Riello RS 28/1 Quick start guide

Installation, use and maintenance instructions
Gas Burners
RS 28/1 - 38/1
On - Off Operation
C6505054 - 2915763 (3)

2
CONTENTS
TECHNICAL DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page 3
Burner models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Burner description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Packaging - Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Max. dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Standard equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Firing rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Minimum furnace dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Gas pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Gas piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Boiler plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Blast tube length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Securing the burner to the boiler . . . . . . . . . . . . . . . . . . . . . . . . . 7
Ignition pilot adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Combustion head adjustment. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Gas piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Adjustments before firing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Burner starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Burner firing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Burner calibration: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1 - Firing output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2 - Maximum output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3 - Air pressure switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 - Low gas pressure switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Flame present check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Propane operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Switchboard layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Appendix - Burner firing rates according to air density. . . . . . . . 18
Start up report. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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
If you smell gas:
• Do not touch any electrical items.
• Open all windows.
• Close all gas supply valves.
• Contact your local gas authority immediately.
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 a.s.l.
(2) Pressure at test point 8)(A)p.4, with zero pressure in the combustion chamber, with open gas ring 2)(B)p.8 at maximum burner output
(3) Sound pressure measured in manufacturer’s combustion laboratory, with burner operating on test boiler and at maximum rated output.
Burner models designation:
ACCESSORIES (optional):
Kit for lengthening the combustion head
L = Standard length
L1 = Length obtainable with the kit
COD. 3010262 L = 81/2” L1 = 1313/16“ • RS 28/1
COD. 3010263 L = 81/2” L1 = 13 13/16” • RS 38/1
Gas train according to ul standards: see page 9.
MODEL RS 28/1 RS 38/1
Output (1) MBtu/hr
kW
617 - 1320
181 - 387
880 - 1761
258 - 516
Fuel Natural gas/ propane gas
- Max delivery SCFH 1320 1761
- Pressure at maximum delivery (2) “ W.C. 3.4 3.03
Operation On/ Off
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
Fan motor rpm
W - HP
V
A
3400
370 - 0.5
120
5.2
Motor capacitor µF 45
Ignition transformer V1 - V2
I1 - I2
120 V - 1 x 7 kV
1.6 A - 23 mA
Electrical power consumption W max 600 600
Electrical protection NEMA 1
Noise levels (3) dBA 70 72
Model Code Voltage Flame safeguard
RS 28/1 C9521100 (3782070) 120/1/60 Burner mounted
RS 38/1 C9522100 (3782170) 120/1/60 Burner mounted
Important:
The installer is responsible for the supply and installation of any required safety device(s) not indicated in this manual.

4
BURNER DESCRIPTION (A)
1 Combustion head
2 Ignition electrode
3 Screw for combustion head adjustment
4 Sleeve
5 Low air pressure switch
(differential operating type)
6 Flame sensor probe (flame rod)
7 Air pressure test point
8 Gas pressure test point and head fixing screw
9 Screw securing fan to sleeve
10 Slide bars for opening the burner and inspecting the
combustion head
11 Indexed selector.
Opens the fan air damper to the value needed by the
burner delivery.
12 Plate with four hole knock-outs for electrical cable
routing
13 Air inlet to fan
14 Gas input pipework
15 Gas train connection flange
16 Boiler mounting flange
17 Flame stability disk
18 Flame inspection window
19 Pilot burner attachment
20 Flame safeguard with lock-out pilot light and lock-out
reset button
21 Terminal strip for electrical connections
22 Air damper
23 Plug-socket on ionisation probe (flame rod) cable
24 Ignition pilot
Note
If the flame safeguard 20)(A) pushbuttom lights up, it
indicates that the burner is in lock-out.
To reset, press the pushbuttom.
PACKAGING - WEIGHT (B)
Approximate measurements.
• The burner are shipped in cardboard boxes 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 burner are given in (C).
Note that if you need to examine the combustion head,
the burner must be pulled backward on the slide bars
and turned upward.
The maximum dimension of the burner, without the
cover, when open is given by measurement H.
STANDARD EQUIPMENT
1 - Gas train flange
1 - Flange gasket
4 - Flange fixing screws
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
(A)
inch A B C lbs
RS 28/1 3931/32“24
13/16“19 11/16“82
RS 38/1 3931/32“24
13/16“19 11/16“86
D88
(1) Blast tube: short-long (obtainable with kit)
RS A B C D (1) EFGHILM
28/1 1823/32“18
21/32“22 13/16“8 1/2-1313/16“5 1/2“13 27/32“6 7/16“31 7/8“4 1/4“6 5/8“1 1/2”
38/1 1823/32“18
21/32“22 13/16“8 1/2“-1313/16“5 1/2“13 27/32“6 7/16“31 7/8“4 1/4“6 5/8“1 1/2”
(C)
(B)
D2336
D2337
D2338
D495

