Why does my boiler keep locking-out?
Davey
come on and the boiler stop working of late, caused by a "non-volatile lock
out" according to manual(!). Turn the boiler off/on, comes back to life.
If I turn the boiler temp down to 3/4 it stops the boiler locking out. I
dosed the system last week with fernox boiler silencer for the 2nd time
which had stopped the kettling for a time and the boiler ran ok on max temp
until yesterday. The kettling has come back but not as bad as it was.
I was thinking the boiler is locking out due to overtemp cutout due to air
pockets in the heat exchanger or is this a red herring?
I also have an Alpha+ pump which lowers the speed of the pump according to
pressure (got TRV's fitted to all rads but one). Could the pumps (sometimes)
low speed be exacerbating the problem?
Roger Mills
Davey <sp...@trap.com> wrote:
How is the pump connected - is it connected in parallel with boiler demand,
or does the boiler control it in order to provide pump over-run (i.e. to
keep the pump running for a bit after the boiler stops in order to carry
away the residual heat)?
I suspect that your boiler needs pump over-run and that either the pump
hasn't been connected correctly or that there's not a big enough flow path
when the TRVs are closed to allow the boiler to dump its residual heat. The
fact that it doesn't happen when you turn down the boiler stat reinforces
that view.
Is there a by-pass circuit and, if so, is it controlled by an automatic
by-pass valve? Smart pumps and automatic by-pass valves are often not very
happy bedfellows. I've had to put my Alpha pump on a fixed speed setting to
overcome just the problem you describe - which somewhat defeats the object
of having a smart pump!
--
Cheers,
Roger
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Davey
"Roger Mills" <watt....@googlemail.com> wrote in message
news:7quj18...@mid.individual.net...
> In an earlier contribution to this discussion,
> Davey <sp...@trap.com> wrote:
>
>> Got a 9yr old kettling GW Micron 50FF boiler which's had the reset
>> light come on and the boiler stop working of late, caused by a
>> "non-volatile lock out" according to manual(!). Turn the boiler
>> off/on, comes back to life.
>> If I turn the boiler temp down to 3/4 it stops the boiler locking
>> out. I dosed the system last week with fernox boiler silencer for the
>> 2nd time which had stopped the kettling for a time and the boiler ran
>> ok on max temp until yesterday. The kettling has come back but not as
>> bad as it was.
>> I was thinking the boiler is locking out due to overtemp cutout due
>> to air pockets in the heat exchanger or is this a red herring?
>>
>> I also have an Alpha+ pump which lowers the speed of the pump
>> according to pressure (got TRV's fitted to all rads but one). Could
>> the pumps (sometimes) low speed be exacerbating the problem?
>
> How is the pump connected - is it connected in parallel with boiler
> demand,
I don't think the GW micron 50FF's have pump over-run. The larger models do
I believe.
> Is there a by-pass circuit and, if so, is it controlled by an automatic
> by-pass valve? Smart pumps and automatic by-pass valves are often not very
> happy bedfellows. I've had to put my Alpha pump on a fixed speed setting
> to overcome just the problem you describe - which somewhat defeats the
> object of having a smart pump!
Indeed. I have taken the pump off the auto adapt setting and set it to one
of the proportional settings to see what happens. There is no auto bypass
valve in my stystem. The bypass consists of a gate valve opened a small
amount.
Is there a module available I can wire in that will keep the pump running
for a minute or two once demand has stopped? Surely this sort of thing would
be relatively simple with just a discharging capacitor keeping the pump
going for a short while?!
cynic
> "Roger Mills" <watt.ty...@googlemail.com> wrote in message
>
> news:7quj18...@mid.individual.net...
>
>
>
>
>
> > In an earlier contribution to this discussion,
>
> - Show quoted text -
Its an ac pump a capacitor, even a very big one, will be no use in
this situation.
If the problem is recent then it is possible that the performance of
the pump is inadequate, the pipes are coated with an obstructive
coating, your gate valve bypass is obstructed (count how many turns to
close it, then open wide with pump running, and reset to where it was,
may clear this). Your thermostat may be "tiring" or your limit stat
may also be drifting.
Roger Mills
Yes - but you can't do it with a capacitor - you need a timer.
I have done mine - in *addition* to what the boiler already does - by using
a timer designed to keep a bathroom fan running after the light has been
switched off.
You'll find a wiring diagram appropriate to retro-fitting your system on
Page 13 of
http://www.diyfaq.org.uk/docs/Sundial-Wiring-Rev1d-2nd%20Edition.pdf [Once
you've loaded the PDF document and found the right page, right click the
diagram, and then click on 'rotate clockwise' to make it easier to read]
Mr Sandman
"Davey" <sp...@trap.com> wrote in message
news:Xho2n.42703$EO5....@unlimited.newshosting.com...
Sounds like inadequate flow through the heat exchanger or scale build up in
there causing it to overheat and lockout. The alpha will shut itself right
down when the rooms are up to temp, so your flow -will- drop and you will
kettleing and over heating. If it works fine at 3/4 id leave it at that, im
sure your rads will be hot enough at those temps.
Otherwise you have to run the pump on full and have a bypass, but as you
say, that expensive pump will not be doing its job in that case. When does
it kettle? when the rads are up to temp or all the time?
Steve