I am just about to replace a 22 year old and very noisy Grundfos 15/60 with a new pump (the same model). All other components in the unpressurised vented system are as installed by the house builder in 1989. Everything has been cleaned, flushed inhibited etc.
In the install instructions it says the pump should ideally be mounted vertically pumping UPWARDS however the existing pump is fitted pumping DOWNWARDS.
Now I am worried that the noise problem is caused by air in the pump (cavitation?) and the new pump will have the same problem. Obviously turning the pump upside down is not an option cos then the boiler flow and return will be swapped.
There is an automatic air valve but its on the hot tank side of the diverter valve. Grundfos say this must be before the pump and effective (their bold type).
Does anyone have experience of Grunfos pumping downwards? How do I tell if the automatic air valve is still effective after this time?
In the install instructions it says the pump should ideally be mounted vertically pumping UPWARDS however the existing pump is fitted pumping DOWNWARDS.
Now I am worried that the noise problem is caused by air in the pump (cavitation?) and the new pump will have the same problem. Obviously turning the pump upside down is not an option cos then the boiler flow and return will be swapped.
There is an automatic air valve but its on the hot tank side of the diverter valve. Grundfos say this must be before the pump and effective (their bold type).
Does anyone have experience of Grunfos pumping downwards? How do I tell if the automatic air valve is still effective after this time?