Now summer has arrived i have turned the central heating slider switch to off but left the hot water on timer, yet when the timer kicks in to heat water up i have found all the upstairs radiators heating up even though the c/h is turned off.
Thanks, the boiler is downstairs in the kitchen and has myson orion on the front, the control panel is potterton and has individual switches for water and c/h, hot water tank is airing c-board and looks like there is a a pump attached to it, and another oblong silver bos with honeywell coming off it, hope that helps if not let me know what more info you need
The oblong silver box will be the actuator, probably a Honeywell V4073 or similar.
Remove the actuator, check the 3 port valve turns freely, and check the actuator turns when HW or CH selected. If it's not turning - replace.
I think you might have to change the whole three port valve though, normally if the actuator fails, all of the radiators will heat up when hot water only selected. If only upstairs radiators heat up it sounds like the valve is turning but not fully closing off the heating side. Therefore letting water/pressure through but not enough to reach downstairs.
Just had to do the same with my own system as it happens. Actuator working fine but valve itself just didn't want to play at all.
Quicker just to exchange the whole thing. Watch out though that your actuator wiring might be slightly different. Older Honeywells had 6 wires the newer ones have 5. There's data on the Honeywell Site about the wiring differences to save repeating it here.
I have a similar problem. Potterton Suprima Combi boiler.
When the termostat is turn right down, the radiators are boiling hot and I've run out of hot water. Sounds like the Actuator to me. In my airing cupboard I have black Honeywell box with a manual and auto lever and I also have a Myson Power Extra which also has a manual lever. Any ideas of which would would be causing the problem??
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!