JohnMo

Sorry it's all rubbish, any glitch in internet the whole lot goes off. Reliant of constant fiddling and the whim of the service provider. Fool proof - too much specific learning needed, to be ever fool proof. SWMBO is right to question. Future proof, is a simple light switch that doesn't need an app to function or a program to run or internet that can be switched or fall over at a moments notice. Amazon fell over the day causing many multi national institutions internet/web services to stop. I had several HA devises and programs on my heating system - all utterly unreliable, all removed. None added price of mine, none added simplicity, none added any really needed functionality or saved my any money just wasted time and money), and none made anything future proof or idiot proof.

Two sorts of fan coils for ASHP a wall mounted unit, that heat and cool, something like this - one needed per room Or a multi room unit. Which you would duct to rooms similar to MVHR, but everything is sized to suit heating and cooling Install depends but no more complicated than a radiator. To heat pump you determine heat loss, how you deliver heat has little bearing on size of heat pump. I wouldn't size for cooling only heating, which is more dominant duty.

Aircon does both heat and cool What exactly do you mean by heat coils? Do you have an example of what they quoted?

I don't have a pre heater at all - I just rely on the inbuilt settings "During very cold weather, the Frost Protection Program will detect temperatures that could cause ice to form inside the unit. It will reduce or stop the supply ventilation rate, thus allowing the warmer stale air to raise the temperature within the unit cell to such a level that prevents the formation of ice. As temperatures rise the Frost Protection Program will increase the supply ventilation flow rate back to the commissioned settings." Have noticed as it gets colder outside, inside humidity drops, so don't see any negatives using the in built first protection.

Stick Aircon in - in the house that is, not the airflow. Leave ventilation to do ventilation. Or if ASHP just install fan coils in the upstairs rooms for heat and cool.

A slightly more advanced photo with more of the battens in place, you will insect mesh as well to wasps out etc.

I used a wide DPC Not the best photo, but should give you the idea

Is the menu saying you have external thermostat(s), if so are there calling for heat?

Basically as they are direct electric the efficiency will be exactly the same heating water. Storage losses may be smaller with a single bigger cylinder if the surface area in the combined cylinder is smaller. But if you already have 2 the cost pay back from improving efficiency, to pay for a 3rd bigger unit, would several life times.

Heating at passive house flow rates is limited to about 10W per m² of floor area. So heating is possible to fully heat a passivhaus or knock the cold off a more normal house. I would just do a single heat bank water coil upstream of the manifold. Then add something like this for £500 https://bpcventilation.com/products/cold-water-duct-cooler-range?variant=53736023261510&country=GB&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gad_source=1&gad_campaignid=22309731029&gbraid=0AAAAADpzxaVuRiJvI1F3wJ3DAy6JrgNmt&gclid=Cj0KCQjwmYzIBhC6ARIsAHA3IkR7VeYyluH-E6sPvQvoP7NgX-nTx-8L6YP-l9OAvZNbuLjgrusSh0QaAtYIEALw_wcB This has the capability to cool and heat as it has condensation drains etc. But this is all you need to heat, depending on dT between coil and air for kW output. To cool you would need an oversized MVHR unit and in cooling mode it would be wired to run full speed. Still won't be great cooling due to UK humidity.

You to look at the exact flow rates and temperature required to get that output. Just checked the datasheet and outputs when you compute them are based on 45 to 55% humidity outside air - not sure we get that very often in the UK? Plus you need a massive flow rate. So science hasn't changed just the prices of equipment - Titon unit is only £8k

Doesn't make the answer correct! Which it isn't. There is an over panelling allowance in the total Watts you can generate, but you still need to stay within the specified amps and volts limits.

That isn't really correct, you have a single string which is a series-parallel array. So in this case voltage 9x a single panel and amps is 2x a single panel. So question, is the amperage within limits of the inverter? Possibly not a concern at this time of year but could be in summer, could be where you may exceed the 26A MTTP limit.

Sounds like you need to step back a little. Plan exactly what you want to achieve, put some realistic numbers to the costs. Write It all down. Get a big note pad use It as brain dump, scribble pad. Put it by your bed and instead of rotating a thought around your head write it down. The process is pretty simple, but gets overwhelming because there are many parts that need to be done in a specific order. Plans are good they keep focus, a snagging list needs to to be added to the plan at every stage so things are out of your head and on paper. I am saying on paper for good reason, it quick and easy, it doesn't crash and doesn't need power or internet. I really found this forum useful at the start and planning stage, but once I started the build I didn't want the noise of a 101 opinions of a forum, I had a plan, a design and stuck to rigidly. It shouldn't be an overwhelming process, steep learning curve - yes. Why two properties? Do you need two, why not just one? Why semi detached, that means you really need to do two properties at the same time? Do you have suitable funding in place?

For me I would Do in recirculated mode and come out at the kickboards below your kitchen units. Then install a dMEV (with automated humidity control) fan in kitchen plus all other wetrooms. Undercut all internal doors and have humidity activated trickle vents on all dry room windows or through their walls. Have a proper ventilation strategy.