Heat pumps - ThisIsMoney

[RJH]

Interesting (if over my head) - thanks again

[Sargan]

Air Source Heat Pumps have a couple of major issues.

1. Efficiency drops with ambient temp, so the 4x efficiency that nice Salesman talks about, is great when air Temp above 35C (when you don't need Heat Pump At below 10C efficiency drops, and really drops off as you get close to

0C (when you need most heat) COP graph will show the trend. If installed form new - at least you won't have boiler costs ... but if replacing a boiler seriously check your payback period. Most Sales guys base payback on 4x efficiency

1. Noisy .... these things can make a lot of noise, as the compressor fans run.

2. Life expectancy .... the cheaper ones (being advertised everywhere) have a poor life expectancy, less than 10 years .. expensive to replace. A simple check is what is the warranty period .... does it at least match the payback period .... most don't 2yr for many.

Ground source is more efficient and not impacted by ambient temp, but much more expensive to install & run.

Will they be the new standard offering for new builds .... or will Hydrogen boilers become the way forward. Competed village trials going on currently.

>

[Fredxx]

Once again, you don't have a clue. Are you saying someone who gets a FIT payment and exports power has some special wiring to their house?

I thought we were discussing Heat Pumps, as per subject?

[Fredxx]

You are so out of touch with reality:

What's wrong? Are you suggesting the combination of electricity generating equipment and heat pump installations are simpler than a basic boiler?

[Theo]

This is the SCOP: the seasonal coefficient of performance. SCOP is calculated on the number of heating days across the year, ie what you get is the average performance over the year (SCOP = heating energy out for the whole heating season divided by electrical energy in).

My ASHP has a SCOP at 35C flow temp of 5.4. That's a bit low flow temp if you have radiators (mine is about 40C unless doing hot water) so the real SCOP is going to be a bit less.

I wouldn't pay much attention to sales guys and their idea of payback. At the very least, predicting where energy prices will go is very much an open question.

Mine is about as noisy as a fridge, when standing a metre away from it.

Mine has a 7 year warranty.

Agreed.

Hydrogen is a scam promoted by the fossil fuel industry. Burning hydrogen for heating has an end-to-end efficiency of about 50%: ie you lose about half of your electrical energy through electrolysis, transmission and combustion.

As above heatpumps have an efficiency in terms of electricity energy of

300-500% (SCOP=3 to 5, 3 being quite pessimistic).

I can't see why you'd want to use something that costs you 10x more to run. Even electric heating would be cheaper.

The only redeeming feature of hydrogen is that it *may* be feasible to store it seasonally using natural gas infrastructure (hence why gas companies are interested). But then you could turn it back into electricity and get your SCOP=3 to 5 gain by having a home heatpump, instead of expensively piping it everywhere.

Hydrogen may have applications in steel production, long distance trucking and shipping, but doesn't make sense for domestic heating.

Theo

[Rod Speed]

We'll see...

Nope. But they certainly have a lot more than just a meter change and the grid outside their home doesn't stay unchanged forever.

But not WATER HEATING, f****it.

[Rod Speed]

We'll see...

Doesnt say that most electricity generation comes from fossil fuels.

Nope, dope.

[Fredxx]

And Theo mentioned water heating. Do keep up at the back.

[Rod Speed]

Not JUST FOR THAT, you pathetic excuse for a bullshit artist.

[Fredxx]

The idea behind it is that if there's an excess of electrical generation hydrogen can at least be stored. There is no other point in making hydrogen fuel.

[Fredxx]

Sign of another lost argument.

[Rod Speed]

You never could bullshit your way out of a wet paper bag.

[alan_m]

Rare to have the outside and inside of the property at the same temperature at any time of year.

[alan_m]

Could it just mean that in the past 50 years the UK has lost all its heavy industry that was a large consumer of energy? The UK has just exported much of its CO2 emissions by importing items we formerly made.

[Rod Speed]

alan_m [e-mail]> wrote

No, because it hasnt most obviously with aircraft wings and the biggest aircraft turbine engines.

And there is still a lot of heavy industry with concrete, roads, bridge building, major buildings etc etc etc.

That's not really clear with even stuff like ship building which hasnt in fact actually been imported at all.

[The Natural Philosopher]

They already are. I pent a year next to tow new builds and they were built exactly according to building regs, with MASSIVE insulation (at least 6" everywhere), air tight doors. (even down to needing clingfilm over the toilet bowls, and extractor fans to meet the pressure tests and heat pumps).

Here there is no gas, and oil is now not allowed I think, They had that or propane, and that was cheaper. The units were patently too small to really work in winter, and log burners had been added as well, without ventilation either.

It will all come good when we finally go nuclear, and electricity gets to be cheap as chips, and climate change is seen to be a load of bollocks - and they can retro install 3 phase direct heating coils instead.

I mean, if energy is virtually free, who cares about efficiency?

[The Natural Philosopher]

Not that rare to within a few degrees.

I know that the three months of winter chew up twice as much oil as i use in the remaining 9 months

I believe UK (and world) average temperature is 9°C. Plus or moins. I like to keep the lower part of the hose around ~19°C and the upper at ~17°C so lets say ~18°C - 9°C is my *average* temperature differential.

But in winter than can go to - with wind-chill at least double that. But in summer its the other way around as temperatures often climb above 15°C.

In the spring and autumn though, with daytime solar gains, those just match teh losses at might and I need almost no heating at all. The reality is that my CH boiler, which I never bother to switch off, simply stops calling for heat from about April thorough to November.

And in June I tend to shut the Aga off as well. And service it.

The reality is that one needs - with a well insulated house with UFH and massive concrete floors, big south facing double glazed windows, virtually no heat beyond solar gains from April to September.

Heat pumps will cope.

However the reality is that whilst October and March are survivable on low heat input, December January and ₣ebruary demand a huge increase in energy input and that is either going to require auxiliary heating or a failure to maintain sufficient internal temperatures

[Smolley]

To help, I have a chart:

[Vir Campestris]

Our radiators run about 50C.

It would not be practical to install radiators big enough to get the same heat output at 35.

It's also not practical to add enough insulation to our Listed house to require less heat.

Some of us aren't going to heat pumps any time soon.

Andy