Vaillant eco tec plus 835 upgrade to unvented cylinder

[Furion]

Hello
I am looking to ultimately go heat pump route when funds allow.

But at the moment I wanted to see if it’s viable to purchase a 300litre horizontal unvented cylinder suitable for a Heatpump and run it off my combo boiler.

I have a VRC 430 controller
5 bedroom property with 2 bathrooms
We have rain showers in both with full bore isos and thermostatic valves.

Automatic taps which have thermostatic feeds.

I am looking to go to this route as I think I can make most of my PV generation to help heat the water during the day via the immersion(s) most of the solar is banked in 12kw battery for use in the evening but a lot of surplus still ends up down the grid.

Ultimately the goal is that the PV most of the year would supply the Heatpump during day light hours.
Most of downstairs is a wet UFH system also.

So my thoughts are have a unvented cylinder which is heated via the boiler and use the excess PV to top off possibly or heat to a slightly higher temp ? To make water last longer.

I have a hot water outlet in the garden which I would use periodically to make sure the hot water side is still used etc

Would appreciate any thoughts if this is a viable solution and what roughly would be needed to go about doing doing this

Thank you

 

[DP]

Fit a motorised valve to radiators and instal second zone for HW
Fit a system bypass

What you are planning gets shoehorned to the additional zone (hw cylinder)
Cylinder could be solar coil and indirect if running off plates to heat water directly ( wet side)

 

[muggles]

You can, just be aware that it'll cost you more and may affect the heat pump warranty. When installed with a heat pump, the cylinder would be zero rated for VAT, but as a standalone install you'll need to pay the VAT on it. Also some heat pumps manufacturers give reduced warranties if a third party cylinder is used. Other than that, yes what you propose can be achieved as DP has outlined above

 

[Furion]

Hi
So got round to making a start.
I decided to ug the controls first.
I have installed sensoComfort 720 and the sensonet 921 and installed the app on my phone as I ultimately will want smart functions.
I have bought a vr66 with a vr10.

I believe this will provide the correct setup.
From the instructions I believe I use the vr66 in its mono setting use 2 two port valves one for the CH and the other for the DHW which would feed the cylinder and wire the vr 10 to the NTC.

Obviously I will need my plumber to setup the unvented cylinder with its fittings and implement a system bypass.

So I’m hoping that the 720 will program for my CH timer and program timings for the DHW.

When I open the tap outlet of the combo boiler tap which I am thinking of having connected to the kitchen sink tap also that will override other demands ie CH or DHW cylinder heating.

Am I correct in thinking that weather compensation will function correctly and also I can set different temps for the CH and the DHW cylinder and that the boiler will be able to implement modulation?

is the temperature for the cylinder going to be the same that would be set for domestic water which would be the combo boiler tap outlet.

Thank you sorry for the barrage of questions just a few thoughts Iv been having whilst reading some of the information.
Cheers