Ignites, proves ignition but goes out shortly afterwards, switching thermisters to fool it, it stays on, measuring thermister both are within spec, replaced anyway proved thermister is not the fault. Can it now be anything but the control board?
Baxi genesis
- Thread starter Paul Barker
- Start date
This boiler is a rebadged C&M Combi 80.
Its main faults are associated with the return filter clogging and the magnetic DHW and system flow switches.
Swapping thermisters, you say, makes it stay on. That makes me wonder if its a flow problem, changing a PCB is the last resort. Have you cleaned the return filter and the mag switches?
Have you dynamically monitored the system flow switch electronically?
Does it deliver the rated hot water?
My advice would be to very carefully check the performance for flow rate deficiencies and then change both thermisters before the pcb.
Tony
Its main faults are associated with the return filter clogging and the magnetic DHW and system flow switches.
Swapping thermisters, you say, makes it stay on. That makes me wonder if its a flow problem, changing a PCB is the last resort. Have you cleaned the return filter and the mag switches?
Have you dynamically monitored the system flow switch electronically?
Does it deliver the rated hot water?
My advice would be to very carefully check the performance for flow rate deficiencies and then change both thermisters before the pcb.
Tony
"Replaced" the thermistors .... do you mean with new ones or you just put them back!?
Could be that the thermistor it worked with had drifted in a fortunate direction. A fixed resistor, or potentiometer on flying leads, is handy for this.
" goes out shortly afterwards" how shortly? - if it's a second or two the temp wouldn't have changed....etc...
Can you bridge the flow switch at the appropriate time to fool it?
Could be that the thermistor it worked with had drifted in a fortunate direction. A fixed resistor, or potentiometer on flying leads, is handy for this.
" goes out shortly afterwards" how shortly? - if it's a second or two the temp wouldn't have changed....etc...
Can you bridge the flow switch at the appropriate time to fool it?
B
BOB.DOLE
Paul Barker said:
is this test done on dhw mode
No I meant I put a new thermister in, so that eliminates the thermisters.
does the same on dhw and ch, after flame proving but not very long after, a few minutes on heating almost right away on hot water, but definately gets past flame proving stage.
So what I am expecting is a fault in the processing of the correct information.
The flow switches are functioning correctly and I never suspected them though I did test them. They were replaced a year ago by previous repair guy, they do their job.
does the same on dhw and ch, after flame proving but not very long after, a few minutes on heating almost right away on hot water, but definately gets past flame proving stage.
So what I am expecting is a fault in the processing of the correct information.
The flow switches are functioning correctly and I never suspected them though I did test them. They were replaced a year ago by previous repair guy, they do their job.
Paul, a one off static test is not always adequate!
You must test them dynamically to see if they are the cause of the fault.
I dont remember, but presumably there is an APS. Have you done a dynamic test on that???
Tony
You must test them dynamically to see if they are the cause of the fault.
I dont remember, but presumably there is an APS. Have you done a dynamic test on that???
Tony
Thanks Tony I tested resistrance of thermister as boiler was heating up it was droping as expected but the boiler cut out still, so I swicthed leeds such that the thermister stayed at max resistance but after a while the boiler still cut out. On reseting it always gets past flame proving but fails soon after.
Do you hold the continuity tester across aps to see if at the moment the boiler cuts out aps also goes open circuit? Thanks for the tip, will check that. Boiler is in Kilham a little way away won't be back there 'till tomorrow.
Do you hold the continuity tester across aps to see if at the moment the boiler cuts out aps also goes open circuit? Thanks for the tip, will check that. Boiler is in Kilham a little way away won't be back there 'till tomorrow.
NO !!! Unless you want to kill the continuity tester!
You can only do dynamic measurements on voltage. You can see what the relevant voltages are for on/off by testing it with the APS air tube on/off.
Something is causing the boiler to go off. You have got to find out what that is by dynamically testing the aps for a start. Then the system flow switch for example.
Tony
You can only do dynamic measurements on voltage. You can see what the relevant voltages are for on/off by testing it with the APS air tube on/off.
Something is causing the boiler to go off. You have got to find out what that is by dynamically testing the aps for a start. Then the system flow switch for example.
Tony
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Baxi genesis
My advice would be to put your tools back in there toolbox, Then put your toolbox into the back of your van and get the hell out of there. (Tongue in cheek)
They are Frances revenge for world war two, The biggest pile of ****e Baxi ever put there name to.I see them all the time and i still cant get my head around them...Good luck though if you fix it you will be a very clever man.
