Which dual immersion cylinder and heat retention radiators?

[Blib]

I own a flat. There is no gas supply to the flat. It is fitted with an electric water boiler/cylinder. The boiler is getting long in the tooth and I've been thinking of replacing it with a more modern unit for some time now.

Last week I had an EPC inspection done. One of the inspector's recommendations to increase the flat's energy performance was to fit a new 'dual immersion cylinder'.

What should I buy to provide the best performing unit for my tenant?

He also mentions that some of the radiators could be replaced with 'high heat retention' storage heaters. Once again, could someone please point me in the direction of those?

The radiators are on an economy 7 tariff.

Thank you.

[Snake the Sniper]

Is the current immersion single or twin element? If it's single, I would expect the meaning to be that you fit one with two elements, one on a 24 hour feed and the other on an economy 7 feed. This will need a new feed run from your current storage heater fuse board, assuming there is a spare way. If it's already a twin, I've no idea what the guys going on about.

As for the storage rads, he mainly means new ones with 45%+, IIRC, heat retention, as that's mainly what that means. How old are your current ones?

[Blib]

Thanks for that. As it's old, I assume it's a single. There's a mix of rads. One is less than two years old. The rest far older.

[Gingerbread Man]

Cylinder wise, is it gravity or mains pressure fed? If gravity you could upgrade it but that relies on a good incoming water main. Often in flats you get combination cylinders with an integral header tank on top of the cylinder. Sometimes the hot runs low pressure and the cold runs high pressure and it makes it a pain when you involve mixer taps.

You can get dual immersion or single. One gets wired up to the economy 7 tariff. The other is a boast and runs off the normal peak electric and is just that, a boost.

[Blib]

It's mains pressure fed. So, here's nothing too trick in replacing with a twin feed? I suppose I can't go wrong with Dimplex when it comes to rads.

[Gingerbread Man]

Same cylinder, one of two immersion bosses welded in. But as stated it'll need another fuse board feed.

[Blib]

Thank you for your help.