GRUNDFOS SELECTRIC

[combwork]

Hi,

I'm a new member so please forgive me if I'm asking a question that's been asked before. I've a hot-water system using a GRUNDFOS SELECTRIC pump. Just above and below the pump there's what looks like a screw on collar. Next to each collar there's a small on/off valve; turn it 90 degrees one way or the other and the water turns on or off.

The pump rotor sounded as if it had picked up a bit of grit or something. With the valves turned off I pulled the pump body. No problem with the rotor. It all went back together and sealed ok but when I turned each valve back on they both leaked. Not a small leak; a fine water spray. I don't know if the valves unscrew but they don't seem to. After turning each one on and off a few times they stopped leaking but only when turned off. Very sensitive; turn the valve a fraction and it starts to leak.

Can anyone give me advice please? It's as if they have internal O ring seals which over time have become brittle.

 

[TCCHeating]

Get some decent pegler pump valves. Unfortunately now you have turned them it is very unlikely they will seal again. You will need to drain the system to replace them. I'm afraid you will have to put this one down to experience! You now know never to touch screwdriver type pump isolation valves

 

[petit_pablo]

haha, yea they are done for and will need changing.

I never touch those valves, they almost leak before you touch them

 

[ianmcd]

You will have to replace them, use gate valves dont use ballofix valves which is what you have they should be banned they are absolute shoite

This is what you need but you will have to check whether you need 22mm or 28mm most likely 22mm

http://www.ebay.co.uk/itm/2-X-PUMP-...DIY_Materials_Plumbing_MJ&hash=item5d33ded756

 

[combwork]

Thank you gentlemen, I had a horrible feeling you might say that.

It's an odd system. The house was built around 1900. The hot water cylinder has the top and bottom riveted on. The header tank in the attic is made out of lead painted inside and supported in a wood frame. Going by hatch access and the size of the tank it must have been made in place. It supplies cold water feed to the hot water upstairs and downstairs. Cold water's off the mains except the cold water supply to the bathroom upstairs; this comes from the lead cistern.

My guess is the system was originally gravity fed off an old solid fuel range or something and was converted to gas fired hot water supply and central heating in the early 1990's. The solder and pipework is very well done so I guess this was professionally done. Where access is very difficult a few parts of 1" internal diameter pipework are still used but joined onto modern pipework as soon as possible.

I'm not a plumber, I repair antique musical boxes. Why not leave the work to a professional? Because some of the original pipework runs behind original wood paneling. Doing the job properly, stripping out and replacing original dark varnished wood would be too expensive.

There's a hell of a lot of guesswork here; all I'm doing is trying to keep the thing watertight until we move.

 

[ianmcd]

try and source a local plumber/heating engineer who is willing to carry out the job , if it was me with your system I would use a freezer kit to isolate each valve one at a time and save from draining down

 

[combwork]

Get some decent pegler pump valves. Unfortunately now you have turned them it is very unlikely they will seal again. You will need to drain the system to replace them. I'm afraid you will have to put this one down to experience! You now know never to touch screwdriver type pump isolation valves

.

Thank you again. They don't have screwdriver slots; they have raised narrow rectangular ridges across the top. Can only be turned with a fine adjustable spanner or pliers. I guess it comes to the same thing though; as been said, lesson learned. The lower one only seals when fully open, the upper one only when closed. Oh well

In reply I'd be happy to help should anyone want advice on cleaning a 19@ musical box. Rule No1 is NEVER work on the governor if the mainspring's wound, even if only a little bit..............

Many Thanks,

combwork

 

[xr4x4]

I can't be sure without a picture....but...

Can't you unscrew the nut, wrap some ptfe tape round the spindle and do the nut back up?

 

[combwork]

I can't be sure without a picture....but...

Can't you unscrew the nut, wrap some ptfe tape round the spindle and do the nut back up?

I don't think so. To do this I'd have to drain the system and if it didn't work, do it all again. I've ordered a pair of 22mm spindle valves. With luck (and maybe shortening a pipe) they should do the trick.

Final question. With the supply switch turned on the pump runs all the time irrespective of control box settings. Even with the boiler switched off at the thermostat it still runs. I can probably find a switched live on the control box but are pumps like this happy being switched on and off several times a day? I'm thinking the current draw from the pump might be more than the control box is designed to take.

 

[muggles]

They're designed to be switched on and off a lot, rather than left running. The old ones also use quite a bit of electric so if you can wire it up to be switched you'll save yourself some money

 

[combwork]

They're designed to be switched on and off a lot, rather than left running. The old ones also use quite a bit of electric so if you can wire it up to be switched you'll save yourself some money

Thanks Muggles, much appreciated.

 

[xr4x4]

I can't be sure without a picture....but...

Can't you unscrew the nut, wrap some ptfe tape round the spindle and do the nut back up?

I don't think so. To do this I'd have to drain the system and if it didn't work, do it all again. I've ordered a pair of 22mm spindle valves. With luck (and maybe shortening a pipe) they should do the trick.

Final question. With the supply switch turned on the pump runs all the time irrespective of control box settings. Even with the boiler switched off at the thermostat it still runs. I can probably find a switched live on the control box but are pumps like this happy being switched on and off several times a day? I'm thinking the current draw from the pump might be more than the control box is designed to take.

Most gate valves you can still do it, even when system is live.

 

[TCCHeating]

Thank you again. They don't have screwdriver slots; they have raised narrow rectangular ridges across the top. Can only be turned with a fine adjustable spanner or pliers.

Ah ok. I know the ones you mean. Still just as leaky as the screwdriver type ones as they don't have the gland nut Xr4x4 is referring to. The valves you have ordered should have the gland nut. So if they were to leak in the future they can be repaired easily without draining as per xr4x4's earlier advice