British Gas heat pumps - some restrictions on their offering FYI

[Beelbeebub]

19 minutes ago, JamesPa said:

Do they really say that.  In which case what is the point of a HT heat pump.  Using it at HT for space heating gives a lousy scop and upgrading radiators is cheap and low disruption  Using it at HT for dhw barely affects the scop and upgrading the cylinder is expensive and high disruption.  So the bang for the buck is to upgrade the radiators but keep the dhw cylinder.

 

Ok I've oversimplified, but manufacturers of HT heat pumps insisting on replacing the dhw tank clearly aren't in the real world. 

 

Is it just a case of hangover from previous generations of.tech where replacing the cylinder was more important?

 

Removing the requirement from the manufacturer spec would require paperwork and internal testing *and* reduce sales of their cylinders.  So I don't expect there is a lot of internal pressure to do so.

[Beelbeebub]

It seems that the advent of new refrigerants has more or less removed the need for "high temp" heatpumps as they are HT almost by default.

 

As we have discussed this actually opens up alot of possibilities for making retrofits more attractive.

 

Not every DHW cylinder will be left in situ, and a good chunk will give worse performance than a new one (if only because of batter insulation!), but it's back to "good enough" and it would save at least a couple of grand on an install.

[JamesPa]

8 minutes ago, Beelbeebub said:

It seems that the advent of new refrigerants has more or less removed the need for "high temp" heatpumps as they are HT almost by default.

 

As we have discussed this actually opens up alot of possibilities for making retrofits more attractive.

 

Not every DHW cylinder will be left in situ, and a good chunk will give worse performance than a new one (if only because of batter insulation!), but it's back to "good enough" and it would save at least a couple of grand on an install.

My gut feel is that this really matters.  It could make the difference, in a significant number of retrofits, between a two a week job and a one a week job.  Also between a highly disruptive job and a job which is only minimally disruptive.   The difference in price is well over 2K, it's where the excessive margin is hidden, and in fairness, the installation risk lies (which consumers pay for).

[markocosic]

6 hours ago, Beelbeebub said:

The point is it is probably better for the UK to get more HPs in even if they aren't being super efficient at DHW, than people sticking with gas boilers because the cost of swapping is too much (because of the cylinder swap)

 

Or, worse still, people diverting PV.

 

If you want to do this today you can do this today. Buy your £3k Vaillant unit. Bash it in. Shove the temperature sensor against your cylinder in the appropriate spot. Enjoy.

 

You don't need to buy the all in one unitower. Or the cylinder.

 

What you won't get with that is any grant funding or any product support of course.

 

It isn't worth the heartache of supporting the nuckfumpties shopping in the speedfit section at Wickes putting together their own designs as a manufacturer. Take the package. Take the bits. Don't expect design support unless you buy the package though.

 

I don't hold it against BG that they won't go unvented cylinder unless flow is adequate. It's probably somebody trying to avoid complaints from those going from vented to unvented on a naff supply; not thinking through that if you're deleting a combi life gets better not worse; and offering in the mixergy instead because their manual says 10L/min is ok therefore customer complaints can point at mixergy.

[markocosic]

3 hours ago, JamesPa said:

The difference in price is well over 2K, it's where the excessive margin is hidden

 

You really do have a problem with people charging what the job is worth to clients; don't you? 😉

[Beelbeebub]

39 minutes ago, markocosic said:

 

Or, worse still, people diverting PV.

 

If you want to do this today you can do this today. Buy your £3k Vaillant unit. Bash it in. Shove the temperature sensor against your cylinder in the appropriate spot. Enjoy.

 

You don't need to buy the all in one unitower. Or the cylinder.

 

What you won't get with that is any grant funding or any product support of course.

 

It isn't worth the heartache of supporting the nuckfumpties shopping in the speedfit section at Wickes putting together their own designs as a manufacturer. Take the package. Take the bits. Don't expect design support unless you buy the package though.

 

I don't hold it against BG that they won't go unvented cylinder unless flow is adequate. It's probably somebody trying to avoid complaints from those going from vented to unvented on a naff supply; not thinking through that if you're deleting a combi life gets better not worse; and offering in the mixergy instead because their manual says 10L/min is ok therefore customer complaints can point at mixergy.

