JohnMo

For me these are the steps I would take. Assuming you keep the existing electric shower. Keep existing cylinder and heat via immersion as and when you need it, a simple immersion timer. Note: At heat pump temps 210L is more suited to a 3 bed house. Use the heat pump for CH only Do not do UFH unless you have lots of insulation below it. Especially if you are going to rip up sooner than later. Do you have idea of how many kWh of electricity you use for heating? Being electric it should run close to 100% efficiency, unlike a badly setup boiler. Use the reference here to check your likely heat pump size https://protonsforbreakfast.wordpress.com/2023/04/02/another-heat-pump-spreadsheet-beyond-the-rule-of-thumb/

That's a bit bonkers, take mains pressure water, drop the pressure, use a pump to make it high pressure again.

I wouldn't buy bearings from eBay way to many dodgy ones being sold. Would try bearing boys or simplybearings, have used in the past, would be my first port of call.

It was a combi boiler so heated the rads and hot water cylinder That is NOT a combi. That is a system or heat only boiler. A combi boiler has no cylinder. Your current shower unit is no longer suitable, so will need to be replaced. Good news is you no longer need a power shower, so a mixer will do .

Adjusted the flow rate on what?

That's the bit that may may need sorting. Do you still have the pump fitted? Is your cylinder an unvented cylinder? A quick look on the Screwfix blurb for that shower, the first thing it says is "Suitable for Low Pressure Water Systems Only", the Q&A section states "The Event XS is a power shower so it requires a cold and hot feed from a gravity supply" if you now have an unvented cylinder you do not have a low pressure system any more. That will be your issue.

I would look to tweek the approved design. Porch needs a bit of thought The end wall blank needs something to lift it design wise Maybe a window change or two Plenty of scope for solar, which is good

If by decorative you mean rounded stones, they provide zero load bearing and just slide about.

Real bargain, thought mine was cheap at £260 for one.

The Myson one you can set different temperatures for different times if you need, plus you can alter the water flow for heating and cooling, above or below (cooling) the fan is activated. With temperature and time program if you set to night you set the Mac speed the fan runs during night hours. I have mine set to 23 all the time, and it tries to manage that room temp with the water it's given, warm or cool.

I already have one but they cannot get past the start of commissioning due to zero communication.

I just tried to apply for one of those and got this

Just checked with Octopus and they are saying that there is nothing they can do to help my reception, think it's a long wave radio thing in Scotland. But they did put me on a cheaper fixed rate E7.

Same as the HRV10 I have. Basically the front cover comes off. Instead of a patch panel.

But if you don't or can't have (no signal) a smart meter you can choose E7 or standard tariff. We have no smart meter signal so are on E7. I was finding batch heating was fine down to about zero outside, below this I couldn't generate enough kWh of heat in 7 hours, to supply 24hrs of heat, so heat pump would continually to run during peak rate at high load and start draining the battery too much.

They are different, controller is completely different.

With battery, some extra PV and E7, when compared to gas heating, and no battery, I was a lot cheaper. But the kWh used was way more than it should have been. So would like to run as it should be, low and slow, single zone, zero controls, straight WC. See how it goes.

We have two Titon units neither are PH certified, there is nowt wrong with them. Could quite easily have chosen a PH certified one from Titon, but it didn't suit out needs flow rate wise. I would really doubt that.

Ball valve just treat the same as a piece of pipe, if it's 100mm long just add that to the pipe length Diverter valves are different they have a pressure drop and some can be quite restrictive. Same for strainers and strainer ball valves. Think you maybe overthinking all this, you don't need to detail the last Pa drop in pressure. Aim for a reasonably low pressure drop. No gate valves, just ball valves for isolation, at least a 28mm diverter, a strainer, that's about all you have in the system. Keep everything simple. I would just plump the whole lot in either copper or Hep2O or a mix of the two, where it best suits the run. Copper tails on any compression joints, the transfer to Hep2O with a straight coupler. High points will need a bottle air trap to bleed air, just need a 28 by 15mm tee for that. Low points need a drain. If you want a low pressure drop diverter an ESBE is fine, I just use a Honeywell 28mm it's fine.

Not really as @Dave Jones said earlier he had cooling on MVHR and it was not good. Ventilation and cooling are different animals, with very different flow rates required, I wouldn't mix together in one unit. Plus if one side breaks down you loose both. Cooling via your UFH loops in not too bad.

On mine no, they are factory set.

MVHR summer bypass works in hot periods when outside air is cooler than the air being rejected. Therefore bypassing the heat exchanger. If the house is cooler than outside it should operate in normal mode. So cool the incoming air via the heat exchanger.

That looks the right unit from mitsubishi. A ball valve is just like open pipe when open, so no restrictions.

This is true but you need to look at what occurs at the heat pump also. The dT between flow and return will increase. The ASHP will try to maintain flow target and dT. If the target dT is 5, and you start removing more heat to play catch up, the dT could move to 6 or 7, the ASHP trying to manage dT will allow the leaving water temp to fall below target. The ASHP ramps up power to full power to try and get to target flow temperature. Question - Can it actually deliver the required power to catch up? Possibly on anything other than design outside temp. But likely to run a full load until it gets back to equilibrium. Will you take a hit in the wallet - most probably. Do you need a buffer to if messing with some room on set backs, maybe. Will it hit your wallet with an uplift of flow temp to have a buffer - probably. I ran my heat pump last year deliberately on this basis, with UFH my set back was 0.5 degs, because heat loss was slow (well insulated and thick screed). I did this way to make use of cheap rate electric. Looking back I used loads of cheap electric. This year it will be straight WC no set backs, the heat pump left to tick away on WC. Last year in summer I ran the ASHP in cooling mode it ran for 3 hrs straight in the morning and the same after DHW in the afternoon, it spent the rest of the time off. Used about 4 to 6kWh a day (free from PV). Made some changes now have had the heat pump running continuously for 10 days, setting is basically if the return temp drops below 19.6 degs, the heat pump compressor starts. It runs 10 to 15mins and the depending on sun and outside temperature the compressor could stay off 30 mins or 3 hrs. Using about 2 kWh a day. Getting a cooler more comfortable house using a between 1/2 and a 1/3 of the electric. Slow and steady well setup is nearly always running at low loads.

Check the internet most are out there somewhere