Posted by: @batpred

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Are you suggesting heating dhw using the immersion heaters? 

No.  I am suggesting, based on what ashp-bobba has shown (and a bit of common sense) that the 'standard' practice of replacing existing DHW cylinders in almost all cases simply to get a larger coil needs to be questioned.  Historically heat pumps could only reach a FT of 55C and the practice dates from then.  Now they can reach 70-75C.

Posted by: @bash

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Having had a brief read through some of the comments, it seems very clear to me that swapping to a HP as a distressed purchase if your gas boiler breaks down will almost never happen, even if it would be the better solution!

If we cant fix the distressed boiler problem we can never make the transition.  I would like to think that humans are cleverer than that!

Why wont it happen - the comments are largely positive.  What (or who) will stop such a thing happening in your view?

Posted by: @jamespa

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Posted by: @batpred

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Are you suggesting heating dhw using the immersion heaters? 

No.  I am suggesting, based on what ashp-bobba has shown (and a bit of common sense) that the 'standard' practice of replacing existing DHW cylinders in almost all cases simply to get a larger coil needs to be questioned.  Historically heat pumps could only reach a FT of 55C and the practice dates from then.  Now they can reach 70-75C.

When getting estimates from the likes of Octopus and Heat Geek, the assumption is any cylinder could be kept. 

Do you mean the practice after the survey is in case R32 is being used, to add costs to replace it so that it warms a bit quicker? I assume a homeowner would not be too pleased with it, having in most cases paid for that survey.. 

Posted by: @jamespa

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If we cant fix the distressed boiler problem we can never make the transition.  I would like to think that humans are cleverer than that!

Why wont it happen - the comments are largely positive.  What (or who) will stop such a thing happening in your view?

Absolutely, it needs to be fixed and reg changes are essential for it. 

Your proposal aims to address many of the issues that make it unlikely distress sales will be made with a heat pump, but using our recent experience I can see others:

• space: people need to accommodate the expansion vessels etc (and we had multiple installers that wanted to make sure they are all near the DHW cylinder where we have limited space). owners with a combi need to give up more space
• sizing of the pump: even if the data on gas consumption is surely available centrally, the heat loss survey is mandatory, requiring scheduling, etc. Why not make the utilities have to continuously calculate the maximum gas consumption they had for the property in any 24hrs in the last couple of years? If installers can access and rely on that, it becomes another source that can help calibrate the epc input into the heat loss calculation and quotation.  
• external unit location: Even if permitted development has been relaxed, BG and other installers still restrict the location of the ODU. We found it took considerable time to find a location acceptable: protecting garden space, allowing access to installer and manufacturer warranty/servicing, and acceptable to neighbours
• heat loss surveys not being reusable across installers. In a distress sale, to be able to have some choice, consumers need to schedule several surveys and wait for the last result. 
• the requirement to apply to DNO: this is probably difficult to defend. Anyone can plug fan heaters around their house with a significantly higher electricity consumption and the DNO has no say in that. 
• estimating practices that are often opaque. We had several estimates on 4/6 page docs but with a single line item for price.
• unclear schedules of payment: in a distress sale situation, most people trust the boiler replacement process and have seen it working. That lack of info for an ASHP means much more clarity is needed in the proposal. 
• lack of electricity tariffs allowing reasonable combination of EV use with a heatpump. Very few people will go to the lengths of getting 35-40kwh batteries to be able to stay on an EV tariff

But I am very positive about the lite reg concept. In fact, I wish it could be used in borderline distress sales like ours... 

"even if the data on gas consumption is surely available centrally,"

If you have a good installer one of the things they'll do is tell people how to use things like Bright EMS to get the consumption data if they have a smart meter. However it's only one element because the grant people are (probably sensibly given houses change ownership a lot here) concerned that the install must meet the (usually wildly inaccurate) heat survey data and achieve temperatures that are sufficient for the majority of people in all of the rooms. 

Heat loss surveys ought in reality to be mostly obsolete if the next generation EPC replacement actually manages to do the job intended, or at least be sufficiently close unless major work has been undertaken.

