Faulty Circulator Pump? Wiring Issues

Scottish1 · Sep 24, 2021

Hi

In a new property and the boiler is not firing.

Investigating the junction box, there is a disconnected wire
-labelled Unknown Red in image
This cable runs from the boiler to the junction box.

My interpretation is that this is likely to be circulating pump neutral?

Any advice would be appreciated!

Thanks

Avo Mk8 · Sep 24, 2021

I'm having difficulty correlating your table with the numbered terminals/functions in the connection box shown at the top of the diagram (presumably inside the boiler?)
Are you able to clarify exactly which wire(s) connect to terminals 1 and 2?
And confirm terminals 1 and 2 are not linked?
Or do you not have access to this? I think to diagnose this you need to be certain exactly which wire is what, and you probably need someone gas qualified to go inside the boiler

PS a red wire shouldn't be a neutral, and I don't think that is what it is - could be wrong?

as things stand, the boiler doesn't seem to have a neutral, a switched live, or a permanent live!

Avo Mk8 · Sep 24, 2021

Hi. Just to clarify - when you say 'new property' do you mean new to you, or a new build?
The red and black wiring implies the original installation was done at least 15 years ago, so hopefully not new build!
Is this a new boiler install?

Scottish1 · Sep 24, 2021

Hi Avo

Yes, old house but new to me ~1990's build.
Boiler is a Glow Worm Ultracom 30hxi installed~2008.

That is my challenge, the numbered wiring diagram is from the boilers instruction manual, however, I cannot get into the boiler to confirm the terminals :-(. So I dont know if 1 and 2 are linked.
I was hoping a bright spark on here like yourself might be possible to back-calculate the wiring?

Interestingly when I request the heating on with the controller I can hear the 3-way valve operate but the circulating pump does not start and nor does the boiler fire.

Thanks for your help!

Avo Mk8 · Sep 24, 2021

Scottish1 said:
Hi Avo

Yes, old house but new to me ~1990's build.
Boiler is a Glow Worm Ultracom 30hxi installed~2008.

That is my challenge, the numbered wiring diagram is from the boilers instruction manual, however, I cannot get into the boiler to confirm the terminals :-(. So I dont know if 1 and 2 are linked.
I was hoping a bright spark on here like yourself might be possible to back-calculate the wiring?

Interestingly when I request the heating on with the controller I can hear the 3-way valve operate but the circulating pump does not start and nor does the boiler fire.

Thanks for your help!

The boiler is responsible for powering the pump. So no surprise the pump doesn't do anything if the boiler doesn't have a live feed.
If the ONLY cable to the boiler is that with the red, yel, blu, earth, conductors, one might deduce that has to be the mains feed. You seem to have established the yellow is connected to pump L, so that leaves red, blu, earth. Should those be providing mains power to the boiler? If someone has already disconnected them, that may indicate there was a problem previously.
I'm not going to suggest you blindly reconnect those without first establishing it would be safe, or getting someone in to do that for you.
Best of luck resolving it.

loz2754 · Sep 24, 2021

You'll need access to the boiler terminal board to see what goes where.

Avo Mk8 · Sep 24, 2021

The manual for your boiler shows an electrical connection 'cartridge' accessible from underneath the boiler. Does this look like yours?
If so, with the boiler isolated, and assuming competence to investigate, it would be quite legitimate for you to unscrew the torx? screws that hold the cartridge up, pull it out, and open the cartridge to check which wire goes to which pin.
But only if you have the same version of interconnect as shown below.

[ElectriciansForums.net] Faulty Circulator Pump? Wiring Issues

https://www.wolseley.co.uk/wcsstore7.00.805.913/ExtendedSitesCatalogAssetStore/images/products/AssetPush/DTP_AssetPushHighRes/std.lang.all/ti/on/Glowworm_UltracomHXI_Installation.pdf

Scottish1 · Sep 24, 2021

Thanks all, some progress.

I have continuity tested the electrical cartridge to identify what's what.
See highlighted in Red below what is the mystery cable.

I also confirmed Pump Live (Boiler Yellow) is correct.

Now knowing that Unknown Red is on the Live and highlighted in the diagram where should it be located?

Thanks!

Avo Mk8 · Sep 24, 2021

If it's a Y plan system I think that red wire should go to the orange wire on the 3 port valve.
I'll get back to you later.

snowhead · Sep 24, 2021

Is this New to you property Owned by you or Rented?
If rented it's the Landlords responsibility to sort it.

If recently purchased by you, did the heating work when you looked around it?
Were you supplied with any paperwork for servicing, recent or otherwise, to show the heating was working without problems.

Was the boiler wiring table at the property or have you compiled that?
If that Red wire has been disconnected recently it's been done for a reason, and that needs finding before the wire is reconnected

loz2754 · Sep 24, 2021

Avo Mk8 said:
If it's a Y plan system I think that red wire should go to the orange wire on the 3 port valve.
I'll get back to you later.

That's correct.
The only thing I don't see is a room stat. Unless it's built in to the 'controller'.

Avo Mk8 · Sep 24, 2021

Back in the room.
It would be helpful to understand the overall position as per snowhead, even if all you want to do is "make it work".

Could you clarify what the 'three way switch' is (you do mean 3-way, not 3-pole?)?
And do you know how room temp is supposed to be controlled - thermostat, TRV's, ??

Seems fairly certain boiler has been disconnected deliberately. Any inkling?

loz2754 · Sep 24, 2021

Avo Mk8 said:
Back in the room.
It would be helpful to understand the overall position as per snowhead, even if all you want to do is "make it work".

Could you clarify what the 'three way switch' is (you do mean 3-way, not 3-pole?)?
And do you know how room temp is supposed to be controlled - thermostat, TRV's, ??

Seems fairly certain boiler has been disconnected deliberately. Any inkling?

I think the '3 way switch' refers to a 3 port valve

Avo Mk8 · Sep 24, 2021

loz2754 said:
I think the '3 way switch' refers to a 3 port valve

That makes sense - thanks ?

Avo Mk8 · Sep 24, 2021

Scottish1 said:
Now knowing that Unknown Red is on the Live and highlighted in the diagram where should it be located?

Thanks!

I and I think others here will be concerned that your boiler has been disconnected for a reason, and that arbitrarily re-connecting it without safety checks (eg section 9.5 of the manual you have) could be dangerous. Not being condescending, but you know you must have appropriate competence to proceed, or bring in an electrician.

All I will say is that in normal circumstances the boiler would need the following power connections on the cartridge in order to operate at all (references as seen in your pic)
5th from right.....Earth, marked with symbol
4th from right.....marked N, Neutral (appears disconnected at the moment?)
3rd from right.....marked L, a permanent live
2nd from right....marked R, switched live (red wire currently disconnected) should connect to 3-way switch orange wire
1st from right......marked F, no connection required

NB the boiler manual says the mains supply must not be interrupted by a timer/programmer, so it's important that a permanent live goes to terminal 3 'L', and the switched live (from the 3 port orange wire) goes to terminal 2 'R'

Faulty Circulator Pump? Wiring Issues

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