My Ariston Eurocombi Boiler has developed an intermittent fault, where
it shuts down (flame goes out) for a second or so, then fires back up
again, whether supplying hot water or the radiators. This repeats
constantly, every 20 seconds or so, whatever temperature the HW or RAD
temp controls are set to.

Fault finding suggests an intermittent fault in the boiler output limit
thermostat, and temporarily bypassing the 'stat restores normal
operation, but is obviously not a safe way to operate the boiler.

Looking at the boiler innards, the design appears to have been modified
since the manual was written, in that there's a bracket on the output
pipe for the 'stat, but tracing the wiring diagram the 'stat now appears
to be integrated in the DHW temperature control, 'ganged' with the DHW
'stat.

Replacing the DHW control would appear to be a high cost, labour
intensive task, involving draining-down and dismantling, but simply
bolting on a previous-model pipe-mounted 'stat and re-routing the
existing wiring would see the job done in a few minutes.

Can anyone see a problem with that idea?
Would I need to use a thermal transfer gel/paste when fixing the 'stat?
The DHW 'stat appears to be working perfectly, switching hi/lo at the
set temperature, but is there a common failure mode which could see the
DHW 'stat fail soon, making it worth replacing the control now?

Thanks in advance
--
Keith
Note NO....SPAM measures, the fix should be obvious

"Keith" wrote in message
...
My Ariston Eurocombi Boiler has developed an intermittent fault, where
it shuts down (flame goes out) for a second or so, then fires back up
again, whether supplying hot water or the radiators. This repeats
constantly, every 20 seconds or so, whatever temperature the HW or RAD
temp controls are set to.

Fault finding suggests an intermittent fault in the boiler output limit
thermostat, and temporarily bypassing the 'stat restores normal
operation, but is obviously not a safe way to operate the boiler.

Looking at the boiler innards, the design appears to have been modified
since the manual was written, in that there's a bracket on the output
pipe for the 'stat, but tracing the wiring diagram the 'stat now appears
to be integrated in the DHW temperature control, 'ganged' with the DHW
'stat.

Replacing the DHW control would appear to be a high cost, labour
intensive task, involving draining-down and dismantling, but simply
bolting on a previous-model pipe-mounted 'stat and re-routing the
existing wiring would see the job done in a few minutes.

Can anyone see a problem with that idea?
Would I need to use a thermal transfer gel/paste when fixing the 'stat?
The DHW 'stat appears to be working perfectly, switching hi/lo at the
set temperature, but is there a common failure mode which could see the
DHW 'stat fail soon, making it worth replacing the control now?

Thanks in advance

Keith


And you're sure it isn't the gas valve ? Have you removed the wiring from,
or by-passed the wiring to, the thermostat to see if the boiler works
properly ? A thermostat only works as a single pole switch to break the
circuit, so connecting the wires from either side and touching them together
won't cause any problems.

Try by-passing the thermostat and firing the boiler up to see if it holds on
properly. If not, then it isn't the 'stat that's at fault.

I

I wrote:
My Ariston Eurocombi Boiler has developed an intermittent fault, where
it shuts down (flame goes out) for a second or so, then fires back up
again,

Fault finding suggests an intermittent fault in the boiler output limit
thermostat, and temporarily bypassing the 'stat restores normal
operation,

You followed up:-

Try by-passing the thermostat and firing the boiler up to see if it holds on
properly. If not, then it isn't the 'stat that's at fault.

It certainly seems like the stat is at fault, but I don't want to run
the boiler with it permanently bypassed, just trusting the overheat
cut-out.

I've two options, replace the whole temperature control, which
incorporates the limit stat, or fit an older version stat to the unused
bracket on the output pipe where it used to be fitted, and save money
and time.
--
Keith
Note NO....SPAM measures, the fix should be obvious

"Keith" wrote in message
...
I

I wrote:
My Ariston Eurocombi Boiler has developed an intermittent fault, where
it shuts down (flame goes out) for a second or so, then fires back up
again,

Fault finding suggests an intermittent fault in the boiler output limit
thermostat, and temporarily bypassing the 'stat restores normal
operation,

You followed up:-

Try by-passing the thermostat and firing the boiler up to see if it holds
on
properly. If not, then it isn't the 'stat that's at fault.

It certainly seems like the stat is at fault, but I don't want to run
the boiler with it permanently bypassed, just trusting the overheat
cut-out.

I've two options, replace the whole temperature control, which
incorporates the limit stat, or fit an older version stat to the unused
bracket on the output pipe where it used to be fitted, and save money
and time.

Keith


Don't run the boiler continually with the thermostat by-passed, just by-pass
it for the duration of the test. Other components can cause the same
symptoms, so the each have to be eliminated from the loop before the real
fault is found. Testing the 'stats is one of the easiest tests to do
because it's normally done by simply by-passing them to see if the fault
clears itself. Running the boiler for 30 minutes to see if the 'stat is
actually causing the problem won't hurt the system as long it's a supervised
test. Don't do the test by turning it on and walking away from it.