@etchedpixels 

A more open EPC process would be another game changer, making installs more straightforward in terms of paperwork.

I say this since our experience has been that almost half the installers that provided an early estimate made it seem they would stick to even when it is clearly not based on all the up to date information. We just dropped those installers from our list, but their salespeople must have decided it was worth doing that. After that, they expect the survey to be prepaid! 

It makes sense an EPC report worth its salt would just replace the heat loss survey. Assuming the owner could confirm it is still applicable. 

Posted by: @jamespa

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If we cant fix the distressed boiler problem we can never make the transition.  I would like to think that humans are cleverer than that!

I agree, and that's why I think the Dutch and the Italians have got it correct with their support for hybrid heat pumps - the old boiler fails, the existing combi or system boiler is replaced with an integrated hybrid unit (often a combi hybrid, with the boiler doing the instant hot water and the heat pump supporting the space heating) which is pretty much a drop-in replacement for the old boiler except that the heat-pump cuts the gas usage by 60-80%.

It's not the perfection of a pure heat-pump, but it's a practicable solution for urgent replacements.

The other option which is less seen in the UK are the refrigerant-split heat pumps, with an indoor boiler-like unit that drops into the place of the boiler, with compact and flexible refrigerant piping to the outdoor unit - that looks a more flexible option than mono-blocks in some situations but you don't see many companies offering those refrigerant split units here. They seem to fall into a gap between the A2A / aircon installers, and the plumbers working on the water based systems.

@temperature_gradient 

If the split refrigerant would remove the need for a hot cylinder that could help people with a combi. Extra points if it would not attract all the MCS certification and paperwork. 

As for hybrid systems, the concept of just slotting in place seems attractive. On the other hand, having a 20+kw gas unit for hot water leaves a lot to be desired, as it adds to regular maintenance. And with so many people here going all the way to remove the gas standing charge, which is around the same as boiler yearly servicing, would we have such a large market (with the current gas prices)? 

@batpred 

The benefit of the split refrigerant units is that the pipework sizes to the outdoor unit are a lot smaller than the primary pipe to a monoblock, quite flexible on the routing because they are vacuumed out and filled with refrigerant and there's no need for frost protection.

Their performance is much the same as a regular monoblock, so they cannot do instant hot water unless as part of a hybrid combi unit, but it opens up a solution of having an indoor hybrid-boiler unit in the place of the existing boiler, with this smaller, more flexible refrigerant pipework out to the outdoor unit, so a simpler and quicker install.

Personally I don't get this concern about the gas standing charge, it's about £120 a year, even 10 years worth of gas standing charge is only £1200, which is just a small fraction of the cost of installing a full heat pump. If a hybrid unit allowed most of the existing plumbing to remain unchanged, I expect the installation savings would pay the standing charge for several decades or more.

@temperature_gradient

And people buying and installing a flashy induction hob, and of course replacing most of their cooking utensils, they may be using that same 120 a year. Either a bit of double counting or - no counting? 😀 

I like the idea but would approach it in a different way.  At the point of distress purchase, people’s minds are on getting the heating and hot water going ASAP.  Once they start hearing about having to install new unvented cylinder, volumiser, etc plus some unknown future work “once we see how well it is running” (and having to clarify “are you saying it may not be warm enough?”), people will balk.  If my wife heard any hint, however obfuscated, that there may be a heating issue, I might just as well put my tackle on the block immediately.

The principle of what you are saying though James is definitely important.  I would look at it as a pull down on the grant to get your home “renewables ready” when your boiler is, say, 8 years+ old (I.e. before it has failed.). Off the top of my head this would entail:

• the DNO, or representative, upgrading the house fuse to support a future ASHP, EV and Solar system plus installing Henley blocks to allow the kit to be installed.  Also, the DNO can identify, plan and make any additional changes, e.g. de-looping.
• Installation of an unvented cylinder at mains pressure, even if not used because of combo-boiler.  If not possible because of space constraints, a plan of action to allow it to happen or an alternative approach.  (I wish we’d done that years ago now I’ve discovered how great the water pressure is in the bathrooms that needed a noisy pump.)
• Increase in loft insulation to min 300mm if needed.
• Advice on additional insulation needed
• A heat loss survey that is acceptable to any installer based on advice given.
• Advice on radiator and pipework changes.
• Identification of suitable location for the ASHP
• Implications for planning permission (e.g. noise) and a submission of planning that will be valid for as long as it takes the work to happen
• and so on…

