do it right a secondary boiler would be needed, however, he didn’t recommend that.
Our question: We’re considering replacing the oil boiler with an electric boiler. Should we still do this upgrade while we consider that change? It will apparently cost about $700. Will this upgrade be applicable/compatible if we do make that switch? Is an electric boiler a good idea? To further complicate the matter, we’re also considering getting an air-to-heat pump system. We’re just trying to figure out the system(s) that will keep us comfortable, not break the bank, and be conscious of climate change impacts.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
All of VT is officially still zone 6A looking at the past few decades of weather data, though with climate change Brattleboro could already be edging over into 5A.
Residential retail electricity is running ~19cents/kwh (see https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a ), which in an electric boiler delivers 3412 BTU/kwh. So at 19cents the cost per MMBTU (million BTU) works out to about $56/MMBTU of heat delivered into the system.
#2 oil is running ~$4.80/gallon after the Russian oil shock in March, and even if the war ends tomorrow it's not likely to come down quickly (The world no longer wants to do business Russian oil having proven to be an unreliable and manipulative supplier.) OPEC could turn up the crank but it takes time. A gallon of oil runs about 138,000 BTU of source energy content, which burned at a (perhaps optimistic) 85% combustion efficient puts ~117,000 BTU of heat per gallon into the system. At $4.80/gallon that works out to about $41/MMBTU, which is still quite a bit cheaper to run than an electric boiler. Even if the as-used efficiency drops to 70% (not likely, unless the thing is old enough to qualify for Social Security) it's still cheaper than an electric boiler.
But a cold climate heat pump will provide MUCH cheaper heat, even when it's in negative digits outside. The advice to just pump harder and live with just the same boiler is the right choice for the time being, but if you're going to be living there for a decade or more it's going to be worth figuring out Plan-B. Hopefully you will have done an aggressive Manual-J type load calculation before specifying the heat pump system?
If it's just a few individual rooms aren't being fully heated by the radiator, small 115V ceramic electric radiators or infra-red panels can make up the shortfall without a huge layout. These can be either be hard wired or plug-in (using a plug-in line voltage thermostat). I recently specified a plug-in ceramic panel rad solution to heat the master bedroom & adjacent bath in a mobile home heated primarily by a ductless mini-split in the main open areas. The 2' tall 3' wide 600W (~2000 BTU/hr) ceramic radiator came in at $130, the thermostat (with RF remote) about $30. With shipping & local taxes it was still only ~$175. It's a bit oversized for the actual heat load, but a 400W watter would not have covered it temps much cooler than the 99% outside design temp, potentially overwhelmed.
With that approach you can fix the comfort limitations in more than a handful of rooms for the purchase price of an electric boiler, and being individually zoned by room it will cost less to run than an electric booster-boiler. If it's just a few rooms even the installed cost of a new beastie pump would be more than a few plug-in panel rads.
If you care to know the details on that project the radiator was a the Amaze AH600USMX:
https://amazeheaters.com/electric-wall-heaters/600-watt-space-heater/ (it's a bit cheaper than that through box stores & other vendors) .
The plug in thermostat w/remote was a NashOne: http://www.nashone-tech.com/smart-temperature-controller/nashone-wireless-temperature-controller.html
The homeowner is satisfied with it at 30s F outdoor temps- we'll see if that's still true at sub 20F temps, though I expect it will be.
Infra red panels are a somewhat different beast (and more expensive), but an appropriate solution in some instances. In a recent study in the Netherlands infra-red panels used only about half the energy of electric radiators/convectors while providing the same comfort at a lower room temp. But average heating season temps in SE VT are substantially cooler than Amsterdam NL, where 32F/0C is considered pretty frigid (and somewhat rare.)
Thank you, this information is so helpful, especially as newish homeowners with no experience making these kind of big decisions.
We have two rooms that, even if we upgrade to a heat pump system, wouldn't be serviced by it. We thought we'd install electric radiators in those rooms--an smallish attic-type space where the main goal is to keep it just warm/dry enough to prevent mildew and a very small 1st floor bathroom that is separated from the main living space. It sounds like the plug-in radiator solution you describe could be an adequate fix for those tough spots.
I think we're inclined to install the heat pump system to bring the home into the 21st century and we're fortunate in VT to have some very generous 0% interest energy improvement loans to help ease the pain of such a (for us) big layout. We've had estimates from a few different companies to install the system, but I wonder if we should ask to see their Manual J calculations to ensure they are as complete and aggressive as you suggest; want it done right.
LbrittBattlebro,
You may find this series of articles useful: https://www.greenbuildingadvisor.com/article/195243
Thank you!
I've been thinking of switching from oil boiler to an electric boiler here in eastern Canada. It would cost more to heat the water using electricity over oil in this part of the country, however in the past few years I've been electrifying my HVAC stuff by installing (1) a heat pump water heater for domestic hot water and (2) a duckless heat pump on the first floor of this 1100 square foot, 100 year-old house. Now I only use my oil boiler a few nights in the winter. Some reasons I want to replace the oil boiler - i'd like to keep the old hot water radiators, my outdoor oil tank takes up valuable space in my small yard and needs to be replaced, the oil tank is also too close to neighbour house, and I'd like to get rid of combustion sources from inside my house. Using the electric boiler would cost me more but it's only needed for a few really cold days.