Crypto-Radiator – Saving money on heating by mining cryptocurrency (xmr/monero)

No really!…actually this is perhaps not quite as silly as it might sound.

Whilst most of our house is heated by gas central heating, the extension is not, and is one of the coldest parts of the house.

Years ago when my office was out there I normally had at least two beefy pcs running 24/7, rendering and whatnot, plus a projector…the extension was super warm then. I moved my office to the front of the house and suddenly the extension was super cold and the front room (previously cold) was now the warmest room by quite a stretch.

Realising that it was kinda ridiculous that in my office i’d have the windows open even in december to get rid of the excess heat, I tried to distribute our 24/7 servers across the house so balance the heat output to where it was needed. So we had a half-cab out the back and whilst subtle, the constant heat and warm air produced by the machines made a noticeable difference to the temperature out there.

Eventually niceties like not having servers everywhere took priority and all the servers got concentrated out of the way but that left the extension quite chilly. We’ve used LCD projectors quite successfully as heaters too since they only use about ~150w and produce a LOT of heat for that, as well as being quite effective at circulating the warm air they produce.

However lately the projector out back wasn’t playing ball so we’ve had to resort to using an electric oil radiator to keep things habitable. We didn’t really think much of it but noticed our electricity bills creeping up (even though it’s not really that much warmer!).

So recently I took some measurements and found that the oil radiator was using around 5.5kwh per day… yikes! That worked out to somewhere between £0.44/0.80 per day, £13.20-£24 per month.


The numbers are a range because there’s a mix of cheap rate/economy 7 rate at night and full price during the day and I cba to work it out more precisely than that. It’s somewhere in that range, and probably around 2:1 towards the expensive end.

That’s between £158-288 per year…and probably more than that during the winter – double yikes! No wonder our bills were up.

That oil radiator uses around 1200w when running and whilst it has a thermostat so doesn’t run all the time, it clearly runs enough to make a noticeable impact.

So how do we do better than that?

Well…I’ve also been interested in cryptocurrency for quite a while and whilst everyone knows mining bitcoin isn’t really feasible anymore without mega expensive dedicated ASIC miners which are obsolete by the time you buy them, lately I’ve been quite interested in Monero/XMR.

I wasn’t following it for its mining potential but it just so happens that it uses a mining algorithm which so far hasn’t been possible to mine on ASICs so whilst it still doesn’t really “pay” to mine it on your home PC (i.e. your electricity costs will usually end up higher than your currency mined) – what if we looked at it a different way.

Assuming you’re already burning electricity (oil radiator) and only getting some heat in return, would it be possible to produce a similar amount of heat by mining XMR and whilst not “profitable”, perhaps at least partially offset the electricity costs?

I thought it was worth investigating a little and perhaps testing just to find out….


And yes it’s clearly the coolest-sounding type of heating out there 😉

So I had a spare AMD x4 955 black edition sitting there doing nothing, plus my #2 pc just recently died so there was an SSD free. With just the addition of a motherboard off ebay (£30), a 2gb stick of ram (~£10) and a couple of heatsinks (~£7), plus a few random bits scavenged from our PC graveyard we had a shiny new form of heating.

The priorities for this PC build were obviously a little different from your average build. Firstly it had to be as quiet as possible. Airflow was also very important to make sure the heat got directed to where it was needed, as well as ease of operation. It should really be no more complex to operate than the oil radiator, and shouldn’t need lots of extra cables either. Literally just a power lead was the aim.

I happened to have quite a nice slimline PC case spare which was made of thin sheet metal, which promptly got a nice big heatsink bolted to the top of it complete with thermal paste as used on CPUs for max heat transfer from the PC to the outside world. Coincidentally the heatsink was from a redundant ASIC miner.

The inside of the pc also got lined with bubble-wrap to deaden sound and block off all airflow except where I wanted it to go, and it got a bit of plastic ducting over the PSU fan exit to reduce the fan noise slightly as well as direct the warm air where it needed to go.

So now cold air comes in via the side of the case direct onto the CPU, and also from the bottom couple of PCI slots which had the blanking plates removed, moves up to the top of the PC. Some of the heat leaves via the heatsink on the top and the rest is expelled by the PSU fan via the ducting.

The software side..

The PC got a bare copy of Lubuntu linux on it and I set up a minergate account so that I could monitor how much it mined without needing direct access to the PC itself. It’s possible to run the actual monero miner on there but that means the PC needs an active wallet on it and you have to log into the machine itself to check progress.

My main PC is an AMD 6x and although it runs 24/7, when I’m not at the machine I clock it down to 10-12x rather than its usual 16-17x when I’m working on it. I’d noticed in the past that overclocking gets increasingly inefficient as you go faster, but *underclocking* gets ever more efficient (to a point). I wondered if there was a way to replicate this on the Crypto Radiator so that there was even a sort of heat control/setting.

Naturally with it being linux there’s a package for that (cpufreq-utils) and it can all be controlled from the command line, so after a little bit of head-scratching and a couple of bash scripts later I was able to force the cpu’s speeds to be operate at specific frequencies from 800mhz to 3.2ghz.

By this point I’d set it up so that upon booting the machine automatically connected to the WIFI and launched the minergate-cli program and started mining. I also set it running a full XMR node too so not only is it mining and heating the house, but also helping process transactions and helping the currency work well.

Although I was feeling pretty pleased with myself by this time I was inspired by the “Hive” advert (when you’re getting crushed by Hercules..lalala etc) I thought why not take it a step further and set up an apache server on the machine and build a little web app so you can control the cpu speeds at the touch of a button, and also switch the machine off. That way when we’re lying in bed and realise I forgot to turn the radiator down (or up) I can clickety-click from my phone and it’s job done.

