Are we targeting ASHP's at the wrong market?

[JamesPa]

38 minutes ago, Beelbeebub said:

Technically speaking the heat in an A2A heatpump is delivered as a hot gas (vapour) that is condensed into a liquid at the point of heat delivery (the room unit heat exchanger coil). 

 

So it is a tricky question if the delivery is via gas or liquid. 

 

I'm not sure the legal system is capable of dealing with the finer points of thermodynamics 

 

 

Thanks for the clarification.  I think you are right that the legal system can't deal with the finer points of thermodynamics but on that account I would say the delivery medium is a gas.

 

It would be interesting to understand what the intent was.  If it's only to allow a2W why use 'liquid' as opposed to 'water ( which may be treated to prevent corrosion or freezing)'

[Beelbeebub]

I've poked around to try and see where the prohibition on A2A might be. 

 

I haven't found it yet, except that the new system must provide all the heating and hot water and no hybrid systems are allowed. 

 

There are very few A2A systems that can also provide hot water. I believe daikin do one, but I haven't actually seen it in this country and I don't think it has any mcs certification. 

 

So maybe it would be as simple as allowing hybrid systems. 

 

Again, I think allowing A2A would see a significant up tick in installs as it would be cheaper and hence might be entirely covered by the grant. It is also potentially less disruptive for some properties. 

 

There would be an issue with skills as we don't traditionally have many A2A fitters in the UK. 

 

That said, if we coukd get our arses into gear around r290 and the manufacturers could produce r290 multi splits, I don't expect there would be much conversion from a gas safe engineer to an r290 safe engineer. There aren't any actual skill sets that are different the main criterion is being responsible and diligent when it comes to ensuring the gas lines are secure. 

 

 

[JamesPa]

7 minutes ago, Beelbeebub said:

I've poked around to try and see where the prohibition on A2A might be. 

 

I haven't found it yet, except that the new system must provide all the heating and hot water and no hybrid systems are allowed. 

 

There are very few A2A systems that can also provide hot water. I believe daikin do one, but I haven't actually seen it in this country and I don't think it has any mcs certification. 

 

So maybe it would be as simple as allowing hybrid systems. 

 

 

 

 

Here are the regs for BUS

https://www.legislation.gov.uk/uksi/2022/565/contents/made

 

Reg 9(2) requires that the heat is delivered by a liquid.

 

Based on your explanation of A2A above I think that excludes A2W but there clearly may be room for debate.

 

Definitely there is no exclusion of units capable of cooling as some maintain there is.  However pd rules don't apply if used for cooling, which is a separate consideration to the grant.

[Beelbeebub]

11 hours ago, JamesPa said:

Based on your explanation of A2A above I think that excludes A2W but there clearly may be room for debate

It would get very technical, how do you define delivery? 

You could argue the heat is *transported* from point of production to the end point by a vapour but *delivered* as a condensing liquid. The bulk of the energy is delivered as the heat of condensation with a minority delivered by sensible heat of the vapour or liquid phases.

 

But the biggest stumbling block is the general lack of DHW provision. 

 

Milliband is talking about removing this restriction.  Which might pave the way. 

[Beelbeebub]

On a side note, the regs exclude any HP over. 45kw total including shared ground loop systems. This would seem to be an issue for. The Kensa "shoebox" systems or any other shared ground loop systems that might be very useful for blocks of flats etc. 

[joth]

15 hours ago, JamesPa said:

 

It would be interesting to understand what the intent was.  If it's only to allow a2W why use 'liquid' as opposed to 'water ( which may be treated to prevent corrosion or freezing

So my guess... One of the main intents of BUS is to support wide scale training in domestic HP installation, hence the instance on MCS and encouraging profit taking by those with said training.

Domestic plumbing is seen as a wet plumbing not F-Gas skill set and so they want people to cross train into the skills that are typically needed to maintain these things going forward 

[Beelbeebub]

54 minutes ago, joth said:

So my guess... One of the main intents of BUS is to support wide scale training in domestic HP installation, hence the instance on MCS and encouraging profit taking by those with said training.

Domestic plumbing is seen as a wet plumbing not F-Gas skill set and so they want people to cross train into the skills that are typically needed to maintain these things going forward 

A reasonable point. But the skillset to install. A2A (basically fgas certification) would also be encouraged by subsidising a2a.

 

The skillset to install any HP (vs gas boilers) is basically in the specification. There isn't anything in installing a HP that a gas safe engineer can't already do.

 

The only tricky bits are getting the system design and sizing right in the first place. 

