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Thread: Wall mounted electric panel heater

  1. #1

    Wall mounted electric panel heater

    Has anyone used wall mounted electric panel heaters as a supplement to their shop heat?

    My shop generally stays between 40-45 F when not heated (attached 2 car garage, well insulated, ~ 400 sq ft) on most winter days. When temps dip into the single digits the shop temp will drop to ~35 F.
    My main sources of heat are an electric 1500w ceramic heater and 18000 btu propane heater. I can raise the shop temp from 45 F to 60 F in a little over an hour.

    I am not expecting to heat the shop exclusively with the panel heater(s), just keep the temp moderated slightly.

    I considered oil filled radiant heaters, but I donít like the idea of taking up floor space and moving them around.

    Has anyone tried something like the Envi heater from Eheat?
    There are other brands as well. Basically 400-500w units that rely on natural convection heating air drawn up from the floor.

  2. #2
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    I have to be honest with you...I'd be very concerned with the cost of operating any kind of electric resistance heat. I am not familiar with the panel heaters you speak about, however.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    I have one of those 'cube' type electric heaters hanging on the wall. It is 220V, can be wired into a simple thermostat if you like, and has a fan. It may be 5000W. Electric baseboard has been around forever, those Envi heaters are just that. At 500W I am not sure they would be enough.

    Electric heat is 1:1 - however much energy you put in is what you get out. I run mine only when working in the shop, to boost the temp to a workable level, not the level inside the house. It is clean, convenient, and hasnt spiked the bill that much. I have never tried leaving it on continuous so am not sure how much that would draw.

    I am a big fan of the split mini - which would also give you AC. Much more efficient than electric resistive heaters unless your outdoor temps are low, then the mini drops to zero output and you need a resistive electrical booster .

    To properly figure this out requires a heat load calculation on how much loss in your shop (maybe search for 'slantfin'). Pretty much all heating/cooling designs are fundamentally driven by insulation (with infinite insulation, you need a single watt of energy to get to any temp you want). So if you are insulated enough, you will need very little heating (and $). Your garage doors and any windows are likely your biggest heat loss. Insulating/sealing those will help. Then insulate some more.
    Last edited by Carl Beckett; 01-12-2022 at 6:17 AM.

  4. #4
    Quote Originally Posted by Jim Becker View Post
    I have to be honest with you...I'd be very concerned with the cost of operating any kind of electric resistance heat. I am not familiar with the panel heaters you speak about, however.
    Jim,

    Here is a link to the units I mentioned.

    https://www.eheat.com/envi-120v-plug...rd-generation/

    Agreed, resistive heating is not the most efficient option. I am only looking to run this during extreme cold snaps, just to keep the shop in the 40-45 F range.
    This morning is a good example....in the northern Lehigh Valley PA, it is 10F at 7AM and the shop is 35F.

    Jay
    Last edited by Jay Norton; 01-12-2022 at 7:16 AM.

  5. #5
    Quote Originally Posted by Carl Beckett View Post
    ..... So if you are insulated enough, you will need very little heating (and $). Your garage doors and any windows are likely your biggest heat loss. Insulating/sealing those will help. Then insulate some more.
    Carl,

    I am insulated pretty well. R13 in walls with drywall. Ceilings are R30. Garage doors are fairly new, R15. I have 1 window (Andersen). Located in Eastern PA.

    The garage door seals could be a good place to look. I think they are sealed well, but there may be some gaps. I will go outside tonight and see if any light shines through when the shop lights are on.

    Jay

  6. #6
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    I put one of the 240V ones with a fan in it in our dogroom. When I built that addition in 2005/6 I didn't have the stuff to take care of mini-splits yet, and didn't have any experience with them. I've been too busy to change it, but it's still working fine after 16 years. The room is 16x24, and super insulated. We get to deduct part of our electric bill for the dog business, which helps, but it's still not a lot different than burning dollar bills.

  7. #7
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    Quote Originally Posted by Jay Norton View Post
    Jim,

    Here is a link to the units I mentioned.

    https://www.eheat.com/envi-120v-plug...rd-generation/

    Agreed, resistive heating is not the most efficient option. I am only looking to run this during extreme cold snaps, just to keep the shop in the 40-45 F range.
    This morning is a good example....in the northern Lehigh Valley PA, it is 10F at 7AM and the shop is 35F.

    Jay
    THanks for the link...those seem to be, based on the photos, to be something like a wall mounted replacement for a closed "oil" type electric radiator and for a small space, like a bedroom. Perhaps it will work for you. I'm only a few miles south of you so I do have an appreciation for the temps you walk up to this week! For the record, my temporary shop (the g.g.g.arage...) was 38ļF yesterday here in Doylestown. I honestly have not been in my shop much lately because of the cold and miss the minisplit I had in the shop at the old property. I'm also left with electric, but am using two radiant units to focus warmth where I"m working. I do understand your struggle!
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #8
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    It went down to 10 degrees at my old house North of Boston last night. Not sure what kind of heater would work for that. I wonder what our friends in Alaska do. Somehow using a wood burning stove to do woodworking seems so wrong.
    - ďItís not that Iím so smart, itís just that I stay with problems longer.Ē Ė Albert Einstein
    - Welcome to Florida. Where the old folks visit their parents

  9. #9
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    We used something like that to heat a bathroom. My wife was an elementary principal and she got up around 05:30. I didnít get up til 07:30 and she didnít want to heat the whole house. One heater did a nice job in our 12x18 master bath with a vaulted ceiling. We ran it for about 2 hours a day on weekdays and it lasted about ten years.

