Hi Russ. That's a nice quick description which is just what I was looking for to help me out. I have a Vallaint ecotech plus currently running HW and CH on an S plan. Ive just had a single zone UFH installed in a large kitchen but not yet wired. It has a typical ZV, TRV and APB set up. To give the engineer who is doing the wiring a running start I did some research on how to integrate my Tado system and it seems fairly clear and your description gave me the final clue. I was wondering if the manifold pump should be fed by the UFH Tado wired thermostat or the ZV orange wire. You say brown wire meaning the manifold pump will run as soon as the Tado UFH thermostat demands heat. See my diagram, my wires are the wonky looking ones! The only question I have is that this means in a situation where the UFH TRV does not need any hot water and is closed and the CH ZV is off BUT the UFH Tado thermostat IS demanding heat the Boiler pump may well run which will force flow either through in the internal boiler APB of the external fitted one. It seems that you think this is not ideal but acceptable? I thought the APB was kind of for 'emergencies only' but here it may be used much more frequently. Can you advise on what bypass pressure should be set at please or how I can figure it out. Many thanks! I have yet to understand what a buffer is but thats my next research as I dont have one...