Nickfromwales

...and shoot the dog!

Except the oven would be in an open room, and the OP's cylinder is locked in a cupboard, eg significantly less convection / direct conveyance of the latent heat to room / whole-of-house.

There's not much to think about, you'd just separate them as they're 2 very different things in a PH. DHW still needs a decent bit of welly, but heating, then, only a thimble ( or 2 ) I've worked for a couple of turnkey M&E clients who insisted on no heat-pump, and with the way electricity costs are going I bet they will soon live to regret there stubbornness. If you have a LOT of PV you can "consider" your options. In the 3 months of winter you'll expect 25% solar irradiance or less, ergo a 10kWp array will deliver 2.5kW or less in winter. IF you are able to channel that into a heat pump, which is an energy multiplier, even in winter, you could then look realistically at offsetting the heating demand from onsite microgeneration. That is based on first considering watt the base loads are for the dwelling and summarising on the averages left over that would contribute to space heating. Without the heat pump........forget about it. Your best friend then will be simply dumping cheap rate electricity into the heat pump and charging the slab like a storage heater. All entirely academic of course, as any excess PV would be long gone on winter DHW. Fit a heat pump. You'll be kicking yourself if you don't.

A bog standard Telford stainless ( lifetime warranty ) will lose at or below 1oC per hour at these temps. Even at 70oC these are cold to the touch. The thing that is out of touch, is your contractor...... With proper pipe insulation local to this cylinder, you absolutely will not have an auxiliary heating system from DHW. If this gets routinely heated by excess PV during the summer months then the numbers warp a little, but you could still simply turn the immersion set-point a bit lower, to say 65oC, to mitigate.

The boiler MI’s will give you pictures and distances from other openings / terminals / opposing or adjacent walls etc so just use those to show your options. Well away from the MVHR inlet is of course a given.

I reckon it’s debris. Even a tiny sliver of copper or solder can take days to grind down to a point that it’ll just ‘work it’s way through’. Keep us posted please!

The 10mm for the bacon will only be effective if it’s the first thing T’d off the outlet of the hot water device. You want zero dead leg if going to the effort of installing a dedicated 10mm basin feed. Will be worth the effort.

Radial will get you as close to silent as possible. Series creates cross talk, and requires huge ducting at the start of the system in comparison. I use Brink and have reports of “complete inaudibility” with attenuators at the unit and airflow managed by design, to compliment. On 2 installs currently using the Brink Flair + main units, plus Brink Air Comfort units for post heating and cooling Fantastic results on my previous passive ( airtight ) projects, all using Brink, and that’s all I use these days tbh. Prices for your install should be a bit above the midrange of what you’ve been quoted, but spec / design will dictate the final price.

Could just be a bit of solder that’s found it’s way into the impeller housing of the pump. Best to open the pump up and visually inspect the impeller housing and impeller blades, before continuing on with any further processes of elimination. A bit of solder / other debris will result in a quiet pump then becoming sporadically noisy. That situation occurs when the pump stops and the debris drops out of the housing, with gravity, then it eventually gets sucked back up into the pump and around you go. It’s that, or a failed / failing pump. Air is not the culprit, I very much doubt that, unless it’s so bad that the pump is running bone dry. If it was, you’d have no flow registering on the manifold flow gauges.

https://plasson.co.uk/catalogue/product/19675 Then 25x 15mm adaptor. That’s 14-18, but they may do one to copper on the other side. Just ask your merchant for the nearest combination.

Geberit every single time for me! Never been let down, and the flush pipes are all single piece moulded items too, so no leaks there, ever.

On my jobs, we retain a hard cold for human consumption at the kitchen sink, and another to use as the filling point for the heating system.

I’d go 300 so you can harvest a lot more lower grade heat as useful energy, eg utilising that to reduce the amount of energy taken to ‘recover’ back to the stat set-point. A bigger cylinder will promote a longer, more definable ‘burn’ for the oil boiler too so will be better for you all round ( imho ).

Single room MVHR units ( through wall ) per bathroom / utility room? Sound good on paper, but results are not amazing.

And the rest of the house / building materials will be safe from the spread of this fire, how, exactly?

Tell me which days you don’t need DHW……… Has to be heated ‘howsoever’ for the days you do! You can run the rads via the TS, or directly, even possible to diverter valve it for seasonal swings between the 2. But…… Should this not negate using oil at all in the summer?

With a dual stat setup and an oil boiler, you’d struggle to not get DHW almost on demand tbh. A TS is a beast for producing DHW, and the heat goes almost directly in / out. With an oil boiler you can size the TS smaller and it will then recover faster, but if ST and / or PV are present on an install you’ll typically want to size a TS significantly bigger to harvest that ‘free’ energy. A TS will give a diminishing output vs an UVC, so needs careful thought and consideration, but if @Gone West has oil as a parachute, they’ll never ever be stuck for DHW with a TS. A 15-20 minute burn from the oil, from cold, and you’ll be able to jump in the shower, assuming a 200L TS vs 21-26kW boiler. To maximise the performance, I always specify a 28mm high recovery DHW coil with my TS installs. Trevor at Cylinders2go can get pretty much whatever you want specc’d / made to order.

Thermal store instead of UVC? Omits the coil and it’s inherent complications in utilising the oil boiler ‘properly’. I very rarely couple an oil boiler with an UVC for this exact reason.

Yup and yup. Always used this supplier and great service every single time. Got 5 of their setups to order in the next few weeks for 3 new full passive builds I’ve got on atm. Very happy with them, supplier and product, and prices are good enough for me to not look elsewhere.

Wet and dry vacuum to suck out the majority, and introduce some air pockets, and leave both ends of the loops just taped over loosely. With walls and roof on, you’ll be fine with that measure for mitigation. Is the garage door on, or can you OSB it to stop the winter wind blowing in / around?

Gravenhill, 1st of the 2 plots done iirc. Was a mess.

Looks busy, but the plumbing looks neat / well executed. Too much going on there to comment tbh. “Carry on!”.

The 27kW Stiebel is a very impressive unit. I’ve a 27kW gas combi, and there is very little in it. I’d be quite happy with that 3ph heater in my own home. 30kW instant is just too big, requiring a jump to 40a/ph. 32a/ph on the 27 is fine.