Only for an electrical resistive heater (i.e., most space heaters). Obviously that calculation completely does not apply to a fuel-based heater like a propane heater. It also doesn't apply to a heat pump (like most mini splits). There you have a "coefficient of performance", which gives you the ratio of heat out to energy in. So if you have a heat pump that consumes 1500 watts, with a COP of 2, you get 3000 watts of heat out. COP is usually in the 2-5 range.
Seeking input on shop heater
- Thread starter fivemike
- Start date
Only for an electrical resistive heater (i.e., most space heaters). Obviously that calculation completely does not apply to a fuel-based heater like a propane heater. It also doesn't apply to a heat pump (like most mini splits). There you have a "coefficient of performance", which gives you the ratio of heat out to energy in. So if you have a heat pump that consumes 1500 watts, with a COP of 2, you get 3000 watts of heat out. COP is usually in the 2-5 range.
1500W/110V = 13.6Amps.
1500W/120V = 12.5Amps
That's generally what residential breakers are, along with the 14G wiring. Anything over that becomes a fire hazard.
True, 1500W is 1500W, some heaters have better heat diffusion or a wider spread of the heat generated.
1500W/120V = 12.5Amps
That's generally what residential breakers are, along with the 14G wiring. Anything over that becomes a fire hazard.
True, 1500W is 1500W, some heaters have better heat diffusion or a wider spread of the heat generated.
While codes and things have changed over time, it wouldn't be strange at all for those outlets to be 20 amp. All my external and garage outlets are at least that. However, few tools made for 110/120 are likely to exceed that, and most items made for continuous use will try and only use 80% of the breaker's rating to avoid nuisance trips. You don't know unless you stick a killawatt on it, but most 1500 watt heaters I've tried were more like 800-1000. At any rate, fine for something you might sit next to but nowhere near capable of heating an uninsulated and drafty shop economically or in a reasonable amount of time.
I do like those parabolic heaters. Resistance heat is resistance heat and it's essentially 100% efficient (I suppose some tiny amount of power becomes light if we want to be pedantic) but directing it helps...
As mentioned, seal up the door. In my last house, I just opened the door to the house and use a box fan for an hour or so. Once the chill was off, I shut the door and it was good enough for the day. Insulating the ceiling is never a bad choice either. Any "flame" type heater needs a constant fresh air supply. Never run a propane or kero heater inside without fresh air. CO and CO2 levels along with the combustion byproducts. Any stove needs proper intake and chimney. Woodworking is hard enough on our lungs, don't push it.
Window mount heat pumps actually are getting to where they work. After sealing up and insulating, might be a valid future choice. Some of them run on 220 so can be pretty big and way cheaper than a mini-split. In hind sight, I might have use a pair of them instead of my split in my shop.
Claus, you are correct for a resistive heater. No magic regardless of the miracles You-Tube shills claim. They are basically 100% efficient and Watts in is Watts out. I keep a cheap 1200 Watt unit around as a back up for power failure as I have a generator.
Window mount heat pumps actually are getting to where they work. After sealing up and insulating, might be a valid future choice. Some of them run on 220 so can be pretty big and way cheaper than a mini-split. In hind sight, I might have use a pair of them instead of my split in my shop.
Claus, you are correct for a resistive heater. No magic regardless of the miracles You-Tube shills claim. They are basically 100% efficient and Watts in is Watts out. I keep a cheap 1200 Watt unit around as a back up for power failure as I have a generator.
Everyone, thank you so much for all the information. As intended, I am glad this post turned into an open exchange of ideas and suggestions for all to read.
As in my case, we are on a rough "few year plan" to sell this house once we begin our family, so this shop is but a temporary workspace for me. When we find the next house, it'll be more of a "forever" home for us (lord willin') and I'll be more open to spending on a properly insulated shop (hopefully detached and dedicated for my workshop). For now, I just want something to knock the chill off my hands and air when need arises.
I'm going to try out something like the combination of an infrared heater (to point at me) and if that doesn't prove adequate, maybe introduce a small radiator to rotisserie my body around for a few seconds when needed. When I said I didn't want to light my wallet on fire, I should have still mentioned I do not mind spending a few hundred bucks, just don't want to get into the thousands of dollars if this is not our 'forever' space (I know y'gotta break a few eggs to make an omelet)...
Cheers everyone- keep the discussion rolling and opinions flowing...
As in my case, we are on a rough "few year plan" to sell this house once we begin our family, so this shop is but a temporary workspace for me. When we find the next house, it'll be more of a "forever" home for us (lord willin') and I'll be more open to spending on a properly insulated shop (hopefully detached and dedicated for my workshop). For now, I just want something to knock the chill off my hands and air when need arises.
I'm going to try out something like the combination of an infrared heater (to point at me) and if that doesn't prove adequate, maybe introduce a small radiator to rotisserie my body around for a few seconds when needed. When I said I didn't want to light my wallet on fire, I should have still mentioned I do not mind spending a few hundred bucks, just don't want to get into the thousands of dollars if this is not our 'forever' space (I know y'gotta break a few eggs to make an omelet)...
