JohnMo

You will get a battery capacity hit as it will self heat using it's own capacity or just give less capacity. Maybe better filling a reasonable sized battery and export. Cosy is 12.7p to buy and they will pay 15p to export. Keep what is cost effective to keep, sell the rest. Fires - battery chemistry is pretty safe in house batteries. Mine is in loft/plant room, fully insulated space. Other thing to look at is inverter size so you can have multiple things drawing electric without sucking in mains electricity, 6kW works well for us. Plus look what happens in a power cut, some systems shutdown most except an emergency circuit, so rest of house goes black. Good thing with AC coupled (GivEnergy AIO) house just runs as normal with no interruption.

The way (for me) to size battery is ignore solar (for now) calculate the electricity demand on your coldest day or close to that. So now you need to get a battery that deliver that electric without have to use peak electricity. Octopus Cosy gives you three cheap periods, think the longest period between cheap periods is 7 hrs. And there are 8 hours of cheap electric, so you can just draw from grid in this periods and recharge battery. So battery only needs to be able to last 7 hrs at highest demand. So in simple terms xkWh, divide by 24, then multiply by 7. Example 40kWh/24, is 1.6kWh, them multiple by 7, so just under 12kWh. With conversion losses (DC to AC) you need to add another 10% so now you are at 13.2kWh. So really an actual capacity closer to 15kWh. Or a GivEnergy AIO, with an available capacity of 13.4kWh, which is what I chose.

I used LoopCad to model house, then balanced room by room output so no supplementary heat was needed or I wasn't over heating rooms. They have used LoopCad to model house put omitted to balance heat output. I need about 3kW heat output at design conditions to heat whole house. My hall uses loops transiting though it to heat the area, by spacing them through the hallway. Did same with utility (manifold location) but some loops required to be insulated so as not to over heat room. 150mm provides a quicker response time, and maybe a degree or so cooler flow temperature. But if doing WC or batch charging floor that doesn't really matter. The compromise position is to do enough loops to get away with one manifold and have enough flow capacity within the ASHP circulation pump so you don't need a second circulation pump. 30 to 40W to drive second pump doesn't sound much, but will drop a will likely cost you £30 to £40 a year to run doing heating only. Double that if you do cooling. Entrance hall has a dedicated loop, plus it has 4 other loops passing through it. Space the 4 loops out across the hall and you have deleted 1 loop. Space ensuite and bathroom at 100 to 150mm centres - you cannot have enough heat in those rooms. Rest of the rooms in 200 to 300mm spacings. A mean flow temp of 30 degs, on 150mm centres will output 40W/m² so your living kitchen looks to be 6x8m so area is 48m² so you are putting about about 2kW into floor on your design day. That floor comprises 5 loops and about 400m of pipe. At 300mm centres same flow temperature you are putting 25W/m² or 1.2kW, which maybe more than you need. You then can do 2 loops and 200m of pipe. Saving 3 loops. Do a similar exercise with each room. Design sheet to assist, attached. The attached doesn't include floor covering tog rating.

To give you some idea on my thoughts Our house is single storey 192m² and have 600m of pipe in floor at 300mm centres and covering about 160m². Our max ASHP flow temp is 32 at -9. Your design relies thermostats to control room temperature. Your design needs to be room balanced. But like choosing a correct size radiators by room heat loss. That plan sells you lots of stuff.

You really need to get built-in circulation pump performance curve (in install manual). Calculate your system pressure drop. So flow and return piping the longest UFH loop pressure drop. Calculate your flow required. Read system pressure drop on pump performance curve and validate if your pump puts out enough flow. Advantage - purchase choices. Route all pipes from ASHP to manifolds in 28mm, so very low pressure drop. High kvs diverter valve. Look at a kvs of 10 or over. Then valve will be invisible hydraulically. If your pump still doesn't flow enough install a second pump on the return from UFH only (not cylinder side) run at a set speed to get the flows you need to see at the UFH manifolds.

Still all fine. The only issue is the sliding doors, leak like a seize.

If you read the instructions, they clearly state in the UK they are not allowed to go in a plug socket, they need to be wired back to the consumer unit.

Do you have a mixed system, radiators and UFH? He is describing a two zone system, you have a single zone. So there are radiators and UFH, each can run independently of the other. If you have just UFH do you need to mix down? Are you setup to up to run priority domestic hot water? Do you have the Vaillant wiring centre he mentions?

Active cooling allows comfortable rooms at much higher air temperature than you think you need. You simply do not need the room at 20 to be very comfortable. Our lounge is sitting at 23, currently and very comfortable (under floor cooling on) if a little too cool. Our summer house with fan coil is sitting at 22, again well comfortable. Was in it yesterday with full sun on it, it was sitting at 24, again a nice comfortable place to be.

