No call for central heating - problem solving

[dishman]

The plot thickens......I

I will need help clarifying the wiring set-up.

But, put simply, the pump does not seem to be getting 240V supplied to it when the timer is energised and calling for heat, which is...obviously confusing.

So accessing the pump area, I also discovered this fuse spur, which I forgot existed.



As I said, i energised the controller and did not detect a voltage on line and neutral.

Now, this is the fused spur and the corresponding back plate to the controller.
As a precaution I tested the fuse in the spur and it was fine, but that makes sense as the timer/controller gets power.



1. Cable comes from conduit and ends up in the as the red cable in CH call.
2. This goes to the pump.
3. Goes to N L and Earth on the back plate
4. Goes to boiler from N, HW call and earth

So, at the moment, for some reason, power is not getting to the pump it seems.


Edit: Just after posting this, I decided to double check the cables on the pump. The neutral seemed loose, and when testing the cable out, I got 240v.

I then re-interested (hoping this was the issue).....i powered up and called for CH I did now get 240v going to the pump! But alas.....no actual pumping.

So maybe I did get just just got an erroneous/mistaken reading on my first test, or maybe that neutral was loose. Who knows.

I opened the cap and gave the motor a manual spin (whilst energised) and it seems to spin fine.

From what i understand, it is unlikely to be the capacitor if I gave it a manual spin (while energised) and it did not power up.

So, the best option is potentially a compatible head replacement?
This system might be in for another year or so, so nothing long term is needed. Cheap and cheerful pattern part? Reconditioned Grundfos?

Are there any other things I should check first? Other cheaper repair options?

Pump did 28 years service according to the date stamp....not bad. As per the image it's a Grundfos UPS 15-50 x 18

 

[Harry Bloomfield]

So maybe I did get just just got an erroneous/mistaken reading on my first test, or maybe that neutral was loose. Who knows.

I opened the cap and gave the motor a manual spin (whilst energised) and it seems to spin fine.

From what i understand, it is unlikely to be the capacitor if I gave it a manual spin (while energised) and it did not power up.

So, the best option is potentially a compatible head replacement?
This system might be in for another year or so, so nothing long term is needed. Cheap and cheerful pattern part? Reconditioned Grundfos?

Are there any other things I should check first? Other cheaper repair options?

If you are getting 240v, at the pump, and the pump is not running, and the pump shaft is free, then you need a replacement pump.

 

[dishman]

I assume just replacing the pump head is an option? Rather than the whole pump.

Something like

Boiler-M8 RS25-6J Universal Replacement Pump Head – 6 m Head for Grundfos UPS 15-50/15-60

Buy the Boiler-M8 RS25-6J Universal Replacement Pump Head – a 6m head, 3-speed selector pump head compatible with Grundfos UPS 15-50/15-60 bases. Cast iron, 220-240V, 2-year warranty.

spares-direct.com

or

Grundfos boiler pump head UPS 15-50 P/N:59745400 12 months warranty

Fully refurbished Grundfos pump head 59745400. Refurbished and quality checked by experienced engineers and comes with 12 months warranty.

www.heatingandcateringparts.com

Grundfos UPS 15-50 15-60 Pump Head almost boiler OEM

PLEASE NOTE THIS IS ONLY PUMP HEAD GRUNDFOS 15-65 ariston alpha baxi main original worcester glowworm potterton vaillant sime can replace all boiler models

www.ukheatingpumps.co.uk

 

[Harry Bloomfield]

I assume just replacing the pump head is an option? Rather than the whole pump.

Yes, if you are certain there is 240v at the input to the pump, but you will need to be able to either isolate the water circuit, above, and below the pump - or drain down to replace the pump head.

 

[dishman]

I'm certain the pump is being supplied with 240v.
As per the picture above, it has those gate valves......I guess the question is whether they will work after not being used for about 30 years .

But I'm hoping a drain down will not be required.