5
FIRING RATES (A)
The burner delivery must be selected within the area of
the adjacent diagram.
Important:
the FIRING RATE value range has been obtained con-
sidering an ambient temperature of 68 °F (20 °C), and
an atmospheric pressure of 394” WC and with the com-
bustion head adjusted as shown on page 8.
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 18 for operation at different
ambient 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. chamber pressure
“WC
Comb. chamber pressure
“WC
D2339
(B) D2918
Diameter (inches)
Length (ft)
Recommended furnace dimensions

6
GAS PRESSURE
The adjacent tables are used to calculate manifold pres-
sure taking into account combustion chamber pressure.
Column 1
Gas manifold pressure measured at test point 1)(B),
with:
• Combustion chamber at 0” WC
• Gas ring 2)(B)p.8 adjusted as indicated in diagram
(C)p.8.
Calculate the approximate output of the burner thus:
- subtract the combustion chamber pressure from the
gas pressure measured at test point 1)(B).
- Find the nearest pressure value to your result in col-
umn 1 of the table for the burner in question.
- Read off the corresponding output on the left.
Example - RS 28/1:
• Natural gas
• Gas ring 2)(B)p.8 adjusted as indicated in diagram
(C)p.8.
• Gas pressure at test point 1)(B) = 2.36” WC
• Pressure in combustion chamber = 0.79” WC
2.36 - 0.79 = 1.57” WC
An output of 795 MBtu/hr shown in Table RS 28/1 corre-
sponds to 1.57” WC pressure, column 1.
This value serves as a rough guide, the exact flow rate
must be measured at the gas meter.
GAS PIPING
• The main gas train must be connected to the burner
head 1)(C), using flange 2), gasket 3) and bolts 4)
supplied with the burner.
• The gas train can enter the burner from the right or left
side, depending on which is the most convenient, see
fig.(C).
• Safety shut-off valves 8)-9)(B) must be as close as
possible to the burner to ensure gas reaches the com-
bustion head within the safety time range.
• The pilot gas train must be connected to the gas con-
nection 5)(C) and can enter the burner from the right
or left side.
(A)
RS 28/1
RS 38/1
MBtu/hr kW
∆p (“ WC)
1
625
699
795
891
986
1078
1174
1232
1320
183
205
233
261
289
316
344
361
387
0.98
1.22
1.57
1.85
2.17
2.48
2.76
2.95
3.43
MBtu/hr kW
∆p (“ WC)
1
871
986
1099
1211
1327
1440
1552
1665
1761
255
289
322
355
389
422
455
488
516
1.02
1.22
1.46
1.69
1.89
2.13
2.36
2.6
2.83
(C)
(B)
D2293
D2340
1
3
2
4

