Baxi 105e Intermittent fault on pump or low system pressure

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Will Silver

I have just started to get a problem with the fault as the title, this is the flashing light by the triangle/ 60 degree section.
This has happened twice now in the last two days.
Neither the central heating or the DHW works for a period of time say an hour then the light will stop flashing and things are back to normal.
I am just wondering if there is a component thats on its last legs, and would look to change that rather than it not coming on at all.
I have watched the operation of the microswitch and the pin for both DHW and CHW and both appear to be working fine, the pump operates then the light starts flashing.
The only thing I can vaguely recall reading somewhere was to do with the automatic air vent on top of the pump, but I am sure somebody will point me in the right direction.
The pressure in the system is fine and I changed the complete DHW pressure differential valve in November of last year.
 
Hi Will Silver ... The micro-switche's eventually get 'dirty' so sometimes the pcb recognises that they've made and sometimes it doesn't! Check the Resistance through the switch, should be zero or really low <1ohm EVERY time it switches. I emphasise every because that's why it can be intermittent! My belief is that the pcb has a built in tolerance may be up to 100ohms or more? Anyhoo's ... check it out if you know how to?
 
Thanks for that Diamondgas, not really something I know how to do, simple thing for me would be just to replace the micro-switches, doesnt look that expensive, so will go down that route. Then i at least I know that they are eliminated from possible causes of problem.
 
Have had no problems up until the weekend now back to the same problem as described above. Had switched back to DHW only after the warm weather we have had, but decided to switch back to both on Saturday with it being a bit chillier. Virtually straight away the flashing red light on the 60 degree section. Fitted the new micro-switches previously purchased, still nothing. Did not come on at all the rest of the day, tried it first thing in morning, nothing.
Tried it a little later and managed to get hot water until late afternoon, where just as we were washing up after Sunday dinner it decided to go off basically midstream.
No hot water this morning, really just want to ask if there is anything obvious I am missing and if there is anybody in my area who could sort it out. Money has been really tight that is why I have had to go down this route, bit easier now so would like an engineer to sort it out now. Just wondering where the problem might be so not going into it totally blind.
 
Hi once again Will Silver :)

The indication light is telling you that a flow of water through the boiler has not been detected as expected. If you know that there is plenty water in the heating system, usually by inspecting the pressure gauge, then it could be several other things associated with the pump or pump flow detection from a simple diaphragm to more complex flow issues. Post up a request here [DLMURL="http://www.ukplumbersforums.co.uk/im-looking-plumber-gas-engineer/"]I'm looking for a Plumber or Gas engineer.[/DLMURL] giving your general whereabouts and await any pm's that come your way! IMO
 
Thanks once again for your assistance, its the random nature of the problem which is puzzling. As you say it could be something simple or more complicated. I have put a call in to a local combi specialist and will see where I go from there, again thanks for your help.
 
Will Silver said:
Thanks once again for your assistance, its the random nature of the problem which is puzzling. As you say it could be something simple or more complicated. I have put a call in to a local combi specialist and will see where I go from there, again thanks for your help.
Click to expand...

You're welcome Will Silver :) Intermittent faults can cause some grief and end up costing a fortune. If you haven't had the appliance serviced in a while why not call someone in to service it and mention the intermittent fault to them. That way you end up with a 'free' analysis or even repair if you're lucky. I often offer my customers that option if their service is due soon or someone contacting me for the first time! Good luck :)
 
Will Silver said:
I have just started to get a problem with the fault as the title, this is the flashing light by the triangle/ 60 degree section.
This has happened twice now in the last two days.
Neither the central heating or the DHW works for a period of time say an hour then the light will stop flashing and things are back to normal.
I am just wondering if there is a component thats on its last legs, and would look to change that rather than it not coming on at all.
I have watched the operation of the microswitch and the pin for both DHW and CHW and both appear to be working fine, the pump operates then the light starts flashing.
The only thing I can vaguely recall reading somewhere was to do with the automatic air vent on top of the pump, but I am sure somebody will point me in the right direction.
The pressure in the system is fine and I changed the complete DHW pressure differential valve in November of last year.
Click to expand...

I have the baxi 105. If getting 240v across terminals 3 & 6 fine, otherwise replace PCB
 
Andrew Davis said:
I have the baxi 105. If getting 240v across terminals 3 & 6 fine, otherwise replace PCB
Click to expand...

Now you're getting technical Andrew Davis as you're taking the cover off and exposing the pcb :) And actually you're not quite correct imho ... 240v does not prove circulation is occuring it just proves that there's a supply for it to do so .. you still need a couple of other things to occur imo :)
 
Simply following the Baxi handbook, fault registers as the circulator. Doesn't state why there is an intermittent fault in the book.
 
Thanks guys for your input, engineer came out this morning and identified the PCB as being faulty. Now have to find a local stockist of board to finish job today.
 
This to me sounds like the primary flow sensor, as in the rear diaphragm not making the micro switch make. Reckon it needs a new diaghragm and the small hole underneath clearing as this sometimes blocks up. You can prove this by checking that the micro switch is not making when the fault light comes on. Pcb sounds a bit strange for that fault. Pm me Will I'm in Coventry if you get stuck.
 
i have had it were they stick and dont retract properly, giving this fault. then after time they do move of microswitch enough for the fault to vanish, my first port of call would be to manually make the switch a few times to make sure its working. then i would replace diaphram and clean spindle etc and try that. as leo said the diaprams on this generation of baxis do persish quite regualry :)

could be pcb but my first port of call is the diaphrams espically if its intermittant! dunno what other people think but i always go for the cheapest part first when intermittant. but if all seems to be working on the spindle etc then pcb would be next port of call
 
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Wish I had waited a bit longer for your replies, would have got to the answer a bit quicker.
Engineer came back about 5 yesterday with a new board swapped it over fired it up and still the same problem. Had gone through the usual checks on the micro-switches that they were making and breaking that appeared to be ok.
Decided to check that there was no break in the cable to the fan and pump all working ok. Checked at the PCB that the primary flow sensor was making and breaking, found that it was making, but not breaking. The problem being as you guys pointed out the spindle was not retracting fully. Managed to get things working again in lieu of getting a new diaphragm etc. The daft thing is we had to put the old micro-switch back on as the new one took further to break then the old one.
Engineer now left with a PCB and charged me a nominal fee for his time on site.
If some of the above doesnt make sense i have probably put my own interpretation on it.
Still, I know where to come next time I have a problem.
Many thanks for your assistance very much appreciated.
 
Please help!!! I have the same problem as above and have read through the thread..... it s in a different language to me. Its a bank holiday with on/off hot water, Circle with triangle light is flashing, and I have 3 dirty smelly rugby playing lads to get clean before we go out to watch Middlesbrough lose to Norwich at Wembly.
 
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