Beelbeebub

Simplicity is about the only thing storage heaters have going for them. Everything else about them sucks. I look after a few properties with them and nobody likes them. Expensive to run, hot in the mornings, cold in the evenings and god help you and your back if you have to change one.

Is this a simple on/off pool unit? In which case isn't it run just like a boiler? All the "logic" is done via the wiring center of the heating system (standard timer, thermostats, 5 wire valves etc) and all the unit gets is on or off signal.

I think that paper was looking at using the same physical equipment but swapping fluids. It is relevent because a chunk of the market is retrofitting older units with newer refrigerants. So effort has gone into working out which new refidgerant to use in a given set of circumstances. As they point out the compressor specs for r290 differ from those of a similarly spec'd r410a unit. R32 is a better "drop in" than r290 But when it comes to a unit designed for r290's properties i think the picture is different. Efficiency wise similar, but with wider operating range, higher max temps.

The problem with bard and other chatbots is they produce something that sounds plausible but is not necessarily true. So if you feed it a bunch of inputs from sales brochures it will simply come up with something that could plausibly be a sales brochure for heatpumps. Little things like the accuracy of numbers quoted are less important than numbers being quoted. All things being equal, R290 can achieve higher water temps than r32 and operate at lower external temps. The efficiencies are similar with system design being more important than the refrigerant. The downside of r290 is it's very flammable, whilst r32 is only mildly. R290 needs special attention to what could happen if it leaks from a fire/explosion perspective. R32 much less so. The downside of r32 is it has a global warming potential in the many hundreds (better than told stuff that was in the thousands tho). If you let the r32 escape from a typical monobloc it it the equivalent of about 1t of co2. R290 has negligible GWP. The r290 from a typical heatpump is equivalent to a few kg of co2.

You could use a multimeter to check if the control signal to the radiator valve is going live or not, and then if the valve is moving when it gets that live signal. What you described sounds like a dodgy valve actuator and/or valve. Regarding your expansion vessel, I assume you mean the one for your hot water tank. The pressure on that should be set when the mains are shut off and the pressure in the water system is relieved. The "at rest" pressure can be calculated by your plumber.

I'd point out you *will* need a controller for the Samsung, and it's about £500. Samsung seem to be a little cheeky in that their "gen6" models are cheap because a) they are superseded so I guess they are having a sale and B) they don't have a pump or controller in them. You have to supply them which adds a bit to the cost. Vaillant do (I think) the smallest air to water monoblock at 3.5kw nominal which might do. It's a bit pricer but does have the pump etc included and uses the newer r290 fluid which gets you higher temps (for legionella cycles) and possibly more importantly goes down to -25 external temp. They're supposed to be very quiet too.

I've been looking at the LG range and they have a monoblock version, which is everything in the outside unit and water (or glycol) running back inside the property and on to your cylinder/emitters They have a split system that has the compressor outside the house but runs refrigerant lines back into the house where a plate heat exchanger and circulation pump (plus other gubbins) live in a "indoor unit" What confuses me is the "hydrosplit" option. This has, explicitly, water lines running into the house. Confusingly they talk about "The LG Therma V Hydrosplit reduces the risk of indoor refrigerant leakage by keeping refrigerant safely outside: only water passes through your home." - which makes it seem like all the refrigerant, heat exchangers etc are in the outdoor unit. In which case, what is the difference between a hydrosplit and a mono block apart from what would appear like a PHX indoor unit? I could understand if the hydrosplit put all the refrigerant, compressors, pumps, heat exchangers etc in the indoor unit leaving just a radiator and fan to sit outside. It would have some advantages for situations where accessing the outdoor unit for servicing was challenging as there would be alot less to go wrong. In my case I was wondering if such a system would allow for shared outdoor units in blocks of flats, not unlike the Kensa shoebox approach but with air to glycol ranter than ground to glycol. But their wording is rather confusing. Anyone know how these work?

It wouldn't be dark, the fridge lights would be on! 😁

Is it something to do with the running time.? I note the valves listed have different setting for the running time from open to closed. If your esbe valve was faster moving than expected it could be stepping too much each time. Ie it wants to close a little, so applies a 20 second pulse to close, which would be about 20% on a valve with a 100 second total time, but if your valve had a 15 second close time it would be full operation.

