Guys, recently had a combi boiler put in (WB Greenstar 40plus); for
whatever reason I have two specific problems:

1) the pressure is increasing over the course of time. I can handle
the pressure gauge (bleeding cold system, keeping pressure close to
the lower minimum). I realise that the pressure goes up with the
heating, but it goes well beyond the recommended upper limit. The
emergency valve does not discharge yet, but I also keep bleeding the
system regularly.

2) Speaking of bleeding. I bleed the system virtually every night, the
attic radiator always has air in it. Should that really be the case?
It's a four bed terrace, so the boiler pump has quite a bit of work to
do to get the top floor heated, but I did not expect that much air in
the radiator.

Any ideas?

Fred

In an earlier contribution to this discussion,
Fred wrote:

Guys, recently had a combi boiler put in (WB Greenstar 40plus); for
whatever reason I have two specific problems:

1) the pressure is increasing over the course of time. I can handle
the pressure gauge (bleeding cold system, keeping pressure close to
the lower minimum). I realise that the pressure goes up with the
heating, but it goes well beyond the recommended upper limit. The
emergency valve does not discharge yet, but I also keep bleeding the
system regularly.

2) Speaking of bleeding. I bleed the system virtually every night, the
attic radiator always has air in it. Should that really be the case?
It's a four bed terrace, so the boiler pump has quite a bit of work to
do to get the top floor heated, but I did not expect that much air in
the radiator.

Any ideas?

Fred

Are you sure it *is* air? If your system has no inhibitor in it, it could be
hydrogen caused by corrosion. Next time you bleed a rad, hold a lighted
match in the stream of gas which comes out and see whether it burns with a
blue flame.
--
Cheers,
Set Square
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"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Fred wrote:

Guys, recently had a combi boiler put in (WB Greenstar 40plus); for
whatever reason I have two specific problems:

1) the pressure is increasing over the course of time. I can handle
the pressure gauge (bleeding cold system, keeping pressure close to
the lower minimum). I realise that the pressure goes up with the
heating, but it goes well beyond the recommended upper limit. The
emergency valve does not discharge yet, but I also keep bleeding the
system regularly.

2) Speaking of bleeding. I bleed the system virtually every night, the
attic radiator always has air in it. Should that really be the case?
It's a four bed terrace, so the boiler pump has quite a bit of work to
do to get the top floor heated, but I did not expect that much air in
the radiator.

Any ideas?

Fred

Are you sure it *is* air? If your system has no inhibitor in it, it could
be
hydrogen caused by corrosion. Next time you bleed a rad, hold a lighted
match in the stream of gas which comes out and see whether it burns with a
blue flame.

Make sure your filling loop valves are turned off fully and not allowing
mains water to gradually pressurise the system. It doesn't sound like that's
your problem, but it would be good to eliminate.

Andy.

2) Speaking of bleeding. I bleed the system virtually every night, the
attic radiator always has air in it. Should that really be the case?
It's a four bed terrace, so the boiler pump has quite a bit of work to
do to get the top floor heated, but I did not expect that much air in
the radiator.
Had a similar situation yesterday in a house where attic rad was cold.
Turned the bleed valve with system off, and nothing. No air, no water
either. Ran the heating, and still nothing. Turned the filling loop on for
10 secs so that the pressure was up around 2.5, and now quite a bit of
hissing, followed by a mug of water, followed by more hissing. Another mug
of water and pressure is back to 1.5, except now the water is hot. Obviously
not an exact science by any means

"Fred" wrote in message
...
Guys, recently had a combi boiler put in (WB Greenstar 40plus); for
whatever reason I have two specific problems:

1) the pressure is increasing over the course of time. I can handle
the pressure gauge (bleeding cold system, keeping pressure close to
the lower minimum). I realise that the pressure goes up with the
heating, but it goes well beyond the recommended upper limit. The
emergency valve does not discharge yet, but I also keep bleeding the
system regularly.

2) Speaking of bleeding. I bleed the system virtually every night, the
attic radiator always has air in it. Should that really be the case?
It's a four bed terrace, so the boiler pump has quite a bit of work to
do to get the top floor heated, but I did not expect that much air in
the radiator.


Could a floor board nail have been driven into a pipe somewhere. I knew
someone who had this problem and it took quite a bit of diagnosing.

mark b

1) Any automatic air vents, especially at top floor/high level &/or on
the return? The system might be under positive pressure when cold, but
the pressures throughout the system will change when the pump is
running, so it is possible that there is a negative pressure at some
points. If there's an open AAV at such a point, it will draw in air
with the pump running. If so, close/screw down the cap (like a tyre
valve cap)on the AAV . Pressurize the system and only vent the air from
the AAV and the problem rad with the system off. See if this solves it.

2) It could be due to hydrogen, as someone's said, but it would be an
awful lot of hydrogen. I think the test is to hold an inverted glass
over the vent. The H2 rises into the glass & can be lit with a (long)
match. If it's this, the system water must be very acidic, probably due
to excessive use of active flux (hydrochloric acid). If you could get
some litmus paper, you could confirm it. The corrosion will be
dissolving your rads. In this case the system needs thorough flushing,
neutralising, refilling and dosing with corrosion inhibitor. Did they
put an inhibitor in it?