Checking Proper Draft

Most boiler and furnaces should have a -.02 draft reading over the fire. There is usually a 5/16" hole in or around the burner observation port.

You need to run the boiler long enough to heat the flue (10-15 min) in the summer should be good enough. Then check the draft

Adjust the barometric damper as needed (open it for less draft, close it fore more draft.

Should do a combustion test as well.

I would check the draft over the fire on this furnace at the screw that is filling the test port where the yellow arrow is pointing. That is why the manufacturer put that hole there. You can then measure the draft at the breech using the same hole you make for the combustion analyzer.

I like the last section of the first elbow coming off the exhaust opening of the furnace. That location should have the least amount of leakage air entering the flue connector, while also avoiding radiant heat from the heat exchanger that could cause a false stack-temperature reading.

When looking at a boiler, you look for the small port near the flame-sight opening for checking over-fire draft (yellow arrows), and then check the draft again at the flue connector.

In my opinion, both boilers and furnaces have the same basic features and requirements when testing and adjusting draft over the fire. You just need to read the equipment instructions for the manufacturer's recommended settings. Some boilers and furnaces operate properly with a slight positive pressure over the fire, but most of the appliances you will work with will require a negative draft over the fire.

@HVACNUT , this happens to be the Buderus G115 boiler I installed in my father’s home in Sea Isle City in 1995. When that house was demolished in 2003, I salvaged the boiler and installed it in my home in Dennisville, NJ.

Over the years, the original Riello burner needed a few parts replaced, and eventually the hydraulic piston that opens the air adjustment failed. It was easier to swap out the burner one winter day than to spend the time trying to locate a replacement hydraulic piston to repair the Riello.

Since I already had another burner completely rebuilt and ready for a swap, sitting on a shelf in my shop, the “odd couple” was created. That temporary patch has now been in place for about nine years.

Not a bad burner when you take good care of them.

I did ask AI to clean up the walls and the boiler a bit, but that is the actual boiler/burner combination you see there.

@HVACNUT said: "Ok. I gotta admit I'm a little weirded out by it, but ok. I would've gone to my van and grabbed a pump plug to eliminate the hydraulic jack myself. But you did… that."

I remember that I had a replacement hydraulic jack in the replacement parts kit I purchased when I started using Riello burners. I remember spending a few hours on that one evening, and it lasted into the late night. There were extenuating circumstances at that particular service call. I think the technical term is “a wife.” Anyway, after too much time wasted trying to do it properly, I just swapped out the burner and got the hot water running again. The heat came soon after that.

And, as with all owner-occupied heating systems, as long as there are no problems, those other finish-up repairs can wait until I get a round 2-it. No one ever gave me one, so it never got done!

@PC7060 Said: "Yes, the odd reflections are give away too. When have you ever seen that shiny of a surface on a boiler! 😂"

@EdTheHeaterMan answered: "The day I put them in, and the day after I tune them up. Some of my customer's boiler rooms look better than the day I installed them."

Then there are the average boiler rooms that you just can't do anything about. Between cats and dogs and workshops and laundry detergent/appliances, they ain't never gonna look nice, especially when the plastic clothes basket melts on the the vent connector!

Just look at the furnace in the other photo, that's my son doing a combustion analysis on a 4 year old AireTemp furnace I installed. I'm particularly happy with the vent connector connection to the chimney base. Struct-O-lite made that seal and there are no cracks in that connection after 4 years. A chimney repair company in Philadelphia showed me that stuff over 40 years ago and I have used it ever since.