You can have a shut-off valve (zone valve) programmed into the MMI so that when it goes into cooling mode it can open or close a valve depending on which setting you apply. I think its under "main zone" and then "shut off valve". Daikin do specifically state that pre-plumbed cylinders must NOT be used with applications that have cooling so would assume its not a Daikin design. The secondary circulator is purely controlled by the setting on the buffer sensor on the Dixell thermostat, there is no way to add a run signal unless you use relays etc.
That’s what I was wondering. That’s how I’ve done it with boilers . Especially as the temperature on the underfloor system could probably be the same with it being a heat pump
That would be a perfect solution if it wasn't for the cooling function. I need to prevent the chilled water from passing through the buffer vessel. Also bearing in mind that I need a signal or 2 construct some kind of control to divert flow on alternative paths to suit the function of the system
I think I would be inclined to use a second 3 port blocking the buffer off in cooling mode and normally open in heating mode, the same type as hot water priority 3 ports. It seems about the easiest solution?
@@andrewmillwardwatford9410 I think so, it only needs to open when the cooling control signal calls. That said i don't fit Daikin so I'm not aware if they're using a bus between the stat and unit or 230v control. May not be easy to implement.
The Daikin manual recommends that you don't use the cooling on the underfloor heating because of condensation forming. It seems a popular idea that you can run the floor chilled buy something like 4 degrees centigrade but this of course would not be suitable for the radiators which will require a far lower temperature. As the mixing valve option is not available in the UK I can't change the temperature in the underfloor from the radiators
@@andrewmillwardwatford9410 fair enough. Thought it would be avalable👍 tbh tho i would just stick an air conditiong unit in. Got a 5kw 2 indoor unit at mine and swear by them for cooling
@@D_pawson I'm interested in the results from this customers cooling system as I was considering putting air-con in my own home. These fan assisted radiators seem like a reasonable idea to take advantage of the cooling cycle available on the heat pump
@@andrewmillwardwatford9410keep us posted. My understanding was it needed humidity control to stop pipes and rads sweating. Be interesting ti o find out how much that limits performance of cooling
Without at least having 1 mixed circuit for the underfloor heating I think it s impossible to achieve this. But clearly having rads and underfloor will decrease the efficiency of the heat pump a lot. Maybe upgrading the rads with thermoconvectors so you can run ghe 2 circuits with the same flow temperature will resolve a lot of problems. I would do it if I was the owner. Simpler overall solution but more importantly much more efficient.
Or take a look at StelRad Vento. They work with flow temp of 35 deg. They are excellent for efficiency and for applications with underfloor heating. This would eliminate the need of mixed circuits entirely
