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AJH[_3_]

On 21/11/2020 20:53, wrote:
On Tue, 17 Nov 2020 21:08:58 +0000, AJH
wrote:

On 17/11/2020 20:31, wrote:
I have a worcester bosch boiler, whose pressure dial is all over the
place. Sometimes it's at close to zero in the red zone, sometimes it's
just in the green zone.

It's been behaving this way for many months.

Is this a problem with worcester bosch boilers in particular, or
boilers in general? When we get a British Gas engineer to fix it, he
increases the pressure so it's in the green zone. After a few weeks
it's fallen again into the red zone.

The boiler is ten years old. Can it be fixed? Should I be looking at a
new boiler? Apart from the pressure dial, the boiler is fine.

It's probably a failed expansion vessel

When the British Gas engineer visited recently, he said something
about "capillary".

Basically the pressure dial drops well into the red zone, and when you
tap it, it goes up into the green zone.

Would that be a problem with the dial itself, "capillary" or whatever,
or would it be a faulty expansion vessel?

Sounds like a sticky needle in the dial gauge. If it were the faulty
expansion vessel the pressure would drop below the point at which a
pressure switch would prevent the boiler from firing.