Help with my heating query

[windchimes]

I have a really stupid question to ask. I have just put the heating on but noticed that it doesn't seem to be working unless I have the hot water heating on. Is that right? I thought you could have the heating on without heating the water. Also sometimes when I turn the thermostat down it doesnt work and the heating stays on reallly hot.
Thanks I am a real DIY ignoramus

 

[kevplumb]

depends on your system and controls

 

[petit_pablo]

Do you have 2 x valves in airing cupboard or 1x with 3 pipes?

Likely to either be the heating valve stuck half open or 3 port valve stuck in mid position

 

[kevplumb]

View media item 11149
View media item 11148

 

[bengasman]

Sounds like dodgy motorised valve