ian192744

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  1. so at 26mm ID its the same bore as 28mm copper so flow rate calculators that assume 28mm copper should be valid. And the compression fittings make it do-able with a spanner. that is really excellent thank you! presume the crimp fittings need the right crimp tool (that your plumber had?), looks like they are about 100 quid, worth having if you are doing lots I guess.
  2. brilliant thanks jenni. that is way cheaper than any copper solution. Do you know what the inner bore size is for that pipe? What fittings do you use to reduce it to 28mm to connect to the rest of your system?
  3. looking at exactly that kind of thing. I've read previous posts on here mentioning the use of "32mm pipe" for HP projects but without being specific about what they used. really hoping someone will come along who said "we used <reference> and it works!"
  4. that is exactly my plan. except that I am not convinced that 28mm (hep2o or john guest type) is big enough.
  5. I wsa reading the samsung 16kw data sheet. 12l/min minimum, 58/l min maximum. Given that we want to be able to run it at full chat in worst, surely designing the maximum is the sizing number? agree with you , probably will need a bigger pump and am allowing for that. however what I don't want is to have to run a pump (or two) with very high head and high power due to noise and efficiency. would rather put in a bigger pipe! do you know of a better online calculator? I do have an engineering degree but that was 25 years ago and I went into IT so all the fluid dynamics stuff is totally gone...
  6. I have to have a long run somewhere. If I put the buffer next to the ASHP then I'd have 15 metres from the buffer to the rad distribution point. so I've still got to move the heat to the rad distribution point over that distance, at a lower temp, so need higher flow rate . albeit that the flow rate of the HP would now satisfied by the buffer. I also know that the rad distribution is quite complex as well - so if I can split the circuit in half and make one half of it "clean" then I'll be gaining. lastly, in my case putting the buffer next to the ASHP is not that easy in terms of the physicals of the rest of the property.
  7. Hi all I have a long convoluted primary pipe run from boiler location to airing cupboard , where the distribution to radiators occurs. Logically the change to ASHP best works with the ASHP outside where the boiler is, buffer tank in the airing cupboard where the radiator distribution is. A lot of the existing primary is 22mm, and it has loads of elbows (7-10 in each direction) . I think its about 30m its "evolved" over time due to various incremental changes in the heating setup of the house. I cannot get over 0.8m3/hr (13l/min) on it regardless of using pump speed III, number of rads open etc. Existing pump is a grundfos alpha2 15-50/60. various ASHP fitters who have visited are all sucking their teeth at the problem, suggesting pumping in both directions or very high heads or "it has to be 28mm". Even with 28mm I don't think it works. certainly not if using plastic. however, I can find an new primary route which will be about 12m each way with 3-5 elbows, and the potential to make some of them swept bends if in plastic. Call it 35m in total from HP->Buffer->HP. I am likely to need a 14-16kw heatpump. so I'm using 58l/min as my flow target for a samsung 16kw. If I get away with less, great. using https://heatpumps.co.uk/pressure+flow/simulator.html to do the maths. 58 l / min over 35m of pipe, 20% glycol, 35mm copper => head of 2metres -> easy for pump switch to 28mm plastic (22.4m ID) we only get 34l min with the max of 5M head. switch 28mm copper needs head of 4.8m to attain 58l/min with same .. just about ok. 35mm copper is of course ridiculously expensive and hard to work with. particularly as I intend to lay this run myself to save cost (I have some spare time). 28mm copper still not great from a cost or working on it point of view. bottom line question - why I am here : is there a plastic pipe size and type suitable for CH primaries that is greater than 28mm, available from UK merchants? Obviously also one that you can get elbow, coupling and reducing (to 28mm at the ends) fittings for? any specific references appreciated! ta Ian
  8. room size 7.5M x 2.5M. ceiling height 2.3M (external side) vaulted to 4.3M (house side). 2 short and 1 long walls external . external area = 22m2 walls , roof 24m2 = total external area 46m2 of which glazed area (2x1.8) + (1.5x2.25) +(1.7x1.3) in walls + 2x(0.9x1.0) in roof = 11m2 I have 10 linear metres of regency OG thermaskirt on 1 short and 1 long side. Ian
  9. I have discrete heat thermaskirt skirting board in one room. I went for one of the taller profiles to get the higher output . Main reason for doing so was there is literally nowhere in the room that rads can go without utterly ruining the room usage / layout, and we have no UFH anywhere so adding UFH to the system for just one room would have been overkill. Its a ground floor "garden room" which was a refit of an existing extension. Its uninsulated concrete floor, solid wood flooring on top of that, with two large windows, a patio door, and two large openings into adjacent rooms, one open plan. what relatively little wall there is, needs to have furniture against it. It runs on a gas condensing modulating boiler at CH temps as separate zone in the CH. It works ok, but due to the absence of convection it warms the room much more slowly than a rad would, and In the coldest part of winter it doesn't have quite enough heat output to keep the room cosy - because the room has a lot of glass its heat loss is pretty high. the room-based zoning (evohome) is therefore key to not wasting heat on an lossy room when its unused . If I had to chose again for this room I would probably end up the same due to all the constraints, but if any other room where the option to use conventional radiators was not impossible, I'd stick with conventional radiators. If the rooms in your house are better insulated than the particular one in my house, then you might well be ok with the output level. I fitted it DIY with labour assistance from the builder who was doing the extension refit work (some long sections, 2 man job). I also had the copper fin type skirting heating in my sitting room - original from the house build (1970's). it was only along a relatively short section of wall, not including the coldest one, and it wouldn't keep the room warm. I ripped it out and put two conventional K2 rads in instead - as there is plenty of space for rads in that room. now its warm! ta Ian
