DanDee Posted May 12, 2023 Share Posted May 12, 2023 7 hours ago, sharpener said: Their so called spec sheet doesn't have proper CoP information and not even the SCOP for temps over 55 so I don't know where this comes from. from page 34 https://www.vaillant.cz/downloads/projek-n-podklady/kl-06-e2-verze-01-18012023-2564719.pdf Link to comment Share on other sites More sharing options...
JamesPa Posted May 12, 2023 Share Posted May 12, 2023 (edited) 10 hours ago, sharpener said: So I can see I will have to keep most of my thoughts to myself if I am going to get a quote out of them! Yes indeed you heretic! If I had known when I was getting quotes what I know now I would have, before asking for quotes 1. Read the MCS rules more thoroughly to look for loopholes 2. Designed the system I want 3. Worked out what lies I need to tell those quoting so that they can use the MCS tools/rules to create the system I want ie reverse engineered it from what I want to what I need to tell them so that they can deliver within their rules. Perhaps you could ask the Vaillant guy why their units are so heavy. I used to work for a telecoms equipment manufacturer, they put chunks of metal in handsets 'to increase the perception of quality', with the result that you got arm-ache on long calls. Just saying... Edited May 12, 2023 by JamesPa Link to comment Share on other sites More sharing options...
sharpener Posted May 12, 2023 Author Share Posted May 12, 2023 3 hours ago, DanDee said: from page 34 https://www.vaillant.cz/downloads/projek-n-podklady/kl-06-e2-verze-01-18012023-2564719.pdf Thanks for that, my Czech is improving by leaps and bounds now. First time I have seen CoP plotted as a function of compressor speed. Looks like 2.0 is what I will get from the 12kW unit providing HW as @JamesPa predicted. 1 hour ago, JamesPa said: Yes indeed you heretic! If I had known when I was getting quotes what I know now I would have, before asking for quotes 1. Read the MCS rules more thoroughly to look for loopholes 2. Designed the system I want 3. Worked out what lies I need to tell those quoting so that they can use the MCS tools/rules to create the system I want ie reverse engineered it from what I want to what I need to tell them so that they can deliver within their rules. Perhaps you could ask the Vaillant guy why their units are so heavy. I used to work for a telecoms equipment manufacturer, they put chunks of metal in handsets 'to increase the perception of quality', with the result that you got arm-ache on long calls. Just saying... I will be silent about the intermittent use of the property, as AFAIR that requires a significant uplift in capacity, can't immediately find it in the rules linked to above. OTOH it says no uplift if you use the -1.6 design temp so that might actually be better. The other issue is the EPC and the loft insulation. At B & Q prices it will cost ~ £500 (plus labour) to double the existing 150mm over 100 sq m, this will save about 20W/K. So multiplying that by 1641 deg-days x 24 hours gives me about 800kWh/year which is about £60 at current oil prices i.e. a payback of ~9 yrs so NBG even if the house were occupied full time during the winter. Based on your experience can you give me a quick precis of the other main lies I will have to tell? I expect as well as the cylinder he will want to rip out the 8 Honeywell wireless zone valves and my home-made internet control box too! Link to comment Share on other sites More sharing options...
JamesPa Posted May 12, 2023 Share Posted May 12, 2023 (edited) 2 hours ago, sharpener said: Based on your experience can you give me a quick precis of the other main lies I will have to tell? I expect as well as the cylinder he will want to rip out the 8 Honeywell wireless zone valves and my home-made internet control box too! I think you have spotted the main ones (20% uplift for intermittent I think unless the design is for the 99.6% OAT case), beyond this and reheat time the scope is limited. MCS 3005-d expressly mandates minimum design room temperatures. The draft of MCS-d also expressly forbade using actual measured demand to size the system (why - its the only known fact!), I cant find that in the released version so that avenue might be worth exploring even if as a sanity check only. It also says that they must design dhw based on the greater of for bedrooms +1 or #pccupants. Possibly it might help to say that everything will be at the same temperature, at least then they wont double count room to room losses, but of course it might push up rad sizes. Its basically a manual of bad system engineering designed to protect the installer from being called because the house is cold. I would strongly advise putting in writing in advance any 'fabric upgrades' (relative to the original house build) and also any extensions which have been built to a higher standard. if possible I would ask them to confirm that they have/will include these before paying. This was the major source of error in my surveys, they assumed the whole house was uninsulated solid brick which is far from the case, as I told the surveyor when they visited. I would also ask for a copy of the detailed design, you have paid for it so you should get it, to check that they have done what they say they have done. However they may well be determined to do it their way and have the luxury of choosing their customers. Good luck and please tell us what happens. Edited May 12, 2023 by JamesPa Link to comment Share on other sites More sharing options...