From that it looks like a hybrid HP of about 5kw could provide carbon savings of upto 50% vs continuing with a gas boiler. the two big determining factors seemed to be the radiators (if they are unchanged and require high temps it drastically reduces the number of days a HP can provide heating, which is compounded by control strategies that switched entirely to boilers when the HP was unable to meet all the demand rather than using the boiler to "top up" the output) The second factor was thought to be running the heating in short bursts which required higher flow temps and hence lower efficiencies and more days when the boiler was used instead of the HP. It estimated the cost of installing a HP alongside an existing boiler, including upgrading radiators, to be £5-7.5k. So it would be within the current BUS £7.5k grant to provide a HP and upgrade the rads at little cost to the owner and cut the carbon output by upto 50% without any risk of "being cold" or costing more.

Your core argument against seems to be that the user will continue to use the gas boiler in preference to the HP. But they won't really have a choice, short of disabling the HP outright. The control system handles which source provides heat. On a mild day like today, it will heat the house via the HP. The user will be none the wiser. The house will be warm and less gas will have been burnt. On the occasions where the conditions are too much for the HP, the boiler kicks in and the house remains warm but burns a bit more gas. It's a win from a carbon perspective and from a consumer perspective as their bills will go down (unles they disable the HP, in which case their bills will remain the same). As upgrading the rads would be a part of the install (paid for by not having to sort out a new DHW system) the house woiod also be more efficient.

The pro em is/was thrat the AGR tech the UK used was not a great fit for civil power. I was told by one of the engineers who had been there from the start (he was in his late 60's and about to retire) the primary driver of the decision to go with gas cooled, graphite moderated was because it was good at making stuff for weapons. The "oh look we can make civil power" but was mostly PR fluff. That's not to say they couldn't make good power stations, tgry did, but that the tech "tree" chosen was not one ideally suited for civil power. The AGRs were kept running past their design life by a huge effort of engineering to understand and measure the stability of the graphite cores, which were becoming dangerously brittle by the mid '00s I think it is and was a dead end technology. The small modular reactors show promise. My understanding is they are basically (sub) marine power plants repurposed for stationary land use. The biggest hurdle will be the regulations and, by extension, the politics. There is a certain percentage of the population who are, rightly or wrongly, implacabley against nuclear power full stop.

All good points but I was thinking more along the lines of allowing HPs to be installed alongside an *existing* boiler system and still qualify for a grant (maybe with different amounts and stipulations about upgrading the rads). Rad upgrades would make the existing system more efficient as well. Fitting a new system as a hybrid should not be done. By allowing "piggyback" installs we can sidestep the "why throw out a good boiler" argument as well as the "but what if the HP can't keep me warm in the depths of winter" one. The HP can then be undersized, or at least not oversized, making it cheaper and more efficient. It can work for most of the year and when it gets to it's limit the existing system kicks in. The control system can prioritise the HP to run only when it is cheaper than gas, ie the conditions allow high cop. This negates the "costs more to run" argument. It woiod also allow installs with combis and sidestep the hot water problem. Finally, when the existing boiler packs in it can be replaced by *another* HP of appropriate size (by then the control system would have a good idea of actual demand). This woukd result in a twin HP system, theoretically more expensive and complex but in practice not so bad as it would be installed in stages. It would then have the huge advantage of a bigger modulation range than a single HP. If the grant could make the install more or less free, then the proposition would be "hey, can I fit this gizmo to your heating system for free that will make it more efficient and cheaper to run?" I reckon people woukd be biting your hand off.

Absolutely. I think air to air systems should be pushed alot more. They can be added fairly simply to houses without needing to touch the existing heating system. They also tend to offer higher efficency than water units. To the point that hitting the magic SCOP, where the HP is cheaper to run than a gas boiler (somewhere around 350%) is achievable. The occupant can then choose which system suits them at any given time. The problem is our regulatory setup which disincentives hybrid and A2A systems in favour of compete air to water replacement systems.

A gas boiler puts out 200g/kwh of co2 at best. So you might halve the total co2 output from the house. The carbon intensity of the grid is roughly 200g/kwh at the moment. Basically the same as a direct gas boiler. So if you took an averagely crap UK house that uses a gas boiler and improved the fabric, you might cut the demand in half and thus the co2 in half also. If you swapped out a heatpump and maybe upgraded a radiator or two to lower the flow temp to below 50C, you coukd easily achive a SCOP better than 2 which would more than halve the carbon output. Of course doing both woukd be better and upgrading the worst parts (uninsulated lofts and single glazed windows) would make it easier to fit a heat pump anyway. I was a "fabric first" fan. I still am a fan of improving insulation. But we have got to the point now where we need to do multiple things at the same time.

