No heating but hot water working

[kateylocks]

Hoping someone can help.
Our heating isn't working. I don't think it's a problem with the boiler as the hot water is fine. I don't know anything about plumbing. Is there anything obvious I should check before calling a plumber?
We had a chap out last week to move a radiator. He balanced the radiators throughout the house at the same time. Since then I have noticed that the hot water has been a lot hotter than normal.
It's a system with a hot water tank in the loft rather than the other type.
I've taken some photos of the boiler and the system in the airing cupboard but can't work out how to upload them.

It sounds like you probably have a zone valve that is stuck. Look for one of these www.screwfix.com/c/heating-plumbing/motorised-valves/cat831028.
You will have either one that has 3 pipes going into it, or two with two pipes into each. If it is the two pipe one, you should have heat on both sides of the valve. If it is the three pipe one, you should have heat on all three pipes. If you don't, then there will be a little lever on one end of the valve. Move that over to the other side which says manual and then back in to a little holding position.

Agree with MuchlyWrong that that’s the most likely, other thing could be your pump, can you hear it running when you turn the room thermostat up? Does the room thermostat click audibly (assuming you have one)? I’ve had to have both replaced at various points in my system.

This happened to us last winter it was a motorised valve, they go after a while especially if you're system is fairly old

When this happened to us it was the zone valve. It didn't take long for a plumber to fix it