Have I drawn the wiring schematic correctly for my VOKERA bolier?

[Richard]

I've traced the wiring and it's here:

want to know, is this circuit a correct one? Are there any errors in it?

I don't understand the thing with the two black wires from the boiler. I've disconnected, and never made a note of which black wire went where. I thought it did not matter. since both are black.

Boiler is VOKERA "Pinnacle 16".

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Vokera "Pinnacle 16" Schematic

If I have not made a mistake, this is how my VOKERA "Pinnacle 16" was wired up.

In the Installation and Service Instructions, an example of the "S Plan System" is given. It is not like this schematic.

In the Service Instructions, the two switches inside the motorised actuators (Danfoss HPA2) are wired in parallel, but both wires (orange - grey) just go into the boiler (to M7, pins 2 & 3).

The boiler has 5 wires going into it, 3 for mains (L N E) and two wires

- both coloured black.

Here you see that the two switches inside the actuators are both in parallel, but live at one end, and the other (orange wires) goes to a black wire into the bolier.

On this schematic, tracing the other black wire from the boiler, it goes onto pins 2 & 5, of the Danfoss SET 3A timer. Pin 1 (Water ON) goes to the cylinder (water) stat, then through the water actuator motor, then to Neutral. Pin 4(Heater ON) goes through the Room Stat, then through the heater actuator motor, then to Neutral.

There is no link connecting the Live wire, in the timer, to any of the pins numbered 1 to 6. Presumably the Live potential is coming from the boiler -out of the black wire.

Is the schematic I've drawn out correct?

What I don't understand is these black wires. There is no way to tell which black wire should be connected to what. I believe you must connect the right black wire to the switches or the thermostat.

Because of the problem with the black wires coming from the boiler, I don't understand this circuit. I don't know what the black wires go to in the boiler or what they supply. Anybody know?

[Richard]

Of course, via timer, to thermostats.

[Dave Osborne]

I'm not an expert on system boilers, but I suspect that your boiler has permanent live and two switched lives - one calling for pump and one calling for heat. Certainly, your schematic does not show the pump. There may well be pump overrun built into the boiler as well. You must not get these signals the wrong way round!

[Andy Burns]

No room for a wiring centre in there to tidy up that exposed rat's nest?

e.g.

[Adrian C]

Above less than a fiver on eBay. Just ordered one to tidy up my own rats nest. Thanks for that post!

[Roger Mills]

Your schematic and the S-Plan diagram in the boiler installation manual are

*essentially* the same - it's just that the detailed implementation is slightly different.

The essential characteristic of S-Plan is that each actuator motor is fed from the programmer via its respective thermostat, and the auxialliary contacts are wired in parallel - with one side having a permanent live feed and the other side connected to the boiler's switched live demand. Both diagrams show this - the only difference being where the permanent live feed comes from. In yours, it comes from the heating control switch and in Vokera's it comes form M7/2 on the boiler which - if you look at Fig 31 in Section 8.1 of the manual, is almost certainly permanently live.

In both cases, the two orange wires are connected to M7/3 - which is pretty certainly the demand for heat.

Yes, as above, this must go to M7/3

That bit's a complete mystery to me! That other black wire is almost certainly a live feed to the switching contacts in the programmer - but I haven't a clue why the main live feed to the programmer isn't used instead. Where on the boiler does that black wire connect?

Probably, but the feed to the progammer remains a mystery.

The black wire which is connected to the two orange wires in the actuators definitely needs to go to M7/3 - there is no doubt about that. As far as the other one is concerned, I would be inclined to get rid of it and connect 2 and 5 to L internally in the timer.

If you get rid of the tank, you will only have one zone - so you can get rid of the motorised zone valves too. If you do that, the output from the room stat will then need to go directly to boiler demand M7/3. [You can probably get rid of the bypass circuit too, as long as there will always be at least one radiator open].

Having said all that, getting rid of the tank still seems a strange thing to be doing. Don't you need any hot water for bathing/showering, etc.? If you

*do*, where are you going to get it from?

[ARWadsworth]

Seconded. And your reply was very good Roger.

But a query about the bypass valve. Should an automatic bypass open up as some of the TRVs close down in the system and help keep the pump from running under excess load?

Cheers

Adam

[Roger Mills]

Thank you, kind sir!

