Central Heating not working after fitting new Rad

[Daka]

Have a problem that's driving me mad. I fitted two new radiators last night, this was moving one that was over sized in the kitchen & replacing the bathroom with a towel rad.
All went ok, I turned the boiler off, drained the system, fitted new radiators. After that I bled the system making sure there was water in the gravity header tank.
Should all be fine.

Problem is that when I turn on the heating it just won't work!

The boiler is working (it's a Baxi back boiler) & the hot water is fine. What seems to be happening is that the pump & value aren't being told that the system wants to go.

If I turn the HW on & turn the valve manually I can get hot water around the system & I have re-bled all the rads to make sure but no joy.
I can't understand why it's not working, any ideas?

 

[John506]

Broken pump?

 

[twgas]

or MV

 

[Daka]

Thanks for the replies but it wasn't the pump because that worked for the hot water, the valve may have issues but that would not have held the pump off.

Weird thing though, I went away for the weekend, come back and it's working! Can't explain why it just seems to work fine.

 

[Agile]

I expect it was just air in the system!