  10. hi nick thanks for your advice and time. I was already seriously considering the 300L UVC option - certainly if I was doing this from scratch with no existing system fitted, thats pretty obviously the best option, have read lots of your previous commentary about that. However, ditching the TS is a big thing - both in terms of physical work , cost, and mental commitment (SWMBO view of nothing wrong with it , its paid for, why get rid?). would adding the buffer be a good thing to do, regardless of any potential decision about ditching the TS to put in an UVC? The objectives being - separate the flow speed , flow temperature and demand curve/timings on the boiler loop from that on the CH loop - facilitate the future ASHP (which is nothing more than an idea right now, probably 2-3 years off). immersion duress boost in winter isn't that sensible - it will draw from battery (which has charge overnight on octopus go) so although only charged at 5p a unit, its a cycle through the battery that is not best use of its lifetime cycles. I was thinking instead I could run the system boiler through an external plate hex, creating a pseudo-combi for the duress boost situation. That gives an immediate lifestyle benefit of enough hot water at all times in winter! See new diagram below. shopping list would be 2x TMV, 1x plate heat exchanger, 1x TDV, 1x pump, 1x 3 port multiposition valve, 1x 100L buffer so nothing too major. does upping to an 8m head CH pump make sense? the PP3 curve is steeper on the 15-80 , so am I correct to think should get more flow rate at the same radiator resistance/pressure level when all are open circuit? regards Ian
  11. hi all long term lurker and reader on here, this is my first post, hopefully I follow the etiquette! House is 1973 built 2 storey 4 bed detached, brick and block, "too-thin" 40mm cavity wall with 20mm EPS in from build time, cannot add more due to lack of width. Loft has 400mm wool DIY'd. Floors are uninsulated concrete. double glazed. All rooms have large radiators, 20 at the last count. flow temps of 50-55 warm the house perfectly well. EPC says 22MwH, in practice we use 15MwH per annum .Full Honeywell Evohome control of CH and DHW. Gas boiler Viessmann 28kw 100WB1B 4 years old. DHW is in 1st floor airing cupboard - a DPS Pandora 210L open-vented store with solar thermal coil at the bottom (which is now unused ). DPS and solar thermal installed 15 years ago. thermal system has gone - it died (long story, not for here) then replaced the roof use with 12kw of PV.. Mains gas, Mains hot water (good pressure 5 bar). 2x Tesla powerwall2 batteries. problems to solve: 1. need more hot water capacity in winter : Condensing boiler cannot achieve the designed store temp (75c). It worked fine with the old nasty non-condensing one!. Boiler has to be made to run extra-hot (79C flow) to reheat store, but even then - 67C is hottest store temp that boiler can reliably achieve in a reasonable amount of time. Bottom part of store is unused capacity. 2. DHW reheat necessitates CH shutdown for 30 mins always happens once , often twice an evening during peak childrens shower time in winter. takes boiler 5 -10 mins to ramp from 50 (CH flow) to 79 (DHW flow target) + another 20 to reheat. if not CH not shutdown , the CH cold return doesn't let the boiler get hot enough, so the HW reheat takes ages. Plus the rads overheat due to the too-high flow temp. 3. Rads group 3 are poorly/not heated if groups1 and 2 are calling in large numbers. Pump is in PP3 mode. Group3 is a long convoluted pipe run , can't do anything about it. Pump on fixed speed3 will reach group3 but is very noisy (very loud resonances as well as flow noise)- when load is low (1 rad open a tiny bit) so have to use a PP mode 4. shoulder season short cycling lowest boiler modulation is 7.5kw. Load with only 1 or 2 rads , house in daytime occupancy, is way below that. 5. increase hot water storage capacity spring<->autumn: PV dump heats upper store to 90C easily - immersion is between the upper and lower coils. increase storage capacity by moving heat into bottom part of store 6. Add ASHP in future, without changing everything else. ASHP would be sized down so still use the gas for the worst days. existing system as per diagram1 constraints - no space to add any additional large tanks or stores. Loft is impractical (tiny hatch, no space for a big tank). No ground floor space that works . Don't want to throw away perfectly good existing kit (store and boiler). my thinking on solutions diagram2: problem1+2 -> loop gas DHW mode additionally through solar coil . Heat in "base" mode through on lower coil only whilst keep CH active. diagram3: problem5 ->add de-stratification loop to run primary water in a loop between the coils until temperature evens out diagrams2 and 3 aren't an either/or they are logically sequential steps which would in practice be implemented at the same time. problem 3-> increase to a higher head pump . current is alpha2 15-50/60. If upgrade to the 80 will this help as its PP3 curve is steeper? diagram 4: problems 4, 6(+3) : rework to include a100L sealed system buffer tank (such as this) to separate CH and boiler flow sides . Mount it ABOVE the DHW cylinder - There is a 3 sided internal wall recess to fit into, so strength to build appropriate wall-mounted supporting frame for it is not an issue. Set a higher flow rate on boiler side vs CH side to decrease store/HW reheat times. Can ASHP and boiler share same primary tappings into buffer via Tee, or better to have additional tappings put in? Not shown on the diagram, but also wondering to perhaps take from the buffer via another plate HEX as a "winter preheat" for the HW, to avoid the cold water being out-of-the-ground cold when it hits the DHW store, to further improve DHW delivery capacity? I'm hoping I haven't completely gone down the wrong track here - not spent any money on new stuff yet but quite some time thinking about it and analysing the behaviours with temperature monitors etc - would appreciate any advice anyone can give. thanks in advance Ian