G'day people. I couldn't find a previous reference here, so I hope I'm not
covering old ground again. If I am, I beg forgiveness and hope somebody can
help. I have a 6-year old Potterton Kingfisher CF60 boiler that is
overheating. It is in a simple system with gravity hot water and pumped
heating. When programmed for hot water only - no heating - it occasionally
(gradually becoming more frequent and now occurring about once or twice per
week) boils so that water is forced out of the vent pipe into the header
tank. If switched off completely and started again from cold (typically
left until next day) it seems to work ok again - until the next time! I am
unable to do the work myself, so a couple of weeks ago, I had a Certified
chappie service the boiler and put some dispersant/detergent goop into the
system to stir up the black sludge ready for draining and refilling. The
overheating problem was in evidence before this, and it did not suddenly get
worse after, so I don't think there is any connection between the events but
thought I should mention it anyway.

After the usual eruption last night, SWMBO turned the boiler off, the way
she does, by means of the control on the front of the unit. I switched it
on again this morning, and it seems to be working ok again as expected. One
thing I did notice, however, is immediately after the gas shut off (after a
fairly short heating time, as the control is on a low setting) there was a
clicking sound, like a relay operating, five or six times, as if it was
trying to re-light, which of course it didn't do until some minutes later,
after the heat exchanger had cooled down. This clicking only occurred for a
couple of seconds right after the flames shut down, it wasn't continuous.

The User Guide, explains that the boiler is fitted with a "safety thermostat
to protect against overheating of the water" which if it operates shuts the
boiler off, requiring a 'Reset' button to be pressed to restart it. The red
warning light has never illuminated, the boiler has never "locked out" like
the Guide says it should and it can always be restarted without the button
being pressed.

I found several very similar posts to this in other groups on the Interweb,
but none that I could see explained the cause and and how to fix it. I am
concerned that this problem seems fairly common - especially in boilers of a
similar age - and I am worried that the 'overheat protect' system allows the
water to boil. I called my CORGI (or whatever they are called this week)
registered man a couple of days ago and he is coming tomorrow to flush out
the system and look at the faulty boiler again. I would be most grateful if
someone here could help me resolve this problem. I have, of course, told my
CORGI man about it, but the boiler operated faultlessly - like they do -
when he came before, and he was (probably quite correctly) reluctant to
spend money on buying replacement parts until he is sure that they will
effect a cure. I won't say cost is irrelevant, because obviously I don't
particularly want to waste money, but I am anxious to get it fixed. If
items 'A' or 'B' could equally well be the cause but we don't know which one
actually is, I would rather replace 'em both than spend more time trying to
find out.

Help! Please?

Mike.
(Hatfield, Hertfordshire)

It does indeed sound like the overheat stat has failed, and shouldn't cost
much to have replaced on spec, even although it appears to work sometimes
- like when the engineer calls.

But you could just turn the boiler down initially to perhaps 80C or so -
it doesn't need to be full up for just heating the water.

--
*The early bird gets the worm, but the second mouse gets the cheese *

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
It does indeed sound like the overheat stat has failed, and shouldn't cost
much to have replaced on spec, even although it appears to work sometimes
- like when the engineer calls.

But you could just turn the boiler down initially to perhaps 80C or so -
it doesn't need to be full up for just heating the water.

Thanks Dave. It was, actually, on a lowish temperature setting already (and
50 to 82 degrees is allegedly the control range).

I have investigated further my looking at a parts list in the installation
manual, and the temperature control systems seems to be a little more
sophisticated than a straight old-fashioned on/off thermostat, using as it
does, a thermistor sensing element, and a potentiometer which are connected
to an electronic control board. As BOTH functions seemd to be dodgy (temp
control AND overheat) it might be something as simple as one (or more) of
those grotty spade connectors that has corroded over the years. I'll ask my
man when he comes to remove and replace the connectors a couple of times.
Can't do any harm and may do some good!

In article ,
Mike Faithfull wrote:
"Dave Plowman (News)" wrote in message
...
It does indeed sound like the overheat stat has failed, and shouldn't
cost much to have replaced on spec, even although it appears to work
sometimes - like when the engineer calls.

But you could just turn the boiler down initially to perhaps 80C or so
- it doesn't need to be full up for just heating the water.

Thanks Dave. It was, actually, on a lowish temperature setting already
(and 50 to 82 degrees is allegedly the control range).

So it looks like two faults.

I have investigated further my looking at a parts list in the
installation manual, and the temperature control systems seems to be a
little more sophisticated than a straight old-fashioned on/off
thermostat, using as it does, a thermistor sensing element, and a
potentiometer which are connected to an electronic control board. As
BOTH functions seemd to be dodgy (temp control AND overheat) it might be
something as simple as one (or more) of those grotty spade connectors
that has corroded over the years. I'll ask my man when he comes to
remove and replace the connectors a couple of times. Can't do any harm
and may do some good!

I'd expect it to be more sophisticated than my Kingfisher which I changed
only a couple of years ago after some 25 years of near faultless service.
Sadly, Potterton lost the plot reliability wise.

--
*A backward poet writes inverse.*

Dave Plowman London SW
To e-mail, change noise into sound.

replying to Dave Plowman (News), Lucky wrote:
I though there was something wrong with my boiler just this week. Had someone
out to inspect and all I can hear them say is 'new boiler, new boiler'. After
doing some troubleshooting (and blind luck) I found my overheatining problem
had to do with the pump (in the loft) being air bound. After venting the
system from the loft (not the radiator), it has gone back to normal.

--
for full context, visit https://www.homeownershub.com/uk-diy...ng-640196-.htm

On Sunday, 7 January 2018 16:14:08 UTC, Lucky wrote:
replying to Dave Plowman (News), Lucky wrote:
I though there was something wrong with my boiler just this week. Had someone
out to inspect and all I can hear them say is 'new boiler, new boiler'. After
doing some troubleshooting (and blind luck) I found my overheatining problem
had to do with the pump (in the loft) being air bound. After venting the
system from the loft (not the radiator), it has gone back to normal.

You'd be luckier if you came here via any other portal. The site you're using is partly nonfunctional, hated by almost everyone, and feeds users threads many years out of date.

http://wiki.diyfaq.org.uk/index.php/...up_access_tips


NT

Yes it is almost like the developer got kidnapped by aliens before it was
finished!

If the message really is current then the question has to be, where did the
air come from in the first place?
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
...
On Sunday, 7 January 2018 16:14:08 UTC, Lucky wrote:
replying to Dave Plowman (News), Lucky wrote:
I though there was something wrong with my boiler just this week. Had
someone
out to inspect and all I can hear them say is 'new boiler, new boiler'.
After
doing some troubleshooting (and blind luck) I found my overheatining
problem
had to do with the pump (in the loft) being air bound. After venting the
system from the loft (not the radiator), it has gone back to normal.

You'd be luckier if you came here via any other portal. The site you're
using is partly nonfunctional, hated by almost everyone, and feeds users
threads many years out of date.

http://wiki.diyfaq.org.uk/index.php/...up_access_tips


NT

In article ,
Lucky m wrote:
replying to Dave Plowman (News), Lucky wrote:

Thanks very much for your help.

But I changed the KingFisher for a Veissmann over 10 years ago.

--
*Snowmen fall from Heaven unassembled*

Dave Plowman London SW
To e-mail, change noise into sound.