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Community and Q&A

Electrical Space Heating with Uninsulated Walls

Lindaloowho | Posted in General Questions on

Happy Holidays! I have a wood house with an air sealed and insulated (R-40) unfinished vented attic and a sealed (as best as I could) and insulated (R-5) above grade wood crawl space, rim joists EPA rigid and spray foamed. Walls of this single storey home are uninsulated, windows (a lot of windows) are wood French style opening with single pane water levelled glass. We have exterior storms in the making. The property is located in Southern Ontario. 

We have a direct vent gas fireplace with a fan, giving out about 20000BTUs in the dining area which sits midway between the open concept living/dining/kitchen area. We are thinking about electric heat to provide intermittent warmth for 3 bedrooms and 2 bathrooms. This is a 1400 square foot area total. 

2 bedrooms and one bathroom open directly into the living/dining/kitchen space. If bedrooms doors are left open through the day, I believe the only time heating would be necessary in the bedrooms/bathrooms would be in the morning (if door is closed through the night) and maybe really chilly nights. 

I’ve read opinions here about radiant cove heating. Then there is electrical fan heaters (is that what you call an electrical resistance heater?) and convection heaters. We would like a thermostat and a programmed timer so the bedroom can get warm before the occupant wakes. 

Still unsure about which heater to use where.  I asked a previous question about using baseboard heaters under windows…the answer sounded like a resounding yes. 

Can I get another review of types of electrical heaters and an opinion regarding which would be best in my situation? 

Thanks Everyone,

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  1. Austin G | | #1

    Not only can electric resistance baseboard heaters be used under windows, that is where they SHOULD typically be placed. Cadet makes a programmable thermostat that can be programmed as you’ve described. I’ve used them myself in this manner, and they work well. The other good thing about baseboard heat is that you can zone each room independently. We heated only our bedrooms at night, but then programmed the bathroom and kitchen to begin warming about 30 minutes before we woke up.

    Let me know if you have any other questions. I purchased, planned, and installed basically the exact same setup you’re proposing - including supplementary gas fireplace in a 1902 house.

    Edit: You mentioned different types of electric heaters. They’re all the same. Resistance heating is nearly 100% efficient, it’s just expensive. The BTU’s you’ll get from X amount of electricity will be consistent throughout all of them, short of a heat pump in which you’re simply moving heat, not converting electricity into heat.

    1. Deleted | | #5


    2. Lindaloowho | | #7

      Great! Tell me everything, Austin. What are the size of your bedrooms and what model and wattage of Cadet did you use?

      1. Austin G | | #9

        It’s been quite a few years, so these would only be estimates - but the whole house was around 1,200 sq ft with a very open floor plan. I had a run along the main wall in the kitchen living space that was approximately 14 feet long comprised of a 6 ft (1500 watt) and two 4 ft (1000 watt) heaters. In the utility room I had a 2ft (350 watt) heater where the water line came in between the hot water heater and washing machine/dryer. In the living room, one corner had a 4 ft (1000 watt) heater on each side meeting in the corner and the other side of the room had another 4ft below the window. The master bed had a 4ft below the largest window and the smaller second room had a 3ft below the window. The programmable thermostat was the Cadet Smart Base:

        My fireplace was pretty central in the home and surrounded with masonry. I was working as a mason at the time so I had access to a lot of material, but the fireplace itself was “vent free.” I’d never do it that way now, but I was young, dumb, and broke and it seemed like the best option at the time. Thankfully the house was leaky as a sieve!

        1. Lindaloowho | | #12

          Thanks so much Austin!

  2. Expert Member
    Zephyr7 | | #2

    You can get line voltage thermostats that can directly run things like electric baseboards. These types of thermostats are often called "snap thermostats", and they're common commerically to run electric heaters in small rooms in places like warehouses. They typically have NO features though -- just set a temperature and that's it.

    If you want to use a smart thermostat, you'll need a contactor and transformer to control the heater (some heaters may already have this internally), since normal residential thermostats run on 24v electrical systems.

    Aside from the controls, electric resistance heat is electric resistance heat. Your choices are basically "with fan" and "without fan" heaters. The baseboard units are probably easiest to install and least visually obtrustive, but you can also get wall-mount units. If this were my house, I'd use electric baseboards and a control interface to use a normal residential thermostat for ease of use.

    Note that this is a pretty expensive way to heat a house in terms of energy costs.


    1. Expert Member
      Malcolm Taylor | | #3


      Isn't this a line voltage smart thermostat?

      I don't think I've seen a 24 volt thermostat in three decades. Maybe a regional thing?

      1. Expert Member
        Zephyr7 | | #4

        You got me excited there for a minute Malcolm :-)

        I looked at the manual for that thermostat, and it IS a 24v thermostat. 24v is the standard control voltage used for most HVAC stuff. The thermostat you mentioned specifically says it is NOT compatible with 120/240 volt electric baseboard heat.

        Are you thinking of the old 2 wire thermostats, the ones that were usually round and did heat only? Those had red and white wiring, which is where the "R" and "W" labels come from. I haven't seen one of those in decards either, but the new stuff still uses the same old interface, just with some extra wires to allow for cooling and blower control, and sometimes a few other things. The standard "low voltage" thermostat interface uses a 24v AC control voltage.

        I was excited thinking there was a line-voltage (120/240 volt) thermostat out there that could do setbacks, or maybe even occupancy. I contract to a lot of commerical buildings that often use electric unit heaters for rooms off of warehouses that are rarely occupied, but need to stay above freezing. People are all the time setting them to 70F+ when they're in the room, but they never seem to remember to turn it back down when the leave. The result is rooms that are occupied maybe a few hours or week or less be kept at a constant 70F+ when no one is there, using electricity for nothing...


        1. Expert Member
          Malcolm Taylor | | #8


          Are you sure? There are quite a few on the HD website all advertised as line voltage programmable thermostats. Here is another:

          That said, I've never used or installed a programmable thermostat, so I defer to your knowledge.

          1. Expert Member
            Zephyr7 | | #11

            That one says it can run on 120v or 240v, so that IS a line voltage thermostat. I'm going to have to remember that, it will be able to save some of my custoemrs some money. Warehouse guys aren't very good at remembering to turn stuff off, but they're sure good at cranking up the heat and leaving the overhead doors open!

            Regular residential thermostats are usually 24v. The low voltage allows for easier control wiring, no need to have an electrician to the install, etc. It's lots less exciting if you drill into a 24v thermostat cable than a power cable too, which is an added bonus.


  3. Lindaloowho | | #6

    Thanks to all of you for your input.

    Austin, you use a gas fireplace and the electric baseboards as your only means of heat? That’s the situation we’re looking at. Basically the fireplace acting as the “furnace” supplying most of the heat and the electric as supplementary.

    Have any of you at any time considered venting off of a direct vent fireplace, running ducts to heat spaces farther from the source? We have some ceiling height we could give up and thought a cool exposed vent look would take the heat where needed and decrease the use of the electrical baseboards and keep it more affordable. But worry that 20k BTU would not be sufficient to keep the main living/dining/kitchen as warm as it stays now.

    1. Austin G | | #10

      Yes, my fireplace and the baseboard heaters were my only heat. My fireplace was “vent free”, which was ridiculously dumb, but at least I was smart enough not to sleep with it on - so at night the house was heated exclusively by the cadet baseboards.

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