Riello RL 28/2 Quick start guide

Installation, use and maintenance instructions
Light Oil Burners
RL 28/2 - 38/2 - 50/2
Low - High Operation
C6505050 - 2915758 (4) - 12/2012

2
CONTENTS
TECHNICAL DATA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 3
Burner models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Burner description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Packaging - Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Max. dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Standard equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Firing rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Boiler plate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Blast tube length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Securing the burner to the boiler . . . . . . . . . . . . . . . . . . . . . . . 6
Choice of nozzles for low and high fire . . . . . . . . . . . . . . . . . . . 6
Nozzle assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Combustion head setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Fuel supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Hydraulic connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Burner calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Final check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Burner operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Switchboard layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Burner firing rates according to air density. . . . . . . . . . . . . . . . . . .20
Start up report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
N.B.
Figures mentioned in the text are identified as follows:
1)(A) = part 1 of figure A, same page as text;
1)(A)p.4 = part 1 of figure A, page number 4.
WARNING
Do not store flammable or hazardous materials in the vicinity
of fuel burning appliances.
Improper installation, adjustment, alteration, service or main-
tenance can cause property damage, personal injury or
death. Refer to this manual for instructional or additional in-
formation. Consult a certified installer, service representative
or the gas supplier for further assistance.
Burner shall be installed in accordance with manufacturers
requirements as outlined in this manual, local codes and au-
thorities having jurisdiction.

3
TECHNICAL DATA
(1) Reference conditions: Ambient temperature 68° F (20° C) - Barometric pressure 394” WC - Altitude 329 ft.
(2) Sound pressure measured in manufacturers combustion laboratory, with burner operating on test boiler and at maximum rated output.
(3) Equivalent Btu values based on 1 USGPH = 140,000 Btu/hr.
Burner models designations
ACCESSORIES (optional):
• Kit for lengthening the combustion head
L = Standard length
L1 = Length obtainable with the kit
COD. 3010250 L = 81/2“ L1 = 1313/16“• RL 28/2
COD. 3010251 L = 81/2“ L1 = 1313/16“• RL 38/2
COD. 3010252 L = 81/2“ L1 = 1313/16“• RL 50/2
MODEL RL 28/2 RL 38/2 RL 38/2 RL 50/2 RL 50/2
Output (1)
Delivery (1)
High
fire MBtu/hr (3) 630 - 1260 896 - 1708 896 - 1708 1120 - 2240 1120 - 2240
GPH 4.5 - 9 6.4 - 12.2 6.4 - 12.2 8 - 16 8 - 16
Low
fire MBtu/hr (3) 364 - 630 448 - 896 448 - 896 560 - 1120 560 - 1120
GPH 2.6 - 4.5 3.2 - 6.4 3.2 - 6.4 4 - 8 4 - 8
Fuel # 2 Fuel oil
Operation Low - high
Nozzles number 2
Standard applications Hot water, steam, thermal oil
Ambient temperature °F 32 - 104 (0 - 40 °C)
Combustion air temperature °F max 140 (60 °C)
Main power supply (+/- 10 %) V/Ph/Hz 120/1/60 208-230 / 460 / 575 / 3 / 60 120-230/1/60
Fan motor rpm
W - HP
V
A
3400
370 - 0.5
120
5.2
3400
550 - 0.75
208 - 230 / 460 / 575
3.2 - 1.6 - 1.3
3400
550 - 0.75
120 - 230
9.8 - 4.9
Motor capacitor µF 45 20
Ignition trasformer V1 - V2
I1 - I2 120 V - 2 x 5 kV 3.7 A - 35 mA
Pump delivery (174
PSI) pressure range
GPH
PSI 22 60 - 260
Electrical power consumption W max 550 600 700 750 700
Electrical protection NEMA 1
Noise levels (2) dBA 68.0 70.0 70.0 75.0 75.0
Model Code Voltage Flame safeguard
RL 28/2 C9511200 (3473270) 120/1/60 Burner mounted
RL 38/2
C9512200 (3474170)
C9512250 (3474370)
C9512251 (3474370)
120/1/60
208-230/460/3/60
575/3/60
Burner mounted
Burner mounted
Burner mounted
RL 50/2
C9513200 (3474670)
C9513201 (3474670)
(3474675)
208-230/460/3/60
575/3/60
120-230/1/60
Burner mounted
Burner mounted
Burner mounted
Important:
The installer is responsible for the supply and installation of any safety device(s) not indicated in this manual.

