Beelbeebub

Or presumably up rate with a larger charge? The "dream" would be to change the rating of a physical unit to match the load simply by adding or removing some charge and changing the software parameters. That would be a win for most people, the manufacturer would have simpler production, suppliers could stock one unit, installers would only need to handle one unit and could adjust "in situ" for the property. I'm pretty sure gas boilers already do this. I was told my WB 18kw was identical to the 12, 15 and 22kw units. Just a different chip in the PCB (which they won't sell you!). Vaillant go even better, their units are configurable by the installer who fits one unit with a wide range and the configures it for the property. Question: My understanding is the upper limit of performance is related to the charge. There is only so much heat you can transfer per kg of fluid. The lower limit is related to how slowly you can run the compressor before it becomes too inefficient. If the York units are physically the same (IE have a big coil and compressor for the 14kw but are down charged and slowed down for the lower ratings) could you extend the modulation of a HP by having a "reservoir" that you can increase or decrease the working charge with? IE, there is a gas bottle off the HP circuit and you can pump gas into it before sealing it off and then the remaing working circuit has less charge land the software rejigs). When you want more capacity you just bleed more gas from the bottle back into the system?

Certain portions of the press!

Agree! Sorry, what I meant was "not brazed joints", flare nuts would be fine but if there was an even more foolproof way (Daikin has a clever one with a green indicator to show it's done up properly) it would be better. It needs to be plug and play As for spares, yes if the system was cheap enough then just replace (hardly very sustainable tho!). The pig is installation. Swapping out a single head or outside unit is not too bad, but if you're replacing all the heads, the outside and then maybe the control wiring it becomes a bigger job. Be nice if it was a simple as a radiator swap.

Are they? Unless you are nicking for scrap, in which case any metal is vulnerable, you have to remove a HP fairly carefully or all you will end up with is scrap. Unless they turn up when you are away and pretend to be legit plumbers doing some work, someone (probably inside the house) will notice.

Ah good point! But an odor chemical would make things alot safer, and the quantities are pretty small, basically 2 or 3 plumbers blowtorch cylinders. I feel careful monitoring for leaks in the unit by looking at temp, pressure and compressor load, could alert the user would mitigate the risk. Maybe even portable gas detectors located on the floor similar to CO2 and smoke alarms. Leaks would mostly come from bad joints and could be mitigated by premade "pushfit" connectors only, no DIY onsite brazing, and damage (surface mounted pipework or armoured and vented trunking). Very small leaks (mg per day) are unlikely to cause any danger except in a very sealed space (say a wall cavity). Larger leaks only cause a (relatively) short term danger window before even a heavier than air gas disperses through natural currents.

I know millions of a2a sets are made and fitted each year. Mostly for cooling (globally the biggest use). If the UK were minded to go the a2a route (as I believe France are) then we could absolutely tap into that market. As @markocosicsays, it would massively improve the logistics. If r290 splits were allowed for home DIY then it would make the cost of installation much lower. If a r290 to water invented cylinder could be made readily available it would solve the dhw issue. The only other hurdle would be interoperability between brands. .The *only* issue with r290 is the flammability - admittedly a pretty big issue! I beleve china and India have been using mini and multisplit r290's for over a decade. Be good to see what the safety record is. But in the UK we (currently) prefer air to water which, as has been pointed out, have more stuff in them and globally, the volumes are small Vs a2a type units. To be honest they are a suboptimal solution, except maybe when it comes to underfloor heating (but that could easily be solved with a r290 to water PHX/manifold/pump unit) but it is where we are. One potential option for my upgrade path is getting an F-Gas cert and fitting a2a units. My one reservation with a2a is the long term spare parts/interoperability issue. If one of my head units plays up in 7years time can I get a drop in replacement easily? With water based systems it's easy. Edit: side thought. The big issue with r290 is the flammability, but we already accept a far higher potential source of flammable gas in the home. The issue as I understand it, is that main gas has an odour chemical added so any leak is deemed to be easily detectable far below dangerous levels. It is currently impossible to use that chemical in the refrigerant circuit. If that hurdle could be cracked why would having an r290 unit in the home be any different from the canister of lighter gas or mini camping stove in the house and why would a DIY fill be any different from changing your BBQ cylinder?

It would seem that improving the modulation is fairly crucial for heatpumps. Gas boilers have good modulation. So as long as you get the heat load about right there is plenty of wiggle room. If you oversized the boiler a bit, no problem. With HPs that is more difficult. If it were easier and you could just fit a "12kw and under"cunut that would be fine down to 2kw output it would make installers life a lot easier. I did notice York heatpumps seem to have a broad output range , from 6kw to 14kw in the same chassis size. That does open up the possibility of a very easy swap over of units if the power supply is rated for it.

