System boiler with vented system (bodged new install, what next)

[ahlondon]

Previously had a WB Greenstar R28 HE System boiler with 4 pipes and vented (gravity fed) cylinder. No valves or pumps outside of the boiler. Worked fine for 20 years.

Decided to change to Viessmann 050-W System boiler when WB failed but keep the same set up with cylinder. Gas Safe installer I chose didn't know what he was doing and reckoned additional motorised valves were needed. Viessmann tech tells me there is already a 2 port valve in the system boiler that serves hot water with priority and heats the central heating. It just needs the correct connections from thermostats, cylinder etc to talk to the boiler and tell the valves which flow and return to heat. 230v switching for hot water can't be directly be wired in without going through a Veissmann box.

So I can approach a competent installer with clarity and knowledge: Does anyone have experience of system boilers with a vented system and specifically getting the non-Veissmann stat/programmer to communicate with the Veissmann boiler?

Can anyone confirm that a system boiler does indeed have the valves and pump to run what I have (like my WB did)?

 

[Madrab]

Not being overly familiar with the Viesmann but if I remember rightly, the 050 system boiler has separate flows and returns for the cylinder connection (it uses the same spots under the boiler that the combi version uses for it cold in/hot out). I also believe that it does have an internal diverter that allows a HWP setup to be enabled.

As far as external controls are concerned then more detail would need to be checked as far as what controls are there already and what connections are needed to the boiler's board to allow a call for HW from an external programmer. Any reason it wasn't WIFI enabled with Viesmann's own controls?