Grundfos UPS2 15-50/60 startup problem

[Steve75]

I have had a grundfos UPS2 15-50/60 pump fitted as a replacement for a failed older UPS type pump.

When the boiler turns on and the pump is powered up it seems to start and stop or pulse for approx. 2 minutes and then run properly, you can hear and feel the initial kick as the pump energises and hear it spin for approx. 1/2 to 1 second before repeating. It is actually the second pump to do this, the first was replaced as we thought it was faulty. I have checked the supply to the pump and it is a steady 235VAC, i've even powered the pump by connecting it to a 3 pin plug and socket thus eliminating the boiler pcb and controller and the same thing happens.

I emailed grundfos and thier reply was that it could be a compatibilty issue with the pump and my system and suggested fitting an alpha2 pump, seems a bit overkill to me and strange because the old pump worked fine for a number of years until it failed and the UPS2 is supposed to be a direct replacement.
It's a sealed pressurised system, baxi solo 3 50pf boiler and 8 rads. Expansion vessel is working fine.

Any ideas?

 

[TCCHeating]

Ups2 has been riddled with problems since launch. In my opinion and many other professionals on here. They are not fit for purpose. I certainly would always go for the alpha2. As it is a much more reliable pump and only a bit more expensive than the ups2. If I were you, i would see if you can get your money back from either grundfoss or the supplier and fit an alpha2.

 

[bill2013]

Fitted ups2 6 months ago,no problems at all.I expected it to pulse but it runs smoothly,pushes the water around 12 rads on setting 1.I don't have a sealed system

 

[Agile]

Why did you expect it to pulse Bill?

Tony

 

[bill2013]

The instructions that came with the Pump where not that good,mostly pictures.I took it that this pump adjusted its self to run as economically as possible depending on the varying demands of the system(trvs opening and closeing)so it would need to vary its speed or pulse

 

[D_Hailsham]

The instructions that came with the Pump where not that good,mostly pictures.I took it that this pump adjusted its self to run as economically as possible depending on the varying demands of the system(trvs opening and closeing)so it would need to vary its speed or pulse

The UPS2 can run in either fixed speed mode (like the 'old' Selectrics) or in proportional pressure mode. The mode is selected by the button.

In proportional pressure mode the speed is changed electronically by varying the frequency of the motors supply voltage according to the pressure difference across the pump. I can't see any reason why the pump should pulse.

 

[Corgigrouch]

And yet they do pulse... I have had a few pulsing for the first few minutes But they always fire up after a little while....One day I'll get round to asking Grundfos about it.....

 

[Dan Robinson]

In proportional pressure mode the speed is changed electronically by varying the frequency of the motors supply voltage according to the pressure difference across the pump. I can't see any reason why the pump should pulse.

Are you sure about that?

 

[D_Hailsham]

In proportional pressure mode the speed is changed electronically by varying the frequency of the motors supply voltage according to the pressure difference across the pump. I can't see any reason why the pump should pulse.

Are you sure about that?

According to the UPS2 Data booklet:

1. The UPS2 is a complete range of circulator pumps with the following features:
• integrated differential-pressure control enabling adjustment of pump performance to the actual system requirement
• motor based on permanent-magnet/compact-rotor technology.

2. The motor is a 4-pole synchronous permanent-magnet motor.

The only way I know of changing the speed of a synchronous motor is by altering the frequency of the AC voltage supplied to the motor.

 

[Agile]

I have to agree with David here!

 

[Dan Robinson]

Wow. . Never saw the bit about proportional control before now. Serves them right for using those stupid picture leaflets instead of proper manuals.


Thanks and apologies David.

 

[Richardthe3rd]

Wow. . Never saw the bit about proportional control before now. Serves them right for using those stupid picture leaflets instead of proper manuals.


Thanks and apologies David.

That's for all the 'Swiss rolls' & 'Lats' that can't read English Dan.

 

[Dan Robinson]

It annoys the 'arris off me that's for sure.

Not as much as those stooooooooooooooopid wiring terminals. . Only fit Grundfos now if there is no choice.