Well yes. But it's a false dichotomy. There is absolutely nothing to stop us upgrading our plasterboard tents whilst also switching to HPs.

It's not a party thing, they were all content to kick the problem into the long grass as our nuclear fleet aged out. The obsession with private enterprise running things was also an issue. The new labour Gov was as bad as the Cons for this and the coalition and post 2015 (and I use the term loosely) government were as bad if not worse. A nuclear fleet needs to be commissioned, overseen and owned by the state as a national resource. Faffing about trying to come up with some way you can make private enterprise responsible for something that needs half a century of concerted attention and where cost cutting in the name of "efficency" is the name of the game is always going to end in tears. Still water under the bridge now, and we are where we are. We need to massively ramp up wind and solar and (this is the controversial bit) state owned CCGT plants and gas storage as a national resource to cover any generation gaps as we transfer demand from gas to electricity and to provide cover for the time when wind/solar aren't sufficient

Nuclear is costly, but mainly because we piss about "shall we shan't we". That add cost and uncertainty to suppliers who then have to pass thar cost on to the end unit price. I have a friend who used to work for the consortium(s) hoping to build a replacement plant at Wylfa on Anglesey. Hundreds of millions were spent on that project for it to be canned. The next lot will look at that and add a few hundred million into their calculations.

The UKs problem is lack of political will. The time to have ordered the new plants was the late 90's. The tech is pretty mature now and the majority of the cost comes from the insane amount of regulation we have around nuclear. To be clear I think that is a good thing, but as someone who has dabbled on the periphery of UK nuclear power, nobody in that industry does anything without commissioning a dozen in depth and exhaustive reports on whether or not changing toilet paper brand in the staff toilets is safe or not. (clearly hyperbole but honestly not far off)

Hove weather comp seems pretty important when it comes to getting efficency, it seems that needs to be enabled. The challange is getting a public used to timers and thermostats used to it. Open loop WC is fine *if* you can calculate and predict the heat loss curve. With today's advancements in machine learning it shouldn't be impossible to implement some sort of learning system where the control system refines what flow temp is required for a given outside temp. The input would either be simply a set temp or the user pressing a "too cold" or "too hot" button. This would initially act as a cue for the curve to be adjusted up or down respectively but over time persistant user intervention would generate a permanent change in the curve. Ideally factors like solar radiation (how sunny it is) wind and even humidity would be taken into account *but* I would be wary of using cloud based weather forecasts or predictions simply because the long term viability of such systems is questionable. I don't want a server in California going down or a hack in Paris stopping my heating from working.

For *new builds* it's a non issue. The heat loss calculations are already part of the work flow, so sizing the HP is trivial as is ensuring all the pipwork is correct and there's a place to put it and the ancillaries like tanks etc. Then they just have a team(s) going in at the appropriate time to fit the units the same as they do with gas boilers now. If anything the work is less skilled as you dint actually need to be gas qualified. If you strip out the design side then a standard plumber capable of following plans and executing work to a good standard will be more than sufficient.

I suspect a plan to whip support amongst the sector of the electorate who are reflexively against anything with a whiff of "green mumbo jumbo" or to do with "that Greta girl". Head lines achieved. Mouth breathers convinced Sunak is all that stands between them and meat taxes. Realistically there is zero reason why new builds need gas connections. They can be designed from the ground up as easy to heat via HP so none of tgr "but you need to replace all your rads!" or "where will you fit the giant tank!?" applies.

That is a reasonable plan for an individual. But it's a lousy plan for a nation. If we all use off peak electricity, it's no longer off peak. Switching the domestic heating load from direct gas to grid electric will require an increase in generation capacity. The size of that increase will be smaller if we predominantly use heat pumps than if we predominantly use direct electric.

The good thing about switching to HPs now is that right now, we produce heat more efficiently by buriing gas in a Ccgt, sending the elec to the grid and then using a HP at thr other end, than we can by just burning the gas in the house. So from a co2 perspective HPs are already a win *even if* we have to boost the grid with gas stations. We would still burn less gas overall. And then that ignores the fact that the grid is getting lower and lower carbon all the time. Capacity issues aside, direct electric heating is now equalt to or lower carbon than gas boilers (gas boilers are about 200g/kwh grid is consistently getting below that).

The hydrogen thing was just a technobabble to give cover for those who didn't want to move from fossil fuels. They say "calm down dear, no need to change from gas boilers because we will be able to use magic gas in the future, so we can keep installing these boilers that can run on gas and magic gas" Then when the magic gas fails to materialise "oh what a shame, good job we can just keep burning gas then"