7
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 head gasket supplied with the burner.
BLAST TUBE LENGTH (B)
The length of the blast tube must be selected according
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): RS 28/1 RS 38/1
• short 8
1/2”8 1/2”
• long (with kit) 13 13/16”13
13/16”
For boilers with front flue passes 10) or flame inversion
chambers, protective insulation 8) must be inserted
between the boiler refractory 9) and the blast tube 7).
This protective insulation must not compromise the
extraction 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)
Before securing the burner to the boiler, check through
the blast tube opening to make sure that the flame rod
(probe) is correctly set in position, as shown in (C).
Now detach the combustion head from the burner,
fig.(B):
- remove screw 11) and withdraw the cover 12)
- Remove the screws 2) from the slide bars 3)
- Remove screw 1) and pull the burner back on slide
bars 3) by about 4”.
Disconnect the wires from the probe and the elec-
trode and then pull the burner completely off the slide
bars, after removing the split pin from the slide bar 3).
Secure the flange 6)(B) to the boiler plate, inserting the
gasket 4)(B). Use the 4 screws, also supplied with the
unit, after first protecting the thread with an anti-seize
product.
The seal between burner and boiler must be airtight.
If you noticed any irregularities in positions of the probe
or ignition electrode during the check mentioned above,
remove screw 1)(D), extract the internal part 2)(D) of the
head and proceed to set up the two components cor-
rectly.
IGNITION PILOT ADJUSTMENT
Place the pilot and electrode as shown in fig. (C).
The pilot works correctly at pressures ranging from 5 -
12” WC.
Important
To set the pilot without main burner operation, proceed
as follows:
- Move the jumper from terminals "30-V11" to terminals
"30-VP", as given in fig. (E), this way the main valve is
cut out.
- With the burner in the manual position, hold the air
damper in the minimum position and make the setting.
- When the setting is correct, replace the jumper on “30-
V11”.
(C)
(A)
(D)
inch A B C
RS 28 /1 69/32“8
13/16“3
/8W
RS 38 /1 69/32“8
13/16“3
/8W
(B)
Probe Electrode
D2292
D2341
D2342
(E)
MB - Burner terminal strip
D2317
D455

8
COMBUSTION HEAD ADJUSTMENT
(For PROPANE operation see page 14).
Installation operations are now at the stage where the
blast tube and sleeve are secured to the boiler as
shown in fig.(A). It is now a very simple matter to set up
the combustion head, as this depends solely on the out-
put developed by the burner.
It is therefore essential to establish this value before
proceeding to set up the combustion head. There are
two adjustments to make on the head: Air and gas .
In diagram (C) find the notch to use for adjusting the air
and the gas, and then proceed as follows:
Air adjustment (A)
Turn screw 4)(A) until the notch identified is aligned with
the front surface 5)(A) of the flange.
Gas adjustment (B)
Loosen screws 1)(B) and turn ring 2) until the notch
identified is aligned with index 3).
Tighten the screw 1) fully down.
Example RS 38/1:
burner output = 1276 MBtu/hr.
If we consult diagram (C) we find that for this output, air
and gas must be adjusted using notch 3, as shown in
figs. (A) and (B).
Note
Diagram (C) shows the ideal settings for the combustion
head. If the gas mains pressure is too low to reach the
pressure indicated on page 6, and if the ring 2)(B) is not
fully open, it can be opened wider by 1 or 2 notches.
Continuing with the previous example, page 6 indicates
that for burner RS 38/1 with output of 1276 MBtu/hr (374
kW) a pressure of approximately 1.8” WC is necessary
at test point 6)(A). If this pressure cannot be reached,
open the ring 2)(B) to notch 4 or 5.
Make sure that the combustion characteristics are satis-
factory and free of pulsations.
Once you have finished setting up the head, refit the
burner 4)(D) to the slide bars 3) at approximately 4” from
the sleeve 5) - burner positioned as shown in fig.(B)p.7 -
insert the flame detection probe (flame rod) cable and
the ignition electrode cable and then slide the burner up
to the sleeve so that it is positioned as shown in fig.(D).
Refit screws 2) on slide bars 3).
Secure the burner to the sleeve by tightening screw 1)
and then refit the split pin into one of two slide bars 3).
Connect gas train and pilot train as shown in fig. (C)
page 6.
Important
When fitting the burner on the two slide bars, it is advis-
able to gently draw out the high tension cable and flame
rod cable until they are slightly stretched.
(C)
(D)
(A) (B)
Notches (Air = Gas)
Burner output
D2343
D2344
D614

