Baxi 105e random led's

[freddy871]

Hi all , general question , happened to notice led's on baxi 105e randomly flashing up and down and do not seem related to any error codes. PCB was replaced with newer model about 5 years ago, Boiler is probably knocking on 12-14 years old so bit long in tooth. Runs fine, heats and gives hot water, but want to try and make sure I do not stumble into a full failure leading up to winter. Took a short video of symptoms and wondered if anyone had any ideas.? Linky here

.. OH and the noise on the vid is not the boiler, but the tumble dryer below. Thanks J

 

[MeldrewsMate]

Do the leds flicker when the boiler is cold (and none would normally be lit)?
When starting from cold how long does it take to heat to, say,the 70C level? At that point are all the radiators at a similar temperature?

Does the flickering still occur when lower or higher flow temperatures are selected?
Does it flicker when only hot water is demanded?

Accurate answers may help a speedy diagnosis.

 

[ianmcd]

if it only does this on CH demand I would try changing the primary thermistor, if it does it on HW demand also I would be looking at the wiring harness or PCB

 

[freddy871]

Do the leds flicker when the boiler is cold (and none would normally be lit)?
When starting from cold how long does it take to heat to, say,the 70C level? At that point are all the radiators at a similar temperature?

Does the flickering still occur when lower or higher flow temperatures are selected?
Does it flicker when only hot water is demanded?

Accurate answers may help a speedy diagnosis.

No flickering when cold , only power light . Hot water demand takes about 30-45 seconds to hit 70 but led,s jump up and down gettingb there. Led's still jump after he demand stopped, is hw demand is off and all led sitting at 80 degrees. Changed to CH and ramped up thermostat, took couple of mins to hit 60 then sat there a while then couple of mins to hit 70 . Rads have room stats but all getting hot. Some flickering on CH also. Flame up to 70, then no flame and led's drop quickly to 30, pump running continuous. Hope this covers questions . Thx

 

[freddy871]

Another question, although led's are playing up, i wouldnt have noticed unless i had flipped the panel down to check pressure. So boiler operates as it should, am i being naive if i just ignore it until some actual symptoms appear. ??

 

[durhamplumber]

Random leds flashing on 105 is pcb usually,but thermistors are v common problem too,but generally tend to just flash 1 led rather than random ones.Leave it if its otherwise ok.

 

[ianmcd]

if doing it on both CH and HW you will need a replacement PCB soon

 

[freddy871]

Cheers all, Being someone who likes to be prepared , managed to source a new genuine PCB at a very reasonable price.. So at least will have it in my back pocket, should things take a turn..

 

[ianmcd]

That was the correct thing to do, when you replace the PCB you have to hold the reset for a fair bit about a minute if I remember correctly and then it will fire up, dont worry if your new pcb (green) looks different to the origional one (white) and the connections are in different places it will still fit, the PCB was changed a few years back, if the pcb you have sourced is new and not reconditioned, set all the controls to minimum or off and the new one will slot straight in as that is what the new one will be set to

 

[freddy871]

That was the correct thing to do, when you replace the PCB you have to hold the reset for a fair bit about a minute if I remember correctly and then it will fire up, dont worry if your new pcb (green) looks different to the origional one (white) and the connections are in different places it will still fit, the PCB was changed a few years back, if the pcb you have sourced is new and not reconditioned, set all the controls to minimum or off and the new one will slot straight in as that is what the new one will be set to

Thanks Ian , have to admit this will be my 2nd PCB. Installed refurb pcb about 8 years ago, but your comments are welcome as no doubt I would have been standing there like a lemon waiting for things to happen. Hopefully this one being brand new will last as long or longer than last .

 

[ianmcd]

the newer ones certainly seem more reliable, I have replaced lots of the origionals but havent been called back to any of the newer ones

 

[freddy871]

the newer ones certainly seem more reliable, I have replaced lots of the origionals but havent been called back to any of the newer ones

So little update,, New PCB arrived and installed to check functional. Installed reset, and fired up perfectly. However random led issue still there.. So seems not PCB related unless I have two with exactly the same issue. So Thought I would check Thermistors, (All readings were taken by removal of PCB connector and tested through plug-loom to sensor) Ran hot tap with boiler off, and then checked DHW, Sat at around 12k..Heaing had been on a tad, so expected CH to be lower, started at 6K, and after 1.5 hours with no heating checked again at 10k. pipes were near as damn it cold at this point. As mentioned all heating and water works as it should but now got the bit between my teeth as to these strange LED happenings.. Have tried CH only, CH Demand and then DHW demand, also changed boiler setting to DHW only and in all situations LED's jump around all over the place.

 

[freddy871]

Update success, well nearly a year on with lights still jumping around, but diverter pin needed a little clean as was sticking. While cleaning thought i would replace heating and DHW thermistors. Pin cleaned, sensors changed and its like a new boiler. piping hot water at 50% on the dial and no more random flashing led's