On Sat, 20 Nov 2004 17:00:57 +0000, Simon Hawthorne
strung together this:

I am in the process of fitting TRVs to all my rads (except the two in
the rooms where the room stats live) - and wondered if you could help
with a question about my current boiler. I thought it was a 'gravity'
system.

It is, on the water side anyway. Gravity sytems are generally pumped
heating and gravity hot water.

The system is set up in such a way that I can eithe rhave hot water
on, or heating and hot water - I can't just have heating. I have also
noticed that when the room stats have reached the set temperature, and
close the zone valves, the pump still works. Is this normal?

Well, it's one way of doing it.

Where
is the water going?

Don't know, can't see the piping that well in the pics, it's probably
pumping against the closed valves, unless there is a bypass between
the pump and valves. You should be able to spot this yourself, it'll
be a pipe between the flow and return with a valve on it.

There is also green marks on nearly all the soldered joints between
pipes - is this normal?

Yes.

I am in the process of designing a new CH system

Good idea!
--

SJW
A.C.S. Ltd