When my HW and CH is on at the same time, the radiators take ages to heat up. When I switch HW off, the rads get hot very quick and reach the required room stat. This has happened ever since the boiler was installed, around 2 years ago, but it has never been resolved.
If the room temp was 17 and I wanted it to be 20, this would take around 3 hours which is not good. With the HW off, it would get to this temp within 30mins.
Hopefully someone might have an idea.
When on hot water only the heat generated by the boiler must be moved quickly to avoid overheat. Check if the pump has a speed selector switch, if it has make sure it is set to max, normally setting No3.
Check that all valves around the hot water storage tank are fully open. Some times a throttling valve is fitted on the heating coil flow or return pipe to encourage flow rate through heating circuit, when running on both heating and HW.
Thank you for your reply.
I have turned the pump onto 3 previously and problem still exsisted.
I have checked all valves and all fully open. It's as if the system is confused as to where the water should go. The cylinder doesn't take long to fill up with hot water, but doesn't then concentrate on the CH. Should the arm on the 3 point valve move? It is always in the same position even when I switch the HW or CH on/off?
There show be a thermostat strapped to the hot water cylinder that wiill pick up the temperature. When the water temp has reached the thermostat setting the stat should send a signal to the 3-port valve which will direct the water to the heating circuit. If, as you say, the 3-port valve is not moving then the system may incorrectly wired or the valve faulty. Have the system control wiring checked firstly, if this proves OK then the valve operation should be checked.