same issue
I had the same issue with my Solo 110 and to some extent i am still having it. First the gas, it seemed to be intermittent, sometimes stronger, sometimes weaker smelling. My gas company went through the unit and was able to detect a small leak which they fixed. I would do this first. I have the same trumpet or train whistle sound on low fire. The conventional wisdom was to make sure the unit air/gas was calibrated correctly, i.e. make sure it's not a lean mixture. Some purport to have fixed the problem by calibrating the unit correctly. I had my unit tested by a TT factory-trained plumber with a digital combustion analyzer and the unit was spot-on. He was able to re-create the trumpet sound issue on a low fire test (amazing! when does this ever happen when the repair guy is there?). He indicated that there were no specs for a low fire calibration. He also tested the LP gas pressure which was 11" - also on-spec. He contacted TT who told him that i should have my pressure lowered to 9". I think the theory was that the regulator may have shown 11" but during the morning (when the sound typically happens) it may be fluctuating above. My opinion is that TT doesn't want to send new parts until they can't point fingers anywhere else. One piece of additional info, I've had the boiler for about three years and this issue didn't happen until about 2 months ago.
(1) I have a Solo 110 that makes a horn-like sound just after firing, goes away after about 15 seconds as boiler moves to "high fire". (2) Also, I smell raw gas coming from the intake elbow that connects to the venturi when in standby. TT told me that there should not be a gas smell anywhere! So they arranged to have a guy put in a new gas valve. That didn't fix it. Sometimes I smell gas in the room. Anybody have trouble like this?
Jack
I had the same issue with my Solo 110 and to some extent i am still having it. First the gas, it seemed to be intermittent, sometimes stronger, sometimes weaker smelling. My gas company went through the unit and was able to detect a small leak which they fixed. I would do this first. I have the same trumpet or train whistle sound on low fire. The conventional wisdom was to make sure the unit air/gas was calibrated correctly, i.e. make sure it's not a lean mixture. Some purport to have fixed the problem by calibrating the unit correctly. I had my unit tested by a TT factory-trained plumber with a digital combustion analyzer and the unit was spot-on. He was able to re-create the trumpet sound issue on a low fire test (amazing! when does this ever happen when the repair guy is there?). He indicated that there were no specs for a low fire calibration. He also tested the LP gas pressure which was 11" - also on-spec. He contacted TT who told him that i should have my pressure lowered to 9". I think the theory was that the regulator may have shown 11" but during the morning (when the sound typically happens) it may be fluctuating above. My opinion is that TT doesn't want to send new parts until they can't point fingers anywhere else. One piece of additional info, I've had the boiler for about three years and this issue didn't happen until about 2 months ago.