4
BURNER DESCRIPTION (A)
1 Ignition electrodes
2 Combustion head
3 Screw for combustion head adjustment
4 Photocell for flame monitoring
5 Screw for fixing fan to flange
6 Slide bars for opening the burner and inspecting
the combustion head
7 Hydraulic cylinder for regulation ofthe air damper in
low and high fire positions. When the burner is not
operating the air damper is fully closed in order to
reduce heat dispersion from the boiler due to the
flue draught which draws air from the fan suction in-
let.
8 Safety solenoid valve
9 Pump
10 Plate prearranged to drill 4 holes for the passage of
hoses and electrical cables.
11 Air inlet to fan
12 Fan pressure test point
13 Boiler mounting flange
14 Flame stability disk
15 Flame inspection window
16 Motor contactor
17 Flame safeguard control
18 Two switches:
- one "burner off - on"
- one for "low and high fire operation"
19 Burner terminal strip
20 Air damper
21 Pump pressure adjustment
22 Low and high fire valve assembly
23 Protection (for RL 50/2 single-phase burner)
Two types of burner failure may occur:
• FLAME SAFEGUARD LOCK-OUT:
if the flame relay 17)(A) pushbutton lights up, it indi-
cates that the burner is in lock-out.
To reset, press the pushbutton.
•MOTOR TRIP
(RL 38/2 - RL 50/2 three phase):
release by pressing the pushbutton on thermal over-
load.
PACKAGING-WEIGHT (B)
Approximate measurements
• The burner is shipped in cardboard box with the
maximum dimensions shown in table (B).
• The weight of the burner complete with packaging is
indicated in table (B).
MAX. DIMENSIONS (C)
Approximate measurements
The maximum dimensions of the burners are given in
(C).
Inspection of the combustion head requires the burner
to be opened and the rear part withdrawn on the slide
bars.
The maximum dimension of the burner, without casing,
when open is give by measurement H.
STANDARD EQUIPMENT
2 - Flexible hoses
1 - Burner head gasket
4 - Screws to secure the burner flange to the boiler:
3/8W x 1”
1 - Instruction booklet
1 - Spare parts list
1 - Adaptor G 1/8” - 1/8” NPT
(A)
(B)
A1
B
A
F
G
E
D
H
C
inch A B C lbs
RL 28/2
RL 38/2
RL 50/2 three-phase
RL 50/2 single-phase
3931/32”
3931/32”
3931/32”
3931/32”
2413/16”
2413/16”
2413/16”
2413/16”
1911/16”
1911/16”
1911/16”
2111/16”
80
84
86
88
(1) Blast tube: short - long (obtainable with the kit)
inch A A1 B C D (1)
RL 28/2 1823/32”-18
21/32”18 13/32”8 1/2”- 1313/16”
RL 38/2 1823/32”-18
21/32”18 13/32”8 1/2”- 1313/16”
RL 50/2 three-phase 1823/32”-18
21/32”18 13/32”8 1/2”- 1313/16”
RL 50/2 single-phase - 213/16”18
21/32”18 13/32”8 1/2”- 1313/16”
inch E F G H (1)
RL 28/2 51/2”13
27/32”2 1/16”26 15/32”- 313/4”
RL 38/2 51/2”13
27/32”2 1/16”26 15/32”- 313/4”
RL 50/2 three-phase 531/32”13
27/32”2 1/16”26 15/32”- 313/4”
RL 50/2 single-phase 531/32”13
27/32”2 1/16”26 15/32”- 313/4”(C)
D2276
D7632
D88
D7631

5
FIRING RATE (A)
The RL 28/2 - 38/2 - 50/2 Model burners are available
in low-high firing configuration.
LOW FIRE DELIVERY must be selected within area A
of the adjacent diagrams.
HIGH FIRE DELIVERY must be selected within area B.
This area provides the maximum delivery of the burner
in relation to the pressure in the combustion chamber.
The firing rate may be found by plotting a vertical line
from the desired delivery and a horizontal line from
the pressure in the combustion chamber. The inter-
section of these two lines is the firing rate which must
lie within area B.
Important:
the FIRING RATE area values have been obtained
considering a surrounding temperature of 68 °F (20
°C), and an atmospheric pressure of 394” WC above
sea level and with the combustion head adjusted as
shown on page 7.
Note:
The FIRING RATE areas given in figure (A) have been
reduced by 10% with respect to the maximum range that
can be reached.
Consult Appendix on page 20 for operation at different
surrounding temperatures and/or altitudes.
MINIMUM FURNACE DIMENSIONS (B)
The firing rates were set in relation to certified test boil-
ers.
Figure (B) indicates the diameter and length of the test
combustion chamber.
Example:
output 1388 MBtu/hr:
diameter 20 inch - length 4.9 ft.
(A)
Comb. chamb. “ WC Comb. chamb. “ WCL Comb. chamb. “ WC
D2279
D2918
(B)
Diameter (inches)
Length (ft)
Recommended furnace dimensions
/2
/2
/2