9
GAS PIPING
KEY (A)
1 - Gas input pipe
2 - Manual valve
3 - Pressure regulator
4 - Low gas pressure switch
5 - 1st gas safety shut off valve
6 - 2nd safety shut off valve
7 - Standard issue burner gasket with flange
8 - Burner
Note
See the accompanying instructions for the adjustment of
the gas train.
(A)
TYPICAL UL SCHEMATIC GAS PIPING
D2345

10
ADJUSTMENTS BEFORE FIRST FIRING
Adjustment of the combustion head, and air and gas
deliveries has been illustrated on page 8.
In addition, the following adjustments must also be
made:
- Open manual valves on the gas train.
- Adjust the low gas pressure switch to the start of the
scale (A).
- Adjust the air pressure switch to the zero position of
the scale (B).
- Purge the air from the gas line.
- Fit a U-type manometer (C) to the gas pressure test
point on the sleeve.
The manometer readings are used to calculate burner
input using the tables on page 6.
- Fan air damper: leave at the factory setting.
Before starting up the burner it is good practice to adjust
the gas train so that ignition takes place in conditions of
maximum safety, i.e. with gas delivery at the minimum.
BURNER STARTING
Close the control circuit.
As soon as the burner starts check the direction of rota-
tion of the fan blade, looking through the flame inspec-
tion window 18)(A)p.4.
BURNER FIRING
Having completed the checks indicated in the previous
heading, the burner pilot should fire. If the motor starts
but the flame does not appear and the flame safeguard
goes into lock-out, reset and wait for a new firing
attempt.
Pilot adjustment has been illustrated on page 7.
Having adjusted the pilot, reconnect the main valve and
ignite the main flame.
Once the burner has fired, now proceed with set up.
(A)
(C)
LOW GAS PRESSURE SWITCH AIR PRESSURE SWITCH
(B)
D2547 D2548
D2346

11
BURNER CALIBRATION
The optimum calibration of the burner requires an analy-
sis of the flue gases at the boiler outlet.
Adjust successively:
1 - First firing output
2 - Maximum output of the burner
3 - Air pressure switch
4 - Low gas pressure switch
1 - FIRING OUTPUT
Pilot adjustment has been illustrated on page 7.
2 - MAXIMUM OUTPUT
The maximum output of the burner must be set within the
firing rate range shown on page 5.
Adjusting gas delivery
Measure the gas delivery at the meter.
A guideline indication can be calculated from the tables
on page 6, simply read off the gas pressure on the U-
type manometer, see fig.(C) on page 10, and follow the
instructions on page 6.
- If delivery needs to be reduced, reduce outlet gas
pressure and, if it is already very low, slightly close
adjustment valve (if installed).
- If delivery needs to be increased, increase outlet gas
pressure.
Adjusting air delivery
Adjust the fan air damper by using the indexed selector
1)(A) after having loosened the nut 2)(A).
(A) D593

12
3 - AIR PRESSURE SWITCH (A)
Adjust the air pressure switch after having performed all
other burner adjustments with the air pressure switch
set to the start of the scale (A).
With the burner operating, increase adjustment pressure
by slowly turning the relative dial clockwise until the
burner locks out.
Then turn the dial anti-clockwise by about 20% of the set
point and repeat burner starting to ensure it is correct.
If the burner locks out again, turn the dial anti-clockwise
a little bit more.
Attention: As a rule, the air pressure switch must pre-
vent the formation of CO.
To check this, insert a combustion analyser into the
chimney, slowly close the fan suction inlet (for example
with cardboard) and check that the burner locks out,
before the CO in the fumes exceeds 400 ppm.
The air pressure switch may operate in "differential"
operation in two pipe system. If a negative pressure in
the combustion chamber during pre-purging prevents
the air pressure switch from switching, switching may be
obtained by fitting a second pipe between the air pres-
sure switch and the suction inlet of the fan. In this way
the air pressure switch operates as differential pressure
switch.
4 - LOW GAS PRESSURE SWITCH (B)
Adjust the low gas pressure switch after having per-
formed all the other burner adjustments with the pres-
sure switch set at the start of the scale (B).
With the burner operating, increase adjustment pressure
by slowly turning the relative dial clockwise until the
burner locks out.
Then turn the dial anti-clockwise by 0.8” WC and repeat
burner starting to ensure it is uniform.
If the burner locks out again, turn the dial anti-clockwise
again by 0.4” WC.
FLAME PRESENT CHECK (C)
The burner is fitted with an ionisation (flame rod) system
which ensures that a flame is present. The minimum
current for plant operation is 6 µA (see maufacturers
specifications).
The burner provides a much higher current, so that con-
trols are not normally required. However, if it is neces-
sary to measure the ionisation current, disconnect the
plug-socket 23)(A)p.4 on the ionisation probe cable and
insert a direct current microamperometer with a base
scale of 100 µA.
Carefully check polarities!
(A)
(B)
AIR PRESSURE SWITCH
LOW GAS PRESSURE SWITCH
(C)
D2548
D2547
D795
24
LFL

