baxi 80e

[desrob]

intermittent firing problem,no running taps and room stat ok,going to have a look today any ideas,ta.

 

[tipintim]

Its not on preheat, is it?
Just thought, no preheat on this model. Sorry

 

[jncalderc]

Sounds like the thermistor

 

[desrob]

Sounds like the thermistor

whats the resistance when cold 8 - 15 ohms?

 

[fixter1]

11 ohms i think sure gasman will give you a answer later

 

[desrob]

11 ohms i think sure gasman will give you a answer later

yes, that sounds about right,would boiler fire when not even calling for heat (timer switch on off),only stopping cycling when temp select dial is turned right down and am i to presume the temp sensor will show open circuit with multimeter or very low ohms if faulty.

 

[fixter1]

i dont think it would be thermister,,dose it have a roomstat or just a clock,, i would be testing controls but im still new to fault finding

 

[desrob]

it had rf stat to eliminate it i put a new baxi clock in boiler. and on the clock, timer,i switched it to off and the boiler cycled and lit only knocking off as said when temp dial was turned right down,i do think it's the thermister but i'm a bit confused on why there seems to be a permanant demand

 

[fixter1]

is it a heating demand its going for or ho****er?????

 

[fixter1]

think i will leave it to some of the lads with more time under the belts

 

[jncalderc]

Hi, the only thing which can call for heat are external controls, and DHW, if this was coming on under DHW it must be related to an open pipe or tap, if it is the heating which is switching on when the time clock is set to off which is what I understand is happening then this is mostly likely caused by the frost stat picking up wrong signals from the thermister. Boiler is fairly straightforward

 

[jncalderc]

Baxi are good on the phone at fault detemining and you can call them on 08448711525 they will nail it immediatley I am sure

 

[Billy Bob Bob]

fixters right look for 11k cold on the thermistor,if its coming on with no demand try isolating the dhw see what it does then

 

[Billy Bob Bob]

Hi, the only thing which can call for heat are external controls, and DHW, if this was coming on under DHW it must be related to an open pipe or tap, if it is the heating which is switching on when the time clock is set to off which is what I understand is happening then this is mostly likely caused by the frost stat picking up wrong signals from the thermister. Boiler is fairly straightforward

fair enough what you say but unless a external frost stat is fitted the 80e does not have one built into the pcb only the bigger 105 does

 

[desrob]

Baxi are good on the phone at fault detemining and you can call them on 08448711525 they will nail it immediatley I am sure

sadly that not what i've experienced,i have them take me round the block and back again and more often than not they seem to point you to the pcb as they did with me on one occasion and it turned out to be the gas valve

 

[desrob]

fair enough what you say but unless a external frost stat is fitted the 80e does not have one built into the pcb only the bigger 105 does

no frost stat so not an issue

 

[Billy Bob Bob]

so talk me trough it does it randomly fire up with no call for heating or dhw?

 

[desrob]

fixters right look for 11k cold on the thermistor,if its coming on with no demand try isolating the dhw see what it does then

this boiler has had a pcb 6 mths ago and a diverter valve 3mths ago,if, i tested thermister and i got a reading of 3k ohms.but it was warm am

 

[desrob]

so talk me trough it does it randomly fire up with no call for heating or dhw?

heating

 

[Billy Bob Bob]

this boiler has had a pcb 6 mths ago and a diverter valve 3mths ago,if, i tested thermister and i got a reading of 3k ohms.but it was warm am

you need to check it cold the resistance decreases with temperature,and answer post 17

 

[desrob]

you need to check it cold the resistance decreases with temperature,and answer post 17

i should point out it happens all the time not just now and again

 

[Hardy1]

no running taps?- is it set on central heating?, check aps could be starting sequence(its getting windy outside)

 

[Billy Bob Bob]

have you tried isolating the DHW supply as far as you can tell does any of the DHW pipework disappear into a cement floor?

 

[desrob]

have you tried isolating the DHW supply as far as you can tell does any of the DHW pipework disappear into a cement floor?

do you think it could be passing(dhw),it's in a ground floor flat

 

[Billy Bob Bob]

do you think it could be passing(dhw),it's in a ground floor flat

it could be isolating the DHW for a few hours would prove it either way