Need some advice on our Alde 3000 heating system if anyone else has one. It heats the radiators around the van and also the water. It has a 1 and 2 KW heater element and can run off gas as well. The question I have is can I run it without the tap water tank being filled? The radiators run on glycol/water mix. The heating controls do not allow for seperate timings. In the instruction book it says you can but it also shows a programmer that has both settings separate, ours does not have this. It seems to be all or nothing. Don't want to try it till we know otherwise we could freeze to death over the New Year. Just wanted to air it out but it is too cold to put water in.