JohnMo

Insurance company doesn't ask you for a copy of you completion certificate. Our house insurance started before we actually had a completion certificate, just declared major work was ongoing and the time scale, they asked for money and I paid it

Would need to read the regs, but I think the ones in the post by @Nickfromwales are exempt from planning rules, as they are basically portable. Just a shaped bucket filled with sand.

How have they done that, unless listed building? What are they - do you have links?

Do you mean secondary return loop on DHW? If not done correctly can deplete the cylinder heat pretty quickly. Pipes in full system need to be well insulated. You need to limit when the system runs, so ideally have on a timer or a trigger of some sort. Ideally have a thermostat at the suction of the pump so it knows when the system is hot, then can cycle the pump on off to limit circulation flow. If you have small bore pipes from a manifold to consumers, it may add little advantages but could be an energy drain. It can limit the water draw off volume before hot out of tap. Good for water conservation We have it but it's just on in the morning now. Evening is showers, so nearly hot by time you have undressed anyway.

Watch any quiz show and 20 to 40 years old contestants have zero clue the difference between centimetres and millimeters. That is all they should learn at school. I'm in my 60's and have only used metric most my life, using imperial on really old stuff only.

Again not correct. You can parge coat (then mix of lime, cement, soft sand, mixed to a cream thickness) applied with a broom (and as in image) or you can do a membrane. We have almost no wet plasterers around us, so that wasn't an option. is is

If you want to chase walls woodcrete isn't your friend, as the woodcrete eats sharp teeth for breakfast, soon blunting them. I did the easy way, service gap with battens and plasterboard (dry lined). Battens are screwed directly in to woodcrete (through thin parge coat) with self drilling screws with a blob of sealant on them as they breakthrough the batten. Only bit I didn't do was the plasterboard or taping/jointing. Big polystyrene blocks are quicker and easier, but require suitable props and support y(they weren't available to us, as we are to far north), to hold it all together while the concrete is poured. Durisol needed a few bits of OSB screwed on at corners. Only thing hired in was adjustable props for the lintel forming. All systems have pluses and minuses, choose what suits you. Various direct experiences of different systems offered, some I wouldn't touch with a barge pole, Durisol I would use again without issue. But would also look at polystyrene based ones as they offer airtight out of the box. But only if all the additional support structure were readily available. Rebar not mentioned, Durisol needs very little, all the webs that @Nickfromwales doesn't like is one of the reasons for this apparently. I have rebar around openings and at a couple of high stress corners and that is about it.

Well that won't make then airtight. Obviously the person doesn't understand airtightness.

Durisol build - zero issues, 2 of us did the walls neither of us builders nor had either of us done it before. Just after WW2, others 30+ year after. If you are wet plaster inside that side is sorted. Render on outside that side is sorted. We lime/cement parged inside, very thin coat. Stone slips, and wooden cladding outside.

It may show on your planning or building warrant, but it's not set in stone. The sewage system is only approved when when you have been through the full approval process with SEPA and have a duly approved certificate for that exact make and model. So up to that point are free to change things, after certificate issue you are not, without reapproval of the full system and new certificate.

Obviously Velox and Isotex are not very good copies of Durisol. So should not be compared as the same.

We are the same 2 off us, but find the house way more comfortable with a steady trickle of heat. You can keep the house cooler and feel way more comfortable, but also use the gas way more efficiently. So actual gas usage is the same or comes down. Combi v cylinder, we have had both, we actually use less energy heating a modern cylinder than the combi did. The water out of the tap comes much quicker also from opening the tap. The combi would just fire up to full load of if you open a tap for a second or two. That doesn't happen with a cylinder.

Observation I thought you were getting BUS grant for ASHP, the grant should cover the installation of the heating system also, so should that bit be covered by the heating installation? Seems mad they are doing everything including supply radiator valves but not the radiators? All sounds expensive to me, I would be looking for a second or third quote.

Not correct. Woodcrete is an open structure and water will free flow under gravity out the bottom. It doesn't readily absorb water. Not sure where you are getting the information but it nothing like anything I experienced doing our build. Are you really talking about woodcrete ICF blocks or something different? Or wood fibre insulation?

The quote is what?

First do a room heat loss. That will tell you. You make no mention of heat source or flow temp, these all have an impact on suitability. BTU, thought people stopped using them 40 years ago unless your from the USA.

That's to be expected. One zone and 10kW output stands no chance of running well. Putting bigger rads in, is unlikely to help if only that zone is allowed to call for heat. Would really try to get it all on or all off, nothing in between. Dumb TRVs that don't fully close, maybe helpful in a small number, not everywhere. You may need to balance the system so room comes up in temperature at a fairly equal rate and use a single thermostat to bring all on and all off together. Keep it simple is generally the only way.

HA has it's merits, until your internet stops, or you have a power cut and the server doesn't automatically restart - been there. I have just moved everything away from HA for heating, so nothing is reliant on internet based services. Think your boiler does Opentherm, so I would look at an Opentherm Tado to manage the boiler for you. Then dump HA from the heating system.

Boiler and equally so heat pumps, just produce heat, if the heat cannot be dispersed to the house, return temp stays too high and you get what you are seeing. Splitting the system with zones will make life hard for the boiler. Are you running with lots of thermostats, TRVs etc. micro bore may not be the issue, actual flow rate may be. Remember the microbore is only carrying the flow to a radiator which will have a decent volume.

That's what I like about Atag boilers there is none of this range rating to do, you can limit max power output, but you don't really need to, and no faffing with boiler flow rates. Everything in fully integrated - pump flow automatically modulates to suit flow and return temp, and output is automatically modulating. They also start differently from other boilers, start up is at minimum output and they slowly ramp up (depending on how you set the gradient setting) settling at min output and suitable dT to support demand. Pretty much the same as my heat pump.

You need a simple form that says Building Regs flow rate and actual flow rates in normal and boost, as a total and room by room basis, plus stating whether it's a extract or supply. Plus you need the flow meter you used, calibration certificate.

And a video https://youtu.be/FohU-RNTA4E?si=4dBQdfkq4eXEVDXD

Think it can be located in various locations depending on exact model and indoor unit purchased. 16L is about 0.6kWh which is equal to the energy used for defrost in the write up. Smaller units maybe don't heat up so high?

Maybe a photo of the hole not the ladder would be good. But I would do a proper job - patch the two walls with blocks and cement, after cutting away to make hole to neat shape. Prior to doing the final wall reinstate insulation in the cavity.

They use a look up table, for indicative build costs.