JohnMo

Would agree. But there are only a few manufacturers and a lot of re-badging going on and a commercial premium, buy lots big discounts on RRP, but buy a couple get charged full wack.

This is well dependent and has to be designed based on water properties from analysis. Leave this to the professionals. No other pumps, no storage tanks. Pump directly connected to 100L accumulator via 25mm pipe (cylinder with a pressurised diagram same as an expansion vessel but bigger). The outlet water goes through filters (mine is a backwash filter to remove debris and convert iron, 10 and 5 micron filters and UV filter), then to a normal stopcock in the house.

Not sure that is really true for fan coils, they have been about very little changed for decades. But the context has moved, were really only ever used in commercial buildings, not homes. The thing that has changed is heat pumps are being installed, people realise they can cool as well as heat. The fan coil in a domestic setting is the thing starting to mature. But a long a long way go yet.

Remote control functions are either open or closed zero volt contacts. One set of contacts are for heat or cool, the other set for heat or cool off. Remote On/off is via a volt free thermostat, this inhibits heating or cooling when it's an open contact see ID3 below Summer winter Open contact or closed contact selects either heat or cool. See ID2 below. Terminal block

You really should state you want Weather Compensation also. Then either dump most the TRVs and run single zone. Then you set the pump flow to match the need of all the radiators. You should get a 25% reduction in gas consumption, because most the time the boiler is in condensing mode. You also no longer need bypass valve.

I doubt you will need 32mm, we are about 25m from pump head (40L Min pump) to accumulator and filters then 6m to house (another 70m to garage) all in 25mm loads of flow. 1200L storage, I just have a 100L accumulator. This has a pressure switch which controls the down hole pump. No additional pumps required. Cold water may benefit from insulation to stop drips from condensation, thin stuff will do. Hot only if you run a secondary return loop, then do that as thick as possible. Just use Cimaflex (grey stuff) cheap and readily available. Our feels and functions just like normal main supply. Have set the pressure to 2.5 bar, zero issues at all the pump can do 40L/min also Think about what you will do in a power cut? Your water is also off. We got a generator, we can run the house with in reason and got a 7.9kW Hyundai generator.

Which bit?

Yes normal switch, just a 2 core cable from switch to ASHP for mine. Many will do it via the controller.

Well after writing the above, I moved the thermostat to control remote on and off, (set 0.1 hysterisis to stop overshoot if flow temp needs to be controlled) and added a switch to move between heating and cooling.

The thermostat can be configured to work in either cool or heat mode. Just a couple of buttons pushes. My worry with current configuration, is in heating mode I get some solar gain or light the fire or have the WC not quite right and the cooling switches on, not the best for efficiency.

A Computherm Q20RF set to 1.0 hysterisis, so that gives +/-1 Deg either side of asset point. Currently set to 21, so at 20 heat comes on and at 22 cooling comes on. But I am thinking the control is too fine so a simple switch (heat cool) may be easier and use the thermostat to give a remote on off. Still a bit of a thought process

Looks to me they would quite easily setup a thermosiphon. Can you replicate the dog leg as seen on the upper pipe in grey, so pipes drop about 150mm before going horizontal and upwards. A check valve may not fix it if remote.

Heat cool switching should be zero volt switching same as remote on off. So you may need two switched but could be a double light switch, one switch on/off the other summer/winter.

You would need two one for heat one for cooling. One uses common plus normally open, this would then close when you hit say 25 the fan would start. When cooling set to say 15 but wire to the normally closed, any flow temp above 15 would not switch on fan. You most likely run via a relay to stop power back feeding itself. You would only use this on @Originaltwist fan coil.

None really, you balance the flows to get the room temperature you want. You get rid of a buffer that comes with zones, so you end up with a better CoP (lower running costs). Your install is minimal so costs less in useless equipment.

But have you actually read the data sheet? Does it do what you think it will? 40 degree flow, for a 200m² house at typical flow rates is just over 1kW heating. If you have UFH your max flow temp should be lower than 30, which represents a 0.4% CoP hit. Cooling flowing 7 degs would yield 1.88kW, on a 20 deg day that would give a CoP of about 5.1, while a fan coil or UFH flowing at 14 would give a CoP of 8.1, so a CoP hit of 3. If you are actually a Passivhaus that maybe ok? Otherwise it could be a waste of more than a £1000.

My Maxa heat pump doesn't have an indoor controller, everything is on the outside unit. I use a thermostat to switch between cooling and heating. Maxa now selling in the UK. Available in R32 and R290 (R290 is flammable so has placement restrictions). But for ease of use and setup I would seriously consider Panasonic. Heat pump generate low temp water for DHW (max around 50 Deg) so 3 bed house needs 210L plus. The cylinder can be horizontal or vertical, could you locate in loft for example?

UFH as a single zone on ground floor and any upstairs bedrooms. Consider fan coils if you need cooling upstairs. Other provision for electric panel heater in bedrooms (don't buy until after you know you need them). Electric towel rads in wet rooms. Make sure you have decent heat loss calculations before going any further. Ideally do them yourself so you know what's what. You don't want the sun shining on the ASHP, ignore any advice that says otherwise. Sun will mess up the heat sensor reading. Indoor controls depends on unit being installed. Many will have an internal thermostat so really needs to in the living space not in a cupboard. They are just like a thermostat. Only consider a monobloc ASHP so everything is outside except a small controller. Don't do any 3rd party controls. Single zone means no thermostats other than the one in your controller, no actuators on the manifold, no need for a mixer or pump on the UFH manifold. Most likely no need need for a buffer or volumiser. Using a Government Grant for the free £7500. I didn't bother was too expensive, so just bought it all myself. Installers just want to rip you off.

Don't do it, you will spend too much time looking at stupid computers and get nothing real done. I pretty much took the opposite approach, research, decide, put on plan. Freeze that bit of the plan. Otherwise procrastination takes over. Stopped looking on here once build started to stop any tangents.

I was thinking more simple, but also adjustable https://www.toolstation.com/corgi-pcs-dual-pipe-cylinder-thermostat/p68281

If draining, mid point when depowered moves to the open position for the cylinder and 2 port would need to be over manually. But drain the radiators etc you would move the 3 port valve position.

Sound reason for this. Couple of assumptions you have an unvented cylinder and the 3 port valve is a mid point valve. A Y plan will be a mid point valve. NOTE: mid point valve - No power - With no power applied, the spring holds the valve in position B, so water only flows to the hot water cylinder. With a mid point valve to comply with G3 you need a fail close valve to protect the cylinder from the heat source. The 2 port should be a normally closed valve and energised to open. Do not remove this valve, it ensures compliance with G3 regulations. All Y plan installs with an UVC should have this valve. S plan does not need the additional valve.

Not sure it can you are only adding around 3kWh to the water to get from 52 to 60 degs. Where are you getting this usage figure from? I suspect to get to 52 degrees every day the immersion is kicking in more frequently than you think. Have you checked? Do yourself a favour and read the details of legionella. We store at 50, within 2 hrs 80-90% of legionella is dead - if it was there in the first place. We do not do a legionella cycle.

You take it off the UFH manifold, I have tee'ed into the flow and return before the UFH manifold. I have a 2 port valve that isolated that circuit only when there is a call for DHW. All other times the 2 port valve is open. Thing to also remember a decent fan coil will just look after itself. They generally have an in-built controller, modulating fan speed based on target temperature. They generally need an external temp sensor for cooling, but work well without doing heating. I just set mine to manual for cooling. No real need to stop flow going to the fan coil, as they work differently to radiators.

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