New boiler problems.

[JohnCT]

I installed a new Slant/Fin Intrepid TR-30 1.10gph boiler this past weekend. When I fired it up, it ran beautifully for about 5 minutes when it started rumbling and flapping the damper. When I opened the sight door, it improved and the damper stopped flapping, but I could feel hot air puffing out of the door. It also showed no draft over the fire and virtually none in the stack.

Since the boiler I just replaced showed similar draft numbers (although it ran well), I immediately suspected a plugged chimney. I had a chimney company come out today and clean the flue and install a cap. They said it wasn't that bad. Uh-oh Andy..

I re-fired the burner (Beckett AFG) and the problem is still there after the flue cleaning. I shut it back down, removed the damper from the flue T, and put a piece of paper over the damper opening. With the burner off, I could feel an ever so slight suction with the paper. When I started the boiler again, the paper started flapping like the damper door did.

I then wondered if the boiler had fouled and sooted up during the first fire so I pulled the top off, and it's as clean as a whistle. I then ran it with out the flue and I can see the flame down through the sections, but even when running it with no flue pipe on top, there is still hot air backing out the sight door.

The settings on the AFG are those that Beckett and Slant recommend for that burner, and I tried opening and closing the shutters, but it doesn't want to run smoothly.

I know it can because it did for the first 5 minutes.

As far as the flame, it's hitting the back target at what would appear to be half the flame distance. The flame curls back around and it seems like the flame tendrils are almost making it back to the burner, like it's got a honking big nozzle at a narrow angle. It's a 80 degree "W" Delavan (or that's what it's supposed to have been shipped with.

Any chance the new nozzle crapped out after 5 minutes? Further info, I bought the boiler about three years ago and it's been sitting wrapped in plastic sitting in the crate in my basement until this week. There is QC paperwork on the burner that shows that the burner was test run. Maybe something happened to the nozzle after sitting for three years?

I have another nozzle I can try if anyone thinks that might help.

I'm stumped and am willing to listen to any suggestions.

John

 

[JohnCT]

So I just swapped the original 1.10/80W with a 0.85/80SS that I had in my collection (The Slant TR-30 will fire at 0.85), and things have changed. Whereas before when the flame hit the target and actually circled around most of the way back, the new nozzle shows a flame more like I recognize: shoots about halfway into the chamber and doesn't hit the back target wall at all. I'm also getting about -.02 draft over the fire now and about the same before the damper, but no positive pressure blowing out the sight door as before. Since it's only heating DHW right now and cycles quickly with no heat load, I don't know if the chimney gets hot enough to create much of a draft right now, but the burner also sounds much better.

In addition, now that the flame is smaller and not totally covering the target wall, I can see a large black spot on the target about 2 o'clock relative to the centerline of the flame, and a small area in the black spot is glowing red, so it seems like the target was peppered with unatomized fuel from the original nozzle.

Also, when I pulled the nozzle tube out, the bottom of the nozzle and the tube had a gelled or hardened coating of red oil. Since this AFG is equipped with the "clean cut" fuel shutoff solenoid on the pump, I'm guessing the excess oil on the nozzle and burner tube happened as it was running.

Tomorrow, I'll play a bit with the adjustments and see how close I can dial it in.

John