Log in to the online community

Want to post a reply? You'll need to log in
Turning Down the Thermostat.
22 Replies
Zoomup
2736 Posts

What the PM wants: No more gas boilers in new builds from 2023, and 600,000 heat pumps installed a year

How much it will cost: £500million of taxpayers' cash on new hydrogen tech



 

Air-source heating systems extracts heat from the outside air, working in the opposite way to a fridge which extracts heat from the inside.

The process is so efficient that it can absorb heat from the air even when the temperature drops to below -30C.

The heat from the air is absorbed into a fluid, which then passes through a compressor where the temperature is increased to heat the home.  

It is considered to be a more efficient and environmentally friendly method of heating as the heat that is being mined is renewed naturally over time.

It also requires less electricity to run, meaning it can be easily powered by solar panels.

There are several downsides to an air-source heating system, however.

They are noisy, similar to an air conditioner, and require larger radiators to heat the home effectively.

Underfloor heating is the most efficient means, which can prove costly, and the system requires a well-insulated home. 



Ha, ha, ha ,ha ,ha, ha, ha haaaaaaaaaaaaaaaah choke!😀

Z.

kfh
162 Posts
I can just imagine the floors of the majority of current housing stock being dug up to instal underfloor heating. If we install larger radiators instead then the pipes may also need to be changed. Of course additional insulation will also be required and it would help if the house were airtight with MVHR installed. it may be cheaper to knock them all down and rebuild to a decent standard. 

I have become very cynical in my dotage.
ebee
1150 Posts
go and live in a warmer climate might be more cost effective/enviro friendly

Oz seems better in that respective and you see lots o` kangaroos too
Chris Pearson
2495 Posts
ebee:
go and live in a warmer climate might be more cost effective/enviro friendly

No, you still need the heat pumps, but run them the other way around.

If underfloor heating becomes widespread, it will certainly affect what we do. No more lifting floorboards, and ceilings down for new circuits!

On the plus side, knees will be preserved longer, although perhaps at the expense of arthritic necks.

Zoomup
2736 Posts
ebee:
go and live in a warmer climate might be more cost effective/enviro friendly

Oz seems better in that respective and you see lots o` kangaroos too

The only trouble with living in Oz ebee is that the creatures that don't eat you will bite you. 

Z.

Redback spiders are lethal too.

Back to heat pumps. I posted this in the Telegraph in response to a turning down the radiators article.

It really is time that the Government took some advice from Engineers. All of these "everything electric" plans are completely unworkable without the replacement of the entire electrical distribution system and 10 new nuclear power stations. The cost £3 trillion. By 2030, you have to be having another laugh at the public. Air source heat pumps sound ok on paper until you understand the specification. With air at -10C (not unusual in Britain) and 50C outlet temperature they perhaps give 2 times the heat available from electricity directly. The electricity costs 4 times as much as gas, guess what, you pay twice as much money to run a complex system which is expensive to maintain! The article above is Green rubbish, no truth whatsoever. As for Hydrogen, forget that, it needs twice the electricity to make it as the heat from burning it. Simple chemistry, not understood by the new "Green" Government.

David CEng etc (Thats a real Engineer by the way!)

I got another Engineers reply

@David Stone 

As another real Engineer I completely agree. Unfortunately the entire government is technically and scientifically illiterate, something that ministers actually seems to revel in. They like to say that they are led by the science but that is simply not true. They are led by dogma. Having "green" taxed electricity to the point where it is uneconomical for high power applications such as heating and transport they now want to mandate it as the only energy source that is "green", which, of course, it is not.

It is not just the Mail!

 

broadgage
611 Posts
There is no proposal to ban gas heating in EXISTING homes, therefore no need to dig up floors in existing homes to fit underfloor heating.
The plan to is to prohibit gas central heating in NEW homes in a few years time.
Improved insulation will also be required in order to reduce heating demand.
Chris Pearson
2495 Posts
Those targets are quite arbitrary and unrealistic, but they will come eventually.

When fossil fuels have become sufficiently scare or difficult to mine, and therefore expensive, electricity will be cheap in comparison.

In the mean time, by all means expand photovoltaic and wind generation if only to make the fossil fuels last longer.
ebee
1150 Posts
Redback spiders are lethal too. Not many actual deaths though I`m told.

