Re: Boiler / Wiring - Emergency response needed from a spark etc

["Chris Miles" <chrismiles@xxxxxxxxxxxxxxxx>]

n.b..... many thanks.

Chris

----- Original Message -----
From: Nigel Giddings
To: ukha_d@xxxxxxx
Sent: Saturday, October 28, 2006 9:50 PM
Subject: RE: [ukha_d] Boiler / Wiring - Emergency response needed from a
spark etc


Chris,

From your description you say you have two boilers? This is unusual
unless it is a very large house? Do you know if the HW has a pump
associated with it or is it gravity fed?

If we can ignore the HW and just concentrate on the CH?

The thermostat should have a neutral connection. This pre heats the
bi-metal strip to reduce the hysterisis in the thermostat (the
difference between the on and off points).

I would have expected the switched live feed from the timer to be
switched by the thermostat and sent on to the boiler. Does the CH boiler
have a permanent live. If not there can be an issue of the hot water in
the boiler remaining in the boiler once the thermostat or timer switchs
off. Again not a problem for old boilers (heavy cast iron ones) but can
be an issue for modern lighter ones...

HTH

Nigel

-----Original Message-----
From: Chris Miles [mailto:chrismiles@xxxxxxx]
Sent: 28 October 2006 18:16
To: ukha_d@xxxxxxx
Subject: [ukha_d] Boiler / Wiring - Emergency response needed from a
spark etc

My father in law changed the front and back plate of a drayton
programmer and is certain every wire is
wired exactly the same way they were. Something is not right though.

The upstairs hot water boiler is working ok, but the downstairs central
heating boiler is not working.

this is how the manual says the circuit works... although it does not
specify how to wire it
up when including a remote thermostat in the circuit (the thermostat
manual doesnt say either)

http://www.chrismiles.pwp.blueyonder.co.uk/therm1.gif
<http://www.chrismiles.pwp.blueyonder.co.uk/therm1.gif>

I understand this I believe (correct me if I am wrong)

HW = hot water
CH = call for hear

both of which have an ON and an OFF position.

And here is how it is currently wired.

http://www.chrismiles.pwp.blueyonder.co.uk/therm2.gif
<http://www.chrismiles.pwp.blueyonder.co.uk/therm2.gif>

First question:

the hot water works fine so I am assuming that the HW is working fine,
although I am confused to why
the live wire going upstairs is connected to the OFF terminal rather
than the ON terminal. I know this
was *definately* correct as the ON terminal is screwed right down and
has never been opened to allow
a wire in.

Second question:

I assume when the second relay kicks in and switches to the ON position,
current is sent up the yellow
wire to the "call for heat" terminal at the thermostat, should
this
yelllow wire connect into the L terminal
or the "call for heat" terminal on the thermomstat?

I assume it doesnt really matter what way round yellow and red are
anyway? Can I do this.

At the programmer... take the yellow as the switched live to the L
terminal on the thermomstat, then
take the red wire back up to behind the programmer and connect to the
red wire for the boiler using
a 13amp connector block just like shown on the picture ?

Third question:

The theromstat says it is essential to have a neutral connection, at the
theromstat the blue wire coming
from the programmer is connected to the N terminal, however at the
programmer it is not connected to
the other N terminal as you can see in the picture, and like I said my
father in law is absolutely certain
thats how it was wired.

Please help if possible

many thanks

Chris

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