 

With a2a the issue is fgas - and there are good reasons for not letting any old sod loose given the higher gwp of the gasses. R290 gets around that issue but does introduce the flammability issue - but that isn't significantly different from gas safe issues. 

[Stones]

I've been reading the comments with interest. So the original question, Are we targeting ASHP's at the wrong market? I think the answer is an undoubted yes.  Or you could say right market, wrong product.

 

For political expediency, ASHP's are being touted as a boiler replacement.  But for the vast majority of existing homes they are not, due to the other work required to allow them to operate optimally / at comparable running cost to gas.  If ASHP's were capable of delivering a CoP of 3.5 - 4 with flow temps of 55C - 60C, they would be.  Until there is no need or requirement to significantly upgrade the heat distribution system, and for the most part I'm referring to radiators and associated pipework, the public are not going to bite.  Improving insulation / airtightness for such housing stock is a red herring, useful in reducing energy use, but is not going to get most homes down to the point where they do not require heating.

 

Take a mid 90's house (that I happen to know well) with an oil boiler and radiators.  If the owners wanted to fit an ASHP, they would need to replace all their radiators with 3 to 4 times larger in terms of btu heating capacity (up to twice the physical size if they could accommodate double radiators) to achieve comparable running costs.  Carpets would have to come up, to get to floor hatches, all the microbore pipe to the radiators would need stripped out and replaced with 15 - 22mm pipework.  Time, disruption, and significant cost if they could even get anyone to do the work.  And what would they get out of it - a warm fuzzy glow that they had reduced their carbon emissions?  Looked at objectively then, why would anyone put themselves through all that?

 

You want change, it needs to be straight forward, meet peoples needs and be affordable.

 

The government needs to move away from ideologically dictating technologies, to setting the framework for the reduction of emissions / reducing the use of FF.  Let the market develop and implement the solution.

 

 

 

 

[PhilT]

23 minutes ago, Stones said:

I've been reading the comments with interest. So the original question, Are we targeting ASHP's at the wrong market? I think the answer is an undoubted yes.  Or you could say right market, wrong product.

 

For political expediency, ASHP's are being touted as a boiler replacement.  But for the vast majority of existing homes they are not, due to the other work required to allow them to operate optimally / at comparable running cost to gas.  If ASHP's were capable of delivering a CoP of 3.5 - 4 with flow temps of 55C - 60C, they would be.  Until there is no need or requirement to significantly upgrade the heat distribution system, and for the most part I'm referring to radiators and associated pipework, the public are not going to bite.  Improving insulation / airtightness for such housing stock is a red herring, useful in reducing energy use, but is not going to get most homes down to the point where they do not require heating.

 

Take a mid 90's house (that I happen to know well) with an oil boiler and radiators.  If the owners wanted to fit an ASHP, they would need to replace all their radiators with 3 to 4 times larger in terms of btu heating capacity (up to twice the physical size if they could accommodate double radiators) to achieve comparable running costs.  Carpets would have to come up, to get to floor hatches, all the microbore pipe to the radiators would need stripped out and replaced with 15 - 22mm pipework.  Time, disruption, and significant cost if they could even get anyone to do the work.  And what would they get out of it - a warm fuzzy glow that they had reduced their carbon emissions?  Looked at objectively then, why would anyone put themselves through all that?

 

You want change, it needs to be straight forward, meet peoples needs and be affordable.

 

The government needs to move away from ideologically dictating technologies, to setting the framework for the reduction of emissions / reducing the use of FF.  Let the market develop and implement the solution.

 

 

 

 

Agreed where we are talking about replacing a perfectly good boiler system. But if it's 30+ years old like mine was, and needs a major upgrade anyway, the net cost to me of a new ASHP, DHW tank and bigger rads was no different to a modern upgraded boiler system. That financial equation of course varies enormously from the cheapest (possibly one of the utility companies like Octopus) to the most expensive (premium expert installers such as Heat Geek)

[MrPotts]

Most people won’t replace a working boiler so the only time that anyone would vaguely consider a HP is during a breakdown but who wants to wait 3+ months for heating to be restored when a new boiler can be installed in days. Surely a better solution is to reduce the price of electricity (BUS grant can be used here) to be the same as gas and install electric heating either by boiler, in place where the old gas boiler was, or panel radiators. By 2030 all our electricity will be provided from renewables anyway, according to Ed, so the subsidy won’t be for long. 😀

[S2D2]

1 hour ago, MrPotts said:

Most people won’t replace a working boiler so the only time that anyone would vaguely consider a HP is during a breakdown but who wants to wait 3+ months for heating to be restored when a new boiler can be installed in days. Surely a better solution is to reduce the price of electricity (BUS grant can be used here) to be the same as gas and install electric heating either by boiler, in place where the old gas boiler was, or panel radiators. By 2030 all our electricity will be provided from renewables anyway, according to Ed, so the subsidy won’t be for long. 😀

I replaced a working 11 year old boiler to avoid this issue, waiting for it to break results in only one realistic outcome, a new combi goes in.

