Grundfos UPS 15-50 Fault - blockage?

[BLIND]

Hello everyone! I've had a scan through the first 2 pages of 'Grundfos pump faults' but can't find anything similar to the problem I have.

I would like to know of possible causes of pump failure. There is power going to the pump, it was fitted in the correct orientation and it was working fine for 2 days before failing. It sounds like the motor wants to spin but it blocked or stuck, this causes back pressure and activates pressure release gate and cuts out boiler.

History: Boiler kept over pressurising and cutting out; replaced expansion tank but fault remained; replaced pump and that fixed it; 2 months on and same fault has returned; expansion tank still ok so thought it might be a dodgy pump so replaced it and this time it lasted 2 days before pump fault returned.

My background: I am a novice plumber who bought a house 1yr ago with a 15yr old boiler and water tank. On moving into the house, I had the boiler serviced and although old, I was advised that it was on good condition but the thermo coupling may need to be replaced at some point.

I am looking to get a local certified plumber in to help diagnose the problem but any advice is most welcome.

Thanks in advance.

Billy

 

[Riley]

Muck in the system is most likely issue

 

[jtsplumbing]

can you give some information on boiler, have you made sure that all valves are open ??

 

[Ch4 plumbing]

Pump valve partially closed and restricting flow!

 

[BLIND]

Riley - thanks. I presume some kind of power flush would be needed to clear the system?

 

[BLIND]

JTS - I'll update boiler specs tonight but all valves are open and pump was working well for 2 days before fault appeared.

 

[BLIND]

CH4 - I'll look into how and why the pump valve is partially closed.

 

[BLIND]

Thank you for your replies.:smile5:

 

[jonnyswamp]

I've had tired pumps straight out of the box, give it a tap when you have power to it and see what happens
If it's a bit of crud it may get dislodged, if not it'll need taking off and inspecting
You can also take the large chrome screw out of the middle of the body to see if the shaft is spinning, this doesn't neccessarily mean the impeller is turning though but it's an easy place to start your checks

 

[BLIND]

Jonny - Thanks, I'll give that a try. I have removed the bleed screw and the shaft is turning but still no pumping. If it is a bit of crud, I'll give it a tap with a hammer and disassemble if necessary. If that fails, what would you suggest?

 

[jtsplumbing]

From your description you have a system boiler, Boiler over pressurising would not be due to pump, does pump feel very hot ?? or is it spinning and nothing moving, if the latter then impeller is not spinning, and you have a faulty pump out of interest what make/model boiler do you have ? do you have a hot water tank ? what other controls on system ? Photos if possible.

 

[BLIND]

Jts - I'll take some photos this evening. The pump is very warm to the touch. I have a hot water tank.

 

[Ch4 plumbing]

if the pump is "turning" but not pumping then maybe isolate and remove the pump head to inspect, some times the impellar breaks off the back but the pump still appears to turn.

 

[Riley]

If they have a system boiler then the cover should not be off the boiler as he's not gas safe

 

[BLIND]

 

[BLIND]

 

[BLIND]

[video=youtube;fQb1Powbqxc]https://www.youtube.com/watch?v=fQb1Powbqxc&feature=youtu.be[/video]

 

[BLIND]

Hello!

Progress: I removed bleed screw and checked if impeller was spinning, as you can see from video (I hope you can view it) the impeller was spinning but not constantly. I gave the pump a fair whack with a wooden mallet; turned it on and it started working again! Once pumping for about 5 minutes the body was hot to the touch. It continued to function for about 8 hours, at 06:30 this morning when the timer was set for the central heating to come on the boiler fired up but the pump was doing the same as it did in the video i.e. impeller spinning and stopping.

 

[BLIND]

If it was just muck in the system and the whack with a hammer dislodged it, then perhaps during the time overnight whilst the pump was dormant, muck had time to settle and get lodged in the pump internals so that when it tried to start pumping again it failed because of blockage? When I removed the bleed screw, there was no air being vented and I've vented the system from the highest point. I can't get my head around the pump working for a significant period of time but after having lain dormant for a period it failed to start up again 😕

 

[ShaunCorbs]

Best bet change the pump as it sounds like it's on the way out

 

[rpm]

Think I`ve got this right ; New pump failed after 2days, hot to touch when running.

So guessing at ; Very dirty water caused pump failure and or problem in pipes or air locked the pump at some stage or faulty pump at the start as new pump should not run hot, warm yes but not hot. Lastly correct pump duty for system?

 

[ShaunCorbs]

Think I`ve got this right ; New pump failed after 2days, hot to touch when running.

So guessing at ; Very dirty water caused pump failure and or problem in pipes or air locked the pump at some stage or faulty pump at the start as new pump should not run hot, warm yes but not hot. Lastly correct pump duty for system?

By the looks of the pump it's the old type so maybe old stock ??

 

[rpm]

By the looks of the pump it's the old type so maybe old stock ??

Haven`t seen the picture also don`t really know how long it was standing not being used and do people sell these as refurbished? All in all more questions than answers from me I`m afraid.

 

[BLIND]

Rpm - thanks for your comments. You're right, new pump from Screwfix was fitted as a like for like replacement of old pump. The problems started about 3 months ago: May bought new pump which was running fine for 3 months; August pump failed so I replaced it thinking that maybe the first one was a dud; replacement worked for 2 days before failing. I will go down the route of dirty water causing failure first. To clean the system, what should I be asking for? Power flush?

 

[rpm]

[DLMURL="http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/"]I'm looking for a Plumber or Gas Engineer[/DLMURL]

You could do a lot worse than post here for somebody.

 

[jonnyswamp]

Time to get someone in I think fella
Also get the electrics checked, could be cable/wiring fault

 

[BLIND]

Rodger that. Thank you all for the advice, it's much appreciated - I'll post a request for help on here and see if there is anyone in the Aberdeen area who can help.

Thanks again!

 

[Simon 45]

Hi
Has the pump been installed at the correct angle

 

[BLIND]

Hi Simon, The pump has been installed as a like for like replacement in the same orientation as the old pump. The old pump had been working for at least 9 months (I only moved into the property 1yr ago). The new pump had also been working for 2 days before the problem started.

 

[Simon 45]

Hi
Have you checked with the manufacturer the angles they have to be installed. I have never had a faulty Grundfos pump, may be I have been lucky. When not used for a long time the spindle needs to be turned via the air bleed screw. With a lot of modern day boilers they will not start up if the water is not circulating they have a built in motion sensor. May be someone has adjusted the pump and set it in the wrong position, before you moved into the house a few degrees can make a big difference.
I have also had pumps not working due to sludge, disconnect the pipes and clean out, the sludge should be visible in or around the pipes close to the pump. You may have an air lock.

 

[Riley]

Hi
Have you checked with the manufacturer the angles they have to be installed. I have never had a faulty Grundfos pump, may be I have been lucky. When not used for a long time the spindle needs to be turned via the air bleed screw. With a lot of modern day boilers they will not start up if the water is not circulating they have a built in motion sensor. May be someone has adjusted the pump and set it in the wrong position, before you moved into the house a few degrees can make a big difference.
I have also had pumps not working due to sludge, disconnect the pipes and clean out, the sludge should be visible in or around the pipes close to the pump. You may have an air lock.

I've had a couple go wrong in the short space of time. I've also seen it where other components have given up and have caused the pump not to start spinning

 

[Voidbetween]

Check u have 240v at pump if you are electrical competent - Volt stick can give an indication of this if u r not.
With voltage present remove middle vent screw and check with small electrical screwdriver to feel if pump is turning - if it is apply a small amount of pressure - if u can stop pump turning easily the the pump motor is at fault