JamesPa

A bit of control electronics to modulate the pump speed. If a cylinder can run Linux (mixergy, alledgedly) then a simple control of pump speed is certainly possible. Also how much does it matter if the hot water is hotter than target, it simply gets mixed down at the outlet as we currently do so you use less in proportion. My gut feel is that getting the stratification right is more important than getting the output temp spot on. Clearly the thermodynamics means this is the case. But a TS can have a rectangular footprint giving 27% more volume for the same useful floorspace. The Harlequin stores are interesting and do appear to have been adopted by RED. However I'm not sure how relevant that is as I can't see any evidence RED are actually doing anything. Maybe I have missed something. I wish I had a lab to run some experiments!

With a coil no, but surely with a PHE between ts and dhw stratification is equally possible as with any hw tank. Take water off at the top for the PHE, return it to the bottom.

That was what I was thinking of, some complexity but not insuperable. With decent stratification, if that is possible (many claim it is and mixergy rely on it) this could work very well, particularly if the thermal store was direct heated. Which perfectly describes my current system that I am almost certainly forced to rip out grr!

Interesting. Nothing to stop a TS having a rectangular footprint AFAIK = 27%more volume for the same useful footprint occupied. If I am forced to replace my dhw tank for no good reason then I think I might prefer this to all the G3 stuff.

Not really. It's back to the 'good enough' discussion. For DHW only, FT65 is not at all silly if it avoids other expenses /compromises. For space heating I agree it is arguably silly, but for dhw not so. Ps I the idea is not supposed to answer @markocosic's question, it's a related idea connecting back to earlier discussions on dhw solutions for retrofits.

Given this, I wonder how many '£3k standard installs' they actually do. It sounds like none or thereabouts' because in practice the number of customers fitting their strict requirements must be minimal.

Silly question (maybe), but if the level of stratification that Mixergy rely on is achievable, why not make a direct TS with a hp operating at say FT 65, plus a water pump and external contraflow HEX to heat mains DHW to say 60 (or 55). Circumvents G3 but delivers mains pressure DHW with no requirement for legionella protection.

I'm not sure I follow what you are suggesting, a normal coil bog standard cylinder with a heat pump so that it's an easy fit under an oven?

Sounds like a good idea and fun too. We could offer the result to cool energy. Ditto for the solution to some of the other problems we have identified! Perhaps we should start with a list?

With open plan becoming more popular A2A becomes more attractive to my mind. Even where living areas aren't open plan (as in my house for example) doors are often left open. However most don't have open plan bedrooms and also value quiet in these areas. The combi of A2A for living areas, where most of the heat demand is, and A2W for bedrooms, where the demand is lower and other considerations come into play, might be attractive if it could be well packaged. Probably too complex to be practical though.

We have only two options. Do it quickly and fairly painfully, or do it slowly/when we are forced to, but even more painfully, quite possibly fatally so and with societal consequences that make today's 'problems' look like nothing. The option to do it slowly with little pain was passed up by us decades ago. Politicians need to be honest with the public that this is the situation. Then the choice becomes obvious. Probability of that?

Exactly, furthermore electricity capacity will only grow when there is demand, that's how markets work. Demand and supply build together. That's ok and the argument by @HughFmakes it doubly ok.

Yes but they can still refuse pretty much for an arbitrary reason. Still an improvement tho. 5.7 If you are unable to provide the certification described in clause 5.5 above, you will need to provide us with any information about your installation that we may request. We reserve the right to refuse you access to the Export Tariff in circumstances where we haven’t been provided with sufficient information about the installation of the generation asset or where we are not satisfied as to the safety, integrity or otherwise of the installation.

I asked MCS that question and they eventually answered that the PD rules were written by, the and the text of MCS-020 approved by, dluhc. So basically they are denying that it's deliberate on their part. I have submitted an foi to dluhc requesting the approval letter, the text to which it refers and some other documents. I await a response which should, if they meet the statutory deadline, come within the next 3 weeks. Meanwhile I have written to my MP (Conservative) asking her how the government defends creating a closed shop which stifles innovation and restricts supply, and other related but less 'loaded' questions. I await the response. I will summarise both on the ashp forum when and if I get them. It would be good if others do likewise.

That's a real issue, particularly for flats, terraces and rows of otherwise similar houses where multiple different units placed at different locations relative to the architectural features have the potential to look truly awful. Having said that it's not necessarily insuperable with some intelligent thought. Solving it however limits personal choice, puts prices up and most likely would end up requiring MCS or equivalent to 'guarantee' that the visual standards are met. In fairness the same problem arises, in those locations, with a2w so we have to solve it or just suck up the changes in appearance. Flats are more common in parts of continental Europe than here, and ashp installation is proceeding faster. So it's not improbable others will show the way.

So far as I can tell 'LPG' = either propane or butane. The red bottles, typically 6-13kg, for boats and caravans are propane. There is a separate lpg qualification, but it's advertised as being an easy conversion from gas safe. Doesn't sound like an insuperable problem and, AFAIK, A2A with its wide modulation ratio doesn't require accurate sizing. In a commercial environment I've seen installers walk in, take a look at the room, decide on a unit, fit it, and you get a cop of 4 no problems. Perhaps this is a more natural route for plumbers than A2W with its requirement for accurate sizing?

Is there any reason why gas safe plumbers can't do R290. Isn't it just propane, which surely at least some do for both commercial and domestic where mains gas is not available (eg off grid or mobile vans, boats etc). Have I got this wrong. Maybe the caravan and boat plumbing industry has a new lease of life?

I made a similar point earlier. Climate change is a gift to the right wing extreme (and not so extreme). The changes that must be made to combat it cost 'the working man' and these are promoted by 'intellectual elites'. The inevitable migration of communities affected will be weaponised by fascists. The elites will be protected by wealth and everyone else, especially those that their ruthless lies are aimed at influencing, will suffer. Just read the headlines in the right wing press if you doubt this. Climate change is a threat to democracy as much, if not more, as it is to the environment and lifestyle. You only have to read the headlines in the right wing press to see the way this could well go.

I get the second, and to me it seems the (almost) ideal solution, it just needs to be productized so installers/the industry accept it. How do you do the first without cutting the cylinder up?

My gut feel is that there are a range of solutions involving Tarrifs Willis heaters Plate heat exchangers and pumps as add ones Use of high temp flow The existing immersion heater where there is one Currently it seems the industry will contemplate none of these, that has to change.

Apologies @JohnMoI might have accidentally reposted something after you had replied. Intermittent connectivity to blame and no offence or attack intended

Just to be clear I'm not arguing for my particular case. I can afford to replace my dhw system when I fit a heat pump. With my engineering background I find doing so offensive, but if that is what it takes then so be it. I'm making this argument for the mass retrofit case which, so far as I can see is 1.4m gas boilers per year which will be a mix of system boilers and combis. We have to do this at a price and disruption the average person will tolerate, most likely when the gas boiler fails or is not economically repairable (because that's when people replace boiler) and also most likely at a time when the dhw tank has not failed. I can't see how that is possibly consistent with insisting on on an unnecessary spend of 2-4k on replacing a functioning DHW system. So to be clear it's not my case I'm concerned about, it's the more general one.

does it? No it doesn't. I run my gas boiler at FT55 in winter with a 0.7sq m DHW coil. My water is hot (in summer I run the DHW from PV - the water is hotter, but the winter water is still definitely hot).

I think @JohnMoprobably meant heat pump space heating and E7 DHW, which is certainly a plausible solution.