Beelbeebub

Planning would need to change so sticking a (certified) box on the wall is totally allowed. The certified boxes would have already met noise standards etc.aybe lock off the cooling function to high 20's to prevent extra consumption form people running cooling too much. Need to get aesthetic options out there, eg offer case colour options other than white (or just make them easy to spray paint, provide masks in the box for grilles etc).

LPG I think. If they just added it as an add on for gas safe qualified, like £100, an online course with a few videos and questions at the end. Would be an easy way to "train up" the workforce.

The development of a really easy to DIY/handyman level ecosystem for A2A would be crucial. If you could get trained on fitting a unit on a.£200nday course, the equipment was a few hundred £ and the units were £2-3k, plus relaxed planning. It would take off. The priority would be for electric only properties, you would get an instant cost saving and you can leave the DHW as is for later. Maybe when the appropriate cylinders become available. That's a big market.

A2A has real potential if a few hurdles can be overcome. FGas certification - we need either low cost, effort certification so ordinary plumbers can add it to their offering with minimal outlay. Or we need DIYable systems. The issue is wemeither have FGasses like r32 where the problem will be DIYers venting it left right and center or hydrocarbons like r290.wjere there may be issues with safety. That said, r290.has been used been used in Chinese and Indian markets for a decade and I don't think there has been a major issue. R744 (CO2) has potential but I don't think anyone makes A2A splits. Not suremif it's a technical thing or a demand thing.

Just watching a BBC documentary on HPs, have to say not doing the cause any good www.bbc.co.uk/iplayer/episode/p0fzltvd Features an 18k install, 6 guys for a week! Described as "average". It looks like a full.monty job basically a full replumb replace all rads, new pipework, possibly even new windows! It does show why HP's installs aren't picking up, at the moment it's a boutique high end product. The knock on is it's seen as elitist, not for everyone solution and is easy fodder for any politician who wants to be seen as "on the side of the working man"

Yes, plus the buggeration factor if the install isn't easy (and they often aren't)

Ok subsidy idea napkin calculation. Average house uses 3,000kwh of elec 12,000kwh of gas Let's say elec.costs 30p and gas 10p So somebody pays 💡3000 X 0.3 = £1000 🔥12000 X 0.1 £1200 £2200 total (ignore standing charges etc) If they switched to a HP that was only 2.25 SCOP (my magic break even for CO2) 💡3000 X 0.3 = £1000 🔥5333 X 0.3 = £1600 £2600 total. the subsidy system records they delivered 12000kwh of heat. It calculates the cost difference assuming 2.25 CoP and comes up with £400, which is deducted from the bill leaving them paying no more. As a side note the £5k current subsidy would pay for over 10 years at this rate. If the HPminstalm has gone badly, the home owner still only gets the £400 calculated assuming 2.25 but even if it was only achieving 2.0 their bill would be £2400, with the £400 subsidy. An extra £200. Not great but not catastrophic. On the flip side if they manage to get their SCOP to 3.5 their bill will be £1600, in effect giving them a boost. The above calculation is shown on the utility bill, including the SCOP as calculated by heat delivered divided by electricity consumed. So the user can see if they are beating the assumed SCOP (2.25). If they aren't they can use the experience of running the system to identify what is causing them to undershoot. Say the crap cylinder they didn't replace! (😂) and replace it with the lure of pocketing the subsidy themselves. over the life of the program (say 10 years) the assumed SCOP would move towards the point where the subsidy was effectively zero, giving a soft landing for the billl payers

Double post

Double post

Yes, a tariff where night electricity was cheaper than standard day electricity would help. But in every case, you have the choice between A) Use the HP in a suboptimal mode on existing cylinder B) Use an immersion fitted to the cylinder. In almost every case A works out cheaper to run. Invoking various tariffs doesn't change that as the same tariff can be used for the HP. If the cylinder is already fitted with an immersion then there is the option to not connect the HP and save on those costs at the expense of higher running costs than HP Fitting a new cylinder will always result in lower running costs at the expense of higher (potentially deal breaking) upfront costs. in summary: From a CO2 perspective HP DHW is almost always best. From a cost perspective there is a balance between lower capital outlay and longer term running costs. IMHO it would be better to get more installs, even if the overall fleet efficency was not as good as the fleet efficency of fewer installs. i.e., lots of good enough beats a few excellent. As for a solution, I've laid out a change to the subsidy regime where, the HP is guaranteed to cost no more to run than a gas boiler for a defined period (say 5 years). That would dramatically lower the pressure to get a very good performing system straight away and make installs much cheaper and quicker.