If your chosen heat pump doesn't have an in-built mixer control you will have to add that, an ESBE valve and actuator aren't cheap either, a third party mixer controller isn't cheap either. Value adding possibly not. So a couple of layers of complexity. So now your flowing at 7 degs, to get max output from fan coils and mixing up to allow UFH, so need a temp above about 13 degs generally. So now just incase you have messed up you need to sense house dew point and make the ASHP do something different in case you start to get humidity issues. Another layer of complexity Then in winter you need more work arounds to get everything happy again for heating, where I assume you would just run straight WC? And another layer. Why would you be getting warm water from the fan coil? If your flowing 7 Deg water into fan coils, if they are running full chat you are likely to see a dT of 5. So return water is 12 degs, below dew point. If the fan coil fan is off because room is cooling enough the dT will be very low, so now you could be pumping water well below dew point. KISS.

No idea why you keep trying to make stuff complex. Just do it all above dew point. Then no mixer no second set point etc

This what I did. Ran mains water pipe mdpe to stop cock. Then converted to 22mm copper and to a cold water manifold. Then from manifold went below floor insulation running 15mm Hep2O in conduit to each room that needed cold water. All joints above ground, ample flow to each room. In theory replaceable, to comply with an obscure rule I found in building regs. You then have a central isolation point for each room that should be easily accessible. Allows each room to be commissioned at different times, and if you get a leak you can just isolate that room while it gets repaired.

Our original plan was loads of small down lights. We now have 6 in total in the kitchen diner, but they are no longer GU10 sized the are like 4x 200mm and 2x 150mm. Well bright, look more like light tubes in looks. Sorry small spots just look rubbish Use something similar to these https://www.screwfix.com/p/luceco-eco-circular-fixed-led-slim-downlight-white-18w-1530lm/663px

I would expect, because block work is made from concrete and when covered with plaster suck the heat from your hand. Plasterboard on the other hand with an air gap doesn't feel so cold. The difference will be also seen in room temperature stability the concrete blocks absorbing and releasing heat energy as room temps fluctuate to give stable room temps. The plasterboard version is somewhat isolated with an air gap will not function in the way. More akin to stud walls. I have always thought dot and dab is a bodge get out jail quick for builders, much like you describe, hide all the rubbish quickly and easily.

You would be surprised how well floor cooling actually works, plus how responsive it is. Plus you have it to try for free. Just run on fixed flow temp and let the heat pump look after itself. A slight leap of faith mentally, because have been brain washed to think we need thermostats etc. mine has been active (not always actively on) since April. Some days it doesn't even start, this afternoon it ran for 3 hours straight, but 20 mins per hour prior to that since 9am.

And about the most dangerous way to store energy. One reason you don't air test pressure vessels is the explosive power of rapid expanding gas or air should you get a failure.

Just tune the heating to be cooler. Or design radiator to match the lower room design temp

Set backs are generally a waste of time, you still need to replenish the heat back in to be building structure you lost during your setback. If running suitably low temperature for weather compensation, the flow temperature should be equal to supplying only the heat lost no more. If you are running the correct temps you never really recover. So instead, you end up running hotter temps than you really need and bouncing of the thermostats. Setbacks are a false energy saving sold by thermostat manufacturers to sell products. There is a handy calculator here https://protonsforbreakfast.wordpress.com/2022/12/19/setback-should-you-lower-heating-overnight/ So you can see for yourself.

Run in conduit then instead of you have a change of direction or just do a straight A to B to keep it simple

My view is very different from some on here. Ignore if you wish. Run on pure weather compensation, all zones open. Let the heat pumps native controller do the calls for heat as it sees required. Mitsubishi have a room biased temp modulation, but states this isn't to be used with UFH only suitable for radiators. Your system with lots of zones needs a buffer to work correctly, otherwise you will be getting flow related issues.

What are using if 22mm is bigger than 32mm waste pipe? All my cold pipes are are under the insulation in ducts, works well

Why do you need rads doing that output with a heat pump system? If you room has that heat loss you must be living in an open shed. Flow rate just sets dT, it is the mean radiator flow temp that sets the output. Why would you cycle the system on and off, or do you mean something else?

Pretty simple cheat sheet below. You really want to aim at zero hydraulic seperation. So 8mm will carry 0.75kW at a dT of 5 etc.

A quick Google search and the following pops up first hit Searched for "running mismatched pv panel parallel strings" Running mismatched PV panel parallel strings is generally a bad idea because it reduces overall system power output and can cause damage due to current imbalances. The string with the lowest voltage will limit the total voltage, while the string with the lowest current will essentially become a load on the other strings. This can lead to reverse currents, overheating, potential damage to the lower-performing panels, and reduced efficiency for the entire array. For optimal performance, it's best to keep strings with identical panel characteristics connected in parallel.

Not thermo wood, mine is Scottish larch which I don't want to grey. Use Cedar Cladding Oil / Decking Oil from Rye Oils. Goes on easy, lasts a couple of years between coats. No colour change in 4 years so far only done two coats to date