Anyone out there hazard a guess on this problem?
I've been through all the service bulletins for a non-working Bosch Aquastar (AQ 125 BO), and have done all the tests I can think of, but still the pilot light won't remain lit. Thermo-couple is putting out about 25 mVDC, right in spec with what it should be, and that leaves me with only the flue gas sensor and the electromagnet assembly as possible culprits. I'm not sure how the flue gas sensor is supposed to work, but as it's sitting on the exchanger coils, I'm guessing heat either opens or closes the contacts inside, thereby making or breaking the connection from the thermo-couple to the electromagnet assembly. This unit sits dormant all winter, and has given me trouble before when getting it ready for use in the spring. At this point, nothing I do seems to be able to keep the pilot light lit, including jumpering out the suspect components (ECO, flue gas sensor).
I'm just about ready to remove the unit and scrap it. Any ideas out there?
Thanks in advance!