JamesPa Posted May 12, 2023 Share Posted May 12, 2023 (edited) 2 hours ago, JamesPa said: The draft of MCS-d also expressly forbade using actual measured demand to size the system (why - its the only known fact!), I cant find that in the released version so that avenue might be worth exploring even if as a sanity check only. Correction, this does still appear in MIS3005-d as part of the pre-contract requirements, where it forbids system sizing based on actual consumption. This prohibition is not repeated in the post contract requirements, so it is open to interpretation whether actual consumption can be considered, even if only as a sanity check, or not. The interpretation that is safe for the installer is 'cannot', the interpretation that, at least arguably, is safer for the customer is 'can'. I leave it as an exercise for the reader to guess/discover which interpretation will be used. Edited May 12, 2023 by JamesPa Link to comment Share on other sites More sharing options...
sharpener Posted May 12, 2023 Author Share Posted May 12, 2023 Yes, there is one bedroom wall dry-lined with plasterboard over sheepswool, hope I can find the receipts as they will require documentation. Don't have continuous records of actual consumption unfortunately. Last time I did a calc based on actual oil usage I got 6kW averaged over a 24hr period, from which I think a reasonable size of HP is 12 - 15kW, it agrees with the total rad output (rated at 70C flow) of 15kW, though at 65C and with zoning I think the max load at any one time is well under 10kW. FWIW this cheat sheet comes up with a 13 -17 kW HP for a house of the same size, age and construction. Another worry is that an HP drawing over 32A and/or with any kind of boost heater (inc AIUI an ordinary immersion in a new tank) will require my supply fuse to be uprated. 6 hours ago, sharpener said: The other issue is the EPC and the loft insulation. At B & Q prices it will cost ~ £500 (plus labour) to double the existing 150mm over 100 sq m, this will save about 20W/K. So multiplying that by 1641 deg-days x 24 hours gives me about 800kWh/year which is about £60 at current oil prices i.e. a payback of ~9 yrs so NBG even if the house were occupied full time during the winter. Found a useful EPC surrogate (from the EST - but oddly not on their own w/site) at Dansk Bank (and other banks). It foresees a saving of £18/yr from an expediture of £444 on further loft insulation, so an even worse investment than my own calcs predicted. Changing the few remaining incandescent bulbs (in storerooms and cupboards) will be a lot easier to do. It seems brownie points are also attached to PV and fortunately I have a lot! It would be nice to find a fully reverse-engineered matrix from the official software so I know what weightings are attached to the various factors in the EPC assessment, but so far I have not discovered one. Will post a proper update w/c 22 May when I have got two visits fixed up now. Link to comment Share on other sites More sharing options...
sharpener Posted May 19, 2023 Author Share Posted May 19, 2023 (edited) On 12/05/2023 at 19:11, sharpener said: Another worry is that an HP drawing over 32A and/or with any kind of boost heater (inc AIUI an ordinary immersion in a new tank) will require my supply fuse to be uprated. Quite by co-incidence my DNO (who is NGED, formerly WPD) have just come back to me with a plan to upgrade my cutout to 80A in response to a 7kW EV charger application put in last December(!). So I am wondering whether that will be enough to support an ASHP as well, and how big? Inverter is rated at 2x for 10 secs so there is something in reserve for startup. Common sense says that 18.4 kW is enough for the EV charger, house loads and charging the batteries overnight at 4kW and still leave 7kW for the HP, but common sense seems to be in short supply in this industry. Meanwhile I am expecting the EPC surveyor on Monday and a Vaillant installer to visit on Tuesday. Is there any way of getting the MCS design process to take account of the Aga in the kitchen, which we have running most of the winter putting out 1.5 - 2kW? As it can't have a control system which is integrated with the HP it does not seem to comply with the MCS rules for auxiliary heating, does anyone have a workaround for this? Otherwise I am concerned they may not only oversize the HP but insist on putting a biggish radiator in the kitchen where there is not the wall space for it. (Plinth heating is not an option because the piping runs would have to cross two doorways). Edited May 19, 2023 by sharpener Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 Went to the Installer Show at the NEC yesterday, lots of interesting stuff. You can still catch it tomorrow. Many more HP companies have got their newly-developed R290 models now on test and will be bringing them to market late '23 to early '24. Among these I talked to were Grant (will be made by Chofu), Toshiba (branded as Carrier), Panasonic, Trianco. Nothing surprising technically but I imagine as the technology penetrates there might be a bit more competition on price. Stiebel Eltron are pursuing a different route and have chosen to go with R454 as a replacement for R410a. Their 15kW machine is incredibly chunky to look at! Ebac have their new British designed and made 5 and 9kW R32 machines (based on Mitsi compressors) with a test house currently, and are working on a bigger inverter to expand range to ?14kW. Will sell direct from factory. Was highly impressed talking to their Head of Development. Another thing which caught my eye were several manufacturers of pipe fittings designed to be pressed/swaged/crimped rather than using grab rings a la Tectite. Apparently public contracts are now calling for these. Rothenberger man was very proud that his battery-powered on-site press was under £1000(!). So I think I will stick to Tectite for my (longer) replacement radiators, don't fancy the large number of Yorkshire fittings involved. Have now had three quotes for MCS HP installation, none very satisfactory, will post details separately in a short while. Link to comment Share on other sites More sharing options...
