Installed LS100 in the loft way back in 2003 and it's never missed a beat. 3 weeks ago I installed a mixer shower to run off it, worked a treat for 3 weeks then noticed water droplets on bottom of casing up in the loft so could have been there a while. When I removed the outer and inner casing could see small leak from top right veting area joint, removed it re-sealed it "sorted"!
Thought I'de check and clean burners while I was there but had to leave after I started it kids in need of shower. Re assembled now use tap or shower and water goes from hot to warm and after about 4 mins on comes flame fail light and it's cold! Re-set it and it's back on heat but repeats again? Could I have disturbed the FF divice on right on the burner "its 4mm gap if I rememer correctly "or should I check elswear when I get at tonight.

strawbear, May 2012

For future readers with LS80 or LS100 (they seem to be very similarr) it may be worth noting that when you remove the inner cover (ie the combustion chamber)you need to ensure you replace it properly when finished and leave no little gaps open (which is very easy to do without realising as the case doesnt always fit snugly) especially at the corners. If you dont ensure this then air will be sucked in throough the gap/s when the fan spins up and the air flow sensors may not detect enough pressure difference resulting in the safety tripping after a few seconds or a little later. To temporarily test this you could stick flame retardent/resistant tape around the seams of the casing and see if makes a difference, ,if it does then ensure the screws on the casing are all in and lined up correctly and adequatley tightened enough to pull the case back on to the rubber seal.

LS80Tuser, March 2013

Morning! removed the AAV and it sounds ok can here the valve rattle inside,replaced re filled, tried boiler again from cold it still ignites on CH or HW but shuts off after about 30 seconds, re-ignites itself then flame fail cuts in! Checked both thermistors and getting a reading from both so look ok. Checked ignition board pcb and can see one resistor is looking like its overheated (number R44) on Honeywell R2C board.Cant get any reading off it so will search internet to try and find one cant see any numbers ,it's brown with yellow orange,white,black band, It's a long shot but better than having to buyi a new one.

strawbear, May 2012

ravenheat LS100
GCN 47-581-33
intermittant DHW
thanks for the detailed history
''repair'' done on autoairvent
boiler ignites but cuts out after 4 minutes
not an ignition or flame detection problem
sounds like boiler overheating
presumably you had to drain boiler in order to repair AAV
if AAV is seized it could stop release of air in heat exchanger and cause overheat problem
i would drain boiler then refill it
listen for characteristic ''hissing'' noise from AAV
no hissing means defective AAV
''hot & cold DHW''
divertor valve/DHW diaphragm needs checking
i would also change CH & DHW thermistors as well to be on the safe side

manwithnoname, May 2012