Potterton Prima F Bolier keeps tripping out
Jason
reset button on my boiler. It appears that when the CH & HW go off
late in the evening the boiler is tripping out and then not igniting
in the morning. The strange thing is that when the CH& HW go off in
the morning the boiler shuts down ok and it relights fine in the
evening for when I get home.
It has only just started happening after I have had a gas fire and gas
hob installed. Could this be the problem? I am paranoid now that there
may be a small leak somewhere that is causing the gas pressure to drop
and this is what is causing the trip to activate - I am just guessing
though and there is no smell of gas anywhere. The fitter has told me
that it is unrelated and is probably an issue with the boiler itself.
Does anyone have any ideas? Thanks.
Roger Mills
Jason <ja...@besant.co.uk> wrote in message
news:77ddc926.03020...@posting.google.com...
This is usually a problem with boilers which only hold a very small quantity
of water - don't know whether yours qualifies or not.
When the boiler and pump stop running, the residual heat in the metal part
of the heat exchanger continues to heat the water - and the over-heat
thermostat trips out. With this type of boiler, the pump should be wired so
it continues to run until the boiler has cooled down a bit - even when all
the central heating controls and thermostats are off. Is yours wired this
way? [The pump should be connected to a connection called "pump over-run" or
some such on the boiler]
I can't explain why this should be a problem at night but not in the
morning!
As a short term fix, you could try turning the boiler thermostat down a bit.
If it doesn't get quite so hot in normal running, it has a bit more leaway
before tripping the over-heat device.
Roger
Jason Besant
down from 3 (out of 5) to 2 but still the same problem. Any other ideas?
"Roger Mills" <roger...@hampton-magna.freeserve.nospam.uk> wrote in
message news:b1r717$jmh$1...@newsg1.svr.pol.co.uk...
Roger Mills
Jason Besant <ja...@besant.co.uk> wrote in message
news:hqf0a.188$6B...@news-binary.blueyonder.co.uk...
This is an odd one! The pump is presumably working ok, and is wired to
over-run - to stop the boiler from over-heating. The over-heat trip is
presumably ok - otherwise it would do it all the time, not just in the
evening.
Sounds like there's some condition in the evening which is preventing the
pump from continuing to circulate water after the boiler has shut down.
Is it a fully pumped system? Does it have separate 2-port valves for heating
and hot water or a single 3-port valve? Is there a by-pass circuit which is
always open and always allows flow to occur?
I can't see how your new gas fire and hob can be causing this. At worst, if
the pipework is inadequate, and if the fire or hob are on at the same time
as the boiler, there may be a reduction in gas pressure at the boiler -
which would reduce the boiler performance, but I can't see how that would
make it trip.
Roger
Jason
Thanks again Roger, you have helped immensely. I checked my timing
controls and found that the HW was set in the evening to run on for 30
mins after the CH goes off. The valve that controls the flow between
CH and HW is acting as a diverter so when it closes the feed to the CH
it is providing more for the pump to send through the HW circuit. On
examination of the pipework it has been stepped down from 22mm to 15mm
just before going into the HW tank. I suspect that this is causing a
restriction in the flow. The only reason I can think that this was
done is because a 15mm Drayton valve has been installed instead of a
22mm one. The Drayton valve is regulating the temp of the HW in the
tank. This valve was stuck in very slightly which I released by
pulling it up gently.
Anyway, just prior to the Drayton valve is a bypass circuit which was
almost closed. Upon opening this the boiler has stopped tripping out.
I think this combined with the partially sticking Drayton valve caused
the water to boil in the heater matrix causing the reset to happen.
Thanks again for your help.
Jason.