When you say turn off power is that just turn the boiler off or shut down electrics thanks so
Kevin
November 2016
I followed the advice and find that my Grundfos pump is running , seems that I need a new Capacitor. My pump is a Grundfos UPS 15 45 x18 . The original Capacitor is Bosch MKP 3uF +/-10 % b , 320V ~DB -25/85 *C . Measures Length 60 mm by Diameter 25 mm. I wonder what is the correct replacement capacitor from Maplin or other supplier ?
Brian
December 2013
took tractorgears advice , I checked when heating turned on there was 240v at supply in to valve ,that was ok then took out the big bleed screw and inserted a screwdriver in end of pump and span it to kickstart the pump, the pump worked so purchased a new capactitor number n39kg fitted it buy pushing in the two wires and them the heating pump worked fine
billiy
April 2013
Replacement capacitor available from Maplin, stock No. N39KG. This is a wire ended 2.5 microfarad 400 volt capacitor which is physically identical to original fitted by Grundfoss and has better voltage rating. Price is £3.09. Push fit wire leads into terminals 4&8. Tip: strip wire ends to same length as on original capacitor or they will not make proper contact.
Tactorgear
February 2013
If capacitor is suspected as being defective, to prove that this is the case, remove bleed screw insert small slotted screwdriver to spin impeller in direction of arrow while power is applied to pump. This action should "kick start" pump if pump motor windings are OK and pump is not seized. Pump will continue to run until power is removed BUT it will not restart when power is re-applied without a further kick start; this is what the starting capacitor does automatically when it functions correctly.
Tactorgear
February 2013
John from Malvern can you tell us who was the ebayer that sells refurbished Grundfos UPS pumps?
Many thanks
Richard
November 2012
Just had a similar problem and found a solution from an ebayer who sells refurbished UPS 15-60s for £35. I bought one off him anyway then swapped it over with the seized one. Dismantled the old one by undoing the four screws that hold it together tapped out the inner impellar assembly from the other side (you can unscrew the silver slotted disk and use a large screwdriver and small hammer and gentle taps). Then clean under running water turning the impeller back and forth to free it. Easy job. Nice one ebayer!
John from Malvern
November 2012
Greiga.......Great work. Checked all that has been advised in your blog and system is all working again. LEGEND.
Shaun
October 2012
...thanks to "greiga" for the tip (remember my Dad doing something like this when I was a wee kid), as it has just got my pump moving again.
sean
February 2011
You could remove venting cap and try turning with small screwdriver, if it rotates freely it may be that the start up capacitor is defective. observe correct position of the 2 wires, I think that it is terminals 4 and 8 this problem may be more noticable when things are hot.
Paul
December 2010
Thanks to griega! Your advice worked PERFECTLY & now I have central heating again & it didn't cost me a penny!
Phil
Phil T.
December 2010
Before going for the pump first check the switch
to see if " central heating plus hot water " has been
selected .
A generic Grundfos manual is available from :
www.screwfix.com/sfd/i/cat/pdfs/01/p3983301.pdf .
With Grundfos UPS 15-50x18 there are no
isolating valves and access is via a central screw.
Putting a little "Fairy Liquid" or similar washing up
liquid into the hole softens the water and has a
beneficial lubricating effect , perhaps more so than
bashing the pump.
Philip
December 2009
1. turn off power
2. put plate or small bucket underneath
3. remove cap with large slotted screwdriver
4. steam and a little water will probably come out
5. wait a few mins
6. use small slotted screwdriver to rotate pump clockwise
7. do this for about 20 turns
8. power up
9 if it doesnt rotate on its own use screwdriver and it should kick start it
greiga
December 2008
the cause of a jamming pump is sludge or the bearing or it's just knackered
hi-spec plumbing & heating.
March 2008
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