Winter is coming. Yeah okay just getting to say that in context makes me feel cool, but let’s talk about feeling hot. I’ll stop trying to be funny.
Here in the UK we enjoy a temperate climate. Warmish summers mean the house stays comfortably over 20*C (sorry Americans, i’m really not going to do Fahrenheit) which is plenty warm enough. As September looms though it’s time to get the heating on, at least in the evenings. By the end of November the heating will be in use through most of the day to keep the house at a stingy 19*C, except when my wife has guests in which case it gets jacked up to low 20s while i’m not looking.
The thing is, heating is expensive. My energy bill for heat and hot water averages about £130 per month. Okay it’s not huge in itself, but on top of all the other bills we have to pay each month, it hurts. You can install all the LED bulbs you like, the fact is heat and hot water make up the bulk of your energy bill.
This summer we enjoyed a mining boom. We also enjoyed an unusually warm summer here in the UK, with daytime temperatures pushing 30*C lasting weeks on end- which for us is highly unusual. This means I spent more than a few hours this year battling heat, trying to keep the miners cool. As the year cools off, so has the mining boom, with difficulty sky high mining in high-electric-cost countries like the UK is far less appealing. This lead to me downsizing one of my farming locations, and selling off a lot of older cards. I still have a few R9 7970 and R9 280X cards laying around gathering dust. So, why not fire them up inside my home over the winter and use them as heaters?
Here in the UK the bulk of homes will use natural gas for heating. Some people are still heating with electric heaters, but this is by far the least cash efficient way to do it. Natural gas on a sensible contract is cheap, at around 4.5p/KW. Electricity even at the best rates you can hope to find in the UK is closer to 13p. A KW is a KW regardless of it’s delivery- so assuming your boiler was made in the last decade, it’s probably efficient enough to heat your home for roughly half the price of doing it via electricity.
This means that when figuring out the cost of heating your home with miners Vs. central heating, it’s important to use the cost of gas as your comparison to the miner, not the cost of electric. 1KW coming from a graphics card is actually going to cost you more than 1KW coming out of your central heating system.
It’s rather lucky then than mining with your graphics card also still provides a sensible return. Let’s look at an R9 280X. It uses around 250w of power (and thus generates around 250w of heat) and will upkeep about 275Hs of ZEC- which at today’s rate translates to about £1.15 generated. 250w works out as 6KW per day, or £0.78p of electricity. That leaves me with £0.37 of profit per card per day- not exactly an amount worth writing home about, but that still counts as me heating my home and making a profit! In theory, you could actually then work out the net benefit by adding in the cost of the gas that you’ve avoided using- which is another £0.27p/day for that same 6KW. So that means by using a graphics card to heat my home, i’m £0.64p per day better off.
The obvious draw back here is the noise and the clutter- and avoiding creating a hot spot in your home. I think in my case i’ve figured out a good place to hide the cards- under the stairs. It’s fairly central to the house so should lead to the heat being evenly spread rather than creating a hot spot. The sound will be annoying, but it’s far enough away from any bedrooms that we probably won’t hear it at night, and fan speed is always something I can control. Claymore’s mining software has complex enough fan controls, so I can create a profile that suits me. By forcing a low fan speed, I can make them rely on a low ambient temperate to stay cool. That means as the house warms, the graphics cards could throttle down or even pause mining completely- thereby acting as a rather crude temperature control for the house temperature itself.
At 64p per day better off, it is probably not worth buying cards specifically for the purpose of heating your home. Even if you get old cards on the cheap, you’re still looking at £120 for a R9 280X, and maybe another £40 in supporting hardware per card. That means you’ve got to recuperate £160 of costs for each card, which at 64p/day is not going to happen over the course of this winter. If however you already have the hardware with which to do it, and it’s just a matter of running it or not running it, then it’s certainly worth doing.
Interestingly enough, that covers your gaming PC too. If you have for example a RX480 or GTX1070 sitting in your gaming computer at home, it’s actually well worth just leaving it on all day with the mining client running, or at least for any periods of time when you would otherwise have the heating on- provided it’s in a location where the heat will get trapped in one room. It will actually make you a tidy little profit. An RX480 bought for around £220, run from say November through to March, will have almost paid for itself (£188 profit after electrical cost) by the time the heating is no longer needed. Yes you will put some wear on the hardware, but warranties are magical things.
So, I think in conclusion the point here is get mining! Don’t buy hardware especially, but if you’ve got it, run it. Keep an eye on the value of your coins to ensure it stays profitable, but i’d say with a high level of confidence that mining will still be cost effective for heating by the end of the winter.