heat pumps anyone ?

And where does the grant money come from? The magic money tree?

Bill

They're going to put gas up until it matches electricity. They don't give a s*it about ordinary working people.

Bill

Of course it works well in Sweden.

If you have suggestions as to how we can suddenly get houses with perfect insulation and lots of air ducting, then feel free to make them.

Not when the house is super insulated.

I think you could rejig the tariffs to encourage people to move away from gas without increasing bills massively.

For example, take the green charges which are currently on the electricity unit cost and move them to the gas standing charge. So it would cost (made up number) £200 a year to have a gas supply, and electricity would become cheaper. There's probably a point at which that's breakeven on current bills. Critically, it doesn't involve increasing the gas unit cost so it doesn't push people further into fuel poverty. Maybe people on benefits and vulnerable groups would have the standing charge rebated to help here, as well as support for replacing their heating.

Then make disconnection free. If people get their gas disconnected they save £200 a year. That would provide a direct incentive to replace gas appliances with those using electricity.

(You'd have to do something similar with oil - I'm not sure how that would work. Although with cheaper electricity the balance would swing away from oil too, and maybe that would be enough)

Theo

No, that's a bit of his rant that only makes sense if you already know what he's talking about.

First of all, heat pumps are more efficient at lower temperatures. Instead of running your boiler at 70-80C you run the heat pump at 40-50C.

That means you need larger heat emitters - bigger radiators, UFH.

For hot water, on a gas system your tank might be at 60C but when you use it you mix it down to ~40C. So it's not a big deal to have a tank that runs at lower temperature, it just means you lose a bit of tank capacity as you're diluting it less.

The kitchen tap is about the only place you actually want 60C hot water - many people mostly use dishwashers, and instant-heat taps are available (either fancy Quookers or $20 versions from China) to boost the temperature..

The only reason[1] to run the hot water immersion is to prevent growth of legionella, which needs 60C water. Which is something you do once a week, and you can do that at a time of cheap electricity. You use the heat pump to get it to 50C or whatever it does, and then boost with the immersion the extra 10C.

So let's say you have a 300 litre tank, on my numbers that 10C boost takes

Not such a good rant any more, is it?

Theo

In theory, of course. But when temperatures get close to 0C the efficiency drops from freezing issues. If you use ground sourced heat then I might agree with you.

Adding UFH is a big cost and a massive upheaval in a house that is being lived in. While larger radiators can be ugly and restrict the placement of furniture.

Which does not work well for a family. We run out tank at 70°C to obtain enough capacity to allow 5 showers one after the other, when we may already have been using hot water for other purposes.

And where do most houses fit a 300l tank? Ours is 40 gallons and we could not increase the size without taking space off an already smaller than really needed bedroom.

Interesting idea but how will the electricity grid cope with the additional loads of:

heat pumps electric cars electric hot water cylinders

and where is all the extra electricity going to come from?

SH wrote on 25/07/2021 :

The smoke and mirrors lol

Which, if it used electricity, would in effect lower the overall efficiency gained by the use of a HP...

How? I have a heat pump tumble drier - it's about 2-3x as efficient as a vented or condenser dryer. It's basically a dehumidifier with a spinning drum (COP=2-3). Heat that leaks out to heat the airing cupboard is not useful heat - you don't want to heat your airing cupboard in midsummer. If you do want drying, use an appliance designed for the purpose. It also avoids increased dampness in your house.

Theo

My 350 l tank has the proper 50 mm of foam insulation, but the losses when hot are still about 350 W.

Chris

I looked into these a couple of years back. I came to the conclusion:

In short it was a no-no, and when used in the winter months it adds to the house heating.

My condensing tumble drier introduces little or no humidity to the house. Vented tumble are not as common as they used to be.

Oftentimes the losses mostly aren't from the tank itself, but from the pipework leading to tank. Are all the pipes in your airing cupboard/etc lagged with decent insulation?

Theo

Yes time taken is longer, but to an extent, so what?

Our old dryer took a few minutes under an hour. The cycle on our new one "takes" an hour and 50 minutes - except that much of the time, it decides the water content of the air is lower than expected and it reduces the time to about 1 hour and 20 minutes

Our old dryer used 4.5 units per cycle, the current one uses about 1.34.

With 5 of us, we use it a lot - especially for school uniform that is needed the next morning.

We figure that it will pay for itself in just over two years (although we did pay a reduced price for it at a clearance outlet).

Tumble driers accelerate the wear of clothes. I prefer more cloth and less felt that a shorter tumble might give me.

Mine perhaps doesn't get the same usage. Perhaps in a few years time you can tell us it hasn't broken down or the heat exchangers aren't clogged? I can dismantle the guts of mine to get rid of the felt and fluff fairly quickly.

The heat exchanger is accessible for cleaning from an opening front panel. Supposed to need cleaning every 6 months or so. The air-flow goes through two filters, so not much gets past them.

We'll see how well it lasts. I hope that it will last a good few years, but as it'll pay for itself in around two years, it won't owe us anything after that.

It sounds as if some thought has been put into the design. Mine has a single filter. But then I can remove the heat exchanger and give it a thorough cleaning.

I liked the idea of a heat pump drier in principle.

Fair enough, it sounds a good choice for you and your family.