Jaguar 28K Boiler F3 code, pump running

[ChrisB62]

Hi all
does anyone have an idea how to fix this, or what is wrong.

Power up, J1 (software version), Pause, click of relay, LED.s flash once & F3 code, pump running.

Will not reset.

This is a sudden occurance.
System was fine, went away for weekend, System was in Holiday mode. came back to an F3 code, and pump running.
I do not trust the handbook, Fault diagnosis of blocked heat exchanger.
As it has not been in use between being good, and showing the fault.

Checked PCB fuses. fine
No birds nests or blockages in the flue
Drained some water off no particles. Bar dropped, as expected. Re-pressurised, bar increased, so px sensor fine
Checked Diverter plunger operation by runnng hot tap. ok
Checked Diverter micro switch clicks, and goes oc cc as expected.
Bridged several sensors to isolate fault. took sensor resistance readings
High limit stat & thermistor not open cct - ok About 44 Ohm
Bridged CH thermistor gets F2 fault Thermister 333 ohm
Bridged DH sensor, no change 14.37K Ohm
Checked air sensor microswitch operation oc and cc and switch over when pipe sucked.
No power to Fan.
Fan free to turn, coil Resistance 43 Ohm.

There are no other sensors to check / spoof.

feels costly PCB, or Burner controller, or both

Any advice?????

 

[matt1e]

Yes stop bridging sensors etc out and get someone in to diagnose it
It's more than likely a blocked HEX anyway

Matt

 

[ChrisB62]

Thanks Matt1e.

There is an engineer coming today, but had to book him a week ago.
was trying to get some hot water between times.

Also System was working fine on the Friday. but came back to a fault code on the Sunday, with the boiler in Holiday mode. So not use when away.

Perplexed at your assumption that the Heat exchanger can have calcified itself over less than 2 days with no use.

To me it seems more likely a sensor has expired, or a small particle has blocked an orifice.

The checks i have been doing have been advised by a friend in the trade, who is to far away to do the physical diagnosis.

Chris

 

[ChrisB62]

Well engineer that wife arranged.

Went straight for overtemp thermistor reset.
scratched beard, sucked through teeth, scratched nose.
switched boiler on and off a few times.
tickled a few sensors.
scratched beard, sucked through teeth, scratched nose.

tried checking for voltage,
eventually left saying will have to call glo-worm for some advice.

Did not leave me with that warm fuzzy feeling that he had any clue whatsoever.

 

[ChrisB62]

Eventually we chased heating engineer up for an answer.
He said they advised changing some sensors, and maybe the ignition board.
I checked the feed from the PCB to the ignition board, There was no power.

Re-read the fault finding page, noticed that values for the temperature sensors is given for nominal temperature ranges.

The CH temp sensor was 333 Ohm, it should have been 10K to 16K Ohm.

Bridged it with a suitable resistor, and hey presto fault disappeared.

At least i know which sensor is required, and can cheat a little hot water from the boiler.
Not safe for central heating, as the burner will not modulate and CH water will be hotter than sensed.
hope this is of help to some of you.
carry a few 1/4 amp resistors in the temperature sensing range to isolate the faulty sensor.
Boiler was too smart to be fooled by a short circuit.

Chris

 

[Agile]

You seem to have a very odd idea of how boiler parts operate.

I am surprised that you did not immediately notice that the identical sensors had different resistances!

It is an unusual fault though unless they have got wet.

Nor is it advised to open the combustion chamber unless gas registered !

I am sorry that your wife chose an engineer who seemed to have so little ability to repair boilers! I do hope that you did not pay anything for his incompetance. If you did then ask for the money back!

Tony

 

[ChrisB62]

Hi Tony

Is not an identical sensor,
This sensor is clipped to the Hot pipe from the boiler.
The other Temperature sensor is screwed into the left side Block.

I just need to get a proper sensor, and a gas engineer to recommission the boiler for insurance purposes.

The other engineer was implying expensive cct boards, just to fault find.

I have some mechanical aptitude, and a healthy respect for flammable materials, and electricity, having worked on helicopters for the last 30 years.

Chris

 

[Agile]

There is non reason why you should not replace the sensors yourself.

I meant electrically as both are nominal 10k thermistors although in different packages. The resistance values are usually shown in the manual.

Having opened the combustion cover then I suggest you now arrange for the boiler to be checked or serviced.

Tony

 

[ChrisB62]

Back up and running.

Got some "Pipe-clip temperature sensors" from Rapidonlinedotcom for less than £2.00 each, plus postage, still waiting for boiler engineer to get his parts.

Old sensor was not sealed, and the sensor head was bonded to the heat transfer plate had become damaged at some time probably by being rotated, or slid on the pipe.
New sensor is probably the same inside, but the heat transfer plate is bonded to the sensor head making a more resilient component.

Will still have to pay boiler engineer, and his expensive parts, as it is a form of verbal contract.
Still. i have heat, and hot water till he comes.