rapid build of air in heating

[opps]

Hi all

My client's home is a 5 story town house.

The boiler and mega flow are in the basement. CH is a sealed system.

The boiler is 4 years old and the heating has been drained down at least 3 times in the last couple of years for building works. It is safe to assume that there is little or no Furnox in the water.

The top floor has two rads and one towel rail. All 3 were full of air on Saturday so I bled them and topped up the pressure.

The pressure in the system seems to be constant, not requiring regular top ups.

After 3 days the towel rail has become devoid of water again. I will bleed it again today and test the air with my lighter to see if it is the result of corrosion.

If the gas is combustible is it safe to assume that the problem is just oxidisation?

I cannot see any leaks any where, other than one of the ball fixing isolation valves which seems to be on some kind of balancing loop between the mega flow and boiler. From memory i don't think this has anything to do with the heating side and it only drips if you touch it (she is having it replaced at some point soon with a levered valve).

If it is just corrosion i would be happy to top it up with Furnox. Does any one know how much you need, is it ok to add a bit too much, can i just remove the bleed fitting from the towel rail at the top of the house and use a funnel?

Many thanks

 

[gas112]

if it was hydrogen you would have smelt it when bleeding it .
Rad emptying that quick i very much doubt gases from corrosion probable leak .
A litre bottle of inhibitor should be enough and with the modern types over dosing is generally ok older types used to create bubbles causing noisy pumps etc

 

[opps]

if it was hydrogen you would have smelt it when bleeding it .
Rad emptying that quick i very much doubt gases from corrosion probable leak .
A litre bottle of inhibitor should be enough and with the modern types over dosing is generally ok older types used to create bubbles causing noisy pumps etc

thanks gas112

If it is a leak, why does the pressure not eventually drop?

tbh, i don't know that i would recognise the smell of hydrogen, hence i was going to use a lighter.