"Matthew" wrote in message
ps.com...
Thanks to everyone for their help on my cylinder queries last week,
much obliged. Am now halfway through redoing everything in airing
cupboard (halfway meaning having removed everything but not put
anything in yet) and was starting to plan the wiring.

New setup is Danfoss 2x2port all-in-one pack. It's got a nice neat
wiring box and instructions as to how to wire it. No problem. Old setup
was a standard 1-gang surface mount box on the wall, with a rat's nest
of cables connected together with loose connection blocks. I've been
deciphering the old one and checking it matches the new one; seems to
be the same, apart from a couple of things.

I'd have gone for Honeywell valves given the choice as I don't get problems
with them whereas I have had a few problems with Danfoss such as going
"stiff", leaking at the spindle, microswitch weld up. YMMV
If in future you have to swap a valve local isolating valves are very useful
to save a drain down.


Instructions for new one shows switched live from boiler connected to
pump live and to Aux Sw Out (orange?) for both valves. Old setup seems
to have two separate switched live cables, one connected to the pump
live and the other to the valves. Does this mean I have pump overrun?

It may do but not guaranteed. If you do have pump overrun then the pump will
be powered from the boiler.
Power "to" the valves microswitches should be "permanent" ie straight from
the supply switchfuse so only a total switchoff removes it. Power "out" from
the valves to the boiler is what is normally termed the switched live. With
non overrun systems this is connected to the pump also so the pump runs when
the boiler does. With pump overrun systems the switched live operates the
boiler which also has a seperate permanent live and the pump is powered up
when the boiler starts and runs on for a period after the boiler stops
firing to transfer heat away from the boiler, this is usually done by a
thermostat or timer built into the boiler which employs the permanent live
as a source.


NB if that sounds like I know what I'm talking about, it's only because
the instructions say 'Refer to Boiler wiring information for boilers
with pump overrun' (which of course I don't have, inherited the boiler
(Potterton Profile 50e) with house).

Without looking at the Profile manual I can't recall if it does have
overrun, perhaps others may have a copy of the manual or your boiler may
have a wiring diagram behind the panel?


If that's the case, presumably I should preserve this split between the
pump and the valves? That seems fairly straightforward, would there be
any other changes I'd have to to make?

One other thing - the whole setup seems to be powered via the cable
from the boiler (via a permanent live), there is no direct mains into
the wiring box. Is this OK to do?

Yes but it would be useful if you could incorporate a local isolator for
servicing.

There is a spare outlet in the
cupboard which is currently unused (maybe originally for a second
immersion?) so I could power everything from there if that's preferable

A second imersion suggests an economy seven system in which cas the outlet
may not be powered during normal hours

- in which case presumably leave the perm live from boiler unconnected?

The boiler and the controls must be fed from one single point of supply,
generally using a 3 amp switchfuse (FCU). I'd be very unhappy about leaving
a disconnected wire carrying a mains supply within a system fed from a
second source. You may know its there but in the future someone could get
the little men up their arm.

Hope that all makes sense and thanks in advance for any help!

HTH