china/India – Cop 26

[Nigel Graham 2Participant @nigelgraham2]

I am told by a friend in the trade – self-employed small-works builder and GasSafe registered gas fitter – that the major boiler manufacturers are now making boilers easily adjusted to take methane/hydrogen mixes, and ultimately just hydrogen.

Whence the hydrogen is another matter, of course.

He also pointed out that if you a house with a combination boiler and microbore plumbing, if you want to fit a heat-pump instead all the pipes and radiators will need replacing as well – oh and you have to consider what to do about hot water for the kitchen and bath/shower. I suppose it's possible heat-pumps will become developed to cope with existing systems but the snag is that the amount of heat they put into the water and the maximum temperature are a lot lower than a decent gas-boiler can give; hence the new radiators and pipes.

My pal then remarked that his house (an ex-Council 1940s end-of-terrace) would not be suitable for a heat-pump, at least not without a heck of a lot of work including finding room for the indirect hot-water tank. Mine (Edwardian end-of-terrace) certainly won't be then.

Somewhere in a small collection I have of engineering text-books from the first half of last centu ry is an intriguing analysis of a heat-pump driven by a small Diesel engine, showing the heat gained for the building is greater than that obtained from simply burning the oil. That does sound like something-for-nothing but I am not going to argue with a book written for professional engineers, on engine thermodynamics!

[J HancockParticipant @jhancock95746]

Not silliness TS , blame any shortage of gas for domestic heating on decisions made by 'officials' in high places who sold off our North Sea gas for quick financial gain.

Used for domestic and industrial purposes only it would have lasted 'indefinitely'.

Used to make electricity , almost criminal waste.

Nuclear and clean coal was the way to go , plus renewables of course.

[Sam B 1Participant @samb1]

Posted by J Hancock on 18/11/2021 22:14:44:

Not silliness TS , blame any shortage of gas for domestic heating on decisions made by 'officials' in high places who sold off our North Sea gas for quick financial gain.

Used for domestic and industrial purposes only it would have lasted 'indefinitely'.

Used to make electricity , almost criminal waste.

Nuclear and clean coal was the way to go , plus renewables of course.

burning gas to make electricity and then using that electricity to run heat pumps is a far more efficient way to heat homes than burning gas directly; switching over to heat pumps allows our limited resources go much further

[Paul KempParticipant @paulkemp46892]

Posted by Sam B 1 on 18/11/2021 23:12:12:

burning gas to make electricity and then using that electricity to run heat pumps is a far more efficient way to heat homes than burning gas directly; switching over to heat pumps allows our limited resources go much further

Have you any credible figures to back that up? Granted CCGT is pretty efficient but taking into account grid losses and then whatever the efficiency of a heat pump is compared to the efficiency of a new condensing boiler that sounds a bold claim?

Paul.

[Sam B 1Participant @samb1]

Posted by Paul Kemp on 19/11/2021 00:49:21:

Posted by Sam B 1 on 18/11/2021 23:12:12:

burning gas to make electricity and then using that electricity to run heat pumps is a far more efficient way to heat homes than burning gas directly; switching over to heat pumps allows our limited resources go much further

Have you any credible figures to back that up? Granted CCGT is pretty efficient but taking into account grid losses and then whatever the efficiency of a heat pump is compared to the efficiency of a new condensing boiler that sounds a bold claim?

Paul.

hi paul, i'll give it a go!