13
MAINTENANCE
Combustion
The optimum calibration of the burner requires an analy-
sis of the flue gases. Significant differences with respect
to the previous measurements indicate the points where
more care should be exercised during maintenance.
Gas leaks
Make sure that there are no gas leaks on the pipework
between the gas meter and the burner.
Flame inspection window
Clean the flame inspection window (A).
Combustion head
Open the burner and make sure that all components of
the combustion head are in good condition, not
deformed by the high temperatures, free of impurities
from the surroundings and correctly positioned. If in
doubt, disassemble the elbow fitting 6)(B).
Burner
Check that the graduated sector that controls the air
damper is secured by the nut 2)(A)p.11.
The tightness of the screws that fasten the cables to the
burner terminal strip must also be checked.
Clean the outside of the burner.
Combustion
Adjust the burner if the combustion values found at the
beginning of the operation do not comply with the regu-
lations in force, or do not correspond to good combus-
tion. Record the new combustion values; they will be
useful for subsequent set up.
TO OPEN THE BURNER (B):
- switch off the electrical power.
- Remove screw 1) and withdraw cover 2).
- Remove screw 3), the split pin 7) and pull the burner
back by about 4” on the slide bars 4). Disconnect the
probe and electrode leads and then pull the burner
fully back.
- Turn the burner as shown in the figure and fit the split
pin 7) into one of the slide bar holes so that the burner
remains in position.
Now extract the gas distributor 6) after having removed
the screw 5) and disconnecting the pilot gas line.
TO CLOSE THE BURNER (B):
- remove the split pin 7) and push the burner until it is
about 4” from the sleeve.
- Re-connect the leads and slide in the burner until it
comes to a stop.
- Refit screw 3), the split pin 7) and pull the probe and
electrode leads gently out until they are slightly
stretched.
- Connect the pilot gas line.
(A)
(B)
FLAME INSPECTION WINDOW
OPENING THE BURNER
D2348
D484

14
PROPANE OPERATION
The RS 28/1 and 38/1 Models burners can be operated
on both natural gas and propane.
FIRING RATE
It is the same as the one calculated for natural gas, see
page 5.
SETTING THE COMBUSTION HEAD
Adjusting air delivery
Adjust the screw 1)(A) as was done for natural gas,
according to the burner output, see page 8.
Gas calibration
Adjust the ring 1)(B) always to the zero position, as
shown in Fig.(B), whatever the burner output is.
GAS PRESSURE
The tables (C) are used to calculate manifold pressure
taking into account combustion chamber pressure.
Column 1
Gas manifold pressure measured at test-point 1)(B),
with the:
• Combustion chamber at 0” WC
• Gas ring 1)(B) set to zero.
(A)
RS 28/1
RS 38/1
MBtu/hr kW
∆p (“ WC)
1
625
699
795
891
986
1078
1174
1232
1320
183
205
233
261
289
316
344
361
387
0.47
0.67
0.87
1.06
1.26
1.50
1.69
1.85
2.09
MBtu/hr kW
∆p (“ WC)
1
871
986
1099
1211
1327
1440
1552
1665
1761
255
289
322
355
389
422
455
488
516
0.51
0.75
0.98
1.26
1.50
1.73
1.97
2.17
2.28
(C)
(B)
D635

