Gas boiler - need help wiring new digital timer

ZV Yoda

Hi folks,

I posted this in the heating forum, but maybe it's more suited to to this one.

I'm replacing our old analogue APT timer with a new EPH T17 digital timer, but I can't figure out the wiring.

There are 3 wires coming out of the boiler (brown, red, blue). The APT had 3 terminals (live out, live in, Neutral). One wire was connected to each terminal. I forgot to note which colour wire connected to each terminal.

The T17 has 5 terminals, so how do I go about wiring it up? The T17 contents included a "jumper" wire. It's to be used to connect terminal 1 and 4 "if an output voltage is required". I’ve no idea what this means.

Any help greatly appreciated.

Robbie.G

ZV Yoda wrote: »

Hi folks,

I posted this in the heating forum, but maybe it's more suited to to this one.

I'm replacing our old analogue APT timer with a new EPH T17 digital timer, but I can't figure out the wiring.

There are 3 wires coming out of the boiler (brown, red, blue). The APT had 3 terminals (live out, live in, Neutral). One wire was connected to each terminal. I forgot to note which colour wire connected to each terminal.

The T17 has 5 terminals, so how do I go about wiring it up? The T17 contents included a "jumper" wire. It's to be used to connect terminal 1 and 4 "if an output voltage is required". I’ve no idea what this means.

Any help greatly appreciated.

On your new clock
1=live in
2= neutral
3=live out
Put connecting wire provide from 1-4

Tow

ZV Yoda wrote: »

I forgot to note which colour wire connected to each terminal.

You will have to open up the boiler see which wire is which. Or, if you turn on the boiler a phase tester will tell you which is live out, a multimeter will (should) tell you which is Live Out and Neutral or if you want to guess at it; Brown = Live Out, Blue = Neutral, Red = Live In.

The moral of the story is don't disconnect wires without noting where they go or at least use your phone to take a picture.

Warning: The wires carry mains voltage which can kill you, if you don't know what your doing get an expert in.

ZV Yoda

Thanks Robbie,
I forgot to to note the feeds going into the old timer when I disconnected it. I have 3 wires - brown, red & blue. How can I tell which is live in, live out & neutral?

Tow, sorry - our posts crossed. Yip, I kicked myself when I realised I forgot to take the picture. If I guess & get it wrong, what's the worst that can happen?

Robbie.G

ZV Yoda wrote: »

Thanks Robbie,
I forgot to to note the feeds going into the old timer when I disconnected it. I have 3 wires - brown, red & blue. How can I tell which is live in, live out & neutral?

Have you a phase tester or multi meter if not you are only guessing.Worst case you could blow the timer.

Bruthal

ZV Yoda wrote: »

If I guess & get it wrong, what's the worst that can happen?

https://www.youtube.com/watch?v=WwlNPhn64TA

ZV Yoda

I don't have a phase tester or multi meter. Off to the local hardware shop so...

Thanks for all the comments

Bruthal

ZV Yoda wrote: »

I don't have a phase tester or multi meter. Off to the local hardware shop so...

Thanks for all the comments

Id say if you connect with brown to terminal 1, blue to 2, and red to 3, that should do it. And your link from 1 to 4.

A way to test that is to connect red and brown into a connector, leave the blue out, and see does boiler work when you switch its power back on.

If it does, then we know blue is neutral at least, which we would expect.

Connect as above, and see that timer has power to it when it has boiler on and off, which shows the brown is the supply, and red the switched supply.

ZV Yoda

Bruthal wrote: »

This

You mean the output of the bolier increases dramatically? That's not so bad...

Actually, now in daylight I can see that the brown wire is actually black. Not sure that makes any difference.

Lesson learned. I'm off to get a multimeter & a phase tester.

Do multimeters all operate in the same way?... i.e. will it tell me easily which is live in, live out & neutral? My electrical skills don't extend much beyond changing plugs/fuses.

Thanks

Bruthal

ZV Yoda wrote: »

You mean the output of the bolier increases dramatically? That's not so bad...

Actually, now in daylight I can see that the brown wire is actually black. Not sure that makes any difference.

Lesson learned. I'm off to get a multimeter & a phase tester.

Do multimeters all operate in the same way?... i.e. will it tell me easily which is live in, live out & neutral? My electrical skills don't extend much beyond changing plugs/fuses.

Thanks

It changes what people might assume might have been used as live and switched live.

Finding the live feed will be easy, finding the neutral, not definitely as straight forward with a meter. A test between the known live and the switched live will probably show 230v on the digital meter, making a tester assume that must now be the neutral.

If it was me and opening the boiler was out (although opening boiler terminal box is what I would actually do), I would put red and black into a connector together with blue in another connector on its own, and switch circuit on. If they are indeed the Live and switched Live, the boiler will come on. If they are neutral and switched Live, nothing will happen.

