@bash we have mostly south facing rooms which would overheat if the radiators were still working on WC plus full sun. In fact in shoulder season the sun is plenty for the whole house in the day.

Our installer said try it for a full year (our installation was September) and see if we needed a TRV in the dining room room , which has the largest windows and no TRV since it was a new larger radiator. Our Vaillant has a mode which is called extended which switches the heat pump off when the room with the control box is too warm, so no issues with overheating.

If your Daikin doesn’t have a similar mode then despite the general advice of no TRV then in the high solar load rooms they might have a use. As long as there is always the minimum volume (perhaps in your hallway radiator and other non-sun rooms with noTRV) then the heat pump will be fine.. You need to set the lock shields to levels to provide you with the heat you need during the evening or very grey days and use something else to stop overheating (room thermostat or TRV.)

You seem to have confidence in your installer so ask them for advice but the simplest may be to have the thermostat in one of the sunny rooms, not necessarily the lounge if that’s logistically difficult.

You will find that you will be swinging any TRV between frost and 2 as a max, simply because your heat pump water flow will always be at a lower temperature.

Thanks @judith 

I think on reflection I need to have the room thermostat in a sunny lounge. 

The lead installer is very experienced and has worked on the tools for many years in gas, switching to heat pumps in the last 10 years.

As pretty much all the rooms are south facing, relying on trvs could end up with less volume than is ideal, so shutting down the whole system on sunny days would probably be the best bet, as our gas boiler does (which has been running at 45c flow temperature).

It's just a shame the Daikin room thermostat is hard wired, otherwise I could move it from room to room to find it's best location.

@bash Haven’t read the small print as my sight just isn’t up to it this morning but it may be worth a browse.

https://www.daikin.co.uk/en_gb/products/product.html/EKRTR.html

Regards,

Toodles.

Thanks @toodles 

I had a good dig around the internet to see if any other Daikin HP owners are using any of the Daikin wireless thermostats with their HP and couldn't find any, which is a shame as it would be great if someone has some experience of this to see if it's viable option.

I'll have another trawl and look into this one in more detail to see if it could work