On Fri, 19 Sep 2008 21:03:58 +0100, Andy Champ wrote:

Roger Mills wrote:
In an earlier contribution to this discussion, Andy Champ
wrote:

PCPaul wrote:
Is this one advantage of a combi? We've had the CH side of it
switched off for months but at least the rest of it has been going
strong. OTOH presumably if the 3 way valve I assume it has inside
sticks it
isn't going to be a local plumbers merchant job to fit my own
spare...
Is this one advantage of a conventional system? We've had the CH side
of it switched off for months but at least the rest of it has been
going strong.

Presumably if the 3 way valve in the airing cupboard sticks it's going
to be a local plumbers merchant job to fit my own spare...

P
Andy

Not necessarily. You can often free them by removing the actuator and
turning the valve spindle with a pair of pliers.

When I had a Y-Plan system, I used to exercise the CH every day in the
summer in order to heat up the bathroom radiator for an hour to warm
the towels (all other rads turned off). This made the valve much less
likely to seize.

I take it that that carefully chosen minimal edit was a waste of effort
then?

Pretty much. It wasn't big, it wasn't clever and it wasn't funny ;-)

What I (the OP) *meant* was.. a combi will be firing up much more often
than a conventional boiler through the summer, every time a hot tap is
used. The CH valve inside the boiler will be constantly in a hot'n'cold
cycling environment which I would think might make it less likely to
seize? Added to which it's probably a simple two way valve not a three
way.

Anyway ISTR that this boiler cycles all it's valves and stuff briefly
every 19 hours if they haven't been used anyway, so it shouldn't be an
issue...