National Oilheat Research Alliance 15
Draft Regulators (aka Barometric
Draft Controls)
Oilheat systems require steady draft. Once
the unit reaches steady state efficiency, the
draft over the fire must remain constant to al-low
for proper combustion and efficiency.
Since natural draft varies depending on
several factors (including atmospheric pres-sure,
temperature and wind), barometric draft
controls are needed to stabilize draft for most
oilfired appliances. Barometric draft controls
lower draft by allowing room air to mix with
the combustion gases as they rise through the
flue pipe. They also help to dry moisture from
chimneys during the burner’s off cycle.
The 2011 edition of NFPA 31 addresses the
draft regulator issue in section 6.4.1:
“A draft regulator shall be provided for
each oil-burning appliance that is connected
to a chimney or power venting system unless
the appliance design, conditions of installa-tion,
or combinations thereof preclude exces-sive
chimney draft, or the appliance is listed
for use without one.”
The reason NFPA mentions “unless…the
appliance is listed for use without one,” is that
some oil heating appliances are designed to
operate without a draft regulator. Their burners
create enough force (static pressure) to move
the combustion products up the chimney and
their heat exchangers are designed to resist the
effects of strong and variable draft. Figure 6.
Draft controls must:
1. Be installed in one of the locations shown
in Figure 7:
2. Be horizontally level and vertically plumb;
Figure 8.
3. Have the weights installed in the proper
location depending on whether the device is
located on a vertical or horizontal flue tee.
Figure 9.
Figure 6:
Draft Regulator
Figure 7
Figure 8
Figure 9