by The Flying »
Sat Apr 28, 2007 2:49 pm
A motorised valve works in three ways, heating only, hot water only and heating and hot water together or it is closed, when your programer asks for hot water it activates the pump and the boiler and the valve opens, if it then wantsyour heating on it moves to the mid position and gives you both. the M means mid- position or htg and hw. I think it could be your S- Plan, which is your electrics.