Blocked Vent Safety Control for
Oil-fired Appliances
Venting systems can malfunction or become
blocked. Animals sometimes enter the system,
soot can accumulate, chimney liners can dete-riorate,
etc. When the vent malfunctions, flue
gases, including carbon monoxide, can enter
the building.
Thermal safety switches detect flue gas
spillage caused by blocked flues, continuous
20 National Oilheat Research Alliance
Figure 11
downdrafts and/or inadequate draft conditions.
Figure 17.
These manual reset devices “lock out” when
they sense a temperature over 200°F. They are
mounted as close to the breech of the appliance
as possible and wired in series with the primary
control to prevent the burner from operating
if there is a blockage in the venting system.
Figures 18 & 19.
Chimney Venting
Today
As a result of the energy
crisis in the 1970s, there have
been many improvements
relating to the efficiency of
homes and the heating equip-ment
installed in them.
Homes have been made
“tighter” by adding insulation
and caulking around windows
and doors. These energy-saving
improvements reduce
Figure 17
Figure 18