Air in system somehere

[Ricky2]

Thought I had posted this question earlier but now cannot find it. Apologies if I've posted in wrong place!

7 year old system Worcester Heatslave boiler serviced annually, Fernox in system shanged after 5 years, 4 bedroom house.

Just one radiator (upstairs airing cupboard) has awful air problems and often "gurgling". I bleed it (lots of air and water) and then re-adjust boiler pressure back to 1.5 bar.
problem is now the time between bleeds is getting shorter and shorter, someitmes just 48 hours, so has to be a leak/air ingress somwhere
No sign of anything in or under boiler
No sign of anything upstairs or it would show on ceiling downstairs
So best bet is under the floorboards
But how do I prove that and track it down with out lifting yards and yards of floorboards?

Education needed badly please!

 

[gas_man_gaz]

are ya sure its not creating hydrogen? try lightin the gas that comes out when ya bleeding 2prove it and add some inhibitor, if it dosnt light id check all the rad valves wen the system is cold (including gland nuts underneath the valve caps) and have a look at the blow off pipe

 

[Ricky2]

Wow. Never would have thought of hydrogen in the system in a million years! How does it get created?

Thanks for suggestions, will do as you say.

 

[gas_man_gaz]

some sort of chemical reation between the metals heat and water i think, not quite sure but i bet 1of the older boys no!

 

[gas_man_gaz]

HYDROGEN GAS is generated in practically all untreated central heating systems as a by-product of corrosion. The gas is flammable and can be tested by igniting it whilst venting a radiator (CAUTION). The addition of Fernox Central Heating Protector will effectively prevent corrosion and the formation of both hydrogen and bacterial gases, such as methane.

quoted from fernox website

 

[Ricky2]

No sign of hydrogen (think I'm relieved at that)
So short of finding an air leak in a valve,(unlikely as no evidence of water on the floors) what else can I do?
interstingly I turned down both the temperature of the water and the speed of the pump and that seems to have improved (but not solved) the situation

 

[Phil 70]

have u checked,the aps outside

 

[Phil 70]

And the auto air vent,inside which may leak but heat hides it as it will dry it up

 

[gas_man_gaz]

what do ya top the pressure up to? does the pressure rise up to 3bar when ya have the heating on?

 

[gas_man_gaz]

have u checked,the aps outside

what do ya mean by the aps outside?

 

[Ricky2]

Phil thanks
Forgot about the aps. Will check that in morning. Absolutely no sign of any moisture inside boiler and have checked the vents/bleeds therin

Gas-man
Thanks again. The pressure drops as I bleed copiously (no pun intended!) from 1.5 bar to 0.5 bar or less. Never goes above 2 bar in operation

 

[Ricky2]

Boiler man sorted it!
It was a partial restriction in the line to the expansion tank that was causing the relief valve to pop. Not enough water to leave a puddle, it evaporated as soon as it popped.
All running now with no further air in radiators
Thanks for the suggestions