I thought that I had to convert the steam capacity (210 MW) in some way, that I couldn't just add it to the electrical, but I guess I was wrong, I just have to input (0.21+0.12) GW as total capacity.
I model everything in PJ.
I didn't input the heat demand straight away because I don't have the exact demand, I have the total of 3 CHP plants, and I have to estimate how much each of them is generating.
So I wanted to see how much steam the CHP generated
using COM_LIM FX for the heat, and got 1.96 PJ as a result, which I have to
convert into tonnes/hour (because that's the unit of demand i have for the total of the 3 plants).
thanks and sorry for being so confusing (my data doesn't help my engineering skills, which are not that strong 
thanks again