I am installing an XCEL 2009 from www.heatweb.com

I have opted for the unvented system option, which introduces a variety
of complications, not least finding a home for the 100 litre expansion
vessel. All resolved though.

Because the overall system volume will approach 600 litres it will need a
lot of inhibitor. I have put check valves all over the place so I can
deal with most leaks or problems without draining down the main store. I
am however troubled by the thought of losing 50 quids worth of inhibitor
If I have to drain down the whole thing!

All being well should be commissioned within a week, and I intend to run
it for a while with no new inhibitor to check integrity first.

Are you using the vented expansion vessel?

Put in full bore valve as isolators to avoid losing the inhibitor.



I've thought hard about this and will be installing a full bore valve at the
main feed to the store.

Whilst not strictly compliant, this will solve the problem.

In any event the store has 2 pressure relief points (one by the expansion
vessel and one at the top). I will also make sure the valve is disabled so
it cannot be casually closed.