PhilT Posted June 28, 2023 Share Posted June 28, 2023 54 minutes ago, sharpener said: Stiebel Eltron are pursuing a different route and have chosen to go with R454 as a replacement for R410a. Seems like R454B may be the new best in class regrigerant for large scale commercial use Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 I imagine that is because of the flammability of R290 despite R454b's worse GWP. Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 (edited) So I have just got DNO approval for a Vaillant Arotherm + 12kW, and now received three quotes via the Vaillant find-an-installer process. Tried similar Daikin process but it has fizzled out. Have not pursued Good Energy option. Results in round number terms: Installer A. Says Vaillant 12kW is not powerful enough, quoted for a Stiebel Eltron WPL 25 ACS at £17800 including labour plus £2000 "installer margin"(?). Design based on flow temp 55C. Originally suggested existing rads would be adequate, when queried would install 7 new rads for an extra £1900. Includes new 300l cylinder in utility room with 100l buffer. Mentions 10-40 l/min flow setter. Excludes removal of oil boiler from site. The Stiebel Eltron is much deeper front to back and needs more space behind it so would stick out 300mm further from the wall. Also uses R410a which is obsolescent. Bottom line after BUS: £14700, subject to a further pre-installation technical survey. Installer B. Would fit Vaillant 12kW for £16000. Design based on flow temp 45C (AIUI mandatory for new bldgs but not for retrofit). Says 11 new rads needed at an additional cost of £2700 installed (including 1 in utility and 3 in shower rooms which I do not want and would be difficult to get pipe runs to) Includes new cylinder where current one is and 100l buffer in utility room Would want to take up half the landing floor as wants to replace main F&R to rads with 28mm Bottom line after BUS: £13700, fixed price valid for 30 days. Installer C. Would fit Vaillant 12kW for £27000 bugetary price Design based on flow temp 45C. Includes 8 replacement rads and much new pipework in 28mm including to the cylinder coil(!) Includes 300l cylinder in existing space and 120 litre buffer with auto bypass and antifreeze valves Some items are un-necessary (e.g. new concrete base and soakaway) but I cannot see them being competitive. Bottom line after BUS: £22000 bugetary price D. DIY Option I can get the basic HP for a discounted price of £6800 inc VAT. I would then envisage doing the following fit a large buffer tank/heat store to enable me to charge it up using off-peak in the small hours and free PV in the daytime, <£1000 re-use the existing cylinder but fit a destratification pump to improve the heat transfer ~£250 fit 7 new rads, possibly with the assistance of recommended local plumber £1000-2000 depending do the wiring under an existing Building Notice and the remaining plumbing myself allow ?£1500-2000 for feet, pipework, valves, basic controls etc etc Bottom line £10550 - £12050 Pros: I get the system I want Higher efficiency/more energy saving Less disruption Less waste Cons: Savings on capital outlay are modest, about £3k at most (no VAT exemption or BUS) Am on my own if the design proves unworkable Poorer warranty conditions Plan: Contact installer B, see if they are amenable to taking out the 4 rads I think are not necessary and maybe this will also remove need to upgrade feed to 28mm. If I go ahead using them then keep the old cylinder so I can add it later as a thermal store at near zero cost. I would welcome any contributions on any of the above! Edited June 28, 2023 by sharpener Link to comment Share on other sites More sharing options...
