8
The two nozzles usually have equal deliveries, but the
low fire nozzle may have the following specifications if
required:
•a delivery less than 50% of the total delivery when-
ever the back-pressure peak must be reduced at the
moment of firing: the burner allows good combustion
values also with a ratio 40 - 100 % between low and
high fire;
•a delivery higher than 50% of the total delivery
whenever the combustion during low fire must be
improved.
Example with the RL 70 Model:
Boiler output = 2130 MBTU/hr - efficiency 80 %
Output required by the burner =
2130 : 0.8 = 2662 MBTU/hr;
2662 : 2 = 1331 MBTU/hr per nozzle;
therefore, two equal, 60°, 174 PSI nozzles are re-
quired:
1° = 7.0 GPH - 2° = 7.0 GPH,
or the following two different nozzles:
1° = 6.0 GPH - 2° = 8.0 GPH,
or:
1° = 8.0 GPH - 2° = 6.0 GPH.
NOZZLE ASSEMBLY
At this stage of installation the burner is still disassem-
bled from the blast tube; it is now possible to install the
two nozzles, after having removed the plastic plugs
2)(A), fitting the wrench through the central hole in the
flame stability disk.
Do not use any sealing products such as gaskets,
sealing compound, or tape. Be careful to avoid damag-
ing the nozzle sealing seat. The nozzles must be
screwed into place tightly but carefully.
The nozzle for low fire operation is the one lying be-
neath the firing electrodes Fig. (B).
Make sure that the electrodes are positioned as shown
in Figure (B).
Finally remount the burner 3)(C) to the slide bars 2)
and slide it up to the flange 5), keeping it slightly raised
to prevent the flame stability disk from pressing
against the blast tube.
Tighten the screws 1) on the slide bars 2) and screws
4) fixing the burner to the flange.
If it proves necessary to change a nozzle with the
burner already fitted to the boiler, proceed as outlined
below:
- Retract the burner on its slide bars as shown in
fig. (B)p.6.
- Remove the nuts 1)(D) and the disk 2).
- Use wrench 3)(D) to change the nozzles.
COMBUSTION HEAD SETTING
The setting of the combustion head depends exclu-
sively on the delivery of the burner at high fire - in other
words, the combined delivery of the two nozzles se-
lected on page 7. Turn screw 4)(E) until the notch
shown in diagram (F) is level with the front surface of
flange 5)(E).
Example:
The RL 70 Model with two 6.00 GPH nozzles and 174
PSI pump pressure.
Find the delivery of the two 6.00 GPH nozzles in table
(D), page 7:
8.17 + 8.17 = 16.34 GPH.
Diagram (F) indicates that for a delivery of 16.34 GPH
the RL 70 Model requires the combustion head to be
set to approx. three notches, as shown in Figure (E).
(A)
(C)
(D)
(E)
SETTING THE COMBUSTION HEAD
(F)
N° Notches
Fuel oil delivery at high fire USGPH
(B)
D691
D2360
D694
D462
D2327
D2281
