External solenoid valves are available either
with or without a delay feature that prevents
fuel from being delivered to the nozzle for a
period of time after burner startup. The delay
enables cleaner startups by allowing the
motor and fan to get fully up to speed before
the valve opens and allows fuel to be pumped
through the nozzle.
On shutdown, these valves close and immediately
stop fuel flow to the nozzle providing a
cleaner flame cutoff.
Integral solenoid valves are built into the
burner’s fuel unit. There are two types of these
currently available:
• “Blocking” valves operate the same way
as external solenoid valves do, opening
when powered and closing on shutdown
• “Dumping” valves control the flow to
the nozzle by diverting fuel flow inside
the fuel unit. On startup the valve closes
opening the piston and allowing fuel
to flow to the nozzle. On shutdown the
valve opens closing the piston and shutting
off the fuel flow to the nozzle
An advantage of both external and blocking
solenoid valves is that they provide an additional
34 National Oilheat Research Alliance
fuel shutoff. In the event that the fuel
unit’s piston “hangs up”, these solenoid valves
will prevent fuel from dripping into the fire
chamber after shutdown.
Nozzle Line Heaters
Nozzle line heaters clamp onto the burner’s
drawer assembly and maintain the fuel temperature
at approximately 140°F. Keeping
the fuel heated lowers the viscosity,
enables better atomization and cleaner
startups, improves efficiency and
decreases the production of smoke
and soot.
Additional information is available
at: beckettcorp.com/support/tech-bulletins/
what-are-the-benefits-of-nozzleline
oil-heaters/
Fuel De-aerators
De-aerators remove the air and gas bubbles
from fuel so that these bubbles don’t cause
problems with the burner such as noise, rumbling,
pulsation and noisy shutdowns.
In addition to eliminating problems caused
by air and gas bubbles, de-aerators enable
systems that would normally require two-pipe
operation to operate with a single line from the
tank to the burner. See diagram on next page
as an example.
As mentioned in an earlier chapter, one pipe
applications offer several advantages:
• they eliminate the potential problems of
leaking return lines
• they dramatically reduce the clogging of
fuel filters and pump strainers
• they enable cleaner combustion