New Grundfos slow to start after 2 weeks, replacement did the same...

[Thandar]

Hi Tony,
How can I check that, one is at the back of the house and the other at the front, on different floors, I could run a cable between them and check for continuty on the existing cable? The cable even goes up into the attic before dropping into the basement where the boiler is, it's a long run...
If I pull the Orange wire maybe, then the power has to be coming from the other wire?
Also I had a brainwave and tried manually spinning the spindle when it's trying to fine, like a starting handle on an old car, if I timed it at the same time it sent a start pulse then it worked...for a second, spun real fast, so it is like it's not getting any power except when it's trying to start up, even though the input seems to showing 240V, I really need to get to the power section on the pump...

 

[D_Hailsham]

I can't get the electrical cover off without taking the pump head off as it's too tight against the isolator valve

Remove head, rotate 90 degrees clockwise, replace head.

The electrical cover is now on the top. Simples.

You now check for 240 V at the pump.

When you changed the pump, did you change the cable?

 

[jackthom]

Can you slightly loosen the pump isolation valve and rotate it out of the way of the electrical cover?

 

[D_Hailsham]

Please tell us which boiler you have - make and exact model. (3rd time of asking. )

 

[Thandar]

I think putting the electrics on the top position will mean the wooden beam will stop it coming off instead, I think I'll have to pull it off, take off the cover then put it back in place without it...
I can try moving the isolator but it it's a bit of a distance, I'm thinking that getting the body off is the only option
The boiler is a Gloworm Fuelsaver F, certainly not state of the art, sorry for the delay as I've not been down there recently and it's a right pain getting to the boiler to read the nameplate
The system is perfect after 2-3 minutes, but it's a hell of a noise until then

 

[Thandar]

Would this be a viable test?
I could pull the wires to the pump, its just the 3 standard live, neutral and earth as far as I can tell, put them in a plug and see what happens?
If it's not the pump it should fire straight up, and if it's the same then it's somethign in the pump electrics, if it never starts then it needs the water heating from the boiler.
Do you think it's worth trying?

 

[D_Hailsham]

The boiler is a Gloworm Fuelsaver F, ... The system is perfect after 2-3 minutes, but it's a hell of a noise until then

The pump has to be connected to the boiler if it's a Fuelsaver.

You will probably find that the brown wire from the pump connects to a terminal in the junction box, with a second wire, in a separate cable, going to the boiler. The second cable will probably carry the wire from the valve orange to the boiler. Open the junction box, take a pic of the wiring and post it.

Are you saying that the problem only lasts 2-3 minutes, then it goes away completely?

 

[simond]

Just wire it into the mains as you suggest, all this other fannying around is a waste of time.

Bearing mind that the gurgling etc could be the thing running dry too, but the 230v straight in will prove whether the boiler pump overrun circuit is working correctly. If there is a dirty relay in the boiler or dry joint you could still be reading 230v at the pump terminals with no current.

 

[Thandar]

Here is a pc of the rats nest that is the junction box, figured I need one if I'm going to try powering it outside this...
I've circled the points the three wires are attached, the live is the brown one at the right end, with the orange from the valve and the neutral from the water heater themostat for some reason, the red wire it connects to goes to the only cable from the attic that goes in at the the bottom of the box on the second picture...

 

[Thandar]

OK, Ran the pump from mains and it's exactly the same, it tries to start for 2-3 minutes and then starts running fine, no sign of it overheating (able to check as it's now running without the boiler).
This is really stange...could be the start capacitor, but how do 2 go identically after 2 weeks each, also manually spinning the motor should start it if that was the case but I couldn't get it to go for more than a split second

 

[Agile]

I think those smart pumps are not just a simple induction motor like the old ones. That means driven by triacs.

Consequently I don't know what to suggest apart from you have now tested them as far as you can and I would conclude that it is a pump fault and perhaps coincidence or a faulty batch if they both came from the same place.

Although you are meant to use them I have a more comfortable feeling with the old ones!

Tony

 

[Dan Robinson]

Perfect testimony as to why we stopped using grundfos outside of OEM applications.

 

[simond]

Never had a single duff Grundfos pump...yet. Just for confirmation, when you apply 230v to the pump, are you saying the indicator lights dont illuminate for 2-3mins, the impeller definitely doesn't turn for 2-3mins (verified by removing screw), or the water isn't moving for 2-3 mins?

 

[D_Hailsham]

OK, Ran the pump from mains and it's exactly the same, it tries to start for 2-3 minutes and then starts running fine, no sign of it overheating (able to check as it's now running without the boiler).

I suggest you contact Grundfos and explain the problem to them.

Grundfos UK

Tel: 01525 850000

Email:[email protected]

 

[simond]

Yes, they'll send someone straight over.