JohnMo Posted June 28, 2023 Share Posted June 28, 2023 Or you could get a cool energy heat pumps for about £3.5k, good for 12kW You would need a huge buffer to make use of off peak charging, if your heat demand is 12kW. Can you configure your zones so you don't need a buffer? Then you are down to £2k for general stuff to install - this could be reduced loads with careful shopping and designing. £3.5k for ASHP £250 for destrat pump £2k for your radiators So about £7.5k £6k cheaper than B. Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 (edited) 1 hour ago, JohnMo said: Or you could get a cool energy heat pumps for about £3.5k, good for 12kW You would need a huge buffer to make use of off peak charging, if your heat demand is 12kW. Can you configure your zones so you don't need a buffer? Then you are down to £2k for general stuff to install - this could be reduced loads with careful shopping and designing. £3.5k for ASHP £250 for destrat pump £2k for your radiators So about £7.5k £6k cheaper than B. Most of the time the only need for water at 55C is to heat up the rads in the master bedroom for an hour morning and evening, a 300l tank would I calc be enough for this, charged up while we heat the DHW as well using cheap/free electricity. I don't think we will get away entirely without a buffer to stop short-cycling and provide the defrost energy. Then the additional cost of expanding it to a 300l TS is not very great, I already have the pump so it could be done with two extra 3-port valves and a couple of relays. I'm of two minds if it is worth the added complication though. The £3.5k for the iVT10 is before VAT. The performance is a bit marginal, my design case is A-0.2/W55 which with a bit of extrapolation from the table below looks like the output might be in the range 10 to 10.5kW. I have in the past tried to get more detailed figures from CoolEnergy, but it's perhaps worth another go. When sent my floor plans they quoted for the bigger IVT-18, inc VAT that would be £5640 and like the Stiebel Eltron it uses R410a. Anyone got any thoughts on other budget HPs like Warmflow, Trianco, Riello? Edited June 28, 2023 by sharpener Link to comment Share on other sites More sharing options...
JohnMo Posted June 28, 2023 Share Posted June 28, 2023 I see what you mean about being marginal. I saw them on eBay from their outlet store, which is normally about 20% off the retail price. Full warranty etc. They have other sizes there also. I looked at Trianco, and they are not inverter heat pumps, when I asked. CoP wasn't great. Riello are rebadged Midea monobloc ASHP. The specs look ok, but no experience, they come up on eBay for good prices. Grant could be worth a look also. Link to comment Share on other sites More sharing options...
JamesPa Posted June 28, 2023 Share Posted June 28, 2023 2 hours ago, sharpener said: Would fit Vaillant 12kW Doesn't this need express planning consent >0.6 cu m. Apologies if you already have that but if not you won't get it in 30days! Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 True. But was waiting for DNO approval before splashing out £270 on planning application. Will apply for "Vaillant 12kW or smaller" installed i.a.w. MCS noise standards. It provides a reason for applying for express PP without disclosing possibiity of not using an MCS installer. Forgot to mention that Installer B wants to replace entire UFH manifold. There are some old streaks from leaking joints long since tightened. Needs a new blending valve, is all. You are surprisingly taciturn tonight @JamesPa <g>, not like you to be short of a comment or three on the physics of it all! Link to comment Share on other sites More sharing options...
JamesPa Posted June 28, 2023 Share Posted June 28, 2023 19 minutes ago, sharpener said: You are surprisingly taciturn tonight @JamesPa <g>, not like you to be short of a comment or three on the physics of it all! I'm genuinely pleased for you that you have a quote you are happy with, whilst still doubtful you really need 12kW. But even if you need only 9kW, the 12kW Vaillant will likely be a reasonable choice from the specs I've read. Re 28mm upgrade, 22mm is good for 6-8kW as you doubtless know. If all the flow passes through one pipe then the installer is likely right If it's split (mine splits 3 ways-upstairs, downstairs, dhw), then they are over-engineering. I hope your LPA is saner than mine. I took essentially the same approach as you are planning. My LPA is currently setting a requirement of 27dB(A). This is 10dB stricter than the pd requirement of 37dB(A), albeit 7 dB better than their starting point of '10dB below a night time background of 30dB'. Their newly elected Green party executive member in charge of planning is tending towards defending this stance because, 'as a keen gardener', she 'wouldn't want to be inconvenienced by her neighbour's ashp'. So I take that as 'Green' unless it causes any personal inconvenience! https://www.ioa.org.uk/catalogue/publication/briefing-note-heat-pumps-–-professional-advice-note is worth reading and maybe quoting. It's a professional briefing note jointly by the institute of acoustics and institute of environmental health. It basically concludes that an adapted MCS methodology, and a target of 35dB(A) (but if necessary applying a penalty for 'tonal characteristics) is justifiable in all cases, with some justifying a more relaxed target. PD is 37 with no penalty for tonal characteristics. So this is a bit more stringent than pd but nothing like as bad as my LPA. Link to comment Share on other sites More sharing options...
