I can certainly suggest a 6m Wilo Yonos Pico that I installed 2 years ago in my 10 rad system like your own and it works perfectly, Grundfos or DAB is often the preferred choice of some, I will suggest one later.
Because you have chemically cleaned you system regularly, I would install the pump first and see how your system performs, if performing exactly the same, I would immediately remove it and re install the old pump until the power wash or whatever is carried out.
But if you are handy yourself, it only takes less than a hour to remove the existing pump head, inspect. clean and replace, the impeller may just be full of crap.
The pump head is the differential pressure (head) measured in meters between the pump suction and discharge and the chosen pump differential head required depends on the frictional resistances in the systems piping, radiator & fittings, boiler Hx resistance etc. at the required flow rate. A 6M pump will be quite adequate for most domestic systems but its very rarely that the pump would have to run on speed3 as a much lower head of say 2.5 to 3.5M is only needed to give the required flow rate.
Because you have chemically cleaned you system regularly, I would install the pump first and see how your system performs, if performing exactly the same, I would immediately remove it and re install the old pump until the power wash or whatever is carried out.
But if you are handy yourself, it only takes less than a hour to remove the existing pump head, inspect. clean and replace, the impeller may just be full of crap.
The pump head is the differential pressure (head) measured in meters between the pump suction and discharge and the chosen pump differential head required depends on the frictional resistances in the systems piping, radiator & fittings, boiler Hx resistance etc. at the required flow rate. A 6M pump will be quite adequate for most domestic systems but its very rarely that the pump would have to run on speed3 as a much lower head of say 2.5 to 3.5M is only needed to give the required flow rate.
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