No problem with making sure the system works, but there is a whole bunch of backside covering going on.

 

If there is no cylinder then you need to fit one and you should get the appropriate one. 

 

The point is, with new HPs it looks like most existing cylinders are "good enough". They won't be the highest efficiency but they will function as well as the previous set up (the exception being undersized high recovery units supported by a large boiler , effectively combis). 

 

By more or less mandating a cylinder swap you are increasing the cost and disruption of the job and thus reducing uptake.

 

To get more uptake HP swaps need to become cheaper and quicker. 

 

The current MCS system is, self evidently, not working.

 

HP installs have a reputation of being a middle class luxury - "only rich people can spend the money to get one and get the grant, poor people have to stick with gas". It's used as an attack against HPs in general

 

I, and some others, think there needs to be a change to "good enough" to speed adoption.

 

For the same subsidy cost you could get much higher uptake, with minimal drop in performance.

[TonyT]

7 hours ago, sharpener said:

 

That's the situation I inherited. It struck me as very unusual but I can only think that (with an S plan setup) it is so the coil cct (which is very short) does not starve the radiator cct when they are on at the same time.

 

Otherwise I agree with all your calcs, I have put similar to Vaillant - as they make a point of pushing their 75C flow in their advertising, wot is point if you cannot make use of it to avoid having to change your cylinder? Will report here in due course.

 

PS would not fit a Stuart Turner booster again. Despite what they say some products are rebranded Far Eastern imports. Have had a shaft seal fail, no spares stocked, zero support after 18 months. Full price replacement has recently developed an unexplained crack in the plastic impeller shroud, with drastic drop in o/p pressure, have now built one good pump out of the bits of two. Endless hassle with it, will buy DAB next time.

 

Decent gas boilers sized  correctly with hot water priority and weather compensation would be an option if you are sticking with gas.  More efficient than s or y plan

[DanDee]

14 hours ago, JohnMo said:

All the above is great in theory, but the ASHP doesn't put out a set temp all the time, it slowly ramps up as the graph above illustrated. It has taken 40+ mins to get to 52 degs flow temp.

 

Not sure how your small coil manages the heat transfer at the lower flow temp. The dT would too low the ASHP would ramp up temperature quickly and basically run out of temperature rise to manage dT and leave you with a slightly warmer cylinder, not hot or usable. It would then just continue to short cycle never achieving set point.

 

 

No cycling in DHW, just poor performance. If it's not the low COP that would drive you crazy, the reheat time will do for sure with a minuscule coil.

 

https://emoncms.org/app/view?name=HighbanksASHP&readkey=a6242a5576f8fa23493b70dad6c7d9fe

 

 

https://emoncms.org/app/view?name=MyHeatpump&readkey=23437bdf4c5212a780f9bcf6f03cc688

Edited August 2, 2023 by DanDee

[markocosic]

8 hours ago, Beelbeebub said:

 

By more or less mandating a cylinder swap you are increasing the cost and disruption of the job and thus reducing uptake.

 

Disagree here.

 

The efficient cylinder is the CHEAPEST solution. Over the product lifecycle.

 

 

I think the REAL issue here, base install cost (less cylinder replacement) aside, is people simply not wanting to spend the money upfront on what is overall the best value solution.

 

 

For some, it's because they're planning to sell within the product lifetime and the new buyers wouldn't value the energy efficiency measures. (I'm in that boat)

 

For others, it's because they're not credit worthy/are already living beyond their means, so can't borrow the money now to save themselves money later.

 

For others, it's simply that they're mean, and have access to the money, but don't want to spend it on heating and hot water.

 

 

Most owner occupiers are in group 1 or 3.

 

 

Same issue with insulation etc.

 

 

Bit they're quite happy to buy anew kitchen or a new car regardless of the economics.

 

[MikeSharp01]

6 minutes ago, markocosic said:

For others, it's because they're not credit worthy/are already living beyond their means, so can't borrow the money now to save themselves money later.

Then, if borrowing to do this work, you need to factor in interest on the loan as part of the cost - which simply, as in easy to understand, pushes the payback time out. People generally don't do a full cost accounting job on such purchases so Net Present Value (NPV) and Rate of Return (RoR) calcs are not performed.