I have the same boiler which I installed about 5 years ago.
It has similar fault as yours.
start from cold flame comes on, goes out comes on, goes out, then fires
normally, for a cycle, then same again, until it is warmed up a bit then its
okay?
I have an external bolt on stat on the pipe.
I'll try the by pass and see if it fixes mine too.
I have tried moving the pots for soft start,cycle delay, etc, no change

Keith wrote:

My Ariston Eurocombi Boiler has developed an intermittent fault, where
it shuts down (flame goes out) for a second or so, then fires back up
again, whether supplying hot water or the radiators. This repeats
constantly, every 20 seconds or so, whatever temperature the HW or RAD
temp controls are set to.

Fault finding suggests an intermittent fault in the boiler output limit
thermostat, and temporarily bypassing the 'stat restores normal
operation, but is obviously not a safe way to operate the boiler.

Looking at the boiler innards, the design appears to have been modified
since the manual was written, in that there's a bracket on the output
pipe for the 'stat, but tracing the wiring diagram the 'stat now appears
to be integrated in the DHW temperature control, 'ganged' with the DHW
'stat.

Replacing the DHW control would appear to be a high cost, labour
intensive task, involving draining-down and dismantling, but simply
bolting on a previous-model pipe-mounted 'stat and re-routing the
existing wiring would see the job done in a few minutes.

Can anyone see a problem with that idea?
Would I need to use a thermal transfer gel/paste when fixing the 'stat?
The DHW 'stat appears to be working perfectly, switching hi/lo at the
set temperature, but is there a common failure mode which could see the
DHW 'stat fail soon, making it worth replacing the control now?

Thanks in advance
--
Keith
Note NO....SPAM measures, the fix should be obvious

Hot water getting red hot at sink next to boiler but only just above cold up stairs any ideas

wrote:
Hot water getting red hot at sink next to boiler but only just above
cold up stairs any ideas

Run upstairs water 4 mins report back with temp

On 14/01/2016 17:52, wrote:
Hot water getting red hot at sink next to boiler but only just above cold up stairs any ideas


Have you just moved into this property ?

If so, are you sure the upstairs hot tap really is the hot tap, and not
the cold tap with the wrong cap ?. If it and the downstairs hot tap
really are connected to the hot water output of a combi then turn on the
upstairs tap and shout down the stairs for some one to turn on the
downstairs hot tap full blast. You should notice a reduction in flow
from the upstairs hot tap.

If there is no obvious drop in flow, then do you still have a hot tank
connected as a heating zone ?. Not everyone removes the hot tank
especially if it is a larger property and teenagers are resident.

On 14/01/2016 17:58, Phil L wrote:
wrote:
Hot water getting red hot at sink next to boiler but only just above
cold up stairs any ideas

Run upstairs water 4 mins report back with temp


That's certainly the first thing to try. 4 minutes is probably a bit
cautious. Do you get the same flow rate upstairs as downstairs? If it is
much slower, then the combi may be cutting in and out.

Can you get water out of the upstairs tap when the downstairs one is
running? (You might have to reduce the flow of the downstairs one).
There will be some heat loss in the pipe run upstairs, but this should
not be particularly obvious unless it is a horribly long run, for some
reason. So with the combi running, and both taps running, you should get
similar temperatures at both points eventually. If you don't, this
suggests that as Andrew suggests, the plumbing is more complicated than
you think.

On 14/01/2016 17:52, wrote:
Hot water getting red hot at sink next to boiler but only just above cold up stairs any ideas


It could be a failed shower mixer allowing cold water to pass though to
the hot pipework.

Is there an isolator on the boiler on either the cold water feed, or the
hot out? If so, turn that off and see if you still get water out the hot
taps.


--
Toby...
Remove your pants to reply

---
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Have Ariston combi gas boiler when I set my temperature for heating rads say at 50 when I come back 30 minits later the temperature has increased to 80
Have tried every thing boiler just fitted 3 weeks ago and have had to shut of as I cant control the temperature on it and waiting for an engineer but wont be for a while

On Wednesday, 26 September 2018 11:59:31 UTC+1, wrote:
Have Ariston combi gas boiler when I set my temperature for heating rads say at 50 when I come back 30 minits later the temperature has increased to 80
Have tried every thing boiler just fitted 3 weeks ago and have had to shut of as I cant control the temperature on it and waiting for an engineer but wont be for a while

do you mean it displays 80 or the water goes to 80 but the display says 50?


NT

On Wednesday, 26 September 2018 12:48:31 UTC+1, wrote:
On Wednesday, 26 September 2018 11:59:31 UTC+1, wrote:
Have Ariston combi gas boiler when I set my temperature for heating rads say at 50 when I come back 30 minits later the temperature has increased to 80
Have tried every thing boiler just fitted 3 weeks ago and have had to shut of as I cant control the temperature on it and waiting for an engineer but wont be for a while

do you mean it displays 80 or the water goes to 80 but the display says 50?


NT

But I guess they sorted the problem two years ago!

Jonathan

On Wednesday, 26 September 2018 14:33:53 UTC+1, Jonathan wrote:
On Wednesday, 26 September 2018 12:48:31 UTC+1, tabby wrote:
On Wednesday, 26 September 2018 11:59:31 UTC+1, wrote:
Have Ariston combi gas boiler when I set my temperature for heating rads say at 50 when I come back 30 minits later the temperature has increased to 80
Have tried every thing boiler just fitted 3 weeks ago and have had to shut of as I cant control the temperature on it and waiting for an engineer but wont be for a while

do you mean it displays 80 or the water goes to 80 but the display says 50?


NT

But I guess they sorted the problem two years ago!

Jonathan

no, check the dates