Every winter a lot of us drag a space heater into the coldest room in the house. The basement office, the spare bedroom, the corner by the drafty window. It hums along all evening and turns electricity into warmth, and that is all it does.
A Bitcoin miner does the same thing with its electricity. Nearly every watt it pulls from the wall ends up as heat in the room. The difference is that while it warms the room, it is also hashing.
Here is how the Magic Miner 40T works as a space heater, and what people ask before they put one in a room they live in.
Why a miner is a space heater
Energy does not disappear. When electricity goes into a space heater, it comes out as heat. When electricity goes into the chips inside a miner, it comes out as heat too, once those chips have done their work.
A small share goes into the fans, and that moving air settles into the room as warmth as well. So watt for watt, a miner and an electric space heater put the same heat into a room.
A creator once said a miner turns “almost” all of its power into heat, and a viewer corrected him in the comments:
“Nitpick: No 'almost' about it, 100% of that electricity is turned into heat. Thermodynamics.”
@makingretro, a comment on a YouTube video on heating a house with a miner
That is the whole idea. The heat you would run anyway now does some work on its way into the room.
How much heat the 40T gives off
Heat output is usually given in BTU per hour, and one watt is about 3.4 BTU/h. The 40T has three modes you pick from its dashboard, and each one works like a heat setting.
| Mode | Hashrate | Power at the wall | Heat output | Noise |
|---|---|---|---|---|
| Eco | 30 TH/s | about 450 W | about 1,500 BTU/h | about 50 dB |
| Standard | 40 TH/s | about 650 W | about 2,200 BTU/h | not published yet |
| Turbo | 50 TH/s | about 850 W | about 2,900 BTU/h | not published yet |
| A small space heater | none | 750 to 1,500 W | about 2,600 to 5,100 BTU/h | varies |
Power is measured at the wall on the bench at 26 C room temperature, from the product page. Heat is that power times 3.412, rounded. The product page gives noise for Eco only.
In Standard, the 40T gives off a little less heat than a small space heater on its low setting. Turbo, at about 850 W, gives off a little more than that low setting.
It will not replace a furnace. It is a room heater, sized for one room that runs cold.
Where it makes sense in your home
The best spot is a room you already heat on its own: a basement office, a spare room, a den, a workshop. Somewhere that stays cold while the rest of the house is comfortable.
One viewer with a wood stove upstairs wrote:
“But we have been running the miner occasionally to heat the basement, as we struggle getting the wood heat down stairs.”
@larryroyovitz7829, a comment on a YouTube video on heating a house with a miner
And under a review of the 40T itself, one viewer already had a spot picked out:
“Been looking for a miner to put on my back porch during the winter and early spring. i think this Magic Miner would be perfect.”
@Hugh_Franklin, a comment on The Hobbyist Miner's Magic Miner 40T review
That comment was posted while the reviewer's giveaway of the unit was open.
What it is like to live with
Pick the mode the way you would pick a heater setting. Eco, at about 450 W, is the quiet one for nights, and the product page puts it at about 50 dB. Standard is the everyday setting. Turbo is for the coldest evenings, when you want all the heat and all the hash.
It plugs into a normal wall outlet with a standard IEC C14 cord, the power supply is built in, and it connects over dual band WiFi or Ethernet.
If you heat a room with electric baseboards or a plug in heater today, this is the same kind of heat. One viewer who made that change put it simply:
“In both instances I replaced electric baseboard heaters. An ideal heating source swap.”
@TrevorWurtele, a comment on a YouTube video on heating a house with a miner
Who this is for
- You already warm one room with an electric space heater or baseboard.
- You have a room that runs cold: a basement office, a spare room, a den.
- You want a Bitcoin miner at home and would like its heat to be useful.
- A steady fan hum in that room does not bother you.
Who should wait
- You want to heat a whole house. This is a one room heater.
- Your cold room shares a circuit with another heater or a big appliance.
- You need a bedroom with no sound at all. It is quiet, not silent.
- Your cold room is already on a heat pump. A heat pump moves about three units of heat for each unit of electricity; a miner makes one.
- You live somewhere warm most of the year, where the heat has nowhere useful to go.
- You need a unit this week. Batch 6 ships November 21.
What people ask
Is it loud?
You will hear it. The product page puts Eco at about 50 dB. In The Hobbyist Miner's review, on early firmware with the fans fixed at full speed, he measured 52 dB at two feet in the 30 TH/s mode and 61 dB in a 41 TH/s mode, and said he would keep it in a basement, garage or family room rather than an office or bedroom. The final firmware is still in development.
What about dust?
It pulls room air through its front grille, and dust comes along. Keep it off carpet, leave clear space around it, and brush or vacuum the grille every few weeks in the heating season.
What do I do with it in summer?
One viewer put it well:
“now that it's hot outside, the biggest challenge is HEAT. difficult to get the laundry room below 100F.”
@darinl848, a comment on a YouTube video on heating a house with a miner
You have three easy answers. Drop it to Eco, move it to a garage or basement where the warmth bothers nobody, or switch it off until the cold comes back.
Where should I put it?
On a hard, flat floor or a sturdy shelf, with clear space all around it so air can move, away from curtains and bedding. Not in a closet: the same reviewer ran his in a warm closet, and in the 50 TH/s mode it overheated. It warms the room it is in, so leave the door open or let a ceiling fan move the air.
How much electricity does it use?
The same as a heater of the same wattage: about 450 W in Eco, 650 W in Standard and 850 W in Turbo. A standard 15 amp, 120 volt circuit is rated for about 1,440 W of continuous load, so Standard uses under half of it.
Keep it off a circuit that already runs another space heater, a microwave or a window air conditioner, and plug it straight into the wall rather than into a thin extension cord.
Batch 6 is open
The Magic Miner 40T is $799 in Batch 6, which ships November 21, right as the cold settles in. You can get a full refund any time before your unit ships.
If there is a room in your house that needs a heater this winter, this one hashes while it warms.