One outcome of this is a universal standard HP interface would be useful. The proprietary control box costs just under a quarter of the price of the physical unit. The good news is that these "fire sale" Samsung units prob sky indicate how much HPs could be sold for regularly. The current 4k for a 5/6kw unit average seems to be a combination of demand and the fact these units are fairly new, there's lots of R&D and setup cost to be amortized. Vaillant have spent £4m on upgrading and expanding its.uk factory and £55m on its.german r&d plant. Hopefully, as more competition comes on the market and volumes (and supply channels) increase the cost will start to drive down.

Honestly, if "sticks out too much" and "not in keeping" are objections..... That's what you end up with.

What is the bivalent temperature? I've seen it a few times.

I beleve it"s "revolutions per second" of the compressor. Basically the modulation of the HP from full power (120rps) down. Note the most efficient speed is not full speed and varies with external temp and flow temp. Also note the max power delivered can increase with falling external

That's what I plan for the elec only flats, they have electric showers and immersion cylinders already. It's the heating load thata makes.tge bulk of consumption. Very useful info, presumably that means I can claim the 5k subsidy which might tip the balance.in favour of that route. It would pay for a cheap pump and some fan coil radiators, I only plan on

I wish I could. Current problems (apart from the cash and space).are the restrictions around fitting them (planning) and the biggie - unless I can "tune" them really well the bills will go up, even if the carbon goes down.

I know grant gets.stick.for.dumbing down the HP.and not running it in theost efficient way, but there is something to be said for making it as close to the boiler people are.used to as possible.

Calm down, it proves you *can* get the cost of HP down to boiler levels. That low cost is fairly unusual cut price. It needs to be come the usual cost. That is pretty much the same as a system or regular boiler. Which is what we want. The flies in the ointment are the mcs requirements, the probability that just a boiler to HP without any other upgrades won't be cheaper to run and (importantly in this case) the control system isn't compatible with a straight swap (afaik) you can't just connect up to the existing system. You need some sort of interface, and you only have one to choose from, the Samsung. Which is why I mentioned the control box cost (which seems extortionate). Shows what's possible tho.

£1,300 or less is exactly where we should be aiming! If the rules allowed that to be stuck on a little flat and run for the same cost as a gas boiler (however that is arranged) uptake would soar and heating related CO2 would start to fall (and fall further as people optimised the systems with experience)

Yeah I've seen those, I think they are being flogged off cheap because the next gen has been released. Basically clearing the decks. But it does underline that they don't need to cost a fortune. Also Samsung's need a Samsung controller which is £400(?!). But IIRC they are the.moat bare bones units, no pump, no expansion vessel, just a HP with a plate heatexchanger. If it had an "open source" control system so you didn't need to use a manufacturer specific one. It would be pretty close to my concept. (Also, paint the damn things black!)

Basic HPs for split Aircon, millions and millions. You can get a 5kw unit for well under £1k. And 8k won't be much more. But stick the monoblock stuff on..... Much lower volumes and much higher prices. A 5kw vaillant is about 4k. Ok, it's well made but where didn't he £3k it costs over a 5kw Aircon unit go? Diamond Heat exchangers? I think a bare bones 5kw monoblock could be under 2k eventually. And yeah market rate for elec would help. Anything that drops the unit price for heating elec. But the difference system they use does drive renewable generation install. So that does need to be considered. The only down side to measuring heat and subsidising is the extra parts needed to do that, but the potential benefits are pretty good when it comes to driving post install optimization (and user awareness)

But the problem is relying on the install to keep the noise to acceptable levels will *always* result in problems, the upfront planning to get the noise levels down, the installation being done correctly and the process missing edge cases (eg line of sight) mean the process will be more costly and fail more. It would be better to make sure only HPs that are quiet in the first place are sold. Of course this will require manufacturers to put in more effort, and there may be compromises with performance. We also need a more general national conversation about noise. Nobody has the right to absolute silence. There ahs to be a level of noise below which you can't complain. Do I complain about my neighbours trees rustling in the wind? We have constant road noise at a low level and sometimes high when someone with a suspect exhaust blasts past. I think noise is another stick that the foot dragging lobby has bigged up to beat HPs with and slow uptake. To listen to some people they think a HP next door is equivalent living next to Heathrow.

