On Sat, 12 Nov 2005 16:53:53 +0000, Set Square wrote:
In an earlier contribution to this discussion,
wrote:
Hello
Installed DanfossRandall Y plan contractor pack.
The HW circuit works fine in all respects, but CH circuit doesn't.
Someone gave me this table:
ORANGE BROWN/WHITE GREY
OFF 0v 0v 240v
DHWonly 240 0 0
DHW + CH 240 240 reduced voltage
CHonly 240 240 240
I checked these off and they all came up fine, BUT
when I pulled off the actuator head to watch it cycling through the
positions it failed to return to the HW only position when I turned
off everything at the controller. Cutting power to the controller DID
make it return. Is this most likely to be an Actuator or Controller
fault?
Also, when I manipulated the spindle of the 3 port valve manually it
made the pump sound as though it was having problems when set to the
CH only position, and it still failed to get the pipes warm...
Also (!) the Boiler fails to stay alight for longer than a few minutes
at a time, especially when set to CH only... under what conditions
does the boiler shut down other than over heat? It is a Glow Worm
Space saver 52. Would it shut down if it was pushing against flow
restriction in the rad circuit ?
Taking all this into account, I reckon I have 3 possible (maybe 4?)
problems.
1 flow restriction in the CH circuit
2 Faulty controller
3 Faulty Actuator
(4 sticky valve in 3 port body causing 1?)
Bearing in mind all voltages across actuator seem fine and it cycles
through all positions smoothly my opinion is that it is an actuator
problem causing it to fail to return to its default HW only position.
But it also seems I have a flow restriction causing the pump some
problems...
Please release me from this plumbing hell, its getting cold and I live
with 3 slightly concerned tenants! At least they can have a hot
shower.
Cheers
The valve doesn't always need to return to the HW position when there's no
demand - it sometimes stays put. Clearly, it needs to return when there is
an unsatisfied HW demand but no CH demand, and it must return when you
remove *all* power by switching off at the FCU rather than at the
programmer. As long as it does these things, it's ok. [Note that the valve
actuator is still powered when HW is off at the programmer - hence the need
to switch off at the FCU].
In CH-only mode, the boiler and pump will only run when there is a demand
from the room stat. [What is that set at? Check that it's wired up
correctly!]. Even then, the boiler will cycle on its own stat if the rads
are not dissipating heat as fast as the boiler can produce it.
If the rads are not getting hot, it could be for any of a number of reasons
including:
* a blockage in the CH circuit
* TRVs at too low a setting
* manual radiator valves or lockshields turned down too much
* a by-pass circuit wide open - providing a much easier path for the water
than going through the rads
* a massive airlock somewhere, preventing proper circulation
There's a few things to have a go at!
Agreed.
I used to name the problem with heating in autumn "The October problem".
With the weather this year looking suspiciously like a climate change the
problem may have to be renamed the "The November Problem".
The problem is that the weather has got colder not so much in absolute
terms but in relative terms. The indoor comfort levels have dropped and we
are not yet wearing warmer clothing and/or getting used to being cooler
indoors.
However the heating system is not triggered by your comfort level but by
the temperature which is still usually enough to keep the heating off.
TRVs often keep radiators shut until it's cooler inside.
Also TRVs that weren't set to maximum for the summer months (that'll be
99%+ of them) tend to jam closed.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at
http://www.diyfaq.org.uk
Gas fitting FAQ
http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ
http://www.makewrite.demon.co.uk/SealedCH.html