JohnMo Posted June 28, 2023 Share Posted June 28, 2023 8 minutes ago, JamesPa said: then they are over-engineering. Really not engineering at all, just guessing at someone's expense. 10 minutes ago, JamesPa said: elected Green party Sounds like the Green party in Scotland, more interested in getting power and independence from England, than anything useful or Green Link to comment Share on other sites More sharing options...
JamesPa Posted June 28, 2023 Share Posted June 28, 2023 5 minutes ago, JohnMo said: Really not engineering at all, just guessing at someone's expense. Fair enough. On second thoughts even 'guessing' implies an active thinking process, which I sadly suspect is optimistic. Link to comment Share on other sites More sharing options...
JohnMo Posted June 28, 2023 Share Posted June 28, 2023 1 minute ago, JamesPa said: Fair enough. On second thoughts even 'guessing' implies an active thinking process, which I sadly suspect is optimistic. Same old, same old, rules of thumb, it's a heat pump it's got to be 28mm. I was being optimistic saying guessing. Possibly a standard cost adder. Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 28 minutes ago, JamesPa said: I'm genuinely pleased for you that you have a quote you are happy with, whilst still doubtful you really need 12kW. But even if you need only 9kW, the 12kW Vaillant will likely be a reasonable choice from the specs I've read. Re 28mm upgrade, 22mm is good for 6-8kW as you doubtless know. If all the flow passes through one pipe then the installer is likely right If it's split (mine splits 3 ways-upstairs, downstairs, dhw), then they are over-engineering. I hope your LPA is saner than mine. I took essentially the same approach as you are planning. My LPA is currently setting a requirement of 27dB(A). This is 10dB stricter than the pd requirement of 37dB(A), albeit 7 dB better than their starting point of '10dB below a night time background of 30dB'. Hardly "happy", involves a lot of unneccesary work at my expense IMO! Will re-visit the heat loss calcs to see if could get away with the Cool Energy or Grant 10kW nominal units which might also be easier to integrate with the controls I already have. Distribution splits 4 ways from boiler location: UFH, 1st floor rads to W, ditto to E (all in 22mm), cylinder coil (15mm!!). Thanks for link re noise, will follow it up. Link to comment Share on other sites More sharing options...
JamesPa Posted June 28, 2023 Share Posted June 28, 2023 (edited) 12 minutes ago, sharpener said: cylinder coil (15mm!!). That's a bit small Having said that, 2 MCS installers have recently suggested to me a dhw solution based on a relatively small coil-less dhw tank, a recirculating pump and a PHE. With a counter-flow plumbed PHE the 'approach temperature' (difference between flow temp and dhw water temp) is less than with a coil and you might just get away with a 15mm feed supplying 4kW or thereabouts, provided you could tolerate the longer reheat time. With a large enough PHE you might even be able to get more than 4kW out of a 15mm pipe by having a larger delta T, albeit at the expense of COP for your DHW. The capital cost is probably no greater than for a heat pump cylinder because the latter attract a premium price. Another advantage of this approach in some circumstances is that the cylinder and PHE do not need to be co-located. Edited June 28, 2023 by JamesPa Link to comment Share on other sites More sharing options...
JohnMo Posted June 28, 2023 Share Posted June 28, 2023 18 minutes ago, sharpener said: cylinder coil (15mm!!). If you put an additional pump on the DHW return side, powered from the same power supply as the three way valve, that will overcome the high delta T of the coil. Mine pulls an additional 31W for an hour or so while doing DHW only. My issue isn't a small coil, but 22mm Hep2O running from 3 way valve for about 8m each way, plus a long run from the ASHP. Link to comment Share on other sites More sharing options...
sharpener Posted June 28, 2023 Author Share Posted June 28, 2023 The 15mm is less than 2m each way so using the trusted flow calculator it looks OK. Though what possessed the original installer to do that beats me. I have yet another spare pump so it would only require a few fitttings to sort out. Glad to know that MCS installers will contemplate fitting a PHE, I will add it to my list of questions. It could go in the utility room directly below the tank with pumped F+R on the DHW side. Reheat time is not an issue. Snag in my case is that the source of the DHW is harvested rainwater, according to this web page the pH needs to be 7.5 or more to avoid corrosion of the copper brazing. Raw pH is about 5.3 from dissolved atmospheric CO2 and despite treatment with NaHCO3 I can't get it above 7.0. I was going to try a mix of calcite and dolomite based media next but they sent it with the wrong size of filter bag so it is in the all-too-difficult pile ATM. Link to comment Share on other sites More sharing options...
JamesPa Posted June 29, 2023 Share Posted June 29, 2023 (edited) 7 hours ago, sharpener said: Edited June 29, 2023 by JamesPa Link to comment Share on other sites More sharing options...
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