[ProDave]

2 hours ago, MrPotts said:

By 2030 all our electricity will be provided from renewables anyway, according to Ed, so the subsidy won’t be for long. 😀

I sprayed my coffee all over my laptop when I read that.  Made my day.  Great sense of humour.

[marshian]

1 hour ago, S2D2 said:

I replaced a working 11 year old boiler to avoid this issue, waiting for it to break results in only one realistic outcome, a new combi goes in.

In my case it was 13 years but same reason - didn’t want it to be a distress purchase - knew what I wanted and how I wanted it set up and saw no point waiting any longer

Edited January 20 by marshian
Typo

[marshian]

5 hours ago, Stones said:

For political expediency, ASHP's are being touted as a boiler replacement.  But for the vast majority of existing homes they are not, due to the other work required to allow them to operate optimally / at comparable running cost to gas.  If ASHP's were capable of delivering a CoP of 3.5 - 4 with flow temps of 55C - 60C, they would be.  Until there is no need or requirement to significantly upgrade the heat distribution system, and for the most part I'm referring to radiators and associated pipework, the public are not going to bite. 

 

In the interest of discussion I'm going to disagree

 

UK has always lagged behind other countries - The mandating of condensing boilers was done without also mandating how to ensure they condense for all of their operating time - for many replacements they were left on virtually the same settings as the previous non condensing boilers - huge opportunity missed IMO

 

Had I been informed that lowering flow temps would have gained me 7 % efficiency gain the rad changes I have made in the last 3 years would have been done 13 years ago

 

As a result we also missed on getting houses ready for ASHP with lower flow temps which is why you state that ASHP with 55 - 60 deg flow temps and a cop of 3.5 to 4.0 would result in far more conversions but those flow temps and COP is not possible with the current ASHP hardware.

 

5 hours ago, Stones said:

Take a mid 90's house (that I happen to know well) with an oil boiler and radiators.  If the owners wanted to fit an ASHP, they would need to replace all their radiators with 3 to 4 times larger in terms of btu heating capacity (up to twice the physical size if they could accommodate double radiators) to achieve comparable running costs.  Carpets would have to come up, to get to floor hatches, all the microbore pipe to the radiators would need stripped out and replaced with 15 - 22mm pipework.  Time, disruption, and significant cost if they could even get anyone to do the work.  And what would they get out of it - a warm fuzzy glow that they had reduced their carbon emissions?  Looked at objectively then, why would anyone put themselves through all that?

 

I upgraded all my T11 rads to T22 of the same overall dimensions - in terms of output at same temp that's 1.4 times bigger (@T50) - you don't even notice they are bigger - That enabled me to go from a ~60 deg flow to a ~30 deg flow - I am on 22mm circuit with 15mm from circuit to rad but even microbore would would flow enough l/min to ensure the rads were warm enough to heat the house

 

Total spend on rad upgrades was far less than the cost of a boiler change

 

5 hours ago, Stones said:

You want change, it needs to be straight forward, meet peoples needs and be affordable.

 

The government needs to move away from ideologically dictating technologies, to setting the framework for the reduction of emissions / reducing the use of FF.  Let the market develop and implement the solution.

 

On this point I agree but I don't trust the government to run a bath let alone set a framework for reducing the use of FF

 

 

 

 

[ChrisMo]

On 12/01/2025 at 10:35, ProDave said:

 

* It IS CO2 reduction because until we reach the point where no fossil fuel at all is used for electricity generation, then each 1kWh of electricity saved at the moment is 1kWh less generated by fossil fuels.

 

By the same token, installing an ASHP increases the electricity you use so that will increase fossil fuel generation at the moment so WILL result in increased CO2 emissions.

I agree with your first points but this is incorrect.

Various websites show national grid data. Here's one:

https://grid.iamkate.com/

Over the last year under 30% of electricity was from fossil fuels. Over 37% was from wind and solar. See for yourself.

