DIY Doctor UK DIY Forums

Hi all,

I had just replaced my immersion heater when I noticed that the hot water cylinder had a slight weep and needed replacing. I have successfully drained and removed the old cylinder and am trying to find a new replacement cylinder.

It is a copper 120 ltr direct cylinder with a 22mm cold feed and hot feed. It also has two 28mm feeds on the opposite side from a solid fuel boiler. These are the pipe sizes. I have seen cylinders advertised with 1 inch BSP boiler connections.

Can anyone tell me how to compare the metric pipe sizes with the imperial cylinder connections. What do I need to look for.

A final question, how do foam lagged cylinders compare with plain copper cylinders, (and a separate jacket)?

Buy a couple of 28mm fittings and compare but be carefull as thread sizes might look the same but normally strip. end feed solder 28mm fittings and inch pipe are copatable with carefull soldering but if its tnk connectors be carefull.
As for foam versus laging you should not be able to buy a bare cylinder without foam as this is not Part 'L'compliant. As for the science behind it double lagging a cylinder is more efficient than foam in the long run as the foam loses its insulating properties over a period of 5 years under lab conditions, lagging does not and maintains its lagging properties for longer and can always be added to.

Thanks plumbers1, sorry for late reply, have been investigating. It seems the 28mm pipes need a 1 1/4 inch tank fitting, and the 22mm a 1 inch.

Finding it hard to find an off the shelf tank, so am ordering a made to measure tank from Gledhill. This has rockwool insulation.

Many thanks for your helpful information.