Waste heat from server cupboard to warm the house?

[Will Cooke]

Hi all,

I built a cupboard in my integral garage to house a few servers.

The door has a large drop in panel filter to remove some dust and mounted in the ceiling of the cupboard is a large in-line extractor fan, connected to a thermostat.

At the moment, when the thermostat switches at 30 deg. C, the hot air is sucked out of the cupboard and blown outside. The air coming back in is drawn from the garage, through the filter.

Now the weather is on the turn I started thinking about if I could use some of that warm air to take the chill of the house. I mean, its just being wasted at the moment.

I expect I would need to fit some kind of diverter valve so I could direct the warm air back outside in the summer, and probably fit a noise baffle.

But what I am missing in this master plan? Would the air be damp or smelly or full of insects? Would it make so little difference as to not be worth the effort?

I'd love to hear your thoughts.

Cheers, Will

[Harry Bloomfield]

Will Cooke used his keyboard to write :

A flame barrier between house and garage is an essential, so I don't think your pumping air directly from the garage to the house would be viable. What you could do though, is maybe use something like the innards of a fridge or freezer to transfer the heat through the wall. Inside parts mounted in server cabinet, heat radiator which is normally on back of freezer inside the house.

Another way would be to circulate the servers air through a room sealed duct with a heat exchanger, then circulate the house air through a co-mounted duct, so just the heat rather than air would be exchanged between the two.

[Tim Watts]

I can see two problems - sucking in fumes from the car (and it does not matter if *you* do not have a car in there now, you might down the line) - and the second is firebreaks - ie fire could now spread quickly from the garage to the house.

The firebreak is soluable - I think. The fumes ingress is not, without using a heat exchanger - but that would be DIY-able and if designed right could deal with the firebreak problem too.

[Jeremy Nicoll - news posts]

I wonder if you could route the incoming cold water main through a spiral in the sevrer area to raise its temperature? But I suspect the temperature change would be tiny, and the risk of getting servers wet if there was a water leak, not useful.

[Brian Gaff]

I'd plump for just pumping the air back in the garage in winter then at least it will have the chill removed if you should need to spend time in there for any reason. Brian

[Will Cooke]

I should have explained a little more about the "garage". The house was de= signed such that the garage could be converted in to another usable room if= required, and that has already been half done. =20

What we actually have is half a garage which is used as a store room for ol= d tins of paint, ladders, tools and of course, servers. The other half, th= e half nearest the centre of the house, has already been converted in to a = utility room for the washing machine and associated bits and bobs.

So, fumes won't be a problem from a car parked *in* the garage - a car simp= ly won' fit, and in order to make it fit you'd have to disassemble the serv= er cupboard and utility room anyway.

That does leave the problem of fire though. Tins of paint, white spirit an= d other flammables are indeed stored in the other bit of the garage.

I expect a ducting firewall would be prohibitively expensive. I also think= a heat-exchanger would be too pricey to warrant the expenditure.

Sounds like my idea isn't a go-er.

Cheers, Will

[John Williamson]

heat-exchanger would be too pricey to warrant the expenditure.

Heat exchanger systems aren't cheap to install.

Just another thought. How much power does your server actually consume? A few hundred watts of low grade heat from it may be enough to prevent condensation in the garage, but I don't think it will make a significant difference to the amount of heat your house heating needs to supply.

Where I used to live, I had no insulation on the hot water cylinder, which was in the airing cupboard in the bathroom, as I used the waste heat from it to keep the bathroom warm. It saved me having to install a separate heater for the bathroom. It got me a much worse energy use rating when I sold the place, but it worked for me.

[Jules Richardson]

It wouldn't be considered a problem here - most houses have basements where things such as tins of paint get stored, and most houses have ducted forced-air systems for heating, and guess where the furnace gets put...

I'm not saying it's not a potential issue, just that the risk is considered so low that most people don't consider it at all.

I don't know how large your large extractor fan is, but the cheapest solution would surely just be a couple of vents which can be tweaked as the seasons change - one venting to the outside and one into the house. Be aware that if you send heat through a long duct and it has chance to cool down due to losses through the duct walls, what you end up coming out the far end is a cool breeze - which might not be desirable in the middle of winter :-)

cheers

Jules

[Tim Watts]

The OP might be able to deal with that with some sort of intumescent vent in the duct - ie one that closes off as soon as fire hits it. Sure I've seen those somewhere.

[Jules Richardson]

True. I wondered about some kind of flap which closes due to gravity, but is held open by a weak link that will fail in the presence of too much heat.

It sounds like the sort of thing that should be readily available as a commercial product, but I've not seen - perhaps the issue is that completely blocking the output on a running system (where the heat source is a wood or propane furnace[1], say) might cause problems of its own. In the OP's case though an accidental failure would just result in overheated servers - which I'd hope would just shut themselves down nicely rather than cooking.

[1] I think ours is designed to shut itself down if it detects too much back-pressure, but there are perhaps older ones still in service which lack such safety features.

cheers

Jules

[Grimly Curmudgeon]

You can get heat-fusible links that hold oil valves open, but they're normally mounted right on the front of the furnace casing, above the burner. Connected to a wire rope, through a pulley that holds up a weight on the gravity valve. Clever design, been around for ages.

[Andy Burns]

Is this sort of thing up to the job?

[Tim Watts]

Sorry for the out of step reply.

Physics building at Imperial has some shutters on the lift doors - at least in the basement level which are held up by fusible links.

So it is an established idea. Intumescent grill is probably more foolproof though.

Probably the dogs bollocks:

but looks OK:

[Tim Watts]

[polygonum]

An intumescent grill sounds a really bad way of cooking bacon or toasting bread...

[SteveW]

In an industrial situation, where a vent is required for safety reasons, but would be a risk in a fire, we use an actuated damper (only takes a few watts to keep it open), with spring return and a sensor. Smoke or heat detection cuts power and the damper closes.

SteveW

[Theo Markettos]

Depends on the volume. It might turn a room or two from 'chilly' to 'bearable', but it's not going to cook the house. It could bring things from, say, 13 to 18degC, assuming a well-insulated room.

I've had 100W computers on in badly-heated rooms in the winter, and it does take the chill off.

Theo

[harry]

in the ceiling of the cupboard is a large in-line extractor fan, connected= to a thermostat.

sucked out of the cupboard and blown outside. =A0The air coming back in is = drawn from the garage, through the filter.

me of that warm air to take the chill of the house. =A0I mean, its just bei= ng wasted at the moment.

t the warm air back outside in the summer, and probably fit a noise baffle.

elly or full of insects? =A0Would it make so little difference as to not be= worth the effort?

Just look at the total wattage of your servers. Every bit will be turned to hat.

[Jim K]

ed in the ceiling of the cupboard is a large in-line extractor fan, connect= ed to a thermostat.

s sucked out of the cupboard and blown outside. =A0The air coming back in i= s drawn from the garage, through the filter.

some of that warm air to take the chill of the house. =A0I mean, its just b= eing wasted at the moment.

ect the warm air back outside in the summer, and probably fit a noise baffl= e.

smelly or full of insects? =A0Would it make so little difference as to not = be worth the effort?

what of the bytes?

Jim K

[Grimly Curmudgeon]

Fascinator!