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