Changed combi boiler pump

[Jamie2017]

Hi

I've just changed my combi boiler pump (vokera Linea 730) due to it dying.

I've refilled the system and bled all the rads but when testing the heating only the upstairs rads get hot. I've tried turning the upstairs rads off completely and I get a small amount of heat downstairs but that's it.
Anyone have any ideas as to why?

Thanks in advance.

 

[terryplumb]

is the new pump spinning, seems like it might not be . what made you decide the old pump was at fault ??

 

[Jamie2017]

It was all working fine but the old pump started tripping RCD in the consumer unit. New pump ( although a refurb) runs fine and is definetly spinning. Do you think with it being a refurb it maybe weak?

 

[terryplumb]

symptom points at lack of circulation ,did you do a full system drain down ? are all valves open ? how do you know it is turning ? can u take pic of pump and boiler.

 

[Jamie2017]

I've taken the priming screw out and the shaft is spinning.
Just removed the pump from the housing and the bearing is no where near as free as the one I've removed. How free are they when there new? Should it keep spinning for seconds after spinning it by hand?

Thanks for your help

 

[terryplumb]

should turn freely ,shouldn't feel tight or as though it's binding.but its not like a fan that will spin with I light flick of your finger.can you take it to supplier and ask them to bench test it ?

 

[ianmcd]

did you just change the pump head ? can you take a pic of what you have replaced it with, not all Grundfoss heads are the same

 

[Jamie2017]

Finally sorted! Thanks for all your help. Looks like I had a bad air lock. Totally drained the system again and refilled. Bled all the rads and the pump. Heating is now back to normal working in all rooms.

Thanks again
Jamie

 

[terryplumb]

happy days...oh happy days....!!!