Boiler + Pump staying on

[chrishutt]

It's definately a 52
The number is 41.315.45

OK, found a reference to it, but no manual. It's an open flued boiler so will have no fan and probably no pump overrun, so I can't see why it should need a permanent live. Nevertheless you have identified the permanent live as the source of the live feedback through the switched live. If it does have pump overrun then the pump overrun stat might be faulty.

Perhaps someone else will come along who knows this boiler or has a manual and can identify the faulty component. I've got to get some fresh air now - good luck.

 

[PhilGP]

Thanks Chris.
I managed to get this photo from inside the cover ...

sorry it's a bit dirty but I have tried to clean it up.

I'm more confused now as my pump is connected to my junction box and not fed from the boiler.

 

[PhilGP]

I 'think' I've found the cause - the frost stat.

I have just confirmed with a cirtuit tester that the cable two live feeds to the boiler are only 'common' when the frost stat closes.
The dial was set at 10 degrees and since it's been getting slowly colder resently, it must have been supplying a permanent live to the boiler+pump.

I will now re-connect the wires and turn the thing down to 3-4 degrees (marked with a blue arrow) !

I hope this fixes things - if not I'll be back.


Thank you for all your answers.

 

[chrishutt]

God knows why I'm spending my one day off like this, but I've found a paper manual for a Space Saver 75 - 41.315.46 - probably a slightly larger version of the same boiler. It has electronic ignition and a short pump overrun provided through a link to the motorised valve (must be slow moving type).

The gas valve is energised through a 24 volt circuit controlled by switches in the thermostat, which also controls the pump. The boiler will be activated by a live input to terminal 8 of the boiler terminal block. This should come from a call for heat from the cylinder stat or from the motorised valve micro switch.

My guess from what you say is that your wiring may be wrong, or you may have a fault with your thermostat. The manual gives a wiring diagram for fully pumped but with only one motorised valve on the heating circuit, which is what you have. I haven't got a scanner or digital camera so can't post it.

The thermostat has two micro switches, one at 24 volts controlling gas valve and one at 240 volts controlling pump operation (through terminal 7), taking current from either a permanent live (9) or switched live (8 ) connection. A short between 8 and 9 on the micro switch would make your switched live a permanent live (which is what you seem to have). You could check the operation of the thermostat (Ranco C77 - P0100 or P01080).

 

[chrishutt]

Thanks Chris.
I managed to get this photo from inside the cover ...

sorry it's a bit dirty but I have tried to clean it up.

I'm more confused now as my pump is connected to my junction box and not fed from the boiler.

The pump must be fed from the boiler as shown above. The red link between 7 and 8 should be removed and the input to 8 taken as described in my previous post. So I was right about the wiring being wrong, although I never thought of a frost stat as the cause of the normal controls being by-passed.

 

[PhilGP]

God knows why I'm spending my one day off like this,

I really appreciate your help and advice.

I'm no expert on boilers but I do know my electrics (although my qualifications are 25 years old now) and the whole wiring here baffles me.
I have, however, restored all wires to their original setup and the system (with new programmer) is working.
I have used a Drayton LWC1 junction box (with obvious ommisions bypassed ) to tidy up the wires which should make life easier when/if I finally get the time+money to bring this system out of the dark ages.

 

[Balenza]

Chrishutt wrote

The red link between 7 and 8 should be removed

Just curious but if the link betwen 7 and 8 is removed then how is the transformer energised ?.

 

[chrishutt]

To answer again your question Balenza -

The boiler will be activated by a live input to terminal 8 of the boiler terminal block. This should come from a call for heat from the cylinder stat or from the motorised valve micro switch.

 

[Balenza]

To answer again your question Balenza -

The boiler will be activated by a live input to terminal 8 of the boiler terminal block. This should come from a call for heat from the cylinder stat or from the motorised valve micro switch.

Silly me. I missed that bit.