On 18/01/2021 23:08, Roger Mills wrote:
On 18/01/2021 19:29, Peter James wrote:
I de-aired the Central Heating system today, a thing I need to do
about once a
month.Â* I did so from the towel rail in the bathroom, the highest
point in the
system.

Following a suggestion from someone on this NG I lit the escaping air
with a
match as theÂ* air was flowing out following the loosening of the drain
screw.
It lit up like a gas welding torch and caused me to all but jump out
of my
underpants.

Is there an expert on this NG who can tell me what this would
indicate?Â* And
any cure for the constant need to de-air the system.

The system is 20 years old from new, but with a new Worcester Bosch
Greenstar
25i boiler that is one year old.
Peter


As others have said, it's hydrogen - which indicates corrosion.

But if you had a new boiler a year ago, didn't the installer do a system
flush and then add inhibitor? If that had been properly, you shouldn't
have this problem after only a year.

Is it a vented primary system, or is it pressurised? If the former, it
could be leaking and introducing fresh oxygen in the top-up water. Or it
could be pumping over and introducing air. If the latter, there could be
a problem with the pressure vessel. In this case, you would be aware of
having to re-pressurise it frequently.

Pump over would aerate/oxygenate the water and the last gas I would
expect to come out of a vent would be hydrogen.

I would also suggest adding inhibitor pretty smartish, perhaps by adding
a magnetic trap if the system doesn't already have one and filling
through that if the system is unvented.