[JohnMo]

47 minutes ago, DanDee said:

No cycling in DHW, just poor performance.

My heat pump doesn't run like that one does, it wouldn't tolerate the small dT.

[Beelbeebub]

Yes fitting a new cylinder and all the ancillary work will make for a more efficient set up in the long run.

 

But the question is "better rather than best"

 

The high level goal is to swap out as many gas boilers HPs because that will reduce the consumption of gas.

 

The additional upfront cost that required moving from a typical existing system to the ideal system Vs going part of the way is a barrier.

 

Would you suggest that MCS mandating UFH being retro fitted throughout is a good idea?

 

UFH has superior performance to radiators for HP installations in every way.

 

It is very expensive and disruptive to retrofit though

 

Or do we say "ok UFH is best, but upgrading one or two rads is good enough"

 

The same logic applies. By all means change the cylinder if the householder is prepared to. But don't virtually mandate that you do unless the existing system is so subpar as to not function at all.

 

At a high level, swapping lots of gas boilers for HPs with CoPs greater than 2.5 is better than a few with CoPs of 4

 

[markocosic]

18 minutes ago, MikeSharp01 said:

Then, if borrowing to do this work, you need to factor in interest on the loan as part of the cost

 

Yep.

 

Say a £1500 uplift (cylinder and gubbins; but not the 3 port valve and pump changes etc that you'd be needing anyway)

 

Repaid on a personal loan over 5 years at 10%; winds up costing £31.55/mo or an extra £393.

 

Say 2 kWh per person per day; 2.4 people; 15 years; 26280 kWh.

 

COP 1.75 vs COP 3.5 at £0.30/kWh?

 

£4500 Vs £2250 over pessimistic 15 year life. More than pays for the cylinder upgrade and the interest. A more realistic life for a decent stainless cylinder will be 30 years or more.

 

But as you say most people are as financially literate as a cabbage and are making these decisions on emotion rather than reason...

 

[JohnMo]

4 minutes ago, Beelbeebub said:

high level goal is to swap out as many gas boilers HPs because that will reduce the consumption of gas.

Or would a bigger % drop in gas consumption come from.

 

Setting up and mandating the following on all boilers

1. Running weather compensation

2. Priority hot water or X plan

3. Sorting zone control, so boilers cannot short cycle. Simple logic controller so min flow rate through system is alway maintained - regardless of what an owner tries to do make it run crap.

 

Would instantly decrease consumption by 20%+ in most installed boilers.

 

And/or a really good tariff for heating the cylinder via the immersion and/storage heating, without the daytime uplift in kWh prices.

 

And on all homes insulate them to a minimum defined level. Areas to be insulated first and last would be by a defined priority based on best bang for the buck. i.e. drafts, roof... Etc.

 

Make grants available to do all to this.

 

Stop grants for heat pumps - only funding the well off at the moment, not everyone.

 

This could be cheaper and less disruptive to the house as a whole.

 

Hydrogen is coming no matter what the ney sayer's may have you believe, it will come un-noticed my most, as a dilution of methane gas, 5%, 10% hydrogen etc.

 

 

[Beelbeebub]

12 minutes ago, markocosic said:

Say 2 kWh per person per day; 2.4 people; 15 years; 26280 kWh.

 

COP 1.75 vs COP 3.5 at £0.30/kWh?

 

£4500 Vs £2250 over pessimistic 15 year life. More than pays for the cylinder upgrade and the interest. A more realistic life for a decent stainless cylinder will be 30 years or more.

CoP of a modern unit is likely to be more like 2.5 Vs 3.5

 

So 26Mwh needs 10Mwh or 7.5Mwh (round figures)  at 30pkwh that's £750 difference over 15 years.

 

I'd agree if your looked at an existing setup and calculated the DHW cop was really crap (let's say below SCOP 2.5) you'd want to change the cylinder.  But as long as it's not *too* bad, let it be.

 

The hurdle should be projected overall SCOP of 2.5+

 

The caveat here is we would need a subsidy regime which meant the cost of heating (at least in the short term) was similar to gas.  If that was put in place I would expect installs to rocket.