  10. #10
    Quote Originally Posted by Jim Becker View Post
    THanks for the link...those seem to be, based on the photos, to be something like a wall mounted replacement for a closed "oil" type electric radiator and for a small space, like a bedroom. Perhaps it will work for you. I'm only a few miles south of you so I do have an appreciation for the temps you walk up to this week! For the record, my temporary shop (the g.g.g.arage...) was 38ļF yesterday here in Doylestown. I honestly have not been in my shop much lately because of the cold and miss the minisplit I had in the shop at the old property. I'm also left with electric, but am using two radiant units to focus warmth where I"m working. I do understand your struggle!
    That would be my intended use, as a replacement/alternative to oil radiators.
    I would be willing to bet I would need at least 2 to keep the shop in the 40 degree range on these colder nights.

  11. #11
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    My concern would be capacity. 500W is not that much (about 1700 BTU). Although you are only trying to get it in the 40's, which will certainly reduce the requirements.

    A quick search on 'how many btu to heat a garage' gave:

    "A basic rule of thumb for forced-air heaters is 45,000 Btu to heat a two- to 2-1/2 car garage, and a 60,000 Btu garage heater for a three-car garage.


  12. #12
    Quote Originally Posted by Carl Beckett View Post
    My concern would be capacity. 500W is not that much (about 1700 BTU). Although you are only trying to get it in the 40's, which will certainly reduce the requirements.

    A quick search on 'how many btu to heat a garage' gave:

    "A basic rule of thumb for forced-air heaters is 45,000 Btu to heat a two- to 2-1/2 car garage, and a 60,000 Btu garage heater for a three-car garage.

    That's why I was asking, since the requirements are not "normal". For myself, a comfortable working temperature is ~60F, so my 18k BTU propane heats up the shop more than enough while working.

    I really just want to keep things (glues, paints, etc) from approaching the freeze point.

    I looked at a calculator that uses sq ft, ceiling height, climate zone, level of insulation and attached/unattached structure for BTU requirements and get ~ 19,500 BTU for my shop. Now that doesn't take into account outside temperature vs what you desired inside temperature is and the time to reach the desired temperature. Another calculator doubles the required BTU when going from outside of 40F down to 20 F

    I have read other reviews/experiences using oil filled radiators to keep cabins/workshops slightly above freezing.

    I did find one review on another woodworking forum for these exact units. The user used 2 of these for an insulated garage shop in PA and was happy with them. It is an older review. I tried contacting the person through the forum, but it seems he/she is not active on the forum these days.

  13. #13
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    I think a reasonable approximation might be to work on temperature difference. So if your calculator was say, 70 inside and 40 outside that is 30 degree. 70 inside to 20 outside is 50 degree difference. That is likely what is driving the doubling.

    So if you are trying to keep it above freezing when its zero out, thats 30 degrees difference. Same heat load as the first scenario.

    I do not believe 500W is enough (even two of these I dont believe is enough). You could run a test and build a panel with 10 100W lightbulbs (all that energy goes into heat, it is the same thing as a heater).

  14. #14
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    What's wrong with continuing to use the 1500 Watt heater? You can always turn it down. I have a wood stove in my shop and haven't gotten around to hooking up my mini split yet. I have a 1500 watt heater that I set on low and it will keep the shop at 55 or 60 degrees overnight when it is 10 degrees outside. My shop is insulated about the same as yours. My walls are 6 inch.

    As Carl said - watts is watts. You can calculate the cost of running an electric heater easily. One kilowatt hour is 1,000 watts for one hour.
    Regards,

    Kris

  15. #15
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    Quote Originally Posted by Kris Cook View Post
    What's wrong with continuing to use the 1500 Watt heater? You can always turn it down. I have a wood stove in my shop and haven't gotten around to hooking up my mini split yet. I have a 1500 watt heater that I set on low and it will keep the shop at 55 or 60 degrees overnight when it is 10 degrees outside. My shop is insulated about the same as yours. My walls are 6 inch.

    As Carl said - watts is watts. You can calculate the cost of running an electric heater easily. One kilowatt hour is 1,000 watts for one hour.
    That is a good point. Buy one of those 'watt meters' that measure consumption of what you plug into it (handy for monitoring efficiency of different appliances). Plug your heater into it, turn it down to read 500w, then let it go for a day or two and see how well it holds up.

    Resistive heaters can be dialed down by a variac (although probably dont have one of those) - or a light dimmer if high enough rated.

    I have a couple that are something like this: (https://www.amazon.com/P3-P4400-Elec...572288073&th=1)

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