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With all high efficiency boilers, care must be taken to minimize
condensation. Therefore, cold standby is not
recommended and may be used only with a piping, bypass
as shown on Figure 12. This requires a change in control
wiring. Please contact factory prior to making that change.
When cold standby is not utilized, the homeowner might
possibly object to the burner starting when space heat is not
required. To avoid this, an optional outside thermostat may
be used to shut down the system totally when outside
temperature is above a specific limit set by the homeowner.
When outside thermostat is not used, Jumper T-T Terminals
on relay.
L8151 CONTROL SETTINGS
Use the following setting for the first adjustment:
17
High Limit Set Point .............. 180°F
Low Limit Set Point ............... 160°F
Differential............................... 20°F
These settings may be altered based on the heating system
response. During very cold weather if the heating system does
not provide quite enough heat, the high limit control setting
may be raised to a maximum of 200°F. If more domestic hot
water is required, the low limit control setting may also be
raised to a maximum of 180°F. Whenever adjusting either the
high or low limit the high limit control setting must be set at
least 20°F above the low limit. The differential control setting
is typically 20°F but may be adjusted to vary the time it takes
the burner to respond to a call for domestic hot water.
Oil Burner and Controls Start-Up and Adjustment
INDOOR DIRECT EXHAUST BOILERS
Instruction manual enclosed in burner carton must
be followed in regard to start-up and adjustment
1. A Beckett model AFG post-purge oil burner is normally
supplied with boilers to be fired at 2.00 gph or less. It is
equipped with an F3 flame retention head, the size most
commonly used. It is possible the head must be
changed to match the nozzle firing rate required, and
it is recommended the installer carry a complete
assortment of Beckett flame retention heads. When head
ratings overlap, a smaller head with air shutter fairly well
open will generally provide better combustion than a larger
head with air shutter near closed.
SEE HEAD SIZE SELECTION CHART ON PAGE 16.
SUGGESTED NOZZLES, HEADS, AND PRELIMINARY
SETTINGS FOR VARIOUS FIRING RATES ARE
SHOWN ON PAGE 40.
2. At firing rates above 2.00 gph, a special Beckett model
CF375 burner must be used and is supplied if specified
by purchaser.
3. Post-purge oil burners are supplied with pump pressure
set at 140 psi. Nozzle output will be approximately 18%
greater than that at 100 psi.
4. The burner is not supplied with a nozzle. The correct
nozzle is the smallest which will do the job properly. Long
continuous runs with minimum starts and stops conserve
the most energy. The nozzle which provides the highest
C02 with the least smoke for a particular application is
always recommended.
5. WARNING: Too low a firing rate can cause excessive
condensation within the boiler and flue resulting in severe
rust and corrosion. A piping by-pass is recommended to
minimize this problem. See Figure 12.
6. If Beckett AFG burner is to be fired at less than 1.00 gph,
it is possible that a low firing rate baffle will be required.
For firing rates not specified on page 40, see chart below
on which an x indicates that a baffle is necessary. See
also instruction sheet with baffle in burner carton.
HEAD FIRING RATE, GPH LOW FIRE BAFFLE
.50 X
.65 X
.75 —
.75 X
.85 X
.90 —
1.00 —
.85 X
.90 X
1.00 —
F0
F3
F6
7. Using three acorn nuts, studs and washers from hardware
package, fasten burner to mounting plate. Do not disturb
chamber when inserting firing head.
8. Mount L8151 control on boiler jacket above and to the
right of burner using sheet metal screws in holes located
in jacket. Wiring harness is provided. When well is used
at the rear of a larger boiler, it might be necessary to
relocate the control with longer wiring not provided.
9. If boiler has a tankless coil, insert well for the L8151 remote
bulb in coil plate. Run capillary tube through sight glass
opening in jacket.
10. If a tankless coil is not used, install 3/4" well and bulb with
a bushing either in the 1 1/2 supply opening opposite the
one used to feed radiation, or in a reducing tee in the 1 1/2
supply opening that feeds radiation.
11. Mount overfire pressure switch at upper right of burner
on screws already in jacket. Connect by 1/4" copper tube
to brass tee at upper left of burner.
Burner will shut down if overfire pressure reaches .17"
H2O due to a plugged flue or high wind. If high wind
causes nuisance shutdowns, mount switch on an angle
bracket with diaphragm horizontal. Shutdown will then
occur at .25" H2O.