Specifications

PCA
®
3
44
4.3 Sampling Point
FORCED AIR FURNACE: For atmospheric burner
or gravity vented, forced air heating equip ment
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
fl ue-gas sample, before any dilution air is mixed in.
HOT WATER TANK: Domestic hot water tanks with
the ‘bell’ shaped draft diverter can be accurately
tested by inserting the probe tip directly into the
top of the fi re tube be low the diverter.
80% EFFICIENCY FAN ASSIST OR POWER
VENTED: Combustion testing of fan assist or
power vented, furnaces/boilers should be done
through a hole drilled in the vent immediately
above the inducer fan.
90% EFFICIENCY CONDENSING: Condensing
furnaces/boilers can be tested through a hole
drilled in the plastic vent pipe (when allowed
by the manufacturer or local authority of juris-
diction) or taken from the exhaust termination.
ATMOSPHERIC OR GRAVITY VENTED
BOILER: Boilers, which have a ‘bell’ shaped
draft diverter on top, should be tested directly
below the diverter through a hole drilled in the
vent connector.
O2, CO,
Stack Temp.
O2, CO,
Stack Temp.
Combustion Air
Sampling Point
O2, CO,
Stack Temp.
O2,
CO,
Stack Temp.
Undiluted Flue
Gas Sample Taken
Under Draft
Diverter in Top
of Fire Tube
Forced Air Furnace
Hot Water Tank
Atmospheric/Gravity
Vented Boiler
90% Effi ciency Condensing80% Effi ciency Fan
Figure 4-1. Sampling Points