CH Overrun timer but no permanent live in airing cupboard

[Davey]

After some contemplation and advice on here (thanks!), I got a manrose timer with a view to using it as a pump over-run timer to cure our boiler's overheating problem.

After a lot of probing with my multi-meter and running about, I wired it in, only to find that the pump didn't run when the HW switched on on Sunday morning. I now realise I don't have a permanent live feed to the airing cupboard as the timer is located in the utility under the boiler. The wiring centre is typical plumbers wiring and with the colour of the wire having little to do with it's purpose, nor is does it resemble much in the way of Y-plan wiring according to the brilliant PDF I downloaded from the uk.d-i-y wiki.

Any ideas without ripping up the floorboards and routing the feed from the utility room, which is not an option?!

Thanks.

[Roger Mills]

Where exactly are all the elements of your system? Presumably the pump is in the airing cupboard? Is the mid-position valve also in the airing cupboard? Where is the wiring centre - such as it is? Where does the pump get its power from?

If the pump is powered from a remote wiring centre, *that's* where to put the timer because there'll be a permanent live there.

[Davey]

The pump and valve are in the airing cupboard upstairs, along with the wiring centre. The timer is downstairs with the boiler, with the fused spur for the entire system. The fused switch and the timer are inches from each other.

The pump gets power from the wiring centre.

That is where I have put the timer.

From my understanding of the Y-Plan wiring diagram, the only permanent live is to the time controller, which is downstairs in the utility. The CH and HW on signals are passed to the wiring centre which then powers the pump according to the position the valve.

Do I still have a permanent live in the airing cupboard?

Thanks.

[ARWadsworth]

You probably do not have a permanet live in the airing cupboard with a Y plan and a fused spur and timer in the utility room.

Adam

[Roger Mills]

You may well be right, Adam.

Under normal circumstances, Connector 1 on the wiring centre would relay the permanent live from the FCU to the programmer - but in the OP's case, this would mean taking a cable up to the airing cupboard and all the way back again, which the installer may not have done - *unless* a multi-core (typically 5-core for this purpose) cable has been used between the programmer and the wiring centre.

[ARWadsworth]

Having had a chance to think about this, I think there may be a solution that does not involve laying a new cable.

You need a single pole double throw 230V relay next to the wiring centre.

Alter the wiring at the back of the programmer so that the HW OFF cable becomes a permanent live at the wiring centre at its own connection point. You can then power your timer from this. The new permanent live can also be connected to the COM terminal on your relay and the relay is activated by the HW ON signal. The NC terminal on your relay is now your HW OFF supply to the wiring centre.

I have not sketched out the drawing yet!

Adam

[ARWadsworth]

A typical older installation is two twin and earths from the programmer to the wiring centre. HW ON, HW OFF, CH ON and the Neutral.

Cheers

Adam

[Roger Mills]

Yeah - that's elegant! It might confuse the hell out of anyone who has to work on the system later, though.

Why not go the whole hog and convert it to an S-Plan? The HW-off is then not needed, and can be used as a permanent live - both for the over-run timer

*and* for the feed to the valves' auxilliary contacts. You'd then have standard - well understood - control logic, with no need of any additional relays.

[ARWadsworth]

I thought Y Plans scared the hell out of anyone even if they were standard circuits (or is that just plumbers!) You could leave a a wiring diagram in the wiring centre.

Cost and time. A relay and DIN mounting box box is less than £20. Two 2 port valves are at least £70 and could take some fitting in a tight airing cupboard.

Cheers

Adam

[ARWadsworth]

Davey

I have done a working diagram that uses a relay to get you a permanent live into the airing cupboard.

If you want it I will post it onto a website for you to have a look.

Cheers

Adam

[Davey]

I would appreciate that. Thanks!

[ARWadsworth]

OK, try

Apologies to Davey Oz for butchering his nice diagram.

Adam

[ARWadsworth]

or this

[Davey]

[ARWadsworth]

Well if you try it out let me know.

Adam