Bleed valve near hot water tank?

[chuzzlewit]

Hi,
I've drained down a conventional vented heating system (c. 1998) and and trying to re-fill. The fill & expansion tank is nicely filled, and I have got a small amount of air out of some of the downstairs radiators, after having set the 3 way valve to M(id). That has now stopped and I have no air (or water) coming out. I've run the boiler for 20 seconds or so, to activate the circulation pump (and it is circulating as I can feel it vibrating slightly), and I've set it to max. speed (3).

Still no joy, but I read about a bleed valve "near the hot water tank". Is this thing in the centre of the attached photo a bleed valve? It looks very likely, but I thought I'd ask on here first as I'm very nervous about unscrewing things I don't understand! I don't want try try to unscrew it if it's a permanent cap for example.

The pump flow is downwards towards the 3 way valve just visible at the bottom of the photo. The pipe coming up vertically from the valve is the HW feed which splits into the HW tank on the right and the possible bleed valve above it.

Any advice greatly appreciated - it's getting cold!

 

[Rickster123]

Yes yes it is.

 

[Gasmk1]

it is but be careful as the rubber sealing washer often often wedges into the bleed hole and you will need to prise it off dont lose it or it wont reseal

 

[Azzer1704]

Possibly a blocked cold feed. Put a magnet on the pipe where it tee's into the flow, if it sticks then it's blocked/partially blocked.

How did you isolate the F&E tank to drain down? If you tied the ball valve up or isolated the cold mains, and the tank remained full then it points to cold feed also.

If you turned off a gate valve on the cold feed then the tank would have stayed full anyway.

If thats the problem then it needs cutting out and replacing at the point where it tee's in, whether it be an air seperator or just a tee.

Hope you get it sorted.

 

[chuzzlewit]

Thanks for all the replies.
Undoing the bleed valve didn't help (no air came out). The header tank emptied fine when I drained the system. I managed to get one downstairs rad. filled, but that's all. When I turn the boiler on to get some flow, there is the most horrendous knocking from the hot water tank and the boiler, so I shut it off sharpish. Pretty sure it's "just" an airlock, but I don't want to do damage so I've had to ask a chap to come out.

 

[Greg Gas]

Try to bleed pump by silver screw at the back of pump. Manual vent has a pin hole which very often get blocked, don't try to unblock when the system is full.

 

[KingDoey]

Try putting your hand in the f and e cistern and actually feeling the outlet to see if any sludge or debris in the bottom has become lodged. Few weeks back i had a slug blocking it!

Failing that it does sound like you have a blocked cold feed...

 

[Gasmk1]

did you make sure the bleed hole was free of rubber i have had them where the rubber has blocked the hole

 

[chuzzlewit]

Just to finish this off, it was a blocked cold feed - chap came in, cut into it and shoved a spring thing down to clear it. Beyond my knowledge and confidence to do that. All good now; thank you for all the helpful replies.