Specifications

5
Instruction 24-9460 • Fyrite
®
InSIght • MyBacharach.com
Performing Tests
Combustion and draft testing fan assist, furnaces/boilers should be
done through a hole drilled in the vent immediately above the inducer
fan. While fan assist equipment operates under a negative draft, it
is good practice to seal the sample hole, high temperature silicone is
generally recommended.
Make sure that the sample point is before any draft diverter/hood or barometric damper so that the
flue gasses are not diluted and the stack temperature has not been decreased by surrounding air
used to balance the draft.
The sample point should also be as close to the breach area as possible, again, to obtain an accurate
stack temperature. This will also provide a more accurate O
2
reading should air be entering the flue
gas stream through joints in sheet metal vent connectors.
When testing atmospheric, forced air heating equipment with a clamshell or sectional heat exchanger
design, test each of the exhaust ports at the top of the heat exchanger. The probe should be inserted
back into each of the exhaust ports to obtain a flue gas sample, before any dilution air is mixed in.
Draft tests should be taken from a hole drilled in the stack downstream from the draft hood.