ALpha CB28 - making hissing noise when turned off/on

[z3usx]

Hi

My Alpha CB28 boiler has started to make a hissing noise when it is cold and also when it is on. Just wondered should i be worried as my boiler cover with alpha will not start until 28 days.

Any advice is much appreciated. Thanks

 

[gas4you]

Is the system pressurised to just over 1 Bar cold? If not hissing could be the auto air vent.

Are you having to constantly top up the pressure?

 

[z3usx]

Pressure is 2.5 bar when its cold as well as hot - the boiler also started to drip water after a bit when turning it on - it has done it a few times before.

However the hissing has now gone. Any pointers on stopping it from dripping?

Thanks

 

[gas4you]

Drop the pressure to 1.2 Bar cold.

 

[z3usx]

Would i do that by bleeding the radiators? If so how much do i release and from one or all radiators? or any other method of reducing the pressure.

Thanks

 

[ChrisR]

First make sure the filling loop is CLosed - or better, disconnected.
Drop pressure by bleeding rads, or letting water out from a drain cock.

See the FAQ'a on pressure problems, for background.

 

[z3usx]

Hi

I managed to drop the pressure on the bioler like you said and i found the filling loop was and has been slightly open since i moved in the flat. Whacked the heating on full from cold and tested the hot water, works perfectly.

Cheers