Originally Posted By: John Furr
This post was automatically imported from our archived forum.
Not only is John 100% correct on the usage of the hole, he is also correct in stating the hole is of no concern.
"The probes are for CO2, stack temp, smoke and draft testing. They are inserted into the flue pipe to gather flue gases. The boiler should be running for about 5 to 10 minutes before testing. Depending on the boiler and burner unit efficiency should be above 80 percent. The boiler in the picture is an old dinosaur, probably running in the mid 70 percent. Not very efficient and might be consuming more fuel oil then needed to heat the home."
What was left unmentioned is that oil furnaces have a volumetric damper that is frequently open much more then that tiny hole is open.
Also, the vent connector is improperly installed in the picture.
The crimped end of pipe must insert into the downstream connector and not the other way around. The idea is to minimize leakage of the venting systems. Some induced draft venting systems on Natural gas systems would have enough pressure to cause enough leakage to be of concern for the long term exposure to CO for children and your household pets.
Given the picture and the fact that the 90 degree elbow is inserted into the vent connector, and the elbow is installed in the reverse direction I would hazard a guess that the whole connector is reversed at least back to the volumetric damper... assuming one is properly installed!
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