Two storage heaters and supply.

[Darkwood]

I personally wouldn't run the load through timers, I would always use a heavier rated contactor to do the switching, this limits costs when elements fail etc as mentioned in my previous post and also heavier rated contactors have a higher chance of handling a fault current without consequence, it is up to you at the end of the day but unless you have different time requirements for the storage heaters then you only need 1 timer otherwise your just creating more work having to program 2 up the same.

 

[Mazak]

If i will buy one timer it must be two channels, right? Then two contractors lets say 20A each, connect all three units will take some time as well. Resistive load in timer I am going to buy is 3.6kW and bigger storage heater is 3.3 so it is still 10% marigin.

 

[Darkwood]

No your timer controls your contactor why do you need 2 separate ones you can do it by 1 timer controlling a 4pole contactor with your 2 circuits controlled by it but I would suggest having 2 contactors so if one fails you have redundancy and heating still.