Cheers everyone- keep the discussion rolling and opinions flowing...
Agree best thing you can do is insulate.
As far as a heater goes, we prefer electric and have used a PowerHouse 4KW Heater for 20-ish years. My "shop" is an insulated 3 car garage - this heater will bring it up to 70 degrees or so in a couple of hours. We like it because there are no concerns with ventilation, and the heating element is contained in what's likely an oil-filled radiator, so it doesn't get hot enough to be a fire hazard, nor does it burn airborne sawdust and smell. It does require a 220V/20A circuit.
The biggest downsides are no AC capability and of course, the electric bill.
As far as a heater goes, we prefer electric and have used a PowerHouse 4KW Heater for 20-ish years. My "shop" is an insulated 3 car garage - this heater will bring it up to 70 degrees or so in a couple of hours. We like it because there are no concerns with ventilation, and the heating element is contained in what's likely an oil-filled radiator, so it doesn't get hot enough to be a fire hazard, nor does it burn airborne sawdust and smell. It does require a 220V/20A circuit.
The biggest downsides are no AC capability and of course, the electric bill.
I have been using a Buddy Portable Heater for 3 years now and it works fine for me. My shop is about the size of a larger single car garage, and is well insulated. I use about 1-1/2 20lb. propain takes a year. The thing that I liked about this heater is:
Automatic low oxygen shut-off system (ODS)
Accidental tip-over safety shut-off
Build in fan
Connects to two 1 lb. cylinders
or Connects to a 20 lb. cylinder with hose
I set the heater in front of the door which I leave slightly ajar and a window at the other side of the shop slightly open. On real cold days I turn the heat to the med. setting till the shop warms up then to low setting. Truth is after a few hours I usually turn the heat off.
This works for me and sure it will not work for all.
Automatic low oxygen shut-off system (ODS)
Accidental tip-over safety shut-off
Build in fan
Connects to two 1 lb. cylinders
or Connects to a 20 lb. cylinder with hose
I set the heater in front of the door which I leave slightly ajar and a window at the other side of the shop slightly open. On real cold days I turn the heat to the med. setting till the shop warms up then to low setting. Truth is after a few hours I usually turn the heat off.
This works for me and sure it will not work for all.
I use one of these. Also have a battery powered CO detector on when I use it. Limiting factor is the availability of K-1 kerosene in your area. Very expensive if you buy it from TSC, etc. We are lucky enough that one of the fuel distributors has a K-1 pump, so it is much cheaper.
Last edited:
I had an about a 350 sq ft shop area in Maine that was partially insulated. Never got to the floor which was on a posts - tight to get under to to insulate so it remained drafty underlayment. I had an old 1500 watt electric heater that was fine for moderately cold weather in the 45-65 range give or take. But Maine has some long cold spells never getting past the 20s so I got one of these kerosene heaters and it was great. I’d just crack open a window a tad and with the drafty floor I never had a CO issue. I generally just used diesel fuel but some gas stations had both.
I had an about a 350 sq ft shop area in Maine partially insulated. I had an old 1500 watt electric heater that was fine for moderately cold weather in the 45-65 range give or take. But Maine has some long cold spells never getting past the 20s so I got one of the kerosine type kerosene heaters and it was great. I’d just crack open a window a tad and with a drafty sub floor I never had a CO issue. I generally just used diesel fuel but some gas stations had both. If you got the budget, consider a higher end wall or floor mount type like a Monitor that you can vent outside and has a thermostat. I also had a LP tank mounted type heater which is more directional. I preferred the kerosene heater which was also more stable, the lp tank could be a little tippy if whacked with something.
As far as electric, 1500 watts is pretty much the max for 120v and works fine for typical 15A circuits, although not so great to have another high amp draw tool on same circuit. No sense to over spend on one of these - some have hi and lo settings, some have fan speeds, some rotate - pick one and try it. Last winter was my first here - we have a small 1500 watt cube heater that I used, did enough to get me by. Current space is 240 sq ft but higher ceiling and well insulated other than the garage door. During this current cold spell I have not yet been in the shop. But I need to do a few things so will be hauling out the little cube to give it a try. Got a feeling it will satisfy my needs although one that oscillates might cover the space better.
As far as electric, 1500 watts is pretty much the max for 120v and works fine for typical 15A circuits, although not so great to have another high amp draw tool on same circuit. No sense to over spend on one of these - some have hi and lo settings, some have fan speeds, some rotate - pick one and try it. Last winter was my first here - we have a small 1500 watt cube heater that I used, did enough to get me by. Current space is 240 sq ft but higher ceiling and well insulated other than the garage door. During this current cold spell I have not yet been in the shop. But I need to do a few things so will be hauling out the little cube to give it a try. Got a feeling it will satisfy my needs although one that oscillates might cover the space better.
Similar threads
