Nest hot water control on Vaillant Ecotec exclusive 627?

[MunkyO]

I have a Nest gen 3 thermostat which is working great for the heating. I’d like it to control when the hot water is turned on but I’ve been told it’s not possible with my boiler. It seems crazy to keep a tank of hot water up to heat at all times. Does anyone know if it can be wired to only heat the water at certain times? The Nest can do it, but it appears the boiler can’t.

 

[CBW]

Who told you that? How does it heat the water currently?

 

[picasso]

Look at nest on an s plan, very standard wiring set up.

 

[MunkyO]

It was my plumber that told me that. He’s done a good job of putting it is as far as I can tell.
Currently the Vaillant heats water all of the time.

I’ll have a look at a nest on an s plan. Thank you!

 

[muggles]

Post a photo of your cylinder cupboard see we can see the pipework in there

 

[ericmark]

Nest Gen 3 has two sets of contacts and a variable voltage connection if using OpenTherm, it is unlikely any reason why Nest can't control DHW independent to CH, however with my house the plumbing will not allow independent control, and my plumber advised me to add the motorised valves to turn off the DHW would likely stress the boiler.

As to if true or not I have not looked into, however I can't see why I would not want DHW, with a 20 minute burn time 3 times a week it keeps the DHW hot, it does not cool fast so there is simply no point stopping it heating up with the central heating.

And the wiring involved to wire a thermostat on the storage tank to a motorised valve at the boiler would involve lifting two floors, just not worth the effort.

In theory changing from Plan C to Plan Y could change it and allow temperature control of DHW, but I would likely be looking at a £500 bill or more, so simply not worth changing.