Truly Skint Posted January 4, 2009 Posted January 4, 2009 Hi All I have a standard gas boiler (Not Combi) and have noticed that one / two radiators are filling with air on a more regular basis than normal. I can bleed the offending radiator and all is then well for 2/3 days. I have also noticed that the overflow from the header tank is periodically overflowing - not sure if this is connected to the problem or not. I have bled the entire system, at the radiators and also opened the bleed screw near the hot water tank. I have also visually checked the system for leaks, thinking that if there was a weak joint or hole in a radiator, this could be the inlet for air, but am unable to find anything. Any ideas ? Many thanks Quote
pistonbroke Posted January 4, 2009 Posted January 4, 2009 No expert but sounds as if the system is pressurising if the overflow is running . could be the heat exchanger is leaking , can you here any boily type bubbling noises ? failing that a leak on the system somewhere , but dont think that would explain the overflow problem . Quote
Truly Skint Posted January 4, 2009 Author Posted January 4, 2009 Thanks for the feedback To put things into perspective, the overflow is not continuously running, I have noticed the odd splash every now and again but very spasmodic Cheers Quote
Man On The Clapham Omnibus Posted January 5, 2009 Posted January 5, 2009 It might not be air but hydrogen or somesuch from corrosion. Have you any Fernox or other antioxidant in the system? In my experience its absence almost guarantees gassing. Quote
DavidR Posted January 5, 2009 Posted January 5, 2009 Have just had similar problem . . . The heating header tank was overflowing once every couple of weeks for a few minutes. Bled the pipes near the pump as they are the first to get air in them, noticed rads had air in and then boiler started making noises . .. Air in rad wasn't air it was hydrogen from corrosion. Found the the corrosion inhibitor had stopped working (worn out / depleted) and the sludge had blocked the cold feed from the header tank to the boiler so air was also getting in through the overflow pipe. Needed a flush through, new inhibitor and everythings ok again. Quote
skOOby Posted January 5, 2009 Posted January 5, 2009 Also had a similar problem - the cold feed was getting blocked, so had a chemical power flush and all rads are piping hot now. Could not believe the amount of crap that came out! skOOby Quote
Hammy Posted January 5, 2009 Posted January 5, 2009 You can check for Hydrogen by setting fire to the gas coming out of the radiator vent. If it lights ( note its a colourless flame, that sets fire to your wallpaper and burns your hand ) you have hydrogen. This in turn means corrosion. ( simplistically: Fe + H20 =Fe0 + H2), if its just air then you need to know that too, as long term it will cause corrosion too. air means its sucking air in somewhere . A common cause of H2 on a newish system is that the system has never been flushed after the install and then no inhibitor then put in. In your case if its overflowing then maybe its also sucking back air through the expansion pipe . Have a look at the tank when you power up to see if the expansion pipe overflows into the header tank . Could be bad design or just wanting the pump slowing down ? look also for weaping joints near rads etc, air can get sucked in here too. I'm no expert but hope that helps ! Quote
jackdaw Posted January 5, 2009 Posted January 5, 2009 cant help with your problem, but recently had problems with hot water from combi boiler found a great forum, diynot.com sorry dont know how to link. solved my problem, may be worth a look. Quote
Truly Skint Posted January 6, 2009 Author Posted January 6, 2009 Thank you for your feedback I will read throuigh it this week and take action when she nags again !! Quote
Major Stare Posted January 8, 2009 Posted January 8, 2009 You can check for Hydrogen by setting fire to the gas coming out of the radiator vent. My mate did this (after we'd had a few beers) and burnt the wallpaper, ceiling, curtains and his hand. After returning from hospital suffering from burns, he had to discuss what happened to his wife........ needless to say, i left at this stage Quote
V8grunt Posted January 8, 2009 Posted January 8, 2009 You can check for Hydrogen by setting fire to the gas coming out of the radiator vent. My mate did this (after we'd had a few beers) and burnt the wallpaper, ceiling, curtains and his hand. After returning from hospital suffering from burns, he had to discuss what happened to his wife........ needless to say, i left at this stage Q the hamster up the bottom ( armageddon) U tube video! Someone put it up please ( no pun intended!) Quote
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