Yeah, but if you have E7 night heating for DHW you're paying E7 day (30% more expensive than regular electricity) from 6am 'til midnight. Unless you have a huge CH thermal store (which would need to be in the 1000's of liters) and plan to onlyrun you HP at night.... you are going to lose by paying 30% more for 80% of your energy to save 50% on 20%.....

Can you explain why a cylinder that works when you pump 65C water through the coil from a gas boiler won't work when you pump 65C water through it from a Heat pump. HP's have a reputation for not being able to provide hot water - I am pretty sure it's from the days when the maximum temp a heatpump could output was around 45C. In that case, yes, you will get lukewarm water unless you have a cylinder with a big enough coil that the stored water can be heated to very close to the flow water temp. But if your HP can crank out 65C+ water what's stopping it heating the water to a suitible temp? (the one caveat is is the flow rate is too small because of the pipework)

Pretty certain nobody is happy on E7. It's more expensive than gas, and requires storage heaters to work, which are rubbish.

we might be at cross purposes. I was thinking in terms of carbon where a HP always wins. If you look at cost per liter of DHW, a HP using standard day rate (about 30pkwh) would need to beat 2.0 to equal an immersion using E7 night rate (about 15pkwh). But then you have to make the assumption that someone with a HP would be on E7 in the first place. That seems daft given the day rate (when your HP is doing heating) for E7 is much higher (40p). If you were on E7 then you would still have to compare the immersion on E7 with the heatpump on E7, where the HP wins. So, yes, in a subset of circumstances* an E7 immersion will be cheaper to run than a HP running on standard or E7 day (30/40pkwh) rates. But that has to be a very rare set of circumstances. * the HP only drops below 2.0 of you need a flow temp of 65 and it's below zero outside.

does it? A heatpump can crank 65-75C out (Ok maybe not in the depths ow winter) a similar temperature to the gas boiler, so why would the water be lukewarm? Will the heatpump be operating at maximum efficiency? Nope Will it be as fast to recover as the old gas boiler? probably not. Here is the performance table for an r290 9kw unit Note that it can punt out 4-6kw at 75C with a CoP above 1.3 for temps as low as -7C

I honestly can't remember if the zones actuate the bolier direct. Possibly not, because that would be mad. I didnt have anything to do with the design of install of the system. It was done 20+ years ago by a now defunct company and pretty much all the documents have been lost. All I'm left with is a maze of wires that constantly trips the RCDs and a lot of leaks! One day it will all be ripped out and it'll just be a single (or possibly per floor) zone on WC and a hot water cylinder possibly unvented. Then I can go back to worrying about something else other than how many times I have to go sort it out each winter. Until then it plods on (ish)

It's actually not terrible. It uses a thermal store as a buffer with the UFH taken from the middle. Short cycling isn't much if an issue 'cos although there are loads of zones, the house is stupidly big so they are plenty big anyway. That said it would work much better with a WC heatpump. The flow temps are sub 40C for keeping the place warm and it would get me out of having to deal with the wiring - just leave everything open, maybe a few rooms on the south side with high temp cutouts Bigger problem is it uses these horrible rubber pipes that are going brittle, several loops have failed already (20 years old) and are going to have to be replaced. I'm praying none of the ones in the slabs go....

So basically using some actual logic (probably microprocessor based) to provide 2 "setpoints" or modes for the boiler to control it's temperature to. As i said, the old way of doing things was just dumb hardwiring of dumb components together that had developed over the decades as more.functions were added and had to be backwards compatible. Yeah, that crap should be ditched. All you need is a 3 port or (possibly more flexible) 2 X 2port valves (s plan) winter directly to the controler and the system works out what flow temp it should be outputting and which valves should be open or closed. Question: unless you have really low thermal mass in your house, do you ever need to have your heating and hot water demands satisfied at the same time? You just stop heating for a bit and supply the DHW at a higher temp, then drop back to heating again?

Can you post a system diagram of "X plan"? As far as I can tell there really isn't any actual difference between S,Y,W or X In essence all of them take the pumped flow through the heat generator and direct it between the cylinder and central heating zone(s) S uses 2port valves on a T (or manifold) Y uses a 3 port valve with a mid-position actuator W uses a 3 port valve with a 2 position actuator. The major difference between them seems.to be in the wiring of the various valves to each other to "hard wire" the logic But from a plumbing perspective there is very little difference, an S or Y plan could be made to function exactly like a W plan by controling the valves with a microcontroller rather than thermostats and timers closing circuits. The only problem might be if you have a very complex system. My parents have a horrendous system where multiple zones are actuated by the thermostat closing a contact that motors a 2port zone valve, then a microswitch in the actuator closes a circuit that power the pump (as far as I can tell directly) and commands the boiler to fire. It's a nightmare to trouble shoot with wires going every which way and multiple points of failure.

