Removing air from hot water cylinder

[diycooper]

I have a open vented system boiler ( ideal Icos He18) in a rented property. While work was getting carried out on the property all radiators was took off system bled. This was 2 months ago, The system was refilled and all air bled out radiators and cylinder re-filled. The tenant has told me of a night she is hearing a loud noise for about 5 mins and its in the pipes, I have asked her is it near the boiler, she tell's me it is not. There is no air in the radiators as I checked today and boiler seems to be running smoothly. She also tells me she has the controls heating set to off and the hot water to continuous so I assume it can only be on hot water side. Since coming home and reading tonight I can only assume there is air trapped on the hot water side , question is how do you bleed it out.

I have took a pic of what looks like a bleed valve next to cylinder and 3 way valve, can it be done via this ?

http://tinypic.com/view.php?pic=25oxkyx&s=8#.VCsEnfRDti8

 

[stardanny]

Yes, that is the bleed screw, open it and let air out if there is.

Also make sure there is water in F&E tank.

Daniel.

 

[diycooper]

Yes, that is the bleed screw, open it and let air out if there is.

Also make sure there is water in F&E tank.

Daniel.

Thanks, There is water in the F & E tank. Do I just used one spanner on this screw as underneath is circular ?

Could this cause the problem I have described ?

 

[Burnerman]

It's a soldered fitting, so use a pair of pliers (gently) to slacken the top, and the air will escape. Water will flow from the F&E tank to replace the displaced air.
John

 

[diycooper]

It's a soldered fitting, so use a pair of pliers (gently) to slacken the top, and the air will escape. Water will flow from the F&E tank to replace the displaced air.
John

Do I do it like a normal radiator till the airs gone and abit of water comes out then shut it ?

 

[Burnerman]

Yep, that's the way!
John