Combustion Analysis and Safety Pt 1- BPI Review of 5 Point Combustion Testing

[sienalaurel]

Ok - I'm confused. Wouldn't the first hole cause worse dilution? I don't recall making 2 holes as standard bpi protocol?

[GreenDreamGroup]

@sienalaurel This is actually a mistake commonly made in the field- CO must be measured prior to dilution air, and draft must be measured 1-2 ft past the draft diverter or first elbow, in a straight section of the flue. That's usually 2 different holes, and lots of technicians are using tools that do both jobs with one probe, which they assume means only 1 hole. If you sample both 1-2 feet past the draft control, the CO is wrong, and if you sample both before dilution, the draft is wrong.

[GreenDreamGroup]

Actually, since the CO sampling should be before any dilution air, you want to get as close as possible to the heat exchanger-- there are some small gaps in the joints between the flue components, and since the inside of the flue is at a negative pressure, it will suck air into the flue, resulting in 'dilution' of the flue gases. That's the reasoning for the lower of the two holes. You would NOT measure draft there, though, since there may be positive pressure lingering from the inducer.

[sienalaurel]

Why do you drill the first hole in the furnace? Was that before you realized it was mechanically assisted? Thanks - great videos

[TheDIYContractor]

When testing for Carbon monoxide in step two how many ppm is acceptable?

[GreenDreamGroup]

@TheDIYContractor For BPI, 25 ppm is the max acceptable in the flue, 35 ppm is the max acceptable in the air around you. 100 ppm or more, and the issue needs to be taken care of before other work in the house is tackled.

[OnCue4all]

Great, concise explanation of CAZ BPI Testing protocol.

[johnnyhvac]

This is Great! Thanks for the Info!

[rexerking]

I think the video was not complete I wanted to see the full test and readings I am taking the BPI test in two weeks

[baikoff]

Would somebody enlighten me, please, if it's common for a BPI certified specialist to drill through a power-vented combustion appliance, even though it's against BPI standards. I just see some programs require you to do that. And the second question is - since there is a fan pushing the combustion gases up, shouldn't there be a greater pressure inside the flue pipe?

[gscottmagnus]

@baikoff I'm taking BPI training right now and we are being told to drill holes. You just have to be sure to patch them up afterwards. Also, the gases aren't being pushed up by a fan by the water heater in this case. It's a natural draft, so when you negatively pressurize the house you may be sucking CO and other bad stuff back into the house.

[bowlculatorman1]

@baikoff Hope this helps. BPI standards allows to drill through a power-vent Furnace if the FLUE is single wall only. If is a DOUBLE WALL FLUE to vent the furnace in some states you are not allowed to drill though a VENT FLUE. And regarding your second question regarding why test for draft on a POWER-VENT furnace??? The answer is that you are making sure that the FAN is working like is suposed to work. If is not working at all, it may fail the draft test.