System not working after replacing 3-port valve - Air Lock?

[ambient]

I just replace the 3-port motorised valve in my new bungalow (because it was always sending heat to both HW and heating), but now when I turn on any combination of HW or heating none of the three pipes around the 3-port valve are heating up. The boiler seems to fire briefly but then go off. The pump seems to over-run for ages.

What might cause this issue, could it be an air-lock?

I've tried continously bleeding from 1. the cylinder bleed valve, 2. the magnaclean bleed valve & 3. the pump (as per pic below). 1 & 2 work good HOWEVER I can remove the metal (bleed) plug from the pump entirely and no water comes out.

Any suggestions greatly appreciated.

PS: when installing the valve I only half drained the system to get level down to below the 3-port valve and save draining all the radiators also. Not sure if that could have contributed to the problem?

 

[CBW]

Is the valve set to mid position? Sounds likely to be an air lock. Have you checked for water in the f&e tank in the loft?

 

[oldbuffer]

Are all the valves you touched during drain down returned to their original positions.
In particular, are the pump valves open.

 

[Madrab]

Is it a sealed system or open vent?

No water from the pump bleed screw isn't really a concern. Can you bleed all the rads above that point? Try only one side of a rad valve open and try to bleed the rad and then close that side and open the other and try to bleed with the pump running both should bleed, if they don't then it's probably an airlock.

You may be able to backfill using that drain point but you'll need a buddy.

 

[terryplumb]

Are all the radiators full of water ?
Sounds like there is insufficient water in the system ,possible blocked feed or airlock.

 

[ambient]

Nevermind, I think I've got it working now. I found another couple of bleed valves in the loft where the pipes go to and from the boiler. Only a little air came out of these, so not sure that was it, but having continued bleeding all the valves the system didn't eventually seem to start pumping hot water. Hopefully its sorted now.

 

[ambient]

Sorry only just saw your response @Madrab / @terryplumb , thanks so much for taking the time to reply.

 

[ianmcd]

You may be able to backfill using that drain point but you'll need a buddy.

Some weegies will do anything for a free holiday

 

[Madrab]

Some weegies will do anything for a free holiday

You know as well as anyone I'm sure ... if you don't ask (or hint) Does it show I need a holibag

 

[ianmcd]

You know as well as anyone I'm sure ... if you don't ask (or hint) Does it show I need a holibag

If its a caravan we could smash it Robert xx