People killed by Cows in Britain/ People killed by sharks world wide (yearly averages) is a number far greater than 1

The real danger actually is the number of sharks (also other animals) killed by a number of the most dangerous animals on this planet - human beings
Simon Barker
865 Posts
davezawadi (David Stone):
Redback spiders are lethal too.

Back to heat pumps. I posted this in the Telegraph in response to a turning down the radiators article.

It really is time that the Government took some advice from Engineers. All of these "everything electric" plans are completely unworkable without the replacement of the entire electrical distribution system and 10 new nuclear power stations. The cost £3 trillion. By 2030, you have to be having another laugh at the public. Air source heat pumps sound ok on paper until you understand the specification. With air at -10C (not unusual in Britain) and 50C outlet temperature they perhaps give 2 times the heat available from electricity directly. The electricity costs 4 times as much as gas, guess what, you pay twice as much money to run a complex system which is expensive to maintain! The article above is Green rubbish, no truth whatsoever. As for Hydrogen, forget that, it needs twice the electricity to make it as the heat from burning it. Simple chemistry, not understood by the new "Green" Government.

David CEng etc (Thats a real Engineer by the way!)

 

If you want to get decent efficiency out of a heat pump, then 50C output temperature is far too high.  Try fitting bigger radiators, and turning it down to the mid 30's.

For new builds, a ground source heat pump would be much better, but they don't make for an easy retro-fit.

whjohnson
440 Posts
What I wonder about is what happens if ground source heat pumps are adopted hugely on a national scale. What does mass lowering of ground temperature do to the local environment? Will we end up with huge desiccated areas pf permafrost? And how well does this serve building foundations and the like?
whjohnson
440 Posts
I was listening to some eco expert on the radio who is not dogmatic about the subject. He was saying it as it is. The government  policy is just hogwash and will never happen. He said that they have done all the easy hidden bits to get towards net zero carbon emissions by shutting down carbon emitting power stations and exporting manufacturing to China. These acts have only gotten us down to the 50% reduction figure.
Now for the difficult bit where it starts to impact upon your everyday voters life. Who on earth has a spare £18,000 lying around if they don't  live in the North London suburbs? No-one!  Who is going to turn down their thermostat by 10 degrees and shiver, No-one!  When a survey was done in America and folk were asked if they were willing to do their bit for the planet and drive an electric car, everyone said yes. Asked how much they were willing to spend per month to do their bit, all they were willing to spend was $10. So much for having a coherent government policy on so-called global warming.  All PPE graduates working in Govt should be banned from being involved in determining polices which have anything to do with science.
mapj1
3421 Posts
We do seem to suffer a generally clueless society at almost all levels of decision making, including newspaper editing.
Looking at that Daily Mail article I wonder how many readers will look at the picture of an external heat exchanger and read the caption.
One of the heat pumps, which extracts the air and turns it into fluid which is heated
And think that  liquid air has something to do with it..
Also running the water in the radiators 10 degrees lower does not mean you run the thermostat 10 degrees lower, just that it takes rather longer for the house to reach the target temperature, and on a cold day it may not make it at all if losses exceed the rate of heating.  Actually quite a lot of the older heating systems that were single pipe ran the rads at the end of the line a lot cooler than that.

It might be better if the govt tried to put some effort into proper eduction of its own officers and more immediately into researching better ways of lagging solid walls, perhaps the mass production of polymer Aerogel insulation, and then training up the next gen of nuclear power engineers. I suggest by around 2030 it will become  obvious we need both.
Mike.
 
Chris Pearson
2495 Posts
mapj1:
... and then training up the next gen of nuclear power engineers. I suggest by around 2030 ...

Are 9 years long enough to get past the hurdle of acceptability? And in any event, the power stations need to be built first. Perhaps we will all have to get used to the idea of local submarine-style reactors? 😁

AJJewsbury
2499 Posts
If underfloor heating becomes widespread, it will certainly affect what we do. No more lifting floorboards, and ceilings down for new circuits!
That's a very good point - perhaps we'll move over to a more continental style of wiring (where solid concrete upper floors are far more common) - often in conduit with horizontal runs somewhere above "picture rail" heights. Maybe a re-consideration of the "safe zones" might be good.

