Looks like the party is over....

[ProDave]

42 minutes ago, JohnMo said:

And not be hot enough to heat the cylinder (assume not combi). 

 

But most people just believe if you only have heating on for short bursts it save money. Forgetting they have a boiler capable of 30+kW and it runs flat out for those short bursts. So 4hrs flat out, instead of 18 to 24 hrs ticking away.

It is a combi.  Changing it for anything with a UVC would be my preference, I hate combi boilers.  But then the whole plumbing in that house is lousy, so much of it irritates me. (see thread about not wanting to move from my nice self build where everything is just right)

 

But my point is just adjusting the system she has, would make the house more comfortable, possibly reduce costs but certainly not increase them.  I wonder how many swap from that to a well set up ASHP and praise how good it is, when a lot of that goodness could have been achieved simply by adjusting what was there?

[JamesPa]

8 hours ago, Beelbeebub said:

If I had an electric 150m range would be doable *if* I could guarentee an easy fill up at the other end. Otherwise I need 300 miles (plus reserve) 

I don't think you wont have to wait long.  My 4 year old Kia e-Niro reliably does >240miles in the worst of winter, 300 in summer.  That's not much less than you need and thats a car from 4 years ago.

[JamesPa]

13 minutes ago, ProDave said:

But my point is just adjusting the system she has, would make the house more comfortable, possibly reduce costs but certainly not increase them.  I wonder how many swap from that to a well set up ASHP and praise how good it is, when a lot of that goodness could have been achieved simply by adjusting what was there?

I actually went down the sequential route as part of the discovery phase for my ASHP.

 

I first reduced my boiler temp to the lowest it would go (50C), then started operating 24x7.  That was as far as I could take it without changing radiators, in fact I needed to up the FT to 55 in the depth of winter.  I also limited my boiler output to the minimum possible (8.5kW in my case).  This arrangement was indeed more comfortable, and used less gas (it wasn't cheaper because prices went up at the same time, but it used less gas).   

 

Upsizing radiators, swapping to an ASHP (obviously with WC) and thus getting max FT down to 45, and FT most of the time to 35 or less, together with removing all but one TRV head made the big difference in comfort though. 

 

One day I will tot up how much I have spent on wholly unnecessary heating control equipment over the years (yes I too was suckered into trying 'smart' TRVs at one point - what a waste of time and money!).

Edited 3 hours ago by JamesPa

[Michael_S]

8 hours ago, JamesPa said:

Transmission losses and power station efficiency etc are all accounted for on the published figures for carbon intensity of fuels, which are updated annually.

 

The carbon footprint from UK domestic electricity per kWh is about 10% less than that of domestic gas, furthermore it's falling as we move to renewables.  That means that a heat pump with a cop of 3 causes less than one third the carbon emissions (actually it's a bit better still than that because most has boilers are set up by the heating industry in a way that makes them less than 100% efficient).  

 

This stuff is well established and the carbon case for heat pumps irrefutable.

 

 

So if it takes 2kwh of gas to generate 1kwh of electricity at the home (60% efficiency, transmission losses), then how come that kwh of electricity does not cost about twice what  a kwh of gas does - we need some allowance for the cost of the gas-fired power station but I believe this is not huge on a per unit basis and perhaps the electricity transmission grid costs more per unit than gas transmission? - but still doesn't explain why electricity is more like 4x the cost of gas?

 

So here is a suggestion.  Given heat pumps give 50% more heat output per unit of gas (50% loss in generation and transmission but 3x gain in COP) why not have a heat pump meter and charge electric units used by the heat pump at 2x the cost of a gas unit (and build the necessary gas generation to support this knowing that by speeding up heat pump roll out we are reducing our carbon footprint) 

[Michael_S]

27 minutes ago, JamesPa said:

I don't think you wont have to wait long.  My 4 year old Kia e-Niro reliably does >240miles in the worst of winter, 300 in summer.  That's not much less than you need and thats a car from 4 years ago.