6
INSTALLATION
BOILER PLATE (A)
Drill the combustion chamber mounting plate as
shown in (A). The position of the threaded holes can
be marked using the burner gasket supplied with the
burner.
BLAST TUBE LENGTH (B)
The length of the blast tube must be selected accord-
ing to the indications provided by the manufacturer of
the boiler, and it must be greater than the thickness of
the boiler door complete with its insulation. The range
of lengths available, L (inch), is as follows:
Blast tube 7): RL 28/2 RL 38/2 RL 50/2
• short 81/2“8
1/2“8 1/2“
• long (with the kit) 1313/16“13
13/16“13 13/16“
For boilers with front flue passes 10) or flame inversion
chambers, protective insulation material 8) must be in-
serted between the boiler's refractory 9) and the blast
tube 7).
This protective insulation must not compromise the ex-
traction of the blast tube.
For boilers having a water-cooled front, the insulation
8)-9)(B) is not required unless it is required by the
boiler manufacturer.
SECURING THE BURNER TO THE BOILER (B)
Disassemble the blast tube 7) from the burner 4) by
proceeding as follows:
- Remove the screws 2) from the two slide bars 3).
- Remove the screw 1) fixing the burner 4) to the
flange 5).
- Withdraw the blast tube 7) complete with flange 5)
and slide bars 3).
Secure flange 5)(B) to the boiler plate inserting the
supplied gasket 6). Use the 4 screws provided after
having protected the thread with an anti-seize product
(high-temperature grease, compounds, graphite).
The burner-boiler seal must be airtight.
CHOICE OF NOZZLES FOR 1st AND 2nd STAGE
Both nozzles must be chosen from among those listed
in Table (C).
The first nozzle determines the delivery of the burner
at low fire.
The second nozzle works in combination with the low
fire nozzle to determine the delivery of the burner at
high fire.
The total deliveries of the low and high fire nozzles
must be contained within the value range indicated on
page 3.
Use nozzles with a 60° spray angle at the recom-
mended pressure of 174 PSI.
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;
• a delivery higher than 50% of the total delivery
whenever the combustion during low fire must be
improved.
(A)
inch A B C
RL 28/2 65/16“8
13/16“3/8 W
RL 38/2 65/16“8
13/16“3/8 W
RL 50/2 65/16“8
13/16“3/8 W
Nozzle
size GPH MBtu/hr
174 PSI
145 PSI 174 PSI 203 PSI
RL 28/2
2.00
2.25
2.50
3.00
3.50
2.47
2.75
3.07
3.68
4.32
2.72
3.04
3.39
4.07
4.74
2.95
3.33
3.68
4.42
5.16
381
428
475
570
664
RL 38/2
2.50
3.00
3.50
4.00
4.50
5.00
3.07
3.68
4.32
4.93
5.54
6.15
3.39
4.07
4.74
5.44
6.12
6.79
3.68
4.42
5.16
5.89
6.63
7.36
475
570
664
762
857
951
RL 50/2
3.00
3.50
4.00
4.50
5.00
5.50
6.00
3.68
4.32
4.93
5.54
6.15
6.75
7.40
4.07
4.74
5.44
6.12
6.79
7.46
8.17
4.42
5.16
5.89
6.63
7.36
8.10
8.87
570
664
762
857
951
1044
1144
60
(B)
(C)
D455
D339
D2280

