I have a standard British heating configuration at home - there is one gas heater that provides hot water both for the boiler (and bathroom etc.) as well as for central heating. There is a small electronic device where you can set if you want to heat the water or run the central heating (it has a timer, etc). The central heating works based on a thermostat in the living room, which shows green when the actual temperature is lower that the set value (hence the heating is working), or red otherwise.
Recently we switched the central heating on for the first time this year, but it didn't work as expected. When the hot water is off everything seems fine. But when the system heats the water up, all the radiators got boiling hot, despite the thermostat showing red all the time. What might have gone wrong? Is it something I could fix myself?
EDIT: To be more precise I did a test and the results are as follows:(CH - central heating, HW - how water)
- HW off, CH off - everything cold [OK]
- HW on, CH off - everything is hot [WRONG]
- HW off, CH on, temp > thermostat - everything cold [OK]
- HW off, CH on, temp < thermostat - everything cold [WRONG]
- HW on, CH on, temp > thermostat - everything hot [WRONG]
- HW on, CH on, temp < thermostat - everything hot [OK]
So it seems that the hot water switch now operates both HW and CH, and the central heating switch does nothing at all (and thermostat is likewise ignored). Is this something I could fix myself?