That way the only interaction needed with the machine is hit the power button to turn it on, and all the rest you can do from the web app.

screenshot of the web app to control the crypto-radiator

As is often the case, making things simple is complex..and this was borne out by the fact that although it had taken me most of a day to put the machine together and get it working right, it took all of 3 mins to explain how to use it to my partner.  I set up a shortcut to the web app on her phone/tablet, “use that to set the temp and turn off…hit the button on the front to turn it on” was literally about all it took. It took longer to wait for it to boot up than explain how to use. Nice 🙂


Well that’s the $64,000 question isn’t it? I ran the machine on full power via a plug-in meter for a few days and we established that it did seem to produce a noticeable amount of heat (not masses but enough to make a difference) and running constantly on full power it ended up using about 3.3kwh/day which is around a 40% saving over the oil radiator right from the outset and works out to about £7.92-.£14.40 per month, or £95.04-£172.80 for the year.

It’s been running about 2 weeks now and actually in practice it’s not been on full power most of the time. It tends to be on min during the day and medium or high at night, so naturally it doesn’t mine at full pelt the whole time but uses accordingly less power too.

Also I’ve started setting my main PC to mine when it’s turned down since it’s on anyway and just mining on the cpu doesn’t seem to really make much difference to the power usage, which does mean I don’t have an exact figure for just that machine,  but in those 2 weeks both machines have mined around 0.086 XMR. which works out to about 0.006 XMR per day. Not massively impressive but that’s around 0.172 XMR per month which is currently worth around £2.88, or £34.56 over the year.

Given that we’re already saving around 40% over the oil radiator with the crypto-radiator running on full power, and given we generally run it on a lower settings, vs our oil radiator at £13.20-£24 per month, we’re looking at more like £7.92-£14.40 per month which is a saving of £5.28-£9.60 just on initial energy used, plus the £2.88 refund from the us a total of  £8.16-£12.48 *savings* per month (£97.92-£149.76). That’s pretty substantial.

Even if you halve the mining proceeds to roughly make it equivalent for just the crypto radiator (it’s slower than my main pc but it runs constantly whereas my main pc only mines at night when I’m not using it) that’s still a decent enough savings to be worth doing.

Also bear in mind that the actual energy used will be less than the 3.3kwh/day since we don’t run it on max normally, and the figures will look even slightly more favourable.

Taking into account the outlay for the motherboard and ram (£40) it should recoup that in about 3-4 months and after that we should see the actual savings.


I know the numbers might not sound that mind-blowing but I’ve learnt from experience that with things which run 24/7/365, even small savings quickly add up. 10% savings is already good, nevermind 40%+. The reverse is certainly true as we found out by our bills creeping up. We sure noticed that.

Also worth bearing in mind is that in the last 6mo or so Monero/XMR has more than doubled in value, and as it gets adopted more widely that may increase too – which would improve the savings yet further.

So all in all instead of just burning quite a lot of electricity and only getting a moderate amount of heat in return, now we burn a smaller amount of electricity, with remote/phone control, as well as recouping some of our energy costs and helping one of my favourite altcoins work better.

I reckon that’s a #win.


The future:

Naturally I’ve been quite encouraged by this and have been wondering how this can be improved yet further and how else it can be applied.

I’ve ordered a small usb temperature probe off ebay which should hopefully mean I can rig up some sort of temperature-sensing so that there’s the option to have it works to maintain a given temp rather than just running on min/med/high/max. I don’t know if that would help the overall usage but it should improve comfort a little.

At the very least I’m thinking to set a cron job to schedule it so that it automatically goes onto a lower setting during peak tarriff hours (when we also need less heat) and heats more during night/economy-7 hours, thereby maximising the heat output vs cost, without having to remember to turn it up or down.

If we find the heat it produces isnt’ sufficient for the winter I think it would be possible to add a GPU and use that to mine. On my main pc it mines about 50H/s on all 6 cores but in chill mode, but on the GPU even on the lowest intensity setting it mines easily double that. Yes Adding a GPU would likely increase the noise too but it’s pretty well insulated in that respect and perhaps the heat tradeoff would be worth it. For now it’s totally sufficient though and super quiet to boot. I did have a couple of graphics cards I tried to put in it but it wasn’t playing ball and I just wanted to get the basic unit up and running rather than getting bogged down with getting the absolute most hashes/sec out of it. But even a cheap card could make quite a difference to both heat and mining output.

I’ve also been wondering whether it would be possible to power the whole thing from a solar panel & car battery. Yes there’d be quite a high initial outlay but we have plenty of flat roof to put panels on and going from 40% savings to 100%+ savings would be quite significant.

Also I’ve been wondering whether it would be possible to perhaps use a cluster of such boards to run something like an immersion heater. It doesn’t produce the sort of concentrated heat you’d need to run a “crypto-combi boiler”, but gently heating a tank full of water would mean our main boiler doesn’t have to work so hard, so even just putting it inline with the central heating, the boiler would just automatically work less.

If you reckon that the average AMD 4x/6x cpu runs around 55-60 degrees C, that’s pretty much exactly what our boiler water temp is set to, so if we can even approximate that somewhat, that could potentially be pretty cool.

I had wondered whether it might be possible to cook using the same technique but I think the temperatures are just too low. Perhaps an array of old Athlon 1s would be enough to run a slow cooker but I doubt they’ll mine much XMR 😉


p.s. If you want the scripts used in this project and/or a how-to just let me know in the comments and I’ll add a post with how to set it up.

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