This could be done as part of the existing grant, I.e. pre-spending some of the £7.5k that is available so no immediate cost to the homeowner, and it is tied to the house.  It should definitely be possible to separate out the installation works into “readiness” elements.  It removes the “decision under crisis” issue, gives time for the homeowner to mentally prepare and research and also perhaps to do some of the upgrade work as part of any decorating.  Clearly there would have to be some rules around how the homeowner could change their house in the meantime, e.g. build an extension, install underfloor heating etc, once the grant has paid out. They’d also know that they have a balance of the grant for the future and could also choose to complete before their boiler fails.

There is another thing that needs to happen independently: sorting out the energy market.  Homeowners need better tariffs and better infrastructure to support renewables.  

Posted by: @andrewj

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• Installation of an unvented cylinder at mains pressure, even if not used because of combo-boiler.  If not possible because of space constraints, a plan of action to allow it to happen or an alternative approach.  (I wish we’d done that years ago now I’ve discovered how great the water pressure is in the bathrooms that needed a noisy pump.

Good topic - why are virtually all installers converting the plumbing and fitting unvented cylinders, even when there's existing plumbing for a vented cylinder? On an emergency install, it would be quicker if the installer just replaced the existing vented cylinder with a heat-pump vented cylinder. Old one out, new one in, leave the cold water tank and all the hot water plumbing as is.

But I cannot see householders, or UK Gov paying to pre-emptively install a cylinder in the hope it might be used some years/decades in the future. I think a better approach would be encouraging more wide-spread use of those Heat Geek Mini-store units, much smaller and compact, but not common, situation in the MCS regs is unclear, but these would really simplify things where there's no existing cylinder.

One good move could be to require that all new hot water cylinders being sold and installed, have coils with enough surface area to ensure they work with a heat-pump. They cost a bit more, but there's an immediate benefit because they improve the efficiency of the gas boiler and speed up reheat, and they would be suitable for a new heat pump install avoiding the need to replace the cylinder at that point, so closer to a boiler swap.

Posted by: @temperature_gradient

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why are virtually all installers converting the plumbing and fitting unvented cylinders, even when there's existing plumbing for a vented cylinder?

because historically heat pumps couldn't reach sufficiently high FT to heat a cylinder with the default coil size of 0.6 sq m.  Since R290 heat pumps can get to 75C this is no longer the case.  Unfortunately some (perhaps many) heat pump manufacturers still specify a min coil area I think

Posted by: @temperature_gradient

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One good move could be to require that all new hot water cylinders being sold and installed, have coils with enough surface area to ensure they work with a heat-pump. They cost a bit more, but there's an immediate benefit because they improve the efficiency of the gas boiler and speed up reheat, and they would be suitable for a new heat pump install avoiding the need to replace the cylinder at that point, so closer to a boiler swap.

Agreed, much like the latest building regs specify a max design temp of emitters of 55C, making it both heat pump ready and ensuring a condensing boiler actually condenses.  The boiler installer will probably still whack the FT up to max though, to ensure that it doesnt condense, the residents are less comfortable and pay more!

Posted by: @jamespa

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Posted by: @temperature_gradient

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why are virtually all installers converting the plumbing and fitting unvented cylinders, even when there's existing plumbing for a vented cylinder?

because historically heat pumps couldn't reach sufficiently high FT to heat a cylinder with the default coil size of 0.6 sq m.  Since R290 heat pumps can get to 75C this is no longer the case.  Unfortunately some (perhaps many) heat pump manufacturers still specify a min coil area I think

That's a reason to replace the existing cylinder to a new one with a bigger coil, but you can buy both vented and unvented cylinders with bigger coils. Deciding to change the hot water system from vented to unvented, with all of the extra plumbing work, is a separate decision and I'm not sure why it is the default in the UK because it's unnecessary and adds to the cost and disruption.