I guess the real challenge is not so much to change the source of heating, but to reduce the heating requirement in the first place. We have the technology now to build new homes that should need no more than about 2kW in space heating even during the coldest nights - and for much of the year next to nothing at all - at that sort of level even simple resistive heating is going to be affordable. Upgrading existing stock is a lot harder, but not impossible. In 2010 I got my current home - which hadn't had much done to it since probably the 1970s so was due a pretty radical overhaul anyway - 1910 stone built semi - pretty cold and draughty - the first winter cost me about £1000 in gas for just one quarter (and didn't really do much more than take the chill off the place) - so probaly have been over £2k/year if I'd kept it on. As we were going 'back to brick' (and joists) anyway, installing a substantial amount of insulation, triple glazed windows and a HR ventilation system wasn't particularly disruptive. The same gas boiler is still the primary source of heat, if supplemented by a small solar thermal panel and a very occasional log fire, but my gas consumption is now below £300 a year (and that's with SWIMBO demanding the room stats several degree higher that I would have set them!)

   - Andy.
Zoomup
2736 Posts
Simon Barker:
davezawadi (David Stone):
Redback spiders are lethal too.

Back to heat pumps. I posted this in the Telegraph in response to a turning down the radiators article.

It really is time that the Government took some advice from Engineers. All of these "everything electric" plans are completely unworkable without the replacement of the entire electrical distribution system and 10 new nuclear power stations. The cost £3 trillion. By 2030, you have to be having another laugh at the public. Air source heat pumps sound ok on paper until you understand the specification. With air at -10C (not unusual in Britain) and 50C outlet temperature they perhaps give 2 times the heat available from electricity directly. The electricity costs 4 times as much as gas, guess what, you pay twice as much money to run a complex system which is expensive to maintain! The article above is Green rubbish, no truth whatsoever. As for Hydrogen, forget that, it needs twice the electricity to make it as the heat from burning it. Simple chemistry, not understood by the new "Green" Government.

David CEng etc (Thats a real Engineer by the way!)

 

If you want to get decent efficiency out of a heat pump, then 50C output temperature is far too high.  Try fitting bigger radiators, and turning it down to the mid 30's.

For new builds, a ground source heat pump would be much better, but they don't make for an easy retro-fit.

If the pipes are too short, ground source heat pump systems have been known to just freeze the soil.

Z.

Simon Barker
865 Posts
Zoomup:
Simon Barker:
davezawadi (David Stone):
Redback spiders are lethal too.

Back to heat pumps. I posted this in the Telegraph in response to a turning down the radiators article.

It really is time that the Government took some advice from Engineers. All of these "everything electric" plans are completely unworkable without the replacement of the entire electrical distribution system and 10 new nuclear power stations. The cost £3 trillion. By 2030, you have to be having another laugh at the public. Air source heat pumps sound ok on paper until you understand the specification. With air at -10C (not unusual in Britain) and 50C outlet temperature they perhaps give 2 times the heat available from electricity directly. The electricity costs 4 times as much as gas, guess what, you pay twice as much money to run a complex system which is expensive to maintain! The article above is Green rubbish, no truth whatsoever. As for Hydrogen, forget that, it needs twice the electricity to make it as the heat from burning it. Simple chemistry, not understood by the new "Green" Government.

David CEng etc (Thats a real Engineer by the way!)

 

If you want to get decent efficiency out of a heat pump, then 50C output temperature is far too high.  Try fitting bigger radiators, and turning it down to the mid 30's.

For new builds, a ground source heat pump would be much better, but they don't make for an easy retro-fit.

If the pipes are too short, ground source heat pump systems have been known to just freeze the soil.

Z.

True.  Unfortunately, too many installers will cut corners.  They usually work well for the first winter.  But they suck so much heat out of the soil that it never recovers over the following summer.

The situation would be improved if the system is designed to operate as air conditioning in summer, sucking heat out of the house and pushing it into the ground.  But the government will only subsidise systems that are not reversible.  So having one extra valve to reverse the coolant flow can cost the customer a fortune.