 

You'd have an option that was about the cost of a gas boiler replacement, would definitely not cost more to run than gas for the next however long the subsidy lasts (say 7 years) which gives time (and feedback and experience) to get the system up to the financial break even point of 3.5 (ish.

[JamesPa]

10 hours ago, markocosic said:

You really do have a problem with people charging what the job is worth to clients; don't you? 😉

Nope, I really have a problem with being told what I want or whats good for me by others

 

1 hour ago, markocosic said:

 

The efficient cylinder is the CHEAPEST solution. Over the product lifecycle.

 

In some cases yes, and in some cases (as @MikeSharp01 points out) no, it all depends on the customer situation.  But that isn't actually the point, the point is about how its sold and the customer right to make their own decisions based on their own circumstances.

 

Today we are invariably told that we must have a cylinder change to have a heat pump.  That's not true in all (perhaps most) cases, but that's how its currently (misre-)presented.  If, as you now seem to accept, the argument is based on lifetime cost then present it that way and let the customer make the choice.  Its not for the installer or the heat pump industry to make this choice, its for the customer.

 

Many customers will make the choice to take the upgrade, likely more comfortably than if they are 'told they must do it'.  Others will choose differently for all sorts of reasons which the installer cannot know and has no right to know.

 

Neither installers nor the heat pump industry in general have the right  arrogantly to tell the customer what is 'right for them'.  Even less do they have the right to hide their view of what is 'right for the customer' behind a technical falsehood.

 

 

 

Edited August 2, 2023 by JamesPa

[JamesPa]

7 minutes ago, JohnMo said:

Or would a bigger % drop in gas consumption come from.

 

Setting up and mandating the following on all boilers

1. Running weather compensation

2. Priority hot water or X plan

3. Sorting zone control, so boilers cannot short cycle. Simple logic controller so min flow rate through system is alway maintained - regardless of what an owner tries to do make it run crap.

 

Would instantly decrease consumption by 20%+ in most installed boilers.

 

And/or a really good tariff for heating the cylinder via the immersion and/storage heating, without the daytime uplift in kWh prices.

 

And on all homes insulate them to a minimum defined level. Areas to be insulated first and last would be by a defined priority based on best bang for the buck. i.e. drafts, roof... Etc.

 

Make grants available to do all to this.

 

Stop grants for heat pumps - only funding the well off at the moment, not everyone.

 

This could be cheaper and less disruptive to the house as a whole.

 

Hydrogen is coming no matter what the ney sayer's may have you believe, it will come un-noticed my most, as a dilution of methane gas, 5%, 10% hydrogen etc.

 

 

Short term yes, long term no.  So until you get a heat pump you should be encouraged to do what you are suggesting.  But this doesnt fix the problem, only a heat pump (with continued decarbonisation of electricity) does.  Hydrogen is just greenwashing, a back door way for the boiler and fossil fuel industry to keep more boilers in homes which in reality will burn gas or mostly gas.  There is no cost effective way to make it without using fossil fuels. 

 

 

Edited August 2, 2023 by JamesPa

[JohnMo]

Didn't say it wasn't greenwash, but you can control how and where the co2 ends up, unlike the home boiler. i.e. pumped underground.

 

You can also make from water, with electric, Scotland is currently 95% renewable energy, with loads more on the way, that excess electric can be used to make green hydrogen. Almost run like a PV immersion diverter, excess electric, hydrogen making process starts.

 

Different discussion through.

 

My point was the heat pump isn't the only solution (and won't be for many), currently way too expensive and generally requires too many modifications to the house to ever be cost effective, without doing the steps I mentioned in my previous post first.

 

one solution will never be fit for all, as you keep saying.

[Beelbeebub]

The bit that the carbon capture (either from direct gas combustion of from hydrogen manufacture) lobby miss out is that capturing carbon is very energy intensive.

 

It is thermally driven, you dissolve the CO2 in a solvent, then heat it to extract it, before recycling the solvent. There is also the not insignificant energy to pump it back underground etc. 

 

It takes something like 25% more gas being burnt per kWh produced to capture the carbon

 

So as soon as you fit you magic CO2 capture tech to a thermal power plant (or a "blue" hydrogen generation plant) your gas consumption goes up by 25%

 

So of course the gas lobby are very keen on this tech, it not only enables them to keep selling their product but actually increases demand!