7
Example with the RL 38/2 Model
Boiler output = 912 MBTU/hr - efficiency 80 %
Output required by the burner =
912 / 0.8 = 1140 MBTU/hr
1140 / 2 = 570 MBTU/hr per nozzle
therefore, two equal, 60°, 174 PSI nozzles are
required:
1° = 3.00 GPH with 2° = 3.00 GPH,
or the following two different nozzles:
1° = 3.50 GPH with 2° = 2.50 GPH,
or:
1° = 2.50 GPH with 2° = 3.50 GPH.
NOZZLE ASSEMBLY
At this stage of installation the burner is still disassem-
bled from the blast tube; it is now possible to fit two
nozzles, after having removed the plastic plugs 2)(A),
inserting 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 care-
ful to avoid damaging the nozzle sealing seat. The
nozzles must be screwed into place tightly but careful-
ly.
The nozzle for the low fire of operation is the one lying
beneath the firing electrodes Fig. (B).
Make sure that the electrodes are positioned as shown
in Figure (B).
Finally remount the burner 4)(C) to the slide bars 3)
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 2) on the slide bars 3) and screw
1) that attaches 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
selected on page 6. Turn screw 4)(E) until the notch
shown in diagram (F) is level with the front surface of
flange 5)(E).
Example:
The RL 38/2 Model with two 3.00 GPH nozzles and
174 PSI pump pressure.
Find the delivery of the two 3.00 GPH nozzles in table
(C), page 6:
4 + 4 = 8 GPH.
Diagram (F) indicates that for a delivery of 8 GPH the
RL 38/2 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)
D458
D2281
D460
D461
D462
D2282

8
HYDRAULIC SYSTEM
FUEL SUPPLY
DOUBLE - PIPE SYSTEM (A)
The burner is equipped with a self-priming pump
which is capable of feeding itself within the limits
listed in the table at the left.
The tank higher than the burner A
The distance "P" must not exceed 33 ft in order to
avoid subjecting the pump's seal to excessive strain;
the distance "V" must not exceed 13 ft in order to per-
mit pump self-priming even when the tank is almost
completely empty.
The tank lower than the burner B
Pump suction values higher than 13 “Hg must not be
exceeded because at higher levels gas is released
from the fuel, the pump starts making noise and its
working life-span decreases.
It is good practice to ensure that the return and suc-
tion lines enter the burner from the same height; in
this way it will be more improbable that the suction
line fails to prime or stops priming.
LOOP CIRCUIT
A loop circuit consists of a loop of piping supplied
from and returning to the tank with an auxiliary pump
that circulates the fuel under pressure. A branch con-
nection from the loop goes to feed the burner. This
circuit is extremely useful whenever the burner pump
does not succeed in self-priming because the tank
distance and/or height difference are higher than the
values listed in the table.
Key
H = Pump/Foot valve height difference
L = Piping length
Ø = Inside pipe diameter
1=Burner
2=Pump
3=Filter
4 = Manual on/off valve
5 = Suction line
6 = Foot valve
7 = Return line
HYDRAULIC CONNECTIONS (B)
The pumps is equipped with a by-pass that connects
return line and suction line. It is factory set with the
by-pass valve closed by screw 6)(A)p.12.
It is therefore necessary to connect both hoses to the
pump.
The pump seal will be damaged immediately if it is
run with the return line closed and the by-pass
screw inserted.
Remove the plugs from the suction and return con-
nections of the pump.
Insert the hose connectors into the connections and
screw them down.
Take care that the hoses are not stretched or twisted
during installation.
Route the hoses through the holes in the plate, prefer-
ably using those on the rh side, fig. (B): unscrew the
screws 1), now divide the insert piece into its two
parts 2) and 3) and remove the thin section blocking
the two passages 4).
Install the hoses where they cannot be stepped on or
come into contact with hot surfaces of the boiler.
(A)
+ H
- H
(ft)
L (ft)
Ø (inch)
5/16” 3/8” 1/2”
+ 13 115 296 500
+ 10 99 263 500
+ 6.6 86 227 500
+ 3.3 69 194 428
+ 1.6 63 174 391
056158355
- 1.6 49 141 319
- 3.3 43 122 283
- 6.6 30 89 211
- 10 13 53 138
- 13 – 20 66
(B)
D2284
D2283
A
B
1
2
3
7
5
6
6
4
75
315/16”
- H + H V
P
HYDRAULIC CONNECTIONS

