"Andy Hall" wrote in message
...
On Wed, 10 Mar 2004 09:26:23 +0000 (GMT), Dave Plowman
wrote:

In article ,
Andy Hall wrote:
Unfortunately, "system" seems to be used to describe anything which
contains more than a heat exchanger, gas valve, safety device and
thermostat (i.e. more than the bare minimum)

I can see the advantage to an installer of having everything in one, but
given that the pump and motorised valve(s) are likely to need replacing
before the boiler (although given the problems some have this might not
be
the case), wouldn't external mounting actually be the better option if
space isn't at a premium?

Having the pump internal allows it to be modulated as well by the
boiler controller, thus dropping the flow rate to match reduced output
as the boiler modulates down.

Ideal say all the components of their boilers can be changed within 15
minutes. No need to change a full pump, just the pump head.

It would be even better if a standard like Opentherm became more
prevalent so that thermostats, pumps and other devices could be mixed
and controlled by different vendors' equipment and controllers.

And pigs will fly.