Heat driven heat pumps

[Mark]

yes

[Theo]

No.

That's not driving a domestic heat pump, it's just heatsinking into the pool water. There's no compressor or refrigerant, just a heat exchanger. Heat never gets transferred to a hotter place.

That said, it would in theory to be possible to use a heat pump to convert low level waste heat into higher grade heat (ie a bigger temperature difference). So you could use datacentre waste heat to boil water if you wanted (and had the right refrigerant). I'd guess that could be useful for something like papermaking or brewing, where you need quantities of hot water. No idea of the practicalities though.

Theo

[Tim+]

I’ve already shared that link. I don’t recall mention of a heat pump in that article, only the direct use of waste heat.

Tim

[Jim Jackson]

We never heated the water. We only had running water from the well for 6 months of the year - after the rains. Then it was delivered in drums filled from the river. Was quite warm to start with!

[GB]

Here is a link:

They claim a 30% saving in gas compared to a conventional gas boiler.

[GB]

I've posted a link showing a 30% gas saving compared to a conventional boiler. In our draughty house that would be a significant saving.

Bear in mind that you get the heat from the gas, and whatever extra heat it extracts from the outside air is a bonus.

[Andrew]

Nothing sucks like an electrolux.

I had one for years, in this country. Silent and could run on any heat source with the correct electrolux kit.

Kept the milk and other stuff cool but didn't have a very useful freezer compartment from recollection. Only two stars I think.

[Theo]

That's interesting. COP of 1.5 which isn't amazing but useful if you're doing gas anyway. Seems the units start at 45kW so that's a bit big for domestic use, but could work for commercial/industrial premises. They also do cooling, which you don't get from a gas boiler.

I suppose it comes down to whether the increase in cost due to complexity over a gas boiler is worth the efficiency saving. I'd guess in most premises for heating you'd not be running the unit all the time (and should look at your insulation beforehand) so the payback might not be so good. But if you were using it in say a laundrette or hotel or something where it was running all day, it could make sense.

Theo

[GB]

I know people paying £10k a year for gas at the moment, so a £3k pa saving would be a 4 year payback. When I last looked, the machines cost £8k, plus say £4k for installation.

There are no grants available, but if your boiler needed replacement anyway, the payback would be quicker.

The downside is that they take up space, and they may make a noise.

[Vir Campestris]

Seems to me the right thing to do is a combined heat and power system. Run an engine to get your electricity, and use the cooling water and hot exhaust as a source for warm water for a heat pump.

That's assuming of course you don't care about install cost!

Andy

[Tim+]

Until the summer when you’re generating expensive electricity and throwing away all your heat…

Tim

[Theo]

I think you'd turn off the CHP and use grid electricity instead in the summer. But the problem is in the spring and autumn: you want *some* heat, but you don't want to run the CHP full-bore because that would make too much. I don't think they're very good at modulating down.

Theo