Hi

I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.

wrote in message
ups.com...
Hi

I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.

It shouldn't get beyond 3 bar : you should have a system overpressure valve
which vents at 2.5 to 3 bar. The ones I have seen are testable by pressing
the
button on the valve. The excess pressure will vent outside via the vent
pipe.
Otherwise, the reason the pressure rises maybe that your air reservoir is
empty of air ( via a leak in its diaphragm or a leaky bicycle valve ). This
item
usually looks like a large metal doughnut, possibly painted red, out of the
way
at the back of the boiler, though they do come as separate items, and may
look like a cylinder then. If you find the air reservoir, depress the nib in
the
bicycle valve - if air comes out that's a good sign though it may need
pumping up.
If water comes out you have a problem.

Andy.

In article . com,
writes:
Hi

I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

Expansion vessel is not working to absorb the water expansion.
See the Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
for repair/replacement instructions.

--
Andrew Gabriel

wrote in message
ups.com...
Hi

I have a Vokera 12-48 R.S Mynute Central Heating Boiler at the moment
which is behaving a bit strangley! When the Heating comes on the
pressure rises gradually up to and beyond 3 bars (which is when I panic
and turn it off!) However when I switch it off the pressure drops back
down again below 1 bar.

I have recently changed a broken fan but other than that nothing has
changed since it used to work.

Any help would be much appreciated.


Did you by any chance get tempted to see what happened when you pushed in
the schrader valve on the expansion vessel? Your symptoms are indicative of
the expansion vessel having lost its gas charge or the connection tube to it
becoming blocked.
Take a look at the faq re sealed systems