Nickfromwales

If there is a lot of large bore primary DHW pipework from the cylinder to the manifold, you're screwed. Even with 10mm radial to a basin, you'll be waiting a LONG time to get hot water. BOOM ?. There goes the dynamite

I have loads of them in domestic and light commercial installations working perfectly well. Zero pumps. You just size for the potential of the main, usually taking advantage of the night time and midday increases in static pressure as the main goes off peak. Non return valve captures and holds that for use therein. Got one install in the arse end of the green belt. Shite cold mains, so 2x 200L accumulators ( so I could fit them in eaves spaces ) on a job with a knock-though extension with them adding in another ensuite. Guy was gobsmacked at how much improved the system was. For completeness, in this house they had so poor a cold mains that the existing UVC could not push hot water upstairs to the bathroom if the kitchen tap was open. You could literally hear the water going down the pipe / air being sucked in through the bath tap when you opened it. Swapped them out to a Vaillant 937 high flow combi, after about 5 other plumbers said they had to keep the UVC and forget ever thinking about a combi. 8 years that's been in, for my mates boss. Fully aware of that, but you still need segregation and a LOT of downstairs space. Still noisy, still very slow to refill / recover, and you need a large expensive pump to do what this member is trying to achieve. I'm advising as to this thread, not for general information For the OP's solution, they would need at least 3x 50 gal CWS. So where are they going to go? You also need to treat water in the break tanks as non potable in the real world, so bathing / not for human consumption only.

Ring around for best scrap prices. Should get a few ££

Oh, I forgot to say…….. ???????????

The cost and annoyance of pumps off an open vented system, with additional pipework, elevated 50 gal or 75 gal tanks minimum, maintenance and then segregation of cold and hot pumped feeds throughout the house…….. vs one pipe to an accumulator with no moving mechanical parts, no electrical connection, and silent in operation. ? Sealed and pressurised systems will have very little heat losses by comparison. You’d also need multiples of pumps and probably 2x 50 gal or even 2x 75 gal open CWS tanks in the attic / races space. They would have ball valves which makes noise whilst SLOWLY refilling the tanks = piss you off if it’s near a bedroom. ???

Weigh them in or list them for sale. They are of zero use whatsoever to you for a domestic new build.

Hmmm. A 250L TS services by a 37kW modulating boiler would just about be suffice eg for the list of hot water dependant devices you list earlier in the thread that you wish to run nigh-on simultaneously. That it a BIG ask of DHW flow rates. That setup would promote almost instantaneous reheat of the cylinder, with a great degree of heat transfer from burner to DHW. Also, a 28mm DHW coil is an absolute no brainer, forget 22mm. I would fit a bigger TS ( minimum of 300l ) or a 500L UVC. If you go UVC you 'could' go for a smaller boiler, but the cost increase is negligible for what extra oomph you're going to get, plus with a bigger max output, even at 37kW, you'll still be able to drop to 7kW-9kW fully modulated. The boiler will only ramp up to suit the demand, and, with your remit for DHW, this is the minimum system specification I would ( and already have done multiple times ) specify and install. Anything less and your wife will be chopping your two best friends off........ Thank me later To get away with a smaller boiler, if you're feeling brave, you would 100% need to configure the system for W-plan aka hot water priority where the boiler > cylinder / heating zone valve is a 3-way DIVERTER valve giving heating OR DHW, never both mixed; ergo the boiler max output would be dedicated solely to reheating the cylinder of choice ASAP. The cold mains will need to be 28mm, from the mains to the UVC control group or TS cold inlet and cold manifold, where the 28mm pipe would then tee off into 2x 22mm feeds to each ( the DHW device and the cold manifold ). In terms of flow rates you are mentioning both types of DHW devices ( TS & UVC ) which are both COLD MAINS DEPENDANT. If you do not fit a minimum of a 300L accumulator ( or 2x 150L if space is difficult ) you will never get the earlier requested DHW performance, not even a chance. In respect of the hot return circuit ( HRC ), you won't manage without it. That is because you will have 28mm primary hot pipework, cascading down to 22mm going to a 3/4" DHW manifold, and then your 15mm and 10mm radial feeds coming from that. The runs from the manifold may seem short enough to give the confidence to abandon the HRC, but the dead cold leg before the manifold will soon shatter that dream. Fit the HRC, insulate, insulate, insulate, and again, your wedding tackle remains to live another day. You could just run the HRC to the end of the DHW manifold, and just one branch to maybe the kitchen sink, and the ensuite basin tap. Enjoy!!

Erm….?. Solar power won’t be man enough to run a heat pump for heating in winter unless it’s a 20+ kWp array with a very good south facing setup. When you need heat, it’s winter, therefore 25% max ( usually a lot less ) PV output. So, in a nutshell, no.