9
PUMP (A)
1 - Suction 1/4” NPT
2 - Return 1/4” NPT
3 - Pressure gauge attachment G 1/8
4 - Vacuum gauge attachment G 1/8
5 - Pressure adjustment screw
A - Min. delivery rate at 174 PSI pressure
B - Delivery pressure range
C - Max. suction pressure
D - Viscosity range
E - Fuel oil max. temperature
F - Max. suction and return pressure
G - Pressure calibration in the factory
H - Filter mesh width
PUMP PRIMING
-Before starting the burner, make sure that the
tank return line is not clogged. Obstructions in
the line could cause the seal located on the
pump shaft to break. (The pump leaves the factory
with the by-pass closed).
- In order for self-priming to take place, one of the
screws 3)(A) of the pump must be loosened in order
to bleed off the air contained in the suction line.
- Start the burner by closing the control circuit and
with switch 1)(B)p.10 in the "ON" position. The pump
must rotate in the direction of the arrow marked on
the cover.
- The pump can be considered to be primed when the
fuel oil starts coming out of the screw 3). Stop the
burner: switch 1)(B)p.10 set to "OFF" and tighten the
screw 3).
The time required for this operation depends upon the
diameter and length of the suction tubing. If the pump
fails to prime at the first starting of the burner and the
burner locks out, wait approx. 15 seconds, reset the
burner, and then repeat the starting operation as often
as required. After 5 or 6 starting operations allow 2 or
3 minutes for the transformer to cool.
Do not illuminate the photocell or the burner will lock
out; the burner should lock out anyway about 10 sec-
onds after it starts.
Important:
the priming operation is possible because the pump is
already full of fuel when it leaves the factory. If the
pump has been drained, fill it with fuel through the
opening on the vacuum gauge connection prior to
starting; otherwise, the pump will seize. Whenever the
length of the suction piping exceeds 66 - 99 ft, the
supply line must be filled using a separate pump.
(A)
PUMP AL 65 C
A
B
C
D
E
F
G
H
GPH
PSI
“Hg
cSt
°F - °C
PSI
PSI
inch
21.5
58 - 261
13
2 - 12
140 - 60
29
174
0.006
D2286

10
BURNER CALIBRATION
FIRING
Set switch 1)(B) to "ON".
During the first firing, during the switch over from low
to high fire, there is a momentary lowering of the fuel
pressure caused by the filling of the high fire nozzle
tubing. This lowering of the fuel pressure can cause
the burner to lock-out and can sometimes give rise to
pulsations.
Once the following adjustments have been made, the
firing of the burner must generate a noise similar to
the noise generated during operation.
OPERATION
The optimum calibration of the burner requires an
analysis of the flue gases at the boiler outlet and
adjustments on the following points.
• Low and high fire nozzles
See the information listed on page 6.
• Combustion head
The adjustment of the combustion head already
carried out need not be altered unless the high fire
delivery of the burner is changed.
• Pump pressure
174 PSI: This is the pressure calibrated in the factory
which is usually sufficient for most purposes. Some-
times, this pressure must be adjusted to:
145 PSI in order to reduce fuel delivery. This adjust-
ment is possible only if the ambient temperature re-
mains above 0°C;
203 PSI in order to increase fuel delivery or to ensure
firings even at temperatures of less than 0°C.
In order to adjust pump pressure, use the relevant
screw 5)(A) page 9.
• Low fire air damper
Keep the burner operating at low fire by setting the
switch 2)(B) to the low fire. Opening of the air
damper 1)(A) must be adjusted in proportion to the
selected nozzle: the index 7)(A) must be aligned
with the rate specified in table (C). This adjustment
is achieved by turning the hex element 4)(A):
- in rh direction (- sign) the opening is reduced;
- in lh direction (+ sign) the opening increases.
Example RL 38/2 - low fire nozzle 3.00 GPH:
18° notch aligned with index 7(A).
When the adjustment is done lock the hex element
4) with the ring nut 3).
• High fire air damper
Set switch 2)(B) to the high fire position and adjust
the air damper 1)(A) by turning the hex element
6)(A), after having loosened the ring nut 5)(A).
Air pressure at attachment 1)(D) must be approxi-
mately the same as the pressure specified in table
(D) plus the combustion chamber pressure meas-
ured at attachment 2). Refer to the example in the
adjacent figure.
NOTE:
in order to facilitate adjustment of hex elements 4)
and 6)(A), use a 1/8” Allen key 8)(A).
(C)
(A)
(B)
12
Burner Stage
Off
On 2°
1°
RL 28/2 RL 38/2 RL 50/2
Nozzle
size
GPH
α°Nozzle size
GPH
α°Nozzle size
GPH
α°
2.00
2.25
2.50
3.00
3.50
14
17
20
22
24
2.50
3.00
3.50
4.00
4.50
5.00
12
18
20
22
23
26
3.00
3.50
4.00
4.50
5.00
5.50
6.00
12
15
18
21
23
27
28
Low fire
RL 28/2 RL 38/2 RL 50/2
Nozzle
size
GPH “WC Nozzle
size
GPH “WC Nozzle
size
GPH “WC
4.50
5.10
5.80
6.40
7.00
7.70
8.30
9.00
2.40
2.50
2.60
2.70
2.80
3.00
3.30
3.50
6.40
7.00
7.70
8.30
9.30
10.20
11.20
12.10
2.70
2.70
2.70
2.70
2.70
2.70
3.10
3.70
8.00
9.30
10.60
11.80
13.10
14.40
16.00
16.00
2.40
2.40
2.50
2.60
2.60
3.00
4.00
3.60
High fire
“WC = air pressure in 1) with zero pressure in 2)
D468
D469
D2287
(D)