I *hope* I got it right, but I was a bit worried after writing it when I delved a bit deeper into the installation manual. That describes the plug M7 as "Low voltage connector (heat request)" - but I was recommending feeding mains back to Pin 3 on it. However, unless *all* the external kit (motorised valves - including 3-port valve for Y-Plan, stats, etc.) shown in the diagrams work on low voltage, M7 *must* have mains on it.

Can anyone clarify?

Possibly. An even better option would be a smart pump - but since this is a system boiler, presumably with an internal pump, the user probably doesn't get to specify the pump.

My point really was that, in the absense of zone valves, there will[1] always be an open flow path to allow pump over-run to operate without needing a bypass valve.

[1] providing not all rads have TRVs

[Richard]

I looked inside the boiler and I saw that the black wires go to M7 (2) & (3).

I've marked M7 (2), so I know, when I reconnect everything, just where that black wire goes, and of course where the other black wire goes.

That's the situation confirmed about the black wires. Don't know if this helps.

[Richard]

I'm strugglimg to know why M7 (2) and M7 (3) are both black wires! :c)

[John Rumm]

Remember that 240V *is* technically speaking "low voltage"... could that be it?

[ARWadsworth]

Not an independent view I know, but I got in from work at 4.30, fed the cats and downloaded

On diagram 8.1 Fig 31 I saw the S plan. A small deviation from the "standard Y plan". But it is the same as I have fitted to a combi with an S plan (don't ask Drivel).

Then I saw fig 32A. QED.

The final proof was fig 34. Control of time clock and room thermostat rated at 230V ac.

All I had to write was seconded. You had done all the work:-)

The bypass is a

to the OPs previous posts.

Point [1] taken into account.

As for removing the hot water then the mind boggles. But it is still a free country and the OP can do that if he wants.

Cheers

Adam

[ARWadsworth]

It would have had a black link wire between M7 (2) and M7 (3) when the boiler was brand new. It is there to confuse people.

Adam

[Richard]

Lets take the auxiliary contacts: They need to be fed by a permanent live feed, and the other side goes to M7/3, which is the demand for heat.

gotcha! :c)

M7/2 MUST be a permanent live feed. As you basically surmise. Really, what is happening is this: Your regular heating engineer would feed the auxiliary contacts with a permant live feed from M7/2. The permanent live feed for the timer switch contacts would come from the heating controls switch.

But in this case the installers reversed the permanent live feeds. Taking the timer live feed from M7/2, and the auxiliary contacts live feed from the heating controls switch.

As you probably realised, but I've just. :c)

What MUST be the case, is that the installer HAD TO KNOW which black wire went to where. Otherwise chances of working were 50/50. :c)

I think I got it now, and feel confident the schematic is as the system was wired before I removed all the wiring connections.

I'm now going to wire it up again.

I've learned something. :c)

Thanks a lot all. Rich

[Richard]

What I will do soon is probably get rid of the tank only.

But other than that leave the plumbing alone.

I will turn off the valve that lets flow to the cylinder. I must do that of course. And close the plumbing at the return side that went to cylinder.

I can disconnect the actuator valve for the water/cylinder. Probably both the motor circuit and the auxilary contacts circuit, (I muse).

Other than that, I think the heating circuit just remains as it is. Not sure about that.

There is a manual/automatic lever on those HP2A actuators. I wonder if the actuators motor for heater should be disconnected, and the lever set to manual. If that means permanently open.

Anyway, I'm just taking out the cylinder, leaving the rest of the plumbing alone, and just have the boiler run the radiators. What that calls for in wiring changes and any lever selection on the HP2A actuators, I'm not 100% sure.

[Roger Mills]

You can certainly keep the valve open with the lever, independent of the motor, but you can't rely on it moving far enough to operate the auxilliary contacts.

You still need a way of having the room stat control the boiler. If the auxilliary contacts are not doing it as the valve opens and closes, you'll need to connect the stat output directly to M7/3 as I said earlier.

[Richard]

I think what I will do, is remove the connection at pin 1 in the SET 3E timer. Then no live will ever get to the water actuator via the cylinder thermostat. You don't want a demand for heat and the valve closed on the cylinder pipe circuit.

Setting the switch to water of course will do nothing. But that is okay.

So, when the room thermostat closes, the heater actuator will open, and close the auxilary contacts, producing a demand for heat, as is normal.

I think that is the solution.

[Roger Mills]

Yes, that will work. But you originally said that you wanted to remove the valves altogether. Then you changed that to leaving the CH valve in place but jacking it permanently open - and I was responding with how you could achieve either of these from a wiring point of view.