In an earlier contribution to this discussion, ARWadsworth
wrote:
"Roger Mills" wrote in message
...
In an earlier contribution to this discussion, Richard
wrote:
I've traced the wiring and it's he
http://homepage.ntlworld.com/richard...RY/boiler.html
I 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".
--------
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.
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 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).
In both cases, the two orange wires are connected to M7/3 - which is
pretty certainly the demand for heat.
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.
Yes, as above, this must go to M7/3
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.
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?
Is the schematic I've drawn out correct?
Probably, but the feed to the progammer remains a mystery.
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.
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? --
Cheers,
Roger
Seconded. And your reply was very good Roger.
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?
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?
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
--
Cheers,
Roger
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