Working on a 2002 vintage Lochinvar Power-fin boiler (M# PBN1500, S#B026550). There are two and, to my knowledge, neither had ever been taken apart. So I made this my home for some days and did one at a time. This is long winded so set yourself down for a min. The first one came apart and cleaned and went back together nicely. The book only requires you to verify the air side pressure differential and make sure it’s close to 3.5”wc at 100% fire. Doesn’t reference combustion parameters at all but when I tested it it was around 38 ppm CO at 3.55”wc diff on the air side. (The ratio gas valve works at 1:1 so it should track pretty close to where the demand places the VFD driven fan (air) diff) When I took the second burner out and cleaned it, I had to do it twice since it was so ratty. The mesh screen was saggy but intact but it sounded like one of those rain sticks you get at souvenir stores since there was so much crap between the mesh and inner perforated core. Lochinvar said to trash it so I scavenged the good bits and replaced it. When I put it all together, the CO was over 200ppm. Less than the 400 Lochinvar says is a-ok on this unit but given the new burner and clean hx, I hoped I could do better. With some talking to tech support and a little trial and error I was able to get the CO and air diff, which had been low, closer to something I was more comfortable with. The second picture was how they told me to adjust the air diff. Below the flange where the burner meats the blower is a 3/8” tube that sticks into the burner assembly above the hot surface ignitor. The further the tube goes in the less the air differential is and vice versa. I landed at about 2 1/4” depth for a diff of 3.2”wc. Anything closer to 3.5”wc would send my CO climbing too high. I’m leaving this here to see if anyone has had any work on this type of boiler but also to leave the tech support notes. Lemme know if you have thoughts.

Posted by Jose Michael at 2021-03-12 18:26:49 UTC