OSO Pressure Reducing Valve

9 Feb 2007
Reaction score
United Kingdom
The engineer just about to install a new central heating and mains pressure hot water system, has just asked if he can swap the cylinder from an Ariston to a OSO Super S Series (both 300 litre) as the OSO will fit easier into the airing cupboard.

My concern is that the Pressure Reducing valve on the OSO is set to 3 bar and on the Ariston it is 3.5 bar. Am I going to be able to tell the difference ? (I like a powerful shower to wake me up)

I have also read on this forum (but a few years ago) that you could replace the pressure reducing valve on the OSO is that still applicable and does it relate to the Super S Series ?

N.B. I have 4.2 bar at 22litres/minute mains supply.
Sponsored Links
Thanks for the response, however can anybody answer the question relating to upgrading the pressure relief valve in case 3 bar is not sufficient
Assuming its the new type of OSO Super S, then maximum cylinder working pressure is 8bar. In theory there is nothing to stop you replacing the 3bar prv insert with a 3.5 bar one (obtainable from RWC). You might have to upgrade the expansion vessel, but probably not.

Why not give OSO a ring and ask them?
Sponsored Links
Have you ever had an unvented cylinder before, set at 3·5bar, if not you'll not know what it's like and consequently will not know any diferent.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local