Hello,
I've searched threads and FAQ for this and haven't found an answer that quite fits, so here goes.
History is as follows. I have a newish (<1 year old) Worcester condensing combi boiler bolted onto an old gravity fed CH system (by an appropriately qualified fitter). Soon after it was fitted, one of the old rads sprung a pinhole leak (moved in recently and the system was probably neglected for years), so I replaced them all myself with brand new Stelrads. All rads are fed from valves at the bottom, with bleed screws at the top, as usual. Pressure still didn't hold, but I tightened some weeping valves and replaced a couple of bad (green) original solder joints. Pressure seems to hold well now, at least over a period of weeks/months. Inhibitor used is Sentinel X-100 (dosed slightly above required level).
The thing is, air constantly accumulates in a towel radiator in an upstairs bathroom (the highest point in the whole system). After bleeding via the screw it's only a week or so until the top bar is cold again. No air accumulates in any other radiator.
Today about the top third was cold (heating had been on earlier, but rads were lukewarm). This time, I took the plug out (after closing isolators on inlet and exit pipes) and filled it with tap water. When I took the plug out there was a whoosh of escaping air under pressure.
After I replaced the plugs and opened the isolators again boiler pressure had dropped from about 1.1 to about 0.8 bar. I topped it up to 1.5 bar, and turned the heating on (water temp set to 5 out of 6). After the readout had climbed to 72, pressure had increased from 1.5 to just under 2 bar. It's now reading 62, with pressure the same.
* How does air/gas get into this towel radiator, given that I'm using a good quality inhibitor?
* Could air enter via a tiny leak, even in a pressurised system?
* If so, wouldn't the system pressure fall away over the same period 9assuming water would have to get out through the leak)?
* By the way, what is an acceptable level of stability in system pressure (how many months/years/aeons are acceptable between topping up the pressure?)
* Should I try the stuff you put in to block small leaks in pressurised systems?
* Why are baboons' bottoms so red?
I've searched threads and FAQ for this and haven't found an answer that quite fits, so here goes.
History is as follows. I have a newish (<1 year old) Worcester condensing combi boiler bolted onto an old gravity fed CH system (by an appropriately qualified fitter). Soon after it was fitted, one of the old rads sprung a pinhole leak (moved in recently and the system was probably neglected for years), so I replaced them all myself with brand new Stelrads. All rads are fed from valves at the bottom, with bleed screws at the top, as usual. Pressure still didn't hold, but I tightened some weeping valves and replaced a couple of bad (green) original solder joints. Pressure seems to hold well now, at least over a period of weeks/months. Inhibitor used is Sentinel X-100 (dosed slightly above required level).
The thing is, air constantly accumulates in a towel radiator in an upstairs bathroom (the highest point in the whole system). After bleeding via the screw it's only a week or so until the top bar is cold again. No air accumulates in any other radiator.
Today about the top third was cold (heating had been on earlier, but rads were lukewarm). This time, I took the plug out (after closing isolators on inlet and exit pipes) and filled it with tap water. When I took the plug out there was a whoosh of escaping air under pressure.
After I replaced the plugs and opened the isolators again boiler pressure had dropped from about 1.1 to about 0.8 bar. I topped it up to 1.5 bar, and turned the heating on (water temp set to 5 out of 6). After the readout had climbed to 72, pressure had increased from 1.5 to just under 2 bar. It's now reading 62, with pressure the same.
* How does air/gas get into this towel radiator, given that I'm using a good quality inhibitor?
* Could air enter via a tiny leak, even in a pressurised system?
* If so, wouldn't the system pressure fall away over the same period 9assuming water would have to get out through the leak)?
* By the way, what is an acceptable level of stability in system pressure (how many months/years/aeons are acceptable between topping up the pressure?)
* Should I try the stuff you put in to block small leaks in pressurised systems?
* Why are baboons' bottoms so red?
