I have recently replaced my grundfos circulating pump because the upstairs rads did not stay hot even after bleeding the system fully. The rads only stayed warm at the bottom when you switch on the pump again. The domestic HW also did not get hot from the boiler, only the immersion. One of the flow/return pipes to the tank is hot (bottom pipe), the upper pipe is cold. When you bleed the system, the top of the rad gets hot and the upper pipe to the HW tank. Switch on the pump again and after a while the top of the rad etc, cool down.
I have changed the pump, but it has no effect.
I think I may be at the max height for a 6.0m head circ pump.????
Any ideas.???
I have changed the pump, but it has no effect.
I think I may be at the max height for a 6.0m head circ pump.????
Any ideas.???