My advice would be to put your tools back in there toolbox, Then put your toolbox into the back of your van and get the hell out of there. (Tongue in cheek)
They are Frances revenge for world war two, The biggest pile of ****e Baxi ever put there name to.I see them all the time and i still cant get my head around them...Good luck though if you fix it you will be a very clever man.
If you watch the voltage at the pcb end with a digital volt meter, there will be a click and the digits will be jumping about and you may have a hard time decidng whether the APS switched then the boiler stopped, or the other way round.
The boiler might take the voltage(mains or 24v, or...?) off the common terminal of the aps when it turns itself off.
A cheap analogue meter or a neon screwdriver for mains voltages, can be a better tool to look for changes.
A tee piece in the air tube can be illuminating, you can watch the pressure to the APS dropping as the boiler warms up, but if the APS is in the air box (I think yours is) you can't get the tube out.
ALternatives -
>>Substitute a microswitch and flying leads for the APS, and monitor the actual APS with your continuity tester while it's disconnected,
>>run the thing with the corner of the cover loose, the APS will probably get a better pressure and the boiler keep going until you shut it.
You can of course short out a flow switch...
The boiler might take the voltage(mains or 24v, or...?) off the common terminal of the aps when it turns itself off.
A cheap analogue meter or a neon screwdriver for mains voltages, can be a better tool to look for changes.
A tee piece in the air tube can be illuminating, you can watch the pressure to the APS dropping as the boiler warms up, but if the APS is in the air box (I think yours is) you can't get the tube out.
ALternatives -
>>Substitute a microswitch and flying leads for the APS, and monitor the actual APS with your continuity tester while it's disconnected,
>>run the thing with the corner of the cover loose, the APS will probably get a better pressure and the boiler keep going until you shut it.
You can of course short out a flow switch...
Good advice to follow. If it's so, note that an occasional problem on Chaffoteaux Britonys (same as Baxi Genesis) is a partial blockage of the fan outlet venturi, which can result in the APS failing to switch, or switching back as pressure differential drops with warming as ChrisR described. The venturi is easily accessed if you first remove the fan. Blast some mains pressure water through all its tubes to clear any rubbish (I once had one blocked by a spider's egg nest!).ChrisR said:
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poxi said:
I thought that was the Bahama
Gaz you got me all excited seeing you had posted, not that my other seniors hadn't already helped me a great deal, I thought you must see these things a lot.
Must be intermittent, because customer hasn't hassled me again yet, blasted thing is 1/2 a day away round trip and I have too much proper work on, replaced an etype with a combi Friday Staurday, have 9.24 to replace with a Buderus Monday and another Genesis (much older which I have decided to do no work on) with a cheap vokera for cheapness as it's that sort of customer (son from far away is paying for mother, might even have found me through here or my website who knows?) Still trying to finish the plumbing on a newbuild in spite of the ******* builder blocking my gas pipes with drywall adhesive and other tricks, plus the usual long list of roundtuit jobs that make me run home early from church before all the old dears waiting for me to come and see to their taps catch me.
this particular genesis that I would like to keep going isn't that old, and the couple have a new baby, which does make a difference. the hard part is I'm imensely busy and it's a country mile away, plus no local spares from the boiler location and last thing I want to be lumbered with is a load of baxi genesis spares. I find jobs like this a total loss usually so am giving what time I do give to it out of charity.
Must be intermittent, because customer hasn't hassled me again yet, blasted thing is 1/2 a day away round trip and I have too much proper work on, replaced an etype with a combi Friday Staurday, have 9.24 to replace with a Buderus Monday and another Genesis (much older which I have decided to do no work on) with a cheap vokera for cheapness as it's that sort of customer (son from far away is paying for mother, might even have found me through here or my website who knows?) Still trying to finish the plumbing on a newbuild in spite of the ******* builder blocking my gas pipes with drywall adhesive and other tricks, plus the usual long list of roundtuit jobs that make me run home early from church before all the old dears waiting for me to come and see to their taps catch me.
this particular genesis that I would like to keep going isn't that old, and the couple have a new baby, which does make a difference. the hard part is I'm imensely busy and it's a country mile away, plus no local spares from the boiler location and last thing I want to be lumbered with is a load of baxi genesis spares. I find jobs like this a total loss usually so am giving what time I do give to it out of charity.
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gazthepottertonengineer said:poxi said:
I thought that was the Bahama
The Bahama to me is the second pile of sh1te
Welcome back Gaz..As senior Baxi/Potterton consultant on here you`ve been missed
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Why thank you not too glad to be back as it was much more fun in Florida only 2 more weeks and i got another rest week anyway god i love the summer
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