Grundfos UPS 15-50 pump intermittently trips MCB/RCD – repair or replacement?

[Johntheo5]

They all have the same/very similar efficiencies, the UPS3, above, on CP1 at 3.0M & 1ms/hr (16.7LPM) flow consumes 22W, my Wilo Yonos Pico 6M would consume 21W. Unfortunately, the UPS3 (& UPS2) do not display the power consumption, most, now, display the flow and the power consumption.

 

[fixitflav]

They all have the same/very similar efficiencies, the UPS3, above, on CP1 at 3.0M & 1ms/hr (16.7LPM) flow consumes 22W, my Wilo Yonos Pico 6M would consume 21W. Unfortunately, the UPS3 (& UPS2) do not display the power consumption, most, now, display the flow and the power consumption.

Are those curves for the UPS3? Perhaps I'm reading them wrong, but from the points with the square blobs, 3.5m head, 1.8 m^3/h and ~ 0.04kW, I calculate efficiency 44%, not 69.2%. The latter figure would be impressive overall efficiency for a small pump.
It's a while since I looked at it, but I thought the UPS 15-50 and UPS2 were quite a bit lower efficiency. Not that it matters much, reliability is more important.

 

[Johntheo5]

Are those curves for the UPS3? Perhaps I'm reading them wrong, but from the points with the square blobs, 3.5m head, 1.8 m^3/h and ~ 0.04kW, I calculate efficiency 44%, not 69.2%. The latter figure would be impressive overall efficiency for a small pump.
It's a while since I looked at it, but I thought the UPS 15-50 and UPS2 were quite a bit lower efficiency. Not that it matters much, reliability is more important.

No the efficiency for both is the same in the examples I gave in posts #14&16, the hydraulic power required, is, (using my calc) (MXLPM)/6.14, so (3X16.666)/6.14, 8.143W, actual power ~ 21W, Effic=8.143/21, 38.78%

Its difficult to give a fair comparison for the UPS2 vs the 6M Wilo as the UPS2 has no CP curves, but the Wilo does and the required head can be incrementally changed in 0.1M steps in both CP & PP modes.
The UPS2 running in CC1 (4.0M) will consume 23W at a flowrate of 1m3/hr at a head of 2.8M, the Wilo set to a CP setting of 2.8M will consume 20W at 1m3/hr, to give a UPS2 efficiency of (2.8*16.666/6.14)/23, 33.04%, the Wilo gives a efficiency of, (2.8*16.666/6.14)/20, 38% BUT the Wilo, is running closer to its design efficiency because its now a "2.8M" pump whereas the UPS2 is using a "4M" pump to give a 2.8M head.

I've attached links to both the 6M & 8M Wilos, for interest. Grundfos probably provide the same info in their product centre.

https://wilo.com/ie/en/Products-and-expertise/en/products/yonos-pico_id199/4215515?tab=product_technical&tab2=product_pumpcurve

https://wilo.com/gb/en/Products/en/products/yonos-pico_id199/4215517?tab=product_technical&tab2=product_pumpcurve

Wilo 6M