If they are Live and neutral, circuit will trip out, and/or spur fuse will go.

If boiler worked, put red into 1, blue 2, black 3, and link 1 - 4. Check timer has power when timer has boiler off, which confirms red is Live supply.

It all sounds complex when written, but is extremely simple for electricians, which is why even seemingly simple tasks are often messed up by DIY persons. Not that I have`t messed up my own DIY efforts before

Bruthal

Have you got the timer connection back plate in position on the wall, with wires out ready to connect into the terminals?

ZV Yoda

I had it connected, but I’ve taken it off again. I should also mention that there is an on/off switch connected between the boiler itself and the timer.

See pic. If I remove the case on the switch, can I trace the wires that way?

If not, I'll pop out & get a multimeter

Bruthal

ZV Yoda wrote: »

I had it connected, but I’ve taken it off again. I should also mention that there is an on/off switch connected between the boiler itself and the timer.

See pic. If I remove the case on the switch, can I trace the wires that way?

If not, I'll pop out & get a multimeter

Just get a connector, and connect the red and the black together into it, and see does the boiler work when you switch the circuit back on.

The worst that will happen is a fuse gone or MCB trips, but if that blue is neutral, which you would expect (but not certain), the boiler will just come on and work. That will confirm blue is neutral.

ZV Yoda

OK, will try that now.

I noticed that the 3 x timer wires are coloured slightly differently than what I posted previously. They are:
Solid blue
Red & black striped
Red & white striped

I had a quick look at the wiring into the on/off switch. There's a heap of wires in there, but from what I can make out, the (red & white) is connected to the "L out" terminal. I can't see where the (red & black) of the solid blue one are connected - there's just too many wires in the way.

ZV Yoda

Right, getting somehwere now. I conncted the red/black and red/white. Nothing happened. I checked the fuse in the switch & it had blown. I replaced the fuse & now the boiler powers up.

So far, so good. What should I do next?

Bruthal

ZV Yoda wrote: »

Right, getting somehwere now. I conncted the red/black and red/white. Nothing happened. I checked the fuse in the switch & it had blown. I replaced the fuse & now the boiler powers up.

So far, so good. What should I do next?

That confirms blue as neutral anyway.

Now we can just assume the red/white is live feed, because getting the feed and switch feed mixed up is no major problem.

Switch boiler circuit off, and put timer base back up.

Connect the link wire into terminal 4 first anyway.

Then red/white into terminal 1 along with the other end of link wire.

Blue into 2.

Red/black into terminal 3.

The above guesses that red/white is the live feed. That will be confirmed by the timer working properly with the timer having the boiler on or off. If it was the red/black that is the feed, the timer will go off when the boiler is as well.

If the timer does indeed be off when boiler is off, or when circuit first switched on, then switch circuit back off and swap red/white wire around with red/black one.

Try the above anyway, test the setup, and post back.

ZV Yoda

Bruthal, you are a legend. Followed your instructions & they worked perfectly. Now, the timer is on when the boiler switch is on. If I turn off the boiler switch, then the timer also switches off.

Does this mean I should now switch the red/black with the red/white?

Thanks a million for you help with this.

Bruthal

ZV Yoda wrote: »

Bruthal, you are a legend. Followed your instructions & they worked perfectly. Now, the timer is on when the boiler switch is on. If I turn off the boiler switch, then the timer also switches off.

Does this mean I should now switch the red/black with the red/white?

Thanks a million for you help with this.

What you need to test is, if the timer itself commands the boiler to be off, that the timer is still on. If the timer goes off at the same time, then swap the two wires. It would be likely that the timer wont come on at all if the wires are wrong anyway, as the timer needs to energise to close its contact, which wont happen if the live feed is into terminal 3.

So,,, if the timer brings on and off the boiler, but the timer remains working, then the timer is wired right.

If you meant the switch in the photo you have of the timer wires, is switching off the timer, that should be ok. Once the timer is fully working when it switches boiler off. Once that is the case, then it is all working as it was with the APT timer now.

ZV Yoda

Bruthal wrote: »

What you need to test is, if the timer itself commands the boiler to be off, that the timer is still on. If the timer goes off at the same time, then swap the two wires. It would be likely that the timer wont come on at all if the wires are wrong anyway, as the timer needs to energise to close its contact, which wont happen if the live feed is into terminal 3.

So,,, if the timer brings on and off the boiler, but the timer remains working, then the timer is wired right.

If you meant the switch in the photo you have of the timer wires, is switching off the timer, that should be ok. Once the timer is fully working when it switches boiler off. Once that is the case, then it is all working as it was with the APT timer now.

OK, understand now. I was talking about the main switch in the picture - that turns everything off.

So, I checked the various settings on the timer and everything seems to be working perfectly now. Your suggested wiring works perfectly.

Thanks again for your help - very much appreciated.