Auto Bottle valve vent.

[mrtrout]

Hi everyone, hope you can help.
I have a problem with the above item which is spewing water out when started up from cold or after a bath has been run etc.
I have a 4 year old property which has a Halfords Hero boiler and a vented heating and hot water system.
Every thing has worked fine until recently, I go away every 8 weeks for 2 weeks so I turn everything off for obvious reasons.
On return I switch the heating on and the hot water and whilst the water is heating, water leaks from the top of the brass auto bottle vent, at the two small holes in the knurled screw.
Yesterday after being away for Christmas, it did it again and approx 4 litres of water came out, it stops once the water is up to temp.
The header tank is fine and working properly and all rads are fine i.e no air in system.
I assume the auto bottle has some sort of gland that only lets out air on expansion and not water? has this split ?
The valve is located in the airing cupboard next to the water cylinder.
As it is a new property so to speak, I know the plumber who did the work, unfortunately on hols, and he is a top bloke.
My three neighbours who have identical systems, have no problem.
Any advice on the workings of the auto bottle and probable cause much appreciated. Thanks Steven.

 

[gas_man_gaz]

iam guessing ya mean a auto air vent? can ya screw the knurled bit in to temp stop the leak and just replace the valve? (10min job). while its removed ya could even fit a manual vent key, aav's do tend to leak alot

 

[mrtrout]

Hi gaz, thanks for reply, yes it is the air vent but the exact description in the Screwfix cat is an auto bottle type air vent and valve.
No if I screw the knurled top down tight it still lets water out through the two little holes on top.
If I have to replace this, will I need to partially drain the system down, and what could go wrong inside the brass valve itself. Can you explain how it works please.
Thanks.

 

[gas_man_gaz]

it has a float fitted inside the bottle which rises with the water level. wen the water level rise's the float rises and closes the air vent, if their is no water the float drops and opens the vent thus allowing any air in the system to be vented automatically.
it prob has some dirt on the seating stoping the vent closing fully and allowing water to leak out.


are you on a sealed sys or have ya got a little tank in ya loft?

 

[mrtrout]

Hi gaz, it is a non sealed system, with expansion tank in loft. Please see my first post. This is all ok and working fine i,e water level in tank is low and ball valve operating fine.
If I took your advice and fitted a manual bleed key fitting would this be safe, or do I have to have an auto vent on a non sealed system?
Thanks for explanation of vent I thought it was something like that.

 

[gas_man_gaz]

reason i asked about the system was to advise ya on how to replace the valve if ya want to try it? like i say its only a 10min job..
yea it is safe and its quite rare the bleed is needed except wen the system has been drained, ya could just fit another aav tho

 

[bengasman]

properly installed open vent system should have no need for an aav.
usual reason for leaking aav is corrosion or limescale.
in your case i would suspect corrosioin
check if the system is clean.
ample info on this on forum

 

[mrtrout]

Thanks gents for your replies.
As it is a properly vented system fitted by a fully qualified plumber 4 years ago, why would he fit an aav other than to make it easier for himself when commisioning the system?
Also If I do just fit another aav, will I need to partially drain the water level down to below the height of the water cylinder.

 

[gas_man_gaz]

id buy a bunging kit, then there is no need for any draining

 

[mrtrout]

Sounds good, but what is a bunging kit?

Have got a Screwfix catalogue here and tried on the Plumb Centre on-line but nothing showing as that, does it have another name?

 

[wiggikins]

Sounds good, but what is a bunging kit?

Have got a Screwfix catalogue here and tried on the Plumb Centre on-line but nothing showing as that, does it have another name?

Try Toolstation Pg 308 order No 31768 £12.00

 

[gas_man_gaz]

if ya look at the f+e tank in the loft it will have a small pipe coming out of the bottom which feeds ya ch system (cold feed) and a pipe which bends into the tank from the top (open vent). if ya block both of these (by bunging it) it creates a vacuum in ya system and stops the water pouring out, you will still get a lil bit of water out tho.

guessing ya cant find um

http://www.toolstation.com/shop/Hand+Tools/Plumbers+Tools/Radiator+Valve+Change+Kit/d10/sd210/p31768

 

[2face]

cut it off and fit an RV35 manual vent. leave a 150mm leg on it for air to build then the rv35 on top of it. then bleed as and when needed.