I have an apartment which has Economy 7 storage heaters installed. There isn't a storage heater in the bedroom (only an electrical on-demand heater), is it possible to replace this with another Economy 7 storage heater by wiring it back to the Economy 7 RCB in the consumer unit? There are two 2.4Kw heaters in the lounge and a 1.7Kw in the hall at present. I would plan to install a 1.7Kw in the bedroom.

Thanks in advance for any help

I will have to check the capacity of the current heater and get back to you later. The Economy 7 is connected back to the central electrical cupboard for the whole block of apartments and is switched by the energy provider. In the consumer unit there is an RCB allocated for Econ 7 storage heaters.

Thanks for the valuable information provided to date i appreciate the inputs. The current on-demand heater in the bedroom at the moment is 1Kw.

An RCBO is not the only way to provide 30mA RCD protection

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I jumped the gun when i assumed that the cu for the night store would be old, its just that the majority of the ones i come across are, but this might not be the case with this scenario. An rcbo could well be used depending on the cu.

Ahh yes, turn it into a sub-main, should of thought of that.

I was thinking of adding 2 x 1.7kW storage heaters in bedroom’s in my daughter’s house and totted up the wattage of the existing 4 downstairs storage heaters plus immersion heater. Divide by 230 volts to get amps = 55.2.

Noticed no seals on anything in meter cupboard!!!! – so pulled main fuse: 60A. Taking advantage of that removed a meter tail and found it’s 7/1.70 (Have micrometer to measure unsquashed core strand)

The meter is a modern digital, says 80A

The existing storage heater consumer unit is 4-way and is full. There is room to add another 2-way cu and feed it from the tails to the 4-way via tail connector blocks but it seems to me I have to get the fuse uprated and maybe meter and tails as well.

It’s quite likely the washing m/c will be timed to come on soon after off-peak is available, unlikely but possible a late night supper in the cooker could add to the load.

I think I need some advice on loading, maybe others will be interested in this aspect..

One more query re earthing the 2-way cu (if the loading doesn’t make the extra heaters impossible): There is room to run an earth cable from the 4-way to the 2-way but I notice that earth wire for each existing cu and a water bonding all run independently back to the earth clamp on the underground cable, each having crimped tag. Is this now the only way of making earth connections – in other installations I have often seen only one earth wire running round all cu’s and occasionally use of an uninsulated earth connector block.