the efficiency of heat pumps comes mostly from them providing more useful heating output for the energy put in since they're moving heat that already exists instead of directly creating more of it. they're typically around 2.5 – 3.5 "coefficiency of performance" for air-source heat pumps (ground-source are higher but they're more complicated to install), so 1kw electricity in would provide 2.5 – 3.5kw of useful heat out

losses on the grid seem to be at most 10% from this national grid eso document https://www.nationalgrideso.com/document/144711/download

the EEA lists efficiency of thermal electricity generation hair under 50% https://www.eea.europa.eu/data-and-maps/indicators/efficiency-of-conventional-thermal-electricity-generation-4/assessment-2

with these numbers if we put 1kw of gas into a power plant we'd generate 500w of electricity, there'd be 450w at the home after transmission losses, then the heat pump would be able to provide 1.125 – 1.575 kw of useful heating

i'm not sure about the losses on the gas network because i can't seem to find anything about it online for the UK (for reference it's about 9% in the US), but even assuming zero distribution losses the gas heater would only provide 940w of heating from 1kw of gas (modern condensing boilers seem to top out at 94% efficiency)

as an aside, a COP of 3 would mean that even if your electricity costs 3x more per kw/h than your gas it would still cost about the same to heat your home

 

one of the youtube people i'm subscribed to has a fairly lengthy video talking about heat pumps and they're really quite interesting things https://youtu.be/7J52mDjZzto

edit: fixed the links!

Edited By Sam B 1 on 19/11/2021 02:48:42

[JasonBModerator @jasonb]

The biggest problem is the COP value drops off as the temperature differential becomes less so just when you want the heat most in the winter you can't get any heat out of them so have to revert to using electric for heating and hot water.

Other times of the year they are very good, many a koi pond is now heated buy them with vast savings but those are people who heat their ponds in summer and the mass of the pond acts as a good heat store in winter so only a small amount from the pump needed to keep it up at the reduced winter running temp.

The Plumber that I usually recommend to clients was telling me he has removed 4 heat pumps (at least 1 was ground source) this year as they were costing the clients too much to run as in winter they would not provide enough heating let alone hot water so were running up big electric bills.

A duel system would work the best using the heat pump when outside temps suit and gas when they don't. even then it's going to make a lot of difference how well your house is insulated and if it has heat recovery and solar panels to help reduce cost of bought in electric.

[J HancockParticipant @jhancock95746]

A very good effort to justify heat-pumps Sam B , problem , compare the price we pay for gas/kwh against electricity/kwh and we see why , so few today , would choose to install heat pumps over a 'conventional ' gas boiler.

[Grindstone CowboyParticipant @grindstonecowboy]

Another friend works for the firm constructing these houses near Lancaster. Apparently no heating is being installed, all heat is supposed to come from appliances used in the homes, such as TVs, cookers, computers, lighting, etc. and the very high standards of insulation keep it in.

I'm just wondering how their air-tightness works alongside current government advice to open all your windows for ten minutes several times a day

Rob

Links to https://www.lancs.live/news/lancashire-news/futuristic-homes-built-lancaster-new-20333681

[Sam B 1Participant @samb1]

Posted by J Hancock on 19/11/2021 08:33:56:

A very good effort to justify heat-pumps Sam B , problem , compare the price we pay for gas/kwh against electricity/kwh and we see why , so few today , would choose to install heat pumps over a 'conventional ' gas boiler.

with current gas and electricity prices heat pumps generally work out to be about the same to run as gas boilers and can even be cheaper if you make use of off-peak hours

(**LINK**)

 

Posted by JasonB on 19/11/2021 07:45:58:

The biggest problem is the COP value drops off as the temperature differential becomes less so just when you want the heat most in the winter you can't get any heat out of them so have to revert to using electric for heating and hot water.

Other times of the year they are very good, many a koi pond is now heated buy them with vast savings but those are people who heat their ponds in summer and the mass of the pond acts as a good heat store in winter so only a small amount from the pump needed to keep it up at the reduced winter running temp.

The Plumber that I usually recommend to clients was telling me he has removed 4 heat pumps (at least 1 was ground source) this year as they were costing the clients too much to run as in winter they would not provide enough heating let alone hot water so were running up big electric bills.

