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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> unvented systems-any good? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1106439573 Message started by peter on Jan 23^rd, 2005, 12:19am

Title: unvented systems-any good?
Post by peter on Jan 23^rd, 2005, 12:19am

i am replacing the CH system to my recently extended and now 5 beds 2 bath roomed house. It will have two thermostatic showers.

Ive been told that i will need at least 115,000 output for rads
20 rads in total.

I have also been told the best option is unvented system the new way forward now a days as combi not up to the job.
i am looking at Vaillant 637 with 150lts Vaillant Vantage water cylinder. will this be sufficient for job and has anybody got any experiance with unvented systems.

Any Advice would be appreciated

Title: Re: unvented systems-any good?
Post by thescruff on Jan 23^rd, 2005, 12:31am

150 lts is pushing it a tad close if all the bathrooms are used at the same time, 220lts would be the norm in my calculations.

Unvented cylinders depend on a good pressure (3 bar) ideal, and a good volume (30/40 lts min), so both need to be checked

Title: Re: unvented systems-any good?
Post by bstyle on Jan 23^rd, 2005, 12:37am

In my experience on multi Bathrooms you need to renew the cold main from external stopcock to a larger diameter, a lot of work but the flow rate was up to scratch once this was done.

Title: Re: unvented systems-any good?
Post by greg on Jan 24^th, 2005, 6:31pm

make sure that the cylinder is located close enougth to an external wall for the discharge pipe to exit