heat sink radiator failing to warm up

[mscg]

Iam putting a new bathroom in a house. The central heating is microbore gravity fed and pumped with boiler timer and room stat. Having drained the system to fit new rad and fired up all is well except for a heat sink radiator near the immersion tank. It is tee'd off the flow and return and I think even when the central heating is off the hot water convects along the pipes are the radiator is always hot. Any way its stone cold now even when the central heating is on( all other rads hot) For some reason the bleed screw is at the bottom of the rad? - have bled it but no joy - any suggestions guys?

 

[stevetheplumber]

Iam putting a new bathroom in a house. The central heating is microbore gravity fed and pumped with boiler timer and room stat. Having drained the system to fit new rad and fired up all is well except for a heat sink radiator near the immersion tank. It is tee'd off the flow and return and I think even when the central heating is off the hot water convects along the pipes are the radiator is always hot. Any way its stone cold now even when the central heating is on( all other rads hot) For some reason the bleed screw is at the bottom of the rad? - have bled it but no joy - any suggestions guys?

if the bleed screw is at the bottom some one has fitted the radiator wrong you dont say which way its piped up if one valve is connected to a top tapping you have to crack open the union to vent the air

 

[mscg]

thankyou - yes one pipe feeds to the top so I will do as you suggest - do you think its likely to be an air lock then

 

[stevetheplumber]

yes its lust air trapped in the top of the rad that you normally vent out only in this case you use he union on the valve rather than a air vent