External expansion vessel size - Halstead Platinum

[DarrenSL]

I need to install a new expansion vessel on my Halstead Platinum. I'm planning on fitting an external vessel as I have plenty of space (in the attic) and it should be a relatively straightforward DIY job.

Can anyone advise what size the tank should be? I did find a product http://www.ptsplumbing.co.uk/uploads/docs/36.pdf which suggests I needed between 24 and 35 ltrs (for 110k btu boler) which seems very large. The tank in the boiler itself doesn't appear to be anywhere near this size.

Thanks.

 

[Andygasman2010]

Those btus are for the hot water so forget them (assuming it's a combi?)

How many rads do you have? Chances are a 12 litre vessel will do. Even that is probably bigger than the one in your boiler.

 

[CBF]

the ev inside the boiler has no realationship to the output of the boiler or the size of the system, some boilers can go from 24kw to 39kw & have the same size ev, an external ev is recommended to go on the ret & as close to the boiler as poss.

 

[Andygasman2010]

an external ev is recommended to go on the ret & as close to the boiler as poss.

Providing the boilers pump is on the return, best check the manual but it probably is.

 

[DarrenSL]

Thanks for the quick replies. Makes sense. Glad I asked the question now

I have 9 rads (including 2x 1.8m x 600mm double panel radiators) which totals about 50btus. So 12 litres it is.

 

[CBF]

an external ev is recommended to go on the ret & as close to the boiler as poss.

Providing the boilers pump is on the return, best check the manual but it probably is.

very true but most are, but a double check is always a good thing