[Beelbeebub]

On 12/01/2025 at 10:35, ProDave said:

By the same token, installing an ASHP increases the electricity you use so that will increase fossil fuel generation at the moment so WILL result in increased CO2 emissions

 

 

An efficient gas boiler emits around 220g of CO2 per kwh of heat. 

 

A gas power plant emitts just under 400g of CO2 per kwh delivered. 

 

So burning gas in a power plant then using an ASHP operating at a Cop of 2:1 would have lower co2/kwh than burning the gas in a domestic boiler. 

 

2:1 CoP is achievable in all but the most ham fisted installation. 

 

So if we could snap out fingers and replace every gas boiler with an ASHP (and build some extra gas power stations etc) we would reduce our co2 emissions. 

[JohnMo]

48 minutes ago, Beelbeebub said:

we could snap out fingers and replace every gas boiler with an ASHP

Our government (past, present and future) are committed to a 4 to 5 year job application, so unlikely to happen. Short term planning wins the day, no-one cares about long term (or those in power, to change things anyway).

 

No upsetting industry, or the voter likely to occur anytime soon. They can't even get energy pricing sorted, so don't hold your breath about bigger stuff happening.

[marshian]

53 minutes ago, Beelbeebub said:

 

 

An efficient gas boiler emits around 220g of CO2 per kwh of heat. 

 

A gas power plant emitts just under 400g of CO2 per kwh delivered. 

Either you have a unit of measure error or the gas power plant is bloody rubbish

[JohnMo]

Burning natural gas produces around 0.185 kilograms of CO2 per kWh. So emissions per kWh changes depending on flow temperature and therefore efficiency.

 

Scotland currently 

 

UK Grid over the last 12 months 

[LnP]

1 hour ago, marshian said:

Either you have a unit of measure error or the gas power plant is bloody rubbish

@Beelbeebub is right. If you're asking yourself why a CCGT looks less efficient than a domestic boiler, it's because in a CCGT the heat energy (gas) has to be converted into work energy (electricity). There's a thermodynamic limit to how efficiently that can be done. CCGT is about 50% efficient. In a gas boiler the gas heat energy is being used directly without being converted to a different form and in theory you could design a boiler which could do that with 100% efficiency.

 

Second law of thermodynamics - there are two types of energy, heat and work. Work can be completely converted into heat, but heat cannot be converted completely into work. No matter how hard you try, you'll never design a device whose efficiency for converting heat into work exceeds the theoretical thermodynamic limit (Carnot cycle efficiency).

 

His sums are also right that installing a heat pump will reduce CO2 emissions even if the electricity is coming from a CCGT power station providing the CoP is better than ~2.

Edited 27 minutes ago by LnP

[marshian]

11 minutes ago, LnP said:

@Beelbeebub is right. If you're asking yourself why a CCGT looks less efficient than a domestic boiler, it's because in a CCGT the heat energy (gas) has to be converted into work energy (electricity). There's a thermodynamic limit to how efficiently that can be done. In a gas boiler the gas heat energy is being used directly without being converted to a different form and in theory you could design a boiler which could do that with 100% efficiency.

 

Second law of thermodynamics - there are two types of energy, heat and work. Work can be completely converted into heat, but heat cannot be converted completely into work. No matter how hard you try, you'll never design a device whose efficiency for converting heat into work exceeds the theoretical thermodynamic limit (Carnot cycle efficiency).

 

His sums are also right that installing a heat pump will reduce CO2 emissions even is the electricity is coming from a CCGT power station providing the CoP is better than ~2.

When I worked for British Sugar we had boilers producing superheated steam to run a steam turbine to generate electricity - the “waste” steam was used to boil the sugar solution under vacuum until it crystalised and was spun off from the molasses 

 

It’s been a while since I was in that game but I guess the advantage was both the electric generated and the steam post turbine were fully used - even the condensate was recovered and put to use.

Current work I was pretty sure our CHP unit (Combined Heat & Power) does better than that too (gas powered monster of an engine that runs a generator to produce electricity but again we use the engine exhaust heat to support our steam generators that also run on gas but have massive heat recovery systems on the flue gases. 
 

Still with a monthly gas bill the wrong side of £250,000 we need to minimise any waste in the system.

 

When gas prices spiked as a result of the Ukraine situation our gas bill hit over half a million per month - that really screwed with our costs to manufacture products!!!!!

 

I’m honestly surprised that a gas powered electricity generator that supplies the grid is as poor as 400g of CO2 per kWh generated - normally generation at scale is a lot more efficient