The point is to get the price of the install down to 5 or 6k so the 5k subsidy really does make it affordable for the normal person. I think the Units should end up around 4k or less as the volume increases and the install 1-2k (2 men 2 days). The key is to not have to upgrade and replace lots of stuff, especially the cylinder! an unvented cylinder is easily north of 1k, more like 2 by the time you've added all the extras. then another 2 men for a day to remove the old one and install new one (assuming no redecoration!). You could burn most of the 5k subsidy on the cylinder swap alone! I agree about the opening up the installs. And yes, low flow temp training, but not absolutely mandate them. that route leads to replacing pipes, rads, cylinder etc. They are definitely a nice to have and crucial for maximum efficiency. Now we have HPs that can achieve high flow temps at reasonable efficiency (which we didn't used to have) Vaillant r290 units can hit 2.5 at rated output at 55C which should do most places heating and can hit 2.0 at 65 to use the existing water cylinder. The issue with the smart meter for the HP with different unit pricing (which was my first thought) is I can see lots of fraud. Lots of people wiring the rest of the house up etc. It also doesn't give any steer on the actual cop. That's crucial for the feedback loop to the customer so they can see the gap coming up when the subsidy runs out.

One idea just occured. If each install had a subsidy pot, lets say £5k, upto 3k of which can be used for the install and any remaining to subsidise any shortfall between the price it would have been in gas and the actual. After 5 years any left over would be split between the bill payer and the installer. Give an installer and householder an incentive to do a good job? Not go overboard on the install.

I mean I guess it makes sense, "PD rights are for installs to a certain standard. The industry body will set out that standard" I don't directly disagree with that approach. The problem is that the standard is too restrictive and ends up hindering uptake. Anecdotally they have failed to prevent poor, noisy installs. If MCS was altered to be less restrictive and more "good enough" focused they could tackle the issues separately. The noise issue could be tackled by a requirement for a "hush mark", basically a set of noise limits (and testing) that HPs have to meet to get the mark. Same as windows needing kitemark for various glass safety standards. The performance issue is partly solved by technology. If a "performance mark" were needed, which meant the HPnhad to have a certain performance envelope, specifically 2.5COP at a given flow temp (say 65c) and rated output (and noise!) during certain external conditions. If a HP can achieve that then it can keep someone warm and burning less gas (in the power plant) than a boiler even if it doesn't save them money. So your "good standard" requirement becomes "use an approved HP". The final bit is the gov have to come up with the "price guarantee" scheme to prevent bill shock and align it with schemes and subsidies to bring installs that are below the final (ie. Above the 2.5 figure) efficency required up to that level, 12 month post install tuning using accumulated data, radiator scrappage schemes, more insulation etc.

Kinda.

Ahem, there might be specific spots on the building that a box can be put and not be visible at all. It's a bit tight for the larger monoblock HPs, which is why I'm thinking the external boxes need to be as small as possible to help with retrofit. But again, planning rules which make installing solar panels, heatpumps, carchargers etc are all political decisions that slow up adoption. I often hear noise cited as an issue, but that could be solved by just having a standard noise limit on the units. As long as it has the "hush mark" you don't need permission. Manufacturers making the damn things in almost any colour other than bloody white would help! As far as I can see the default white comes from air con units which are used in hot, sunny countries and any additional absorbed solar radiation hurts their efficiency. For aheat pump, any additional (however slight) gain from a dark casing on bright winters day can only help, and a black or brown or brick red box on the outside of a building is much less intrusive than a bright white box. How many of those plastic "garden lockers" are proposed up against the side of houses in the UK? Are planners up in arms over the visual blight?

All the faff is to do with the grant. I've looked at grants because I have potentially 30 odd properties to do. So I'm thinking £5k a property....nice. But the key bit is the cost to me. The fact that I'm getting £5k off something that would cost £14k still means I pay £9k, and if I could get a system for less than £9k without a grant it'm still better off. I plan intialky to tackle the electric only properties because they are going to win whatever. Then the gas properties, that will be harder as I will have to hit financial break even or the tenants will get cross. The other wrinkle, is I asked our EPC assessor what effect swapping to a HP would have (on an electric flat). His answer was "almost none". The EPC appears to be based on the state of play 10, 15 years ago when the grid was 50% coal and heatpumps were assumed to get cops of less than 2 at best. Until that's solved the EPC is a barrier (in fact it drove us to install gas in several properties as the easiest (almost only way) to get a C in an old property was stick a gas boiler in.