I bought my first house in December and one thing I've noticed over the winter is higher than expected gas usage which I'd like to try and get down if at all possible. The house is a three bedroom (two plus box room really) semi-detached UK house built in the 30s if thats relevant. The previous owner had recently installed a new Ideal Icos HE24 combination boiler but with a standard thermostat and timer.
I'd like to replace the thermostat and timer with two programmable thermostats for upstairs and downstairs and use valves to control heating flow to the two zones. I've seen drawings on the internet showing this using a standalone boiler with separate pumps wtih each zone but am not sure if zones are achievable using combination boilers or whether I'd be placing stress on the boilers internal pump?
My thoughts so far involve one valve for the upstairs flow and one for downstairs flow, from what I've seen I don't need return valves as well?
Working with heating systems isnt something I've done before so I guess I may have some things wrong here but would be interested to hear peoples thoughts.
Best Answer
As long as the boiler is capable of providing enough hot water through the system to heat the whole house if necessary you shouldn't have a problem.
What you are proposing is a "coarser" version of thermostatic valves on each radiator and that is perfectly safe for a combination boiler.
I don't think you need return valves.
Make sure that you leave one radiator "open" (usually the bathroom one) so that there is some flow around the circuit.
By the way the fact that it's a combination boiler is a red herring. The "combi" bit refers to the hot water heater, the central heating aspect is pretty much the same as a "standard" boiler with integral pump.
Update
If you want to control the times each room is heated independently you can get combined timer and thermostatic radiator valves - My Greener Home has some for example.