Grundfos 15-50 pump - can it be cleaned???

[Vinnie]

My combi boiler has a Grundfos 15-50 pump. The pump started making unusual noises intermittently and varied in volume. Central heating first and now hot water have stopped working. Hot water did work for a while when I ran the hot water taps at a low volume. I have drained the boiler - water brown in colour. I have also removed the pump head by unscrewing the 4 allen key screw. (Thanks Mickyg for your advice so far). Thought this might allow me to see if there was dirt jamming the pump or limiting the water flow. Having removed the pump head (which just seams to be the electrics),I see I have very little to work with as the impeller etc.. are still incased . I can see through the whole in the front that there is dirt (black grit) in the pump. but how do I get into it to clean it??? or can I??? Have tried to remove the pump itself but I can't budge the nuts.

Fyi the boiler is a Protherm 80e - 7 years old

 

[mickyg]

View media item 4266
With the pump head in your hand you will see the bottom look something similar to my wonderful piece of artwork above
Any muck caught in the places pointed out should be cleaned out as best as possible. More likely you may need to replace the pump, but you can try cleaning it if you like. Your water quality is a bit of a concern as the plate heat exchangers on these boilers are prone to blocking on dirty systems, so that will probably be your next problem

 

[Vinnie]

Your drawing and words seem to indicate I should have more in my hand that I actually do. What I have is the electrics. This impellor and parts I need to clean are still in the main body of the pump in the boiler Is this correct.[/img]

 

[ChrisR]

So you're looking at a shiny cylindrical part about 4cm diiameter, right? In that case you have the stator coils in your hand, and the spinny bits have stuck to the gasket on the wet end. Thump it sideways with the heel of your hand and it'll probably come off.
A dirty rotor, and an old but clean one:

 

[Vinnie]

cool, got it. Mine looks looks dirty but not as bad is your image. also some loose black bits of grime. will clean as best I can. should it spin freely within the shiny sliver casing or should it be locked tight. mine is locked tight, won't budge

 

[Vinnie]

now it moves but not very freely

 

[kirkgas]

not sure if you have done this or not but with the pump head in your hand remove the bleed screw cover and gently tap the screw to split the head into two parts, clean the rotor shaft with washing powder and it will come up gleaming, the tolerances are fine and the cleaning will make a huge difference

 

[Vinnie]

Thanks guys,

Pump clean any working. Have hot water back. Doesn't fix the problem with the CH . Keeps cutting out at the same temp. Could dirt somewhere else be restricting water flow and cause overheating or could there be other possabilities???? Low pressure in the expansion tank? Dirt in differential valve??? something electrical. Have cleaned the heat exchanger water is flowing through it fine. Replaced the Thermistor at it looked damaged (wire came away from therminal).

 

[Vinnie]

Revisiting the cleaning of the pump as I heard noise coming from it last night.

Last time I hadn't cleaned the rotor shaft and now when I shake the pump head (shiny cylindrical part minus the stator coils) I can hear little bits rattling around in it. some black grit did flow out in the water.

Question how do I get at the rotor shaft.

Kirkgas mentioned
"not sure if you have done this or not but with the pump head in your hand remove the bleed screw cover and gently tap the screw to split the head into two parts, clean the rotor shaft with washing powder and it will come up gleaming, the tolerances are fine and the cleaning will make a huge difference"

I have tried this to remove the rotor shaft from within the "shiny cylindrical part " but is is jammed. It it a matter of tapping harder or do I need to undo something else. I'm afraid of breaking it.

Thanks

 

[kirkgas]

my description wasn't great to be honest!! with the allen srews removed and the pump head only in your hand remove the bleed screw cap and gently (or not so gently) hit the exposed part to seperate the two parts then clean everything up as best you can with soap powder

 

[kirkgas]

don't know if these 3 photos will help!! PS please note this pump is brand new and shinyView media item 4468 View media item 4469 View media item 4470