Vertical valve fitted on the return pipe of my 24CBi boiler

[FatMonk]

Can someone tell me what the vertical valve is likely to be that is fitted on the return pipe on my Bosch 24CBi boiler?

The pipework enters the boiler from above and the pipework T's to go down to the return connection on the boiler and up to what looks like a valve of some sort.

I noticed this afternoon that this valve appears to have been leaking pretty significantly at some point over the last 24hrs.

The heating and hot water seems to be working as it always does and there is no current leaking but there is a green mark down the pipework as though it has leaked and the area below the boiler is really quite wet.

I didn't notice the wet area yesterday when I was in that area.

Any pointers as to what this valve is and what might cause a leak would be gratefully received.

-FM

 

[Dan Robinson]

Picture please.

Could be a strainer, filter, balancing valve, additional service valve, non return valve.......

 

[FatMonk]

This is a view of the left hand side of the boiler showing the 'valve' assembley on the return pipe.

Worcester Bosch 24CBi with valve on return

• FatMonk
• 9 Feb 2015
• 1

Does this hero identify it?

Thanks,

FM[/img]

 

[45yearsagasman]

It's an auto air vent. If it's leaking then it needs to be replaced. Temp fix can be to tighten down the little plastic cap on the top of the valve. View media item 35609

 

[FatMonk]

Thanks,

I guessed it would be either air or pressure relief (although water pressure relief that just releases into the open seemed like a bad idea to me).

There seems to be a big variation in price (£10-£60) for different types.. I'll take a look this evening to see if I can see a part/model number on the one that's fitted.

Out of interest, is there anything that causes them to fail (limescale build up, problems in the rest of the system) or do they just fail after a time anyway?

Thanks,

FM

 

[45yearsagasman]

They fail after time. Replaced lots for that reason. You will have to drain down or bung system to change it.

 

[FatMonk]

Now all I need to do is find the correct replacement...

Can anyone point me in the right direction from these photos

Auto air vent top view

• FatMonk
• 10 Feb 2015
• 1

Auto air vent side view

• FatMonk
• 10 Feb 2015
• 1

As I mentioned in a previous post, there seems to be quite a variation in price - is this largely siren to the max pressure they deal with? (It looks like this one is Pmax 14bar and is that max temperature 120C?)

-FM

 

[Gasguru]

Any old 1/2 auto air vent will fit but I'd ditch it and fit a manual air vent...this sort of thing...

http://www.heatingcontrolsonline.co.uk/image/cache/data/DSC_0147-500x500.jpg

I also suggest you have that boiler safety checked...they have a major design flaw. The right hand side of the heat exchanger has a cover plate, the seals fail and the whole lot rots through. Every CBi I've seen has failed so far. It's an expensive repair if not caught early but Worcester may do a fixed price deal.

Untitled

• Gasguru
• 20 Mar 2014
• 3

 

[FatMonk]

Most of the boiler was replaced about two or three years ago as we had a heat exchanger link.

The heat exchanger and burner were replaced, and if I remember right the fan as well. Pretty much the only thing not swapped was the circuit board.

Regarding the valve, are there disadvantages to the auto valves, or is it just an expense thing?

-FM

 

[Gasguru]

Auto vents always leak or block up and IMHO are a waste of time. If they leak and it's not noticed they can do considerable damage.

Presumerably the flow and return pipes drop down from the boiler (but why they didn't jut rotate the pipes in the first place is a mystery). If you had a leak on the system air could be drawn in through the vent...another reason to ditch it.

 

[FatMonk]

Well after all that, and a bit more investigation over the weekend, it turns out that it is not the valve that is leaking - it looks like the heat exchanger is cracked again.

We are getting water leaking only when the heating and hot water is off - ie when the boiler has cooled down.

So Mr Bosch is coming tomorrow to fix...

-FM