Via a buffer to allow segregated supplies at varying temps?

A decent ventilation void on any sun baked elevation will pay dividends. 25mm of rockwool is not worth the effort. EWI would not compensate fully for solar gains, so factor in mitigation against the most prolific problem causer.

And a bunch more reasons on top. MVHR is whole of house in a reasonably airtight house, or zilch. Flow rates are so low, infiltration ( natural ) often exceeds the design room ACH values, so essentially is just blowing past the MVHR. Retro-fit of MVHR is a complete an utter pig to get right, with a lot of build fabric amendments and also needing a very close eye on detail ( so you couldn't trust most 'general builders' to execute this on your behalf ).

I have my moments......usually 3-6 months apart though

2 boilers is just way overkill. Scrap that idea Ok, does the alpha have a secondary hot return connection, or will they allow you to feed that back into the cold inlet? If you have no option for hot return then your problems can only be managed by reducing pipe size to outlet and getting rid of the huge amount of 22mm supply pipework ( as that is where all of your major dead-leg issues will stem from, not the pipe runs ). Centralise the boiler and manifolds wherever you like, and run a HRC to the furthest most outlets to suit. You can run 22mm feeds to 2x DHW manifolds either ends of house for max flow rates, that would be best case for flow, but they would need to be serviced by an HRC and be worst case for efficiency.

Drill one 50mm hole in from the 3rd boss on the fitting under the branch, then T everything waste wise in, inboard of the beam? At worst you'd be drilling 2x 50mm holes and then going through those 2 holes either side of the boss once per side? If a BCO is involved you will need to demonstrate that you've drilled the beam in accordance with the MI's Check before drilling !

Vent for the kitchen extractor should be 150mm if the fan is anything more than a box standard extractor. Anything less than that will remove very little from the cooking. Why not combine 2x 100mm outlets and split them off a 150 Y branch from the extractor? Use the 3rd with a damper to allow fresh air in during the summer to offset the heat from cooking. Or blank it off. Oh, and MVHR for a single room in this house will be useless. Just stick with extraction.

That’s 415 again. Ask for one with a 32a single blue socket outlet if poss. As it’s short term, get one which just connects to the CU without arsing around

You can fit 2x 25L tanks also. Having one rad on bypass ( no TRV and open lock shield ) will give about 5-7L of additional system volume, and you may get away with that. Hopefully that would be the absolute worst case and if you’re using heating, hopefully a couple of other rads would be at least allowing a trickle through partially closed TRV’s elsewhere on the system. Go for it, but try to keep an eye on the boiler cycling to see how it performs.

You can (expletive deleted) off too

You'll be able to sell a tidy one on again. That other thing needs to be gotten rid of as is, eg less any bastardization etc.

Absolute total and utter garbage for designs and system principles. I wouldn't EVER go to them for a quote for UFH, not even for supply only. They made a proper mess of a £2m build and it cost a fortune trying to retrospectively delete all of their errors in a nearly completed project. They didn't even know what kit they'd installed on site, and the plans the client had been issued for M&E reference were toilet paper. Wunda or any others!

Seriously ?!? Do NOT even THINK of running different phases in a caravan off that red outlet. Lethal advice, unless you go to a new 3ph CU with all RCBO's. Cheaper to buy a proper 1ph genny. Leave it well alone and sell off this boat anchor. ?

Ok, lol, so my 2 penneth is to Foxtrot the castellated panels right off and do as the angry cup ninja above suggests and use clip rails. You want that void full of screed and not part full of worthless air anyhoo, as the screed is your heat emitter. Oh, and all this nonsense about air lifting and whatnot.........time for more tonic / less Gin "NEXT PATIENT PLEASE !!"

No further action required then. BCO to confirm of course.

If the steels are not fully exposed, in a standards residential dwelling these do not require any further detail. Eg if the entire dwelling interior is plasterboard and skim, then you already have the prescribed level of fire break / integrity required between steels and open flame. Will you have any exposed steel, like in eaves or plant space? Normally these are contained inside the plaster-boarded envelope for this reason. Again, the BCO will have seen the drawings and should have highlighted this already, if so required. Fire and drainage are the big ticket items for BCO’s, with most other requirements being satisfied by 3rd party certification ( ventilation / electrics / structural etc ).

Air con pipework is 8mm and 10mm copper in most instances. It needs to be wrapped in black neoprene high grade insulation also. Would fit in , say, a 40mm waste pipe if you need some idea of footprint. Plus a garden hose sized condensate pipe, plus cables ( communication and power with some ).