On Sat, 01 Feb 2020 14:53:55 +0000, John Rumm wrote:

On 01/02/2020 11:13, Bev wrote:

We are in the thought process of removing night storage heaters and
having new full central heating and hot water from a kerosene fired
boiler.

The issue is whether we go for a combi boiler or a system boiler with a
much smaller HW cylinder than at present and with the smaller cylinder
relocated to the loft.

Why a smaller cylinder?

Because the one that is in the cylinder cupboard is 263l and is a low
pressure system fed from loft header tank and it takes up far too much
space. My thoughts were to go with a pressurised unvented cylinder
(which, I think, is what you describe below---) in the loft with the
relief being discharged outside into the drain. The discharge route is
easily achievable.



Have you considered a system boiler and an unvented cylinder? That gives
the advantages of both at once - lots of stored hot water and mains
pressure delivery, with no need for an additional header tank.

Guidance on choosing a system he

http://wiki.diyfaq.org.uk/index.php/..._Water_Systems

Unvented systems he

http://wiki.diyfaq.org.uk/index.php/Unvented_DHW

Thanks for the links (and to others for their responses too)