[markocosic]

30 minutes ago, Beelbeebub said:

CoP of a modern unit is likely to be more like 2.5

 

Is it?

 

Any examples?

 

Boggo MCS installs average 2.8 for hot water (usually with new cylinder) AND space heating.

 

I'm not convinced they'll be more like 2.5 when you're having A N Other doing the installs on A N Other cylinder myself.

[JamesPa]

13 minutes ago, JohnMo said:

Didn't say it wasn't greenwash, but you can control how and where the co2 ends up, unlike the home boiler. i.e. pumped underground.

 

You can also make from water, with electric, Scotland is currently 95% renewable energy, with loads more on the way, that excess electric can be used to make green hydrogen. Almost run like a PV immersion diverter, excess electric, hydrogen making process starts.

 

Different discussion through.

 

My point was the heat pump isn't the only solution (and won't be for many), currently way too expensive and generally requires too many modifications to the house to ever be cost effective, without doing the steps I mentioned in my previous post first.

 

one solution will never be fit for all, as you keep saying.

Agreed.

 

Incidentally I would probably agree with your suggestion to remove the grant on hps provided that, at the same time, PD rules were changed so that MCS is not required and zero rating for vat applied also to self install. 

 

I would be willing to bet that if this were done the HP industry would suddenly discover it could do things more cost effectively.

Edited August 2, 2023 by JamesPa

[markocosic]

32 minutes ago, JamesPa said:

Today we are invariably told that we must have a cylinder change to have a heat pump.  That's not true in all (perhaps most) cases, but that's how its currently (misre-)presented.  If, as you now seem to accept, the argument is based on lifetime cost then present it that way and let the customer make the choice.  Its not for the installer or the heat pump industry to make this choice, its for the customer

 

I'm happy to say it looks like it'll function (fudged up working left for all and sundry to see!) but I think you'd be daft to spend say £5k to do a half job rather than £6.5k to do the whole job; especially given the lifecycle cost benefits and probably also the property value uplift from having decent hot water (vs a tiny old gravity tank)

 

I don't sell heat pumps btw. Or install them. I actually work in the district heating/cooling sector...

[Beelbeebub]

Just now, markocosic said:

 

Is it?

 

Any examples?

 

Boggo MCS installs average 2.8 for hot water (usually with new cylinder) AND space heating.

 

I'm not convinced they'll be more like 2.5 when you're having A N Other doing the installs on A N Other cylinder myself.

Taken from data table of a r32 York unit (the vaillant tables are similar)

 

A 16kw unit can put out a  60C water at better than 2.5CoP anywhere above 5C external temp. And 65C anywhere above 10C. 

 

Ok that doesn't include cycling losses etc but it shows its not too far from what is needed 

 

I've dm'd you.

 

 

[JamesPa]

6 minutes ago, markocosic said:

 

I'm happy to say it looks like it'll function (fudged up working left for all and sundry to see!) but I think you'd be daft to spend say £5k to do a half job rather than £6.5k to do the whole job; especially given the lifecycle cost benefits and probably also the property value uplift from having decent hot water (vs a tiny old gravity tank)

Fair enough, but my point is that the decision, on that basis, is one for the customer not for the installer or the industry. 

 

The installer needs to tell the customer the facts that they know and let the customer decide based on those facts and  the facts only thee customer knows.

 

Also the dhw upgrade can still be done later if the customer changes their mind, with nothing lost.  Or done a different way if PHEs take off in the hp world, which seems at least plausible if not likely.

Edited August 2, 2023 by JamesPa

[markocosic]

2 minutes ago, JamesPa said:

Incidentally I would probably agree with your suggestion to remove the grant on hps provided that, at the same time, PD rules were changed so that MCS is not required and zero rating for vat applied also to self install. 

 

Agree with MCS and PD

 

I don't think this should be zero rated. That, like grants, is liable to end up in the installer pockets.

 

Yes to grant removal BUT it should be along with carbon (i.e. gas) being taxed to create the no brainer commercial model.

 

If you need another incentive, perhaps to sweeten the deal for the homeowner who initially does the work, rather than subsidising the long term operation too highly, I'd perhaps make it a stamp duty rebate of £5k.