JohnMo

None of the ICF build systems are rocket science. If there is build manual, just follow that. Basically stand a block on foundation repeat, add rebar per structural engineer drawing. Make sure the insulation is in line throughout the building.

Interestedly I had the same discussion with the electrician who wired my ASHP up the other day, similar output, senn a couple on new builds but nothing more.

Not sure but this may be the source, or just another using the same unit. https://www.auer.fr/en/products/heat-pump-water-heaters/edel-water-heat-pump-water-heater/

We lived in Singapore for a year or so. The showers there are somewhat different to ours. We had no boiler or stored hot water tank. The showers were not electric showers as such, not the same as we have here. But seemed to have a store of hot water in the wall, at point of use, assume heated by an immersion, shower performance was good as well. Electric bills were not excessive from I recall.

You would be hard pushed to find a combi that does 20l/m, summer or winter. We have combi rated at 32kW for DHW, at a delta T of 28, it is rated at 18.8l/min. The 23kW model is rated at 11.6l/min at the same conditions.

My pallet shed is held together with bog standard screws and off cuts of wood. M10 rod sounds a bit OTT. It remained standing for the last 3 years no issues.

I used this website to find out what size PHE I needed. Bigger the better at low flow temps https://www.heat-exchangers.uk/online-calculator/

1, no 2, what size heat pump are you being quoted and does the RED, come in that size?

Having a read of the helpguide, it mentions degree-days being above 15.5 degrees heating isn't required, below 15.5 it is. This is a variable and really depends on the insulation levels of the property, well insulated could set that at about 10 to 11 degrees. So not perfect. I would just use the spreadsheet I linked to. It costs nothing except 30mins of your time.

Not sure I would use one, mine failed in less than a week. Use the thermostat to open/close a relay, use the relay to call for heat and start/stop the pump. No need to open the wet parts of the system to fix anything, if/when it does go wrong.

Sorry just re read, I must have been on a tangent - you did say bedrooms.

The problem with city plumbing calculation and many other is it's based on general rules of thumb, no input for air changes, only does generic double glazing, flat roof insulated, no idea what u value is used, same for the wall and floor. Just re did one room the kitchen, and it was equal to my entire house heat loss. It's just a selling tool for radiators. A few years ago I used the same tool for sizing radiators for our last house, an 1830s house, it just as rubbish for that house, said my living room needed 4 huge radiators, doing the calcs long hand it only needed one large radiator. No issues heating the room. This spreadsheet works pretty well, does the house as a single entity not room by room. It doesn't take account of people in the building and other heat sources, so does over state the heating in warm or mild months, but for the design case condition it pretty good. https://forum.buildhub.org.uk/topic/439-fabric-and-ventilation-heat-loss-calculator/

If they are solid and not just hollow I wouldn't bother. But that me, our house (new build) with undercuts seems pretty quite with the doors closed. They are defeating ventilation requirements. Just undercut and move on to the next question.

Just about all property with mechanical ventilation have door undercuts. The noise transfer is insignificant. Stop over thinking. It doesn't stop you do sound insulation in walls and that should be done.

I would think of it the other way round. On a sunny day your cylinder temp will be high by the end of the day, so will not need heating by E7 overnight. Size and operate for the same temps as a heat pump. So use E7 to keep the cylinder as 50 to 55 size at 300l plus. Set the other immersions to heat to max temp the cylinder allows.

Two ways to self built, pay someone else to it or do it yourself. I started in the first camp, pay someone else, then I got the prices, picked myself up and moved into the later camp, not fully but mostly. Some jobs like the roof, the plasterboard and second fix woodwork were to big for me, so got someone else to do it. Just managed that process, got the quotes, made the 101 decisions required to cover things not on drawings etc. I had done DIY beforehand, the process developed through the planning stage, how do you do this, how do you do that etc. The process from site clearance to completion certificate was almost 3 years to the day. Ended loosing 2 stone in weight, tired, unstressed and learnt lots, but most all I enjoyed it. I can also say I built that, not many people can say that truthfully - but plenty on here can.

Had my ASHP with power yesterday, pre ran all the cables, connected everything except the consumer unit, had the electrician check everything over and do the final connection in the consumer unit. Electrician and his apprentice were here for 3 hours, including first fix wiring our summer house. Just need to complete the plumbing and I am ready to go - just to many competing jobs on the go.

Most UK manufacturers seem to do custom cylinders if you want them. So you could in effect have any number of immersion heaters at different levels. So you could for instance, have E7 one dedicated, have one at a high level for not so sunny days, this would then move to the a lower one once the top is satisfied on a really sunny day. @Nickfromwales go to place seems to be Trevor at cylinders2go. So it may be worth having a discussion direct with them, other suppliers are available.

https://www.bes.co.uk/plumbing-supplies/plumbing/hotwaterpumps/pumps/?gclid=Cj0KCQjw27mhBhC9ARIsAIFsETFYeNMlSSGzUeUme2rWauEIbYepRD48FcqQjE9KDeDLoILZR8x8IlQaAoXWEALw_wcB

Which actually means nothing, must, shall, will, mean to have to Recommend means if you want, we would like you to, but you don't have to.

Yes for the pump, but mount the pump as low as you can, just above the bottom elbow by the cylinder, this will give the pump the best suction pressure and keep it away from cavitation. For the PHE flows hot from ASHP, need to be on the same side as the hot water going to the cylinder. So you HP flows swop sides. See attached

You really need to calculate the heat loss, rules of thumb and heat pumps is not good enough. Rules of thumb and heat pumps is a recipe for high running costs. I used the city plumbing app and how house needed around 14kW, in fact the correct size is just over 3kW.

The discussion was bathroom rads not bedroom.

That's a bonkers price for supply only How big is your house going to be to need that size of heat pump. I could run 600m2 with that size of heat pump, and have room to spare.

Just put an electric element in the bathroom rads. Why heat a huge volume of water, pump it around when you can heat the bathroom rads which contain a few litres of water. They work all year round if you want, with the heating off.