Why do I have 2 Expansion Vessel

[Rahul Sood]

I have Gledhill 300L unvented water cylinder storage system with Vaillant Boiler. We are using it for UFH and radiators. My plumber has fitted 2 expansion vessels

1) Zilmet - 18 Litre Red Heating Expansion Vessel & Sealed System

2) MULTIFUNCTIONAL TANKS WITH REPLACEABLE MEMBRANE

Why has he got tanks? Is one for UGH and other for Radiators?

Thanks,

Rahul

 

[ShaunCorbs]

One for the unvented/ cylinder one for the heating

 

[gmartine]

Yes, both masses of water need something to expand into when heated.

 

[rahul sood]

One for the unvented/ cylinder one for the heating

thanks mate.