11
FINAL CHECKS
• Obscure the photocell and switch on the burner: the
burner should start and then lock-out about 5 s after
opening of the low fire nozzle valve.
• Illuminate the photocell and reset the burner: the burn-
er should go into lock-out .
• Obscure the photocell while the burner is in high fire
operation, the following must occur in sequence: flame
extinguished within 1 s, pre-purging for about 20 s,
sparking for about 5 s, burner goes into lock-out.
• Switch off operating control while the burner is running:
the burner should stop.
MAINTENANCE
Combustion
An analysis ot the flue gases at the boiler outlet is
required. Significant differences with respect to the pre-
vious measurements indicate the points where more
care should be exercised during maintenance.
Pump
The pump delivery pressure must be stable at 174 PSI.
The suction must be less than 6.5 PSI.
Unusual noise must not be evident during pump opera-
tion.
If the pressure is found to be unstable or if the pump
runs noisily, the flexible hose must be detached from the
line filter and the fuel must be sucked from a tank
located near the burner. This measure permits the
cause of the anomaly to be traced to either the suction
line or the pump.
If the problem lies in the suction line, check to make
sure that the filter is clean and that air is not entering
the piping.
Filters (A)
Check the following filters:
• on line 1) • at nozzle 3), pump 2) and clean or replace
as required.
If rust or other impurities are observed inside the pump,
use a separate pump to suck out any water and other
impurities that may have deposited on the bottom of the
tank.
Fan
Check to make sure that no dust has accumulated
inside the fan or on its blades, as this condition will
cause a reduction in the air flow rate and create incom-
plete combustion.
Combustion head
Check to make sure that all the parts of the combustion
head are in good condition, positioned correctly, free of
all impurities, and that no deformation has been caused
by operation at high temperatures.
Nozzles
Do not clean the nozzle orifices.
Replace the nozzles every 2-3 years or whenever nec-
essary. Combustion must be checked after the nozzles
have been changed.
Photocell (cad cell) (B)
Clean the glass cover from any dust that may have
accumulated. Photocell 1) can be removed by pulling it
outward forcefully.
Flame inspection window (C)
Clean the glass.
Flexible hoses
Check to make sure that the flexible hoses are still in
good condition.
Boiler
Clean the boiler as indicated in its accompanying
instructions in order to maintain all the original combus-
tion characteristics intact, especially the flue gas tem-
perature and combustion chamber pressure. Lastly,
check the condition of the flue gas stack.
TO OPEN THE BURNER (D)
- Switch off the electrical power.
- Loosen screws 1) and withdraw the cover 2).
- Unscrew screws 3).
- Fit the two extensions 4) supplied with the burner onto
the slide bars 5) (model with long blast tube, obtaina-
ble with the kit).
- Pull part A backward keeping it slightly raised to avoid
damaging the disk 6) on blast tube 7).
FUEL PUMP AND/OR COUPLINGS REPLACEMENT (E)
See fig. (E). Dimension X should be set as follows:
RL28/2 - 1/4“
RL38/2 - 5/32“
RL50/2 - 5/32“
(B)
(A)
(C)
(D)
(E)
D482
D484
D483
D486
dimension
D2854
X