A duel system would work the best using the heat pump when outside temps suit and gas when they don't. even then it's going to make a lot of difference how well your house is insulated and if it has heat recovery and solar panels to help reduce cost of bought in electric.

the COP drops as the difference between the input and the output gets larger. if we go by the coldest recorded temperature in the UK of about -27c in 1995 this COP graph suggests that if we wanted to heat a home to 15c (42c difference) it would still be close to that 3.5 COP, so should still economica

(**LINK**)

Edited By Sam B 1 on 19/11/2021 15:17:37

[JasonBModerator @jasonb]

Most people I know heat their houses to at least 20, 25plus where i've been working recently* which is not comfy. plus hot water for a family will need to be hotter and take a lot longer to heat a tank full.

People also want their heating on during the day so economy 7 is not going to be available then

 

* This is also one of the houses I mentioned the plumber having removed the ground source pump from, it's only 10-11 years old so well insulated and being on a sloping side one side of the ground floor is below ground so even more insulated by the natural warmth of the ground. Underfloor heating throughout so does not need the circulating water as hot as traditional radiators and the slabs make a good heat store. Yet it did not work well and cost considerably more than gas would. And that was for the previous owners who I doubt liked the temperature as my clients who bought the house earlier this year.

Edited By JasonB on 19/11/2021 18:55:14

[SillyOldDufferModerator @sillyoldduffer]

Posted by JasonB on 19/11/2021 18:52:01:

Most people I know heat their houses to at least 20, 25plus …

Am I the meanest coolest bloke on the forum? I run my heating at 18°C for 90 minutes in the morning and 17:30 to 22:00 in the evening.  During the day it's off. And I like to sleep with the window cracked open.

The secret is partly dressing warmly but mainly getting used to a lower ambient. If I toast myself at 24°C for a week or two, it feels normal and anything less is uncomfortable. Now I'm used to 18°C anything more is too hot.

Of course this is nothing compared with the good old days. I think it's Kilvert's Diary that mentions needing to break the ice on his morning bath…

And talking of Christmas, bah humbug,

Dave

 

 

Edited By SillyOldDuffer on 19/11/2021 20:47:56

[Paul KempParticipant @paulkemp46892]

Ok, I see how the figures Sam B1 is quoting could stack up on efficiency but running cost is another perspective that is probably more important to the average householder than efficiency. On the efficiency question the figure Sam quoted for generation efficiency is a little lower than my off the cuff guess but the transmission loss a little higher so ball park around what I was expecting.

In terms of cost the latest averages I can find for September despite the gas price rises put electricity per kWh at around 4.3 times the cost of gas. I also did a bit of digging on heat pump COP and it would seem that yes a COP of 4 or higher is achievable in ideal conditions but the norm is between 2.5 and 3.5 – so considering the high capital cost plus the higher running cost only the most dedicated of greens would be attracted.

In Dave's (SOD) example of heating use a heat pump system considering its apparent average limit of 40 degrees C on the hot side he would need to be running it considerably longer to get the same heating rise in the house?

Seems another example of the gap between environmental sustainability and economic sustainability to me. Granted price differentials may change between energy sources and legislation may drive change but if it's the latter there will be a lot of people driven below the poverty line.

Paul.

[Grindstone CowboyParticipant @grindstonecowboy]

As I understand it, heat pumps will basically need to be run 24/7 throughout the colder periods in order to keep the mass of the building warm – coming home to a cold house and then turning the heating on to warm the place up for the evening will no longer be an option. It may just about work in well-insulated structures with low thermal inertia, but not in traditional UK builds. Additional heating will be a necessity, along with long woolen underwear. Winter draws on, as they used to say

Rob

[duncan webster 1Participant @duncanwebster1]

I'm now looking at replacing a gas wall heater which seems to have developed a fault in its control board, now obsolete. If it wasn't gas I'd have a go at making one from an Arduino. 2 fans, various sensors and a board full of electronics. My first gas fire had an on/off valve and you lit it with a match. OK I'd have a flame failure device nowadays, but the replacement will be as simple as I can get. Heat pump sounds to me to have the potential for a lot of expensive maintenance.

[Author]

Posts