EVDB says 165 winter, 210 summer at 70mph.  IMHO if you have home charging then the range number that matters is range while travelling at long distance journey speeds, being able to get 240 around town makes no odds.

[Michael_S]

20 minutes ago, JamesPa said:

I actually went down the sequential route as part of the discovery phase for my ASHP.

 

I first reduced my boiler temp to the lowest it would go (50C), then started operating 24x7.  That was as far as I could take it without changing radiators, in fact I needed to up the FT to 55 in the depth of winter.  I also limited my boiler output to the minimum possible (8.5kW in my case).  This arrangement was indeed more comfortable, and used less gas (it wasn't cheaper because prices went up at the same time, but it used less gas).   

 

Upsizing radiators, swapping to an ASHP (obviously with WC) and thus getting max FT down to 45, and FT most of the time to 35 or less, together with removing all but one TRV head made the big difference in comfort though. 

 

One day I will tot up how much I have spent on wholly unnecessary heating control equipment over the years (yes I too was suckered into trying 'smart' TRVs at one point - what a waste of time and money!).

We had a weather comp boiler that modulated down to under 2kw and heated 24/7 with  night time set back, the curve went to about 55 flow at -10 when it ran at about 7.5kw constant.  WE had  hot water tank in the loft so only needed a 18kw boiler which gave the good modulation.  Funnily enough now with an oversized heat pump and a heat demand when it is mild of about 1-2kw we get a lot more cycling than we did with the boiler....

[Beelbeebub]

4 hours ago, ProDave said:

I am often asked should I swap from a gas boiler to an ASHP.  I ask what are your expectations and reasons for doing so?

 

If they just want to save money my usual reply is don't bother.

I have exactly this dilemma, being responsible for 30 odd boilers. 

 

Thry are small, relatively cheap and can provide heating and hot water from pretty much any property. 

 

From the late 90's we converted lots of our properties from E7 to gas, it cost a bit to put the radiators and pipes in and the early combi boilers didn't last long (we reckoned 10y) but was much cheaper for occupants and reduced CO2. 

 

Now we are faced with going back the other way!

[Beelbeebub]

1 hour ago, Mike said:

Or get a car where you can swap the batteries about as quickly as filling one with fuel, when they reach the UK: https://www.youtube.com/watch?v=WOsy_EvtHr4

 

A possible solution to fast recharging but the capital cost of of those stations has to be higher than a charger station and then you woikd have an even bigger problem with compatibility. Imagine if you could only fill your car up with Shell petrol rather than any brand. 

 

One thing I do like about that system is it demands the battery is easily interchangeable. Which implies it would be easy to change the battery if it were to degrade, or battery chemistry improves. 

 

We can see this with Nissan leafs. Now the older ones are more or less open source there are replacement battery packs available with larger capacities that can swap out in a morning at a small garage 

[Beelbeebub]

52 minutes ago, JamesPa said:

I don't think you wont have to wait long.  My 4 year old Kia e-Niro reliably does >240miles in the worst of winter, 300 in summer.  That's not much less than you need and thats a car from 4 years ago.

My neighbour has one, I tried it out. Very nice. Would do us very well with one problem....I don't fit. 

 

I'm quite tall and most of it is in my upper body, so I have an issue with headroom in cars and the Nero is one of them. My head presses into the headliner and I can't see put of the front very well. Worse, the rear mirror doesn't twist enough for me to see out of the back window, I just look into the passengers laps. 

 

 

[marshian]

36 minutes ago, JamesPa said:

I actually went down the sequential route as part of the discovery phase for my ASHP.

 

I first reduced my boiler temp to the lowest it would go (50C), then started operating 24x7.  That was as far as I could take it without changing radiators, in fact I needed to up the FT to 55 in the depth of winter.  I also limited my boiler output to the minimum possible (8.5kW in my case).  This arrangement was indeed more comfortable, and used less gas (it wasn't cheaper because prices went up at the same time, but it used less gas).   