12
BURNER OPERATION
BURNER STARTING (A)
Operating control closes.
The motor starts and the ignition transformer is con-
nected.
The pump 3) sucks the fuel from the tank through the
piping 1) and the filter 2) and pumps it under pressure
for delivery. The piston 4) rises and the fuel returns to
the tank through the piping 5) - 7). The screw 6) closes
the by-pass to the suction side of the pump and the so-
lenoid valves 8) - 11) - 16), de-energized, close the
flow to the nozzles.
The hydraulic cylinder 15), piston A, opens the air
damper: pre-purging begins with the low fire air deliv-
ery.
At the opening of the solenoid valves 8) and 16) the
fuel passes through the piping 9) and filter 10) and is
then sprayed out through the nozzle, igniting when it
comes into contact with the spark. This is the low fire
flame.
If the high fire control device is closed, the solenoid
valve 11) is opened and the fuel enters the valve 12)
and raises the piston which opens two passages: one
to piping 13), filter 14), and the high fire nozzle, and
the other to the cylinder 15), piston B, that opens the
fan air damper for high fire.
FIRING FAILURE
If the burner does not fire, it goes into lock-out within
5 s of the opening of the low fire solenoid valve.
The flame safeguard indicator light will light up.
LOCKOUT DURING OPERATION
If the flame goes out during operation,the burner shuts
down automatically within 1 second and automatically
attempts to start again by repeating the starting cycle.
(A) D2288

13
APPENDIX
Electrical connections
NOTES
The electrical wirings must be carried out in conformity with the regulations in force in the countries of destination, and by
qualified personnel.
Riello S.p.A. cannot accept any responsibility for modifications or connections other than those shown in these diagrams.
The burner is factory set for low - high operation and it must be connected to the OCR control device to control fuel oil valve V2.
If on - off operation is required, instead of control device OCR install a jumper lead between terminals T6 and T8 of burner terminal strip.
FIELD WIRING CONNECTIONS
• For electrical connection use flexible cables according to local Regulations.
• The setting of the thermal overload must be according to the total burner amperage draw.
• The RL 38/2 - 50/2 three-phase burners leave the factory preset for:
- 208-230V power supply: only in this case, if 460V power supply is required, change the fan motor connection from delta to double star
and change the setting of the thermal overload as well;
-or 575V power supply;
depending on the burner model (see page 3).
• The RL 50/2 single-phase burner leaves the factory preset for 120V power supply: if 230V power supply is required, change the fan
motor connection as shown in Figure below.
• The RL 28/2 - 38/2 - 50/2 burners have been type-approved for intermittent operation. This means they should compulsorily be stopped
at least once every 24 hours to enable the control box to check its own efficiency at start-up. Burner halts are normally provided for auto-
matically by the boiler load control system.
If this is not the case, a time switch should be fitted in series to OC to provide for burner shut-down at least once every 24 hours.
EXTERNAL FUSES (SEE THE ELECTRICAL DIAGRAM)
RL 28/2 - RL 38/2 - RL 50/2 Single-phase burners
RL 28/2 RL 38/2 RL 50/2
120V 120V 120V 230V
FU1 (A) T10 T10 T15 T10
FU2 (A) T6
RL 38/2 - RL 50/2 Three-phase burners
208/230V 460V 575V
FU1 (A) T6 T6 T4
FU2 (A) T6 T6 T6
ATTENTION:
- Do not invert the neutral with the phase wire in the electricity supply line.
- Only use original spare parts to replace the components.
IMPORTANT
NOTES
ABCDE
120V
ABCDE
230 V

14
RL 28/2 - 38/2 SINGLE PHASE

15
RL 50/2 SINGLE PHASE

16
RL 28/2 - 38/2 - 50/2 SINGLE PHASE

17
RL 38/2 - 50/2 THREE PHASE

18
RL 38/2 - 50/2 THREE PHASE

19
Key to Layouts
+ BB - Components on board burners
+ BQ - Components on board main panel
+ BC - Components on board boller
DISC1 - Disconnect switch motor
DISC2 - Disconnect switch auxiliary
FU1 - Motor fuse
FU2 - Auxiliary fuse
HL - High limit control
LAL - Control box
LT2 - Remote lock-out signal
LT3 - Low fire signal
LT4 - High fire signal
LT5 - Power on signal
LT6 - Limit satisfied
MC - Motor contactor
MTR - Fan motor
OC - Operating control
OCR - High-low control
OL1 - Thermal overload
PS - Remote lock-out reset
PSCR - Photocell
PB - Switch: burner off - on;
- Switch: low and high fire operation
SOL1 - Low fire solenoid valve
SOL2 - High fire solenoid valve
SOLS - Safety solenoid valve
T1 - Ignition transformer
TB1 - Burner terminal strip
TB2 - Burner ground (earth) connection
W1 - Cable fan motor