15
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.
Field Wiring Connections
• The RS 28/1 - 38/1 burners have been type- approved for intermittent operation. This means they should compulsorily be stopped at least
once every 24 hours to enable the flame safeguard 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 IN to provide for burner shut-down at least once every 24 hours.
RS 28/1 - 38/1
120V
RS 28/1 RS 38/1
FU1 (A) T10 T10
FU2 (A) T6
Important note
When installing for the first time and after any maintenance work, make sure the gas valves are connected properly to the
orange terminals before proceeding to ignite the burner. Insert auxiliary lamps or check, with the aid of a tester, that power
is not being supplied to the valves during standby or pre-purging. Burner ignition with the gas valves open during pre-
purging may cause the generator to burst.
- Do not invert the neutral with the phase wire in the electricity supply line.
- Only use original spare parts to replace the components.
NOTES

16

17

18
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 8.
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
APPENDIX
- 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°C)
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
Q
2

19
BURNER OPERATION
BURNER STARTING
Control device closes.
Fan motor starts.
The air damper is set on maximum adjustment output.
The pre-purge stage follows.
Ignition electrode strikes a spark.
Pilot valve opens. The pilot flame is ignited.
After about 12s the main flame ignites and starting cycle
ends.
STEADY STATE OPERATION
At the end of the starting cycle, the flame safeguard con-
tinues to check that the flame is present and that the air
and gas pressure switches are in the correct position.
The burner continues to operate at constant output. If
the temperature or pressure in the boiler continues to
rise, and opens load control, the burner will stop.
Legend for the times
t1 Purge time
t2 Safety time
t3 Pre-ignition time, short (ignition transformer on
terminal 16)
t4 Interval between start of t2 and release of valve
at terminal 19
t5 Duration of startup sequence
t6 Running time of pilot
t7 Second safety time with burners using pilot
t8 Permissible after-burn time
FIRING FAILURE
If the burner does not fire, it locks out within 2.5 seconds
from opening the pilot valve and then within 5 seconds
from opening the main valves.
BURNER FLAME GOES OUT DURING OPERATION
If the flame should accidentally go out during operation,
the burner will lock out within 1s.
LFL 1.335 Series 01
t1
t2
t3
t4
30s
4s
2s
12.5s
t5
t6
t7
t8
61s
16s
4s
12.5s
(A) D7782
t4 t7
t1
t5

20
BURNER FAULTS
Control program under fault
conditions and lock-out
indication
In case of any disturbance, the sequence mechanism stops and with it the lock-out indicator. The symbol
above tPhe reading mark of the indicator gives the type of disturbance:
No start, e.g. because one contact is not closed. Lock-out during or after control program sequence
due to extraneous light (e.g. non-extinguished flames, leaking fuel valves, defects in the flame
supervision circuit, etc.)
Interruption of startup sequence, because the OPEN signal has not been delivered to terminal 8
by limit switch “a”. Terminals 6, 7 and 14 remain under voltage until the fault has been corrected!
Lockout, because there is no air pressure indication at the beginning of air pressure control.
Every air pressure failure after this moment in time leads to lock-out, too!
Lock-out due to a fault in the flame supervision circuit.
Interruption of startup sequence, because the position signal for the low-flame position has not
been delivered to terminal 8 by auxiliary switch “m”. Terminals 6, 7 and 14 remain under voltage
until the fault has been corrected!
Lock-out, because no flame signal is present after completion of the (1st) safety time.
Lock-out, because no flame signal has been received on completion of the 2nd safety time (flame
signal of the main flame with interrupted pilot burners).
Lock-out, because the flame signal has been lost during burner operation.
If lock-out occurs at any other moment in time between the start and the pre-ignition which is not marked by
a symbol, this is usually caused by a premature, i.e. faulty flame signal, e.g. caused by a self-igniting UV
tube.
P
1
2