Mass switching of heaters.

[SparkyNinja]

Want your advice if you please,

I've been asked to supply a quotation to supply electric heating to a building which is being converted into a nursery. Due to the nature of the building I suggeseted underdfloor heating but they've decided they want fan heaters.

So I've looked at the drawing and come to the conclusion they will need 14 total. The chosen heater is up to 3kw. Ideally I would like them each on there own 20amp circuit, but they may ask for a couple of rings.

Anyways, they want it all on one switch to isolate at night. So I'm thinking of something along the lines of a switch fuse, feeding a contactor feeding the db, supplying the final circuits.

My previous experience with this was at ascot racecourse where we had lovely DC contactors on huge panels, but this is only in a pump room.

 

[electronicsuk]

Despite what you tell the nursery, if you put in a master isolator then they will not only use it for isolating the fans at night, but also turning them all back on at the same time in the morning.

If they really do need 14x 3kW heaters then that's going to place some burden on the supply already, and the initial start-up current while the elements get to temperature may be something worth considering. You might have to look at some sort of phased startup, but my experience with electric heating is limited so will leave that for someone else to comment on.

I also think they must be mad, I can't imagine them using the heating much when they see their electricity bill.