Balancing Problems Since Drain and Refill

[michael fearn]

Since drain and refill of our gravity fed system I cannot get heat to alot of the downstairs rads. One downstairs rad is boiling but turning that off doesn't have any positive effect.
Most of the upstairs get nice and warm but if I turn off all of the upstairs rads then the boiler simply turns off instead of pushing heat downstairs. Boiler only gets call for heat again once upstairs are turned back on.

Any ideas please. Thank you

 

[SimonG]

Air.

 

[michael fearn]

But where mate. I've bled the radiators to death. Also bled pump and magnaclean

 

[Jones82]

is the system zoned or perhaps a valve closed some where on the downstairs circuit

also sealed system or open vent?

If its open vented you could have a bad airlock in the downstairs circuit

 

[Chuck]

If the above suggestions aren't the answer, you're left with 'sludge' blocking the downstairs circuit. Easily washed down in the draining process if you weren't very careful. Assuming the pipes are copper (or plastic) you may have some luck locating the blockage with a strong magnet.

 

[michael fearn]

It's a vented with a tank in loft. When draining down they drained fine and refilled OK thou. Can't access most of pipework unfortunately

 

[townfanjon]

Do you know if your rads are on “ drops” , or do they come out of the floor and come up ?

 

[michael fearn]

Come out the floor with pipes going up

 

[Jones82]

Close the cylinder return gate valve, close all upstairs radiators, turn the boiler temperature down so it doesn't lock out.

Put the heating on, the pump should circulate around the downstairs circuit and push the air out. You might want to close all but one of the downstairs radiators then open them up one by one as they get hot.

I'd be listening for air moving around the system and watching the vent pipe over the tank to see if it pumps over, if it does your looking at sludge in the downstairs circuit.

If nothing happens I'd be checking the pump

Too be honest your getting into heating engineer territory

 

[michael fearn]

I'm guessing that the value bottom right is the cylinder return. Thank you.