On 2016-11-29, Roger Hayter wrote:

Adam Funk wrote:

On 2016-11-29, NY wrote:

"Adam Funk" wrote in message
...
On 2016-11-26, newshound wrote:

Don't Combis normally have a tap on the DHW outlet? That said, turning
off the main at the inlet (or the stop tap) is all that is needed. It's
perfectly safe to leave the CH running with the mains stop tap turned
off.

Thanks, everybody. I do remember that her boiler has separate
controls for turning the CH & hot water on & off.

I was wrong about that --- the HW control knob ranges from low to
high, not including off.

What I mean is this (just to clear):

1. turn the boiler control for hot water off;
2. turn off the main stopcock;
3. cut into the pipes and add service valves for the hot & cold taps
(might as well, in case the cold one goes next);
4. turn the main water back on & check that the service valves don't
leak;
5. turn the boiler control for hot water back on (so she can use hot
water at the other sinks);
6. fix the dodgy tap as necessary, reconnect, & turn the new service
valves on.

I assume the CH can't work with the hot water control turned off? This
seems to be true of all the combi boiler designs I've seen, though I am
happy to be proved ignorant.

AFAICT the CH did keep running with the water supply (main stopcock)
turned off; but I was wrong about being able to turn the HW function
off at the boiler (without turning the boiler completely off).