Our government is really clueless, thrashing around in the dark and grasping at 'solutions' that are mainly greenwash.
Our electricity generating capacity isn't going to cope as it is if there is a high take up of electric vehicles. Where do they think the capacity to run 'all electric' homes is going to come from?
My twopennyworth for an increase in renewable energy solution - tidal stream turbines close to population centres. The Pentland Firth is all very well but not many people living up there. There are very useable tidal streams at Portland race, West Solent and Severn bridge. All in the populated south of England. 
That backed up with a fleet of small, local British designed and built nuclear power stations would fit the bill.

Are the pigs fuelled and ready for takeoff?
mapj1
3421 Posts
  

Maybe they do not need fuel. ?
ARE
3 Posts
"Unfortunately the entire government is technically and scientifically illiterate." 
David, if you are minded to explain 'entropy' to our politicians I wish you well ;-)

Tony E
Andy C
26 Posts
Simon Barker:
davezawadi (David Stone):
Redback spiders are lethal too.

Back to heat pumps. I posted this in the Telegraph in response to a turning down the radiators article.

It really is time that the Government took some advice from Engineers. All of these "everything electric" plans are completely unworkable without the replacement of the entire electrical distribution system and 10 new nuclear power stations. The cost £3 trillion. By 2030, you have to be having another laugh at the public. Air source heat pumps sound ok on paper until you understand the specification. With air at -10C (not unusual in Britain) and 50C outlet temperature they perhaps give 2 times the heat available from electricity directly. The electricity costs 4 times as much as gas, guess what, you pay twice as much money to run a complex system which is expensive to maintain! The article above is Green rubbish, no truth whatsoever. As for Hydrogen, forget that, it needs twice the electricity to make it as the heat from burning it. Simple chemistry, not understood by the new "Green" Government.

David CEng etc (Thats a real Engineer by the way!)

 

If you want to get decent efficiency out of a heat pump, then 50C output temperature is far too high.  Try fitting bigger radiators, and turning it down to the mid 30's.


So, assuming normal UFH type temps of 40/30C and room temp of 20C, dT=15C. That means my (t)rusty steel panel radiator will chuck out about 20% of its dT50C rated output. So for a typical room of about 1kW heat loss I now need a radiator which is rated at 5kW! Or looking in my Stelrad book I go from a 500mm long rad to a 2.5m long rad. More's the problem, how the hell do I fit that in the room????

As it happens, I've been working on alterations to a very large domestic property which has UFH from an ASHP. The new owner is planning to build a major extension, just about doubling the floor area, and this was designed with UFH throughout. He later added a requirement for air conditioning to several existing rooms plus several more rooms in the new extension. I am now thinking, why bother with UFH in the new build, just install a/c throughout. No need to heat an intermediate liquid (water), just use the a/c units for heating (and cooling) plus the added bonus of being able to transfer heat extracted from the rooms in summer into the hot water system.

Which gets me back to the o/p, why are we going on about rads? If we want decent levels of heating in the existing building why not go down the a/c route? Okay, if you already have a wet heating system then you'd have to rip it out but since you'd have to do most of that anyway to fit the mega-size rads needed you are already halfway there! The downside is such systems will be more expensive to install, plus you still have to get the juice from somewhere (perhaps the hot air from parliament could be harnessed to solve the issue!).

Finally, one more sting in the tail for ASHP use: check the rated outputs at your design outside temps. I had a community centre with UFH fed from a ASHP, total heat requirement about 70kW for -4C outside design temp. Manufacturers came up with what they said was a suitable unit but when I checked I found the figures were quoted for 7C outside temp. When this was pointed out to them they upped the size to a 100kW unit which also wiped out most of the spare capacity on the new transformer which was going into the site!

mapj1
3421 Posts
Better designs of heat pump exist  for use with a wider range of operating temps however, the offerings currently available commercially are all single stage and quite basic by comparison. There is the complication of  different optimum refrigerant in the cascade design as well.. Confusingly some are described as dual mode, where the single compressor has switched bypass ports in the middle of the scrolls that allow better optimised operation at two different pump rates (as opposed to variable speed drive - compressors get inefficient at low rates, as the refrigerant has time to sneak back round the outside of the moving bits.).
diagrams below indicate some possible futures that may make it just about possible  have an ASP with gas boiler exit temperatures and sensible COP without too much upheaval. Just have to wait for them to make it out of the lab into production. (Evaporator is cold side, condenser is hot side...,)
Mike.
better heat pumps

Share:

Log in

Want to post a reply? You'll need to log in