Hot Up, Cold Down

[Aqua Mechanica]

Just checked a friends central heating system, all rads upstairs are hot and all cold down stairs. It's a fully pumped system so I thought the pump's knackered.

I turned Room Stat up full and went to see Pump kick in - nothing. I bled the pump, it did have trapped air, then pump kicked in - apparently pump hadn't been working for 5 days and nor had heating and the rads have been bled too.

Half an hour later, downstairs rads still cold. Any ideas?

 

[Mike Jackson]

Could still be the pump, just because it appears to be working doesn't mean that it's working properly.

Mike

 

[Aqua Mechanica]

All evidence points to pump. Apparently it is a 12 year old Grundfos. I just didn't want them to shell out for a new one if it was possibly something else.

 

[Deleted member 2053]

Take it to bits first and examine it then. You will need a 4mm allen key....
Average life of a Grunfoss pump seems to be about 10 years so they have had their money's worth.

 

[Aqua Mechanica]

Thanks for the advice y'all

Ben 🙂

 

[mcmoby69]

before you start pulling the pump to bits! shut off all the rads upstairs. turn the rads on downstairs fully (both valves) fire the central heating up. do they get hot? if they do, it may be a balancing issue. sytem may have sludge build up at the valves(possible at the lowest points) opening and closing the valves may loosen it and get it moving. if it is sludge then a flush may be in order. fitting a new pump will not shift any blockages which you have to rule out first.