Could someone please identify this?

[Vaskunito]

Hi, can somebody tell me what this red thing is?

http://www.cs.ucl.ac.uk/staff/V.Zografos/pic1.jpg
http://www.cs.ucl.ac.uk/staff/V.Zografos/pic2.jpg

It is installed near the water pump (I believe onto to the hot water pipe).

It started leaking a few days ago (not too much though) and I think it needs to be replaced.

on the sticker (not to clear from the photo) it says:

AIRFIX
capacity 2L , and 2.5 and 0.5 bar. Most of it is written in German.

Can anyone help me please?

Thank you
V.

 

[kevplumb]

it's an expansion vessel

see this

 

[ChrisR]

It looks like the white one might be a repalcement of the same thing, on the cold pumped supply. Size isn't critical, but don't get one intended for central heating, it has to be suitable for potable water.
Suggest you search on Zilmet, marketed by Altecnic and available to order through any plumbers merchant. Check the fitting size, usually 3/4" bsp,which measures about an inch across.

 

[Vaskunito]

ok cheers guys thanks for the info.

By the way, is replacement of these things difficult (i.e. should I call a plumber) or can I do it myself?

I am not bad at DIY but I am not sure how to replace it. I obviously have to turn of the main water supply and empty the boiler yes?

Unless it is more dangerous than I thought.

What do you guys say?

Thanks
V.

 

[chrishutt]

I obviously have to turn of the main water supply and empty the boiler yes?

No. You're dealing with a separate system fed from one or more water tanks in the roof space. There should be sufficient isolating valves on the pipes supplying the pump to enable it to be isolated and the expansion vessel changed. Trace the pipework backwards and draw a diagram of the system.