Just a side note: I've mentioned the "magic" CoP of 2.5 a few times. This is the efficiency a heatpump needs to hit so that less gas is burned in a gas power station to provide heat in the home than if that gas was burned in a boiler to produce the same heat. 2.5 is derived from the assumption that the efficency of electric power delivered to consumer Vs calorific value of gas was 40%. That was slightly outdated. It looks like the UK grid has got a bit more efficient and the generation at plant is now 49%, which with 5% transmission losses gives a final value a bit above 0.45. this would require the HP to achieve a magic CoP of 2.2 which is very doable for modern HPs and certainly possible for SCoP. This calculation is based on the actual UK CCGT station performance (49%) Apparently (for reasons I don't know, possibly a newer fleet) Spanish CCGTs hit 55%, which would drop the magic CoP to less than 2.0.

Neat idea. I like the everything up top idea. I also like the fact the outdoor unit can be small from a planning (and just finding a space for it) pov. The only negative is the need for fiddling with the refrigerant. Plumbers can't do it and people with F-gas don't want to do plumbing (in general). Technically r290 isn't F-Gas and releasing it isn't a global warming or ozone issue. Plumbers are used to working with (and qualified for) flammable gases, though it should probably be a small seperate add on qualification.

We have some flats using electric vented thermal stores. Work really well. That's said we had one brand of TS where a pin hole developed after about 7 years in the DHW coil. The F&E tank kept filling up about 2lpm then overflowing. Tenant called complaining of high elec consumption, cool showers and "dripping" noises At first I thought the ball cock had failed. But that was all fine. Eventually traced to the only explanation (failed coil). Swapped the whole thing out for another brand in a morning. Biggest balls ache was getting the things up 3 flights of stairs! A HP driven one using high temps (65C flows) from a small capacity (sub 5kw) unit might make sense for small flats. The lower cop for DHW is still higher than direct electric. The smaller HP is then sized for more efficient running at the lower end of the scale (10C external say) where we spend most of the heating season. Only running flat out on a few days if the year, I wonder.if you could set it up so the electric immersion in the vented tank could contribute heat to the CH system?.... Maybe not the highest efficiency, but as long as it can hit 3.5ish that's ok, and a smaller external box and small tank..... Hummm

Yeah, we switched out all the UVCs (we didn't have many) after that. Went to combis and in the case of electric places, electric showers and vented cylinders. It's also why I'm thinking of doing heat only HPs for the electric flats and leaving the existing cylinder/shower arrangement. Any future upgrade would be to vented tank heated by large coil and if pressure is an issue, a pump. The combi flats and houses are tougher. But almost all did have a tank at one point, so it would be possible to refit one. Probably go with vented and pumped.

Problem we had is at very low drips, the water tracked from inside to outside around the arms between the top and bottom halves. It's really poor design, there is no drip feature on the top part of the tundish. Little drips will track down the arm. I modified them by drilling the top "end stop" out and inserting the copper pipe just a few mm further into the tundish so there was a sharp drip feature. And yeah, the pipework can't take full flow. But, in fairness, I don't think they are supposed to. The PRV isn't a blow off valve, all or nothing. It's supposed to "crack" open and allow a dribble of water out, thus bleeding energy. In theory it only needs to bleed a flow rate equivient to the energy input and delta between incoming mains and activation temp. Even a 30kw boiler jammed on full power would only require 5lpm to stay cool. It was part of why we suspected the tenant was playing with the valve. The second time it happened it was an overflow because the valve had opened so far and was stuck on the little "detent" before it snaps back. The resulting flow overwhelmed the tundish pipework and flooded the floor. The floor which the tenant stacked lots of "priceless" papers that he forbade me to move our of the standing water when I arrived. Neither I, the G3 guy or the valve manufacturers could envisage how the valve could be activated to that level of opening without manual intervention. The tenant claimed against our insurance for damage to the papers and items (despite me having written to him previously to warn him not to store items next to the tank). Luckily I had all the communications, and testimony from the manufacturers, engineers etc His claim was denied. 😁

Just seen! It's a typo!😁🫢 Should read "Every single home owner I know with an UVC hasn't had it inspected. Several didn't even know they had an UVC. One didn't even know where the cylinder was!" Basically, apart from me, getting inspections because it's a legal requirement, nobody in private homes seems to be - alot of people don't get their boiler serviced every year. Most people are oblivious