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Electric hot water boilers.

Swilson08
Swilson08 Member Posts: 35
So what's everyone's thoughts on these electric hot water boilers. Slantfin, electro industries and etc. I stumbled across them while searching around for info and figured I'd ask if anybody has experience with them since it is something I don't see normally.

Comments

  • flat_twin
    flat_twin Member Posts: 292
    I can share a new homeowners point of view. One of the other old greek revival homes in our neighborhood has an electric boiler and finned baseboards. The new owners of this home shared with me that they were looking for other heating options as their monthly electric bill in the winter was over $900.
  • Swilson08
    Swilson08 Member Posts: 35
    That's what I thought. I was looking at the numbers and figured these draw a ton of power.
  • Jamie Hall
    Jamie Hall Member Posts: 17,122
    They do. A kilowatt -- 10 amperes on a 120 volt circuit -- is only about 3500 BTUh. Many residences don't even have enough mains power coming in to run them -- never mind the price.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 3,987
    For places with cheap hydroelectric power, mild winters, or locations where installing a fuel burning appliance would be astronomically expensive.
  • GroundUp
    GroundUp Member Posts: 1,283
    Depends entirely on cost of electricity. I install a ton of Electro boilers in my area and have worked on many jobs with 20+ year old Electro units that have never even been serviced. Electric resistance is 100% efficient, while even a high efficiency gas boiler seldom gets above 92% actual efficiency. In my area, if you can get a dual fuel or off-peak rate the power costs about $.05/kwh. LP at 92% eff holds about 84,000 BTU per gallon which is equivalent to roughly 25 KW. At $.05, that's $1.25 so if propane is above that, electric ends up being more cost effective to install and operate as well as cheaper to maintain. Obviously if you double the electric rate or even triple for some parts of the world, the cost comparison drives up laterally as well. Electric has its ups and downs but is not the right answer for every application
  • Jamie Hall
    Jamie Hall Member Posts: 17,122
    edited September 2019
    Electric rates where Cedric lives are triple what you quote, @GroundUp . As you note, makes a big difference. You also don't note that on larger buildings -- such as Cedric's home -- you are going to need a big electric service. Where Cedric lives, three phase is not available, and 240/120 is the best you can get. Which translates to a 500 ampere service entrance (1,000 MCM aluminum wire...) to replace Cedric. Ah... that alters the economics a little bit, eh?

    Further, please note that while the electric boiler itself is almost 100% efficient, the power generation isn't. For fossil fueled plants --the majority of most power in New England, anyway -- the peak efficiency is more like 40%. Which alters the environmental picture, if you care about that, somewhat...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • GroundUp
    GroundUp Member Posts: 1,283
    @Jamie Hall I don't see any mention of a heat load, location, or anyone named Cedric in the above discussion- my input was merely a blanket statement to help explain a bit about an electric boiler- nothing specific to whoever Cedric is. 240v single phase 200A service is more than enough for the majority of midwest homes with electric heat sources, but of course those items will vary with location and the minority of homes with a 400,000 BTU heat load as would require the 500A service you've mentioned. Valid points, absolutely- thanks for the additions.
  • zac_2
    zac_2 Member Posts: 30
    My favourite ones that i've installed thus far are Thermolec. They have a stainless steel pressure vessel, built in outdoor reset (albeit fairly primitive) and the best part: solid state relays. A common problem with most electric boilers is the points of the element relays overheating and welding closed (not a fun situation) but solid state relays fixes that, they can pulse on and off so frequently that it essentially becomes a true modulating boiler. The build quality is very nice on them too.
    http://www.thermolec.com/_documentationcache/cd-264-English Boiler flyer booklet.pdf
  • Jamie Hall
    Jamie Hall Member Posts: 17,122
    GroundUp said:

    @Jamie Hall I don't see any mention of a heat load, location, or anyone named Cedric in the above discussion- my input was merely a blanket statement to help explain a bit about an electric boiler- nothing specific to whoever Cedric is. 240v single phase 200A service is more than enough for the majority of midwest homes with electric heat sources, but of course those items will vary with location and the minority of homes with a 400,000 BTU heat load as would require the 500A service you've mentioned. Valid points, absolutely- thanks for the additions.

    Sorry. Cedric is the Weil-McClain 580 fired at 2.75 gallons per hour which heats (but only just barely!) the main building -- the centerpiece of a National Historic Register farm complex -- which I care for. The main building is a 7,000 square foot residence located in northwestern Connecticut, and is in no way particularly unusual for this area. It already has a 200 ampere service -- which is adequate, but not by much, for the normal loads.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    GroundUp
  • jimct
    jimct Member Posts: 10
    Not at all sure of the wisdom of electric heat in Connecticut. Electricity generation charge is about 10 cents/kWh and the distribution charge is 9 cents/kWh.
  • Jamie Hall
    Jamie Hall Member Posts: 17,122
    edited September 2019
    jimct said:

    Not at all sure of the wisdom of electric heat in Connecticut. Electricity generation charge is about 10 cents/kWh and the distribution charge is 9 cents/kWh.

    And those rates are just going up as we get more renewables. Indeed, not much wisdom in electric heat here.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,307
    Electric is a good backup, a lot of 100% wood burners use it as backup.

    Its (relatively) cheap to install and requires no maint even if it isn't used in years. Here in the northeast resistance electric is by FAR the most expensive BTU you can buy.

    But for simplicity and reliability, electric cannot be beat. If you have a big solar array and generate an excess of kWh, then electric heat can be used to use power that you would otherwise give away to the POCO.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
    GroundUp