 

Upsizing radiators, swapping to an ASHP (obviously with WC) and thus getting max FT down to 45, and FT most of the time to 35 or less, together with removing all but one TRV head made the big difference in comfort though. 

 

One day I will tot up how much I have spent on wholly unnecessary heating control equipment over the years (yes I too was suckered into trying 'smart' TRVs at one point - what a waste of time and money!).

 

Similar here (I won't repeat myself here) except I've not transitioned to ASHP yet.

 

I've still got the "smart" TRV's but they are serving me well whilst I get the Danfoss RAS-B2 rad valves aligned to the room temps (the app gave me a starting point for all my T22's and single K33 but it's not great for vertical rads - once that's done conventional TRV heads are going on (Just as temp limiters for solar gain in the shoulder seasons) and WC can take care of the house temps 24/7

 

 

[SteamyTea]

1 hour ago, Mike said:

get a car where you can swap the batteries about as quickly as filling one with fuel

Most car journeys are really quite short, hardly seem worth manufacturing extra battery packs, building an infrastructure for the extraordinary journey.

Battery technology in its current form is only about 30 years old, shall we remind ourselves what cars in the 1920's were like.

 

 

Now let us look at what an EV from the 1990s was like.

 

[DamonHD]

I am a bit late to this party, but my HP + smart TRVs (obvs!) combo seems to work well.

 

I'm about to start a paper on my work showing that TRVs and retrofit HPs can work well, and one difficult area is 'comfort'.  I am happy with daily temperature cycling and summer and winter, and not heating more than needed overnight for example feels like a win on energy and comfort (and I hope to be able to share experimental results to that effect), but huge numbers of people seem to feel that the only comfortable temperature is a rock-steady one at or above 18C...

 

Which amused Prof Mackay then Chief Scientific Advisor at DECC, when told it by a senior boffin from BRE (I think) at a big meeting at the end of 2012.  Mackay said that his family (including very young child) turned the heating up for a bit from 14C if they began to fell chilly.

 

Anyway, am I the only one happy with daily temperature cycles?

[Roger440]

On 15/11/2025 at 15:47, JamesPa said:

I think householders do need to understand WC at least a bit.  The probability that an installer has correctly set it up is small (particularly if the installation is in summer) and even if the installer has set it up correctly if the householder doesn't understand a bit about WC they wont understand why their radiators are rarely warm.  Its hardly a difficult concept though, water circulating through system,  is hotter when it colder outside and colder when its warm outside.

 

They dont need to understand scheduling of the CH though, just leave it on!

 

I do think interfaces need to get better.  The likes of Vaillant, who have had to cope with boilers featuring WC for a couple of decades  (because its been compulsory in some mainland European countries), have more or less got it; the interfaces for some of the far eastern machines are really poor.

 

 

 

 

Gosh, i go away for 2 days and we have another thread, much the same as the previous ones.

 

I think its good for you to occasionally come back to planet earth though. There is absolutely no possibility at all, ever, of getting the average man on the clapham ominibus to understand WC. We live in an era where people think tuning up the thermostat on the heating or an oven to max will heat it up "quicker"

 

You idea is fantasy.

 

And nor should it be necessary. The industry needs to (though i accept it wont) up its game and make stuff that "just works". The automotive industry, until recently anyway, were masters at taking what is, a far more complex product and delivery a usuable one to the consumer. There was a time that owning a car meant you did really need to know the basics of how it works. They took that problem and engineered it out. Succesfully. 

 

The should be no need to "understand" WC and if there is, its doomed to fail.

[Mike]

55 minutes ago, Beelbeebub said:

the capital cost of of [car battery swap] stations has to be higher than a charger station... One thing I do like about that system is it demands the battery is easily interchangeable. Which implies it would be easy to change the battery if it were to degrade, or battery chemistry improves

The deterioration of a fixed battery must have a negative impact on resale value; the economics of battery swapping might work if that is taken into account.