20
The FIRING RATE area values have been obtained considering a surround-
ing temperature of 68°F (20°C), and an atmospheric pressure of 398” W.C.
and with the combustion head adjusted as shown on page 7.
The burner may be required to operate with combustion air at a higher tem-
perature and/or at higher altitudes.
Heating of air and increase in altitude produce the same effect: the expan-
sion of the air volume, i.e. the reduction of air density.
The burner fan's delivery remains substantially the same, but the oxygen
content per cubic meter and the fan's head are reduced.
It is therefore important to know if the maximum output required of the burner
at a given combustion chamber pressure remains within the burner's firing rate range even at different temperature and altitude con-
ditions. Proceed as follows to check the above:
1-Find the correction factor F in the Table (A) for the plant's air temperature and altitude.
2-Divide the burner's delivery Q by F in order to obtain the equivalent delivery Qe:
3-In the firing rate range of the burner, Fig. (B), indicate the work point defined by:
Qe = equivalent delivery
H1 = combustion chamber pressure
The resulting point A must remain within the firing rate range.
4-Plot a vertical line from Point A as shown in Figure (B) and find the maximum pressure H2 of the firing rate.
5-Multiply H2 by F to obtain the maximum reduced pressure H3 of the firing rate.
If H3 is greater than H1, as shown in Fig. (B), the burner delivers the output required.
If H3 is lower than H1, the burner's delivery must be reduced. A reduction in delivery is accompanied by a reduction of the pressure in
the combustion chamber:
Qr = reduced delivery
H1r = reduced pressure
Example, a 5% delivery reduction:
Qr = Q x 0.95
H1r = H1 x (0.95)2
Steps 2 - 5 must now be repeated using the new Qr and H1r values.
Important: the combustion head must be adjusted in respect to the equivalent delivery Qe.
Qe = Q : F (MBtu/hr)
H3= H2x F (“ W.C.)
"w.c.
MBtu/hr
Qe
H1
H3
H2
A
(B)
D2617
Burner firing rates according to air density
above sea level average barom.
pressure
CORRECTION FACTOR F
Air temperature
°F (°C)
ft m “ W.C. mbar 0 (0°C) 41 (5°C) 50 (10°C) 59 (15°C) 68 (20°C) 77 (25°C) 86 (30°C) 104 (40°F)
0
329
658
987
1316
1645
1974
2303
2632
2961
3290
3947
4605
5263
5921
6579
0
100
200
300
400
500
600
700
800
900
1000
1200
1400
1600
1800
2000
399
394
389
385
380
376
372
367
363
358
354
346
337
329
321
313
1013
1000
989
978
966
955
944
932
921
910
898
878
856
836
815
794
1,087
1,073
1,061
1,050
1,037
1,025
1,013
1,000
0,988
0,977
0,964
0,942
0,919
0,897
0,875
0,852
1,068
1,054
1,042
1,031
1,018
1,007
0,995
0,982
0,971
0,959
0,946
0,925
0,902
0,881
0,859
0,837
1,049
1,035
1,024
1,013
1,000
0,989
0,977
0,965
0,954
0,942
0,930
0,909
0,886
0,866
0,844
0,822
1,031
1,017
1,006
0,995
0,983
0,972
0,960
0,948
0,937
0,926
0,914
0,893
0,871
0,851
0,829
0,808
1,013
1,000
0,989
0,978
0,966
0,955
0,944
0,932
0,921
0,910
0,898
0,878
0,856
0,836
0,815
0,794
0,996
0,983
0,972
0,962
0,950
0,939
0,928
0,916
0,906
0,895
0,883
0,863
0,842
0,822
0,801
0,781
0,980
0,967
0,956
0,946
0,934
0,923
0,913
0,901
0,891
0,880
0,868
0,849
0,828
0,808
0,788
0,768
0,948
0,936
0,926
0,916
0,904
0,894
0,884
0,872
0,862
0,852
0,841
0,822
0,801
0,783
0,763
0,743
(A)
H1r = H1x ()
Qr
Q2