grundfos selectric 15/60

[robt2005]

Hi There,

I have a problem which i think is a faulty grundfos selectric 15/60 pump. My boiler periodically fires up, but then turns off a few minutes later. The pump is making a loud rattling noise. The pump itself is hot and also the pipes either side. I have read about turning the shaft but the info is not clear regarding the screw on the front being a bleed screw? I have unscrewed this half a turn to see if water is coming out and it does, but is it safe to access the shaft by removing this silver coloured screw? Also, is it worth doing this as there has been hot water (but not any more because the boiler wont fire up). I have also set the the speed switch to "2" as it was on "3" but no difference. Does this sound like a classic faulty pump problem?

Any help would be greatly appreciated.

Cheers, Rob

 

[stardanny]

Does the heating or hot water come on fully?

If you have a feed and expansion tank ( small tank in loft ) check that it has water in it.

It will be fine to remove silver screw, have a towel handy and open it and check if spindle is spinning.

It could mean that the pump is worn out and not pumping well.

Daniel.

 

[bellairaphon]

What boiler do you have?

Nath

 

[robt2005]

Hi There,

Thanks for reply. I turned off the power supply in the airing cupboard to the pump and let the whole thing cool down for last couple of hours. I then switched back on and turned the hot water on and sure enough the boiler fired up and i could hear water flowing in the pipes and pump but that lasted for about 2 mins and boiler has gone off. I have a potterton boiler.

 

[bellairaphon]

Ok has Danny has said you need to check if you have water in your system. It could be a possible blocked cold feed to your system.

Nath

 

[robt2005]

Hi There,

OK have been up in loft and there is a full tank of water. I tested the ballcock valve by pressing the ball down and water flowed in ok.

Cheers Guys

 

[bellairaphon]

One big tank and a small tank? If the small tank is full then you have a blocked cold feed.

Nath

 

[robt2005]

Hi Nath,

Have been back in loft and yes there is a large tank and a small tank next to it. Its about half full which looks normal by the water line level and the ballcock works ok.

 

[JohnD]

does the pump get hotter than the pipes?

When you bleed the highest radiator in the house, does water squirt out forcefully, without dying away?

 

[robt2005]

Hi Nath

I reckon the pump does get hotter (feels really hot to me) than the pipes either side of it, even though they are really hot, and yes the furthest rad does squirt water out without fading away.

Rob

 

[JohnD]

if the pump is hotter than the pipes, then water is not flowing through it. Either the rotating part is jammed; or the pump is dry; or the flow is obstructed.

Start by undoing the silver screw in the centre of the pump (turned off). Do a few drips of water come out?

If you put a screwdriver through the screwhole, and engage the slot in the end of the spindle, does it spin easily?

How long has this been happening?

Does the hot water cylinder heat correctly?

Do any of the radiators get hot? e.g. some of the upstairs ones?

the furthest rad does squirt water out without fading away.

Not the furthest rad. The HIGHEST rad in the house.

 

[robt2005]

Hi There,

Start by undoing the silver screw in the centre of the pump (turned off). Do a few drips of water come out?

Yes drips of water come out

If you put a screwdriver through the screwhole, and engage the slot in the end of the spindle, does it spin easily?

Yes - seems to spin easily

How long has this been happening?

Just today (as in the boiler firing up and then 2 mins later it goes off) but i have noticed that the pump has been noisy for quite a while.

Does the hot water cylinder heat correctly?

I don't know. It has a polystyrene type cover on it. The pipe coming out of the top of it gets pretty hot.

Do any of the radiators get hot? e.g. some of the upstairs ones?

No - because the boiler is not constantly on, the rads do not get hot. What i mean is, i turn on the heating but the boiler goes off but its the same if i turn on just the hot water, the boiler goes off after 1 - 2 mins.

 

[robt2005]

Sorry - yes the furthest rad is the highest rad

Thanks

 

[JohnD]

If the pump is rattling, it is probably worn out, but might be dry. If it drips, it is probably not dry, so it is probably worn out or clogged, or both. A new pump is not very expensive. If you are going to change it, have a look inside the old pump, and the pump valves, to see if they are clogged with hardened sediment.


edited
on consideration, the following is probably not relevant, you can give it a try if you want

I am also considering if the primary circulation from the boiler is blocked, or if it is short-circuiting.


turn off and let it get cold. Use up all the hot water in your cylinder

turn it on, with CH on, HW off, room stat turned up.

Feel along the pipes, near the boiler, around the pump, by the 3-port valve, near the cylinder, and if any rads start to get hot. see how far the pipes get hot, and if the tap water heats up.

Later turn off and let it get cold. Use up all the hot water in your cylinder.

turn it on, with HW on, CH off, room stat turned down..

Feel along the pipes, near the boiler, around the pump, by the 3-port valve, near the cylinder, and if any rads start to get hot. see how far the pipes get hot, and if the tap water heats up.

 

[robt2005]

OK John - many Thanks for your advice.

Cheers