 

55 minutes ago, Beelbeebub said:

you would have an even bigger problem with compatibility. Imagine if you could only fill your car up with Shell petrol rather than any brand.

Standardization would certainly help. The EU already has a directive (2023/1542) require that "batteries, as well as individual battery cells included in the battery pack, are readily removable and replaceable by an independent professional at any time during the lifetime of the product", so it wouldn't be a huge step to go further and specify standard battery pack sizes.

 

A quick search also shows that the European Committee for Standardization is already drafting "Technical specifications for swappable battery system applied to L-category vehicles"

 

Edited 1 hour ago by Mike

[Roger440]

2 hours ago, JamesPa said:

As a recent ASHP owner I would probably agree (although I do save a significant amount of money with mine)

 

However I would also say that, if you want a much better heating experience with a house the whole of which is comfortable 24*7 for about the same or possibly less running cost then do bother.  (Obviously also if you want to reduce the carbon footprint  of your heating by a factor of 3 they do bother)

 

Low temperature heating (the conversion to which makes up a major part of the differential cost) is just so much better, but how many people who haven't experienced it know that?.  Just be sure to do your research so you avoid the cowboys, as you must for absolutely anything which involves any of the building trades which, lets face it, are in parts about as dodgy as it gets. 

 

You keep going on about its "better" in your never ending crusade. You are wasting you time.

 

My house runs on oil (probably permanently if the eco4 grant goes the way of the dodo) i run it at 20c during the day, 16 at night, and its "on" 24/7, Ive screwed the flow temps down as far as i can. The house is warm and comfortable. My previous house, exactly the same. Whatever this "better" is, frankly i have no need or desire for it to be "better" because it perfectly OK as it is. I certainly dont feel an overwhelming urge from a comfort perpective, to spend a five figure sum and rip my house to pieces to make it "better". 

 

Its just not a argument that has any relevance to real life. You make lots of valid points, this isnt one of them.

 

I accept ive probably done more than 99% of people with what i have done, and Prodaves post earlier highlights how bad a lot of systems are. But they dont need to rip it all out and spend £15k (they likely dont have) to make it better.

[Roger440]

On 15/11/2025 at 17:24, Beelbeebub said:

Except there is some discussion of removing the green levies on elec hence the proposal to reduce the eligibility for the 7.5k grant (as they aren't proposing to stick the green levies on gas)

 

So the elec/gas ratio (which is the important metric) might fall from the current 4.2 times. 

 

Green levies make about 15% of the current elec price, so we"d drop from 26p to around 22p.  Assuming gas stays the same that's 3.5x ratio. 

 

That's an achievable SCOP and That"s before things like time of use tariffs which can drop the price even lower. 

 

The frightening close to being sensible!

[Oz07]

How many people who go on about this comfort mode are either retired or part of the wfh laptop class? Alarm clock britain (fast disappearing) is fine with a bit of heating morning and night. They don't want a physics degree to understand how to work their heating or an inflated electric unit price to justify spending thousands on batteries. 

[Oz07]

Excuse the naivety but how does weather comp even save much? Surely you have a thermostat once the heating hits this or gets close it turns off. Is it just trying to stop it overshooting too much? In my last place I had gas and rads, ran 24/7 with thermostat set at a temp. Never felt over hot (due to heating, exc summer) or to cold. I'm probably perfectly demonstrating why the average man on the street won't understand it 🤣

Edited 38 minutes ago by Oz07

[Dillsue]

26 minutes ago, Oz07 said:

 They don't want a physics degree to understand how to work their heating 

My wife doesn't have a degree and isn't technically minded but got the gist of how the HP works in about 15 mins followed by a couple of questions over the following few days.

 

A couple of those 15 minutes was explaining WC ie the water in the radiators/UFH gets warmer as it gets colder outside and the reverse as it warms up outside. That's all she needs to know about WC and all any householder needs to know.