Advice for timer for 3.4kw storage heater

Ian Syn · Nov 25, 2023

Hello folks.

Just looking for a little help please. Recently I fitted a fst77 timeguard for a single 2.5kw simplex model NLSH18MN. This works well and allows me to just turn it on the charge for the last couple of hours of the e7 window. Now I'd like to fit one for our larger NLSH24MN model but this is rating 3.4kw so I believe would be too much for the 13amp fst77 timer. Can anyone recommend something that would be suitable? I was thinking a 16amp rated immersion type timer would be ok. Obviously needs a battery backup to keep time during non e7 window.

davesparks · Nov 25, 2023

Your E7 supply should already be set up to charge the storage heaters during the E7 period, individual timers shouldn't be necessary.

The backup battery in these timeswitches is designed to allow it to survive through occasional powercuts, it won't last very long being expected to be the main source of power to the timeswitch during every day.

justsomeguyyouknow · Nov 25, 2023

davesparks said:
Your E7 supply should already be set up to charge the storage heaters during the E7 period, individual timers shouldn't be necessary.

The backup battery in these timeswitches is designed to allow it to survive through occasional powercuts, it won't last very long being expected to be the main source of power to the timeswitch during every day.

Thanks Dave, appreciate the response. You're right, the e7 circuit is working as expected. The reason I've fitted one in our bedroom is the heater kicks in very early hours, heats up the bedroom too much and wakes us up. It now comes on at 5am to 7am (which seems to store enough heat energy) instead which is much better and the heat lasts throughout the day (it's also used as an office). Appreciate your point about the battery backup perhaps not being suited to that scenario. If it fails I'll tackle it then. So would there be a timer suitable device I could do the same thing with for a 3.4kw heater? Or you just simply wouldn't recommend it.

Resu · Nov 25, 2023

Can you not just adjust the input/output controls on the heater?

mainline · Nov 25, 2023

justsomeguyyouknow said:
Thanks Dave, appreciate the response. You're right, the e7 circuit is working as expected. The reason I've fitted one in our bedroom is the heater kicks in very early hours, heats up the bedroom too much and wakes us up. It now comes on at 5am to 7am (which seems to store enough heat energy) instead which is much better and the heat lasts throughout the day (it's also used as an office). Appreciate your point about the battery backup perhaps not being suited to that scenario. If it fails I'll tackle it then. So would there be a timer suitable device I could do the same thing with for a 3.4kw heater? Or you just simply wouldn't recommend it.

You could add a timer and contactor.

justsomeguyyouknow · Nov 25, 2023

Resu said:
Can you not just adjust the input/output controls on the heater?

You'd think so wouldn't you. Storage heaters are pretty rubbish to be honest (well the ones we have are). Even with output at zero they still emitt a good portion of their heat. The output dial just controls a small metal flap to open or shut.