autovent valve problem?

[pedro63]

Greetings, can anyone please give me some advice? i have an open vented c/h system powered by an ideal classic boiler,grundfoss pump and 3 way honeywell diverter valve. over the past year ,the autovent valve in the airing cupboard has been expelling a small quantity of water when it vents(there has never been a red cap on the valve since i have lived here ,12 years approx). a few days ago,a lovely large bubble appeared on the living room ceiling, which gave me about a qurter of a pint of brownish water when pierced. i traced the leak to the autovent which was continuessly expelling water. i temperarely bunged the little nozzel on the top of the pot to stop the leak. today i purchacesd a new autovent, bunged the feed and vent in the header tank, and fitted it. when i removed the bungs water again spewed out from the top nozzel, but this new vent had a red screw cap which i shut down to stop the leakage. i suspected the vent to be faulty , so changed it, and had a chat with the chap in the shop who said to close the red cap right down remove the bungs in the header, then open the red cap about half a turn, he said i should then here the air expelling. I did all this but water still trickles out unless it is screwed firmly down. My question is is this correct? if so how does it vent automatically with the red cap screwed firmly down?, by the way the vent is 10 barr,thats the only one they stocked. would really appreciate any solutions. many thanks and regards.

[Paulo83]

The new auto air vent shouldn be leaking continuously (perhaps a small splutter as it just finishes venting air but thats all). Either just screw down the cap (i would, unless theres often airlock problems) or goto the bother of fitting another new one.

[pedro63]

Many thanks for that,

that is what i thought, this is in fact the second one that i have fitted as i thought the first one was faulty.

why these are leaking i just dont know but i think to save any hassle i will just screw it down

cheers

[htg engineer]

They shouldn't be leaking. Could be a faulty batch of valves, try using a different auto airvent (reputable make).

What's the point in fitting an auto airvent if it's going to be closed ???

Auto airvents should be left open as any air left in the system will eventuially escape via the auto airvent.

If you are going to leave the capeed screwed down - then why not just fit a manual airvent ?

[pedro63]

Yeah good point,

I'll have a shop around and see if i can get another make

cheers