where does the live for central heating pump come from?

[3759allen]

hi all.

i'm after a little bit of help if you'd be so kind?

i have an old central heating system with a back boiler and cold water tank in the loft.

where does the live come from for my central heating pump?

there are 2 fused sockets, 1 goes to the boiler and 1 goes to the pump. both the fuse sockets use a 3 core and earth cable (old style 3 core and earth cable, yellow, red, blue and earth)

the one for the boiler uses a red wire for the live and the pump one uses a yellow wire as the live.

the boiler powers up fine but there seems to be no power coming from the pump socket.

i have only been able to check this with a non contact voltage pen.

i have put a new fuse in the socket and still the same.

so i guess i need to trace the yellow wire back to diagnose the problem further, but not sure where the yellow wire comes from?

should the pump be running all the time?

i hope all this makes sense, please let me know if i've missed anything.

thanks in advance.

 

[Tibbot]

Pump live will be supplied via programmer and roomstat and pump will only work with CH demand. Your HW is probably gravity so only boiler live supplied through programmer when set to HW only.

 

[3759allen]

thanks for the reply.

so if my thinking's right would this point to a problem with the roomstat?

 

[Dan Robinson]

A volt stick?


A quality diagnostic tool you have there sir


Crack on

 

[Tibbot]

The pump will only operate with CH selected as well. If HW only it's not meant to work. If you mean pump not working with CH demand, then you need to trace back from pump to roomstat to programmer to supply. A multimeter or proper voltage tester with probes is recommended for this.

 

[3759allen]

A volt stick?


A quality diagnostic tool you have there sir


Crack on

to be honest i'm only a basic diy'r, anything that can't be diagnosed using the volt stick i'll get a qualified sparky in. i don't want to start probing live wires when i don't know what i'm doing.

 

[3759allen]

found a loose connection in the roomstat wiring connections.

all working as it should now.

thanks for all the help and advice.

 

[Dan Robinson]

All joking aside the best thing you can do is use it to assault a parking warden. Otherwise they are horrible and dangerous things.

If a multimeter scares you, please get a good heating man/woman in. It is probably a simple fix.

On the whole electricians shouldn't be allowed near boiler electrics

 

[Tibbot]

In the words of Basil Fawlty ''satisfied customer, we should have him stuffed''.

 

[Dan Robinson]

found a loose connection in the roomstat wiring connections.

all working as it should now.

thanks for all the help and advice.

Result! Have a light ale to celebrate