Riello RS 28/M Quick start guide

2915760 (9) - 12/2013
Installation, use and maintenance instructions
Forced draught gas burners
Low-High-Low or Modulating Operation
CODE MODEL
3781070 RS 28/M
3781270 - 3781470 - 3781475 RS 38/M
3781670 - 3781675 - 3781676 RS 50/M
GB

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
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 first firing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Servomotor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Burner starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Burner firing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Burner calibration: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1 - Firing output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2 - Maximum output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3 - Minimum output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
4 - Intermediates outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
5 - Air pressure switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
6 - Low gas pressure switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Flame present check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Burner operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Appendix A - Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Appendix B - Burner firing rates according to air density . . . . . . . . . .19
Appendix C - Burner start up report . . . . . . . . . . . . . . . . . . . . . . . . . .20
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 maintenance
can cause property damage, personal injury or death. Refer to this
manual for instructional or additional information. Consult a certified in-
staller, service representative or the gas supplier for further assistance.
Burner shall be installed in accordance with manufacturers require-
ments as outlined in this manual, local codes and authorities having ju-
risdiction.

3
TECHNICAL DATA
(1) Reference conditions: Ambient temperature 68 °F (20 °C) - Barometric pressure 394” WC - Altitude 329 ft.
(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 LPG operation: The kit allows the RS 28-38-50/M burners to operate on LPG.
• Modulating control kit: Under modulating operation, the burner automatically adapts to one of an infinite number of firing rates between the low
and high flame output position, thus ensuring stable operating conditions in terms of temperature or pressure. Two components should be ordered: •
Modulating control to install to the burner; • probe to install to the boiler.
•Gas train according to UL Standards: see page 9.
• Kit for lengthening the combustion head
L = Standard length
L1 = Length obtainable with the kit
COD. 3010256 L = 81/2” L1 = 1313/16“ • RS 28/M
COD. 3010257 L = 81/2” L1 = 13 13/16” • RS 38/M
COD. 3010258 L = 81/2” L1 = 13 13/16” • RS 50/M
Model RS 28/M RS 38/M RS 38/M RS 50/M RS 50/M
Output (1) High MBtu/hr 617 - 1232
181 - 361
880 - 1665
258 - 488
880 - 1665
258 - 488
1099 - 2201
322 - 645
1099 - 2201
322 - 645kW
Low MBtu/hr
kW
198
58
266
78
266
78
321
94
321
94
Fuel Natural or propane gas
- Max delivery SCFH 1232 1665 1665 2201 2201
- Pressure at maximum delivery (2) natural
gas
“ WC 2.95 2.6 2.6 2.83 2.83
Operation Low - high-low or modulating
Standard application Boilers: 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 transformer V1 - V2
I1 - I2
120 V - 1 x 7 kV
1.6 A - 23 mA
Electrical power consumption W max 600 750 700
Electrical protection NEMA 1
Noise levels (3) dBA6870707272
Model Riello code RBNA code Voltage Flame safeguard
RS 28/M 3781070 C9521300 120/1/60 Burner mounted
RS 38/M
3781270
3781470
3781475
C9522300
C9522350
C9522351
120/1/60
208-230/460/3/60
575/3/60
Burner mounted
Burner mounted
Burner mounted
RS 50/M
3781670
3781675
3781676
C9523300
C9523301
tbd
208-230/460/3/60
575/3/60
120-230/1/60
Burner mounted
Burner mounted
Burner mounted
Burner RS 28/M RS 38/M RS 50/M
Output MBtu/hr 358 - 1232 437 - 1665 549 - 1986
Blast tube length inch 81/2“13
13/16“8 1/2“13 13/16“8 1/2“13 13/16“
Code 3010270 3010271 3010272
Parameter to be checked Probe Modulating control
Range Type Code Type Code
Temperature - 212...+ 932 °F (- 100...+ 500 °C) PT 100 3010110
RWF40 3010212
Pressure 0...36.3 PSI (0...2.5 bar)
0...232 PSI (0...16 bar)
Output probe
4...20 mA
3010213
3010214
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 Screws securing fan to sleeve
10 Slide bars for opening the burner and inspecting the
combustion head
11 Servomotor controlling the gas butterfly valve and air
damper (by means of a variable profile cam mecha-
nism).
When the burner is not operating the air damper is
fully closed in order to reduce heat loss.
12 Plate with four hole knock-outs for electrical cable
routing
13 Air inlet to fan
14 Gas input connection
15 Gas butterfly valve
16 Boiler mounting flange
17 Flame stability disk
18 Flame inspection window
19 Ignition pilot
20 Motor contactor and thermal overload reset button
(RS 38 - 50 three-phase)
21 Plug-socket on flame rod probe cable
22 Flame safeguard
23 Power switch for different operations:
automatic - manual - off
Switch for:
manual modulation of servomotor
24 Burner terminal strip
25 Air damper
26 Bracket for mounting the PID modulating controller
RWF40 (optional)
27 Protection (for RS 50/M single-phase burner)
Two types of burner failure may occur:
•FLAME SAFEGUARD LOCK-OUT:
if the flame relay 22)(A) pushbutton lights up, it indi-
cates that the burner is in lock-out.
To reset, press the pushbutton.
•MOTOR TRIP (RS 38 - 50 three-phase):
release by pressing the pushbutton on thermal over-
load 20)(A).
PACKAGING - WEIGHT (B) - Approximate measure-
ments
• The burners 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 burners 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 give 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
inch ABClbs
RS 28/M 3931/32“24
13/16“19 11/16“84
RS 38/M 3931/32“24
13/16“19 11/16“88
RS 50/M 3931/32“24
13/16“19 11/16“91
RS 50/M 3931/32“24
13/16“21 11/16“93
D88 (B)
(1) Blast tube: short - long (obtainable with the kit)
inch AA1 B C D (1)
RS 28/M 1823
/32”-18
21
/32”22
13/16”8 1
/2”- 1313 /16”
RS 38/M 1823
/32”-18
21
/32”22
13/16”8 1
/2”- 1313 /16”
RS 50/M three-phase 1823
/32”-18
21
/32”22
13/16”8 1
/2”- 1313 /16”
RS 50/M single-phase - 213
/16”18
21
/32”22
13/16”8 1
/2”- 1313 /16”
inch E F G H I L M
RS 28/M 51
/2”13
27/32”6 7
/16”31
7
/8”4
1
/4”6
5
/8”1
1
/2”
RS 38/M 51
/2”13
27/32”6 7
/16”31
7
/8”4
1
/4”6
5
/8”1
1
/2”
RS 50/M three-phase 531/32”13
27/32”6 7
/16”31
7
/8”4
1
/4”6
5
/8”1
1
/2”
RS 50/M single-phase 531/32”13
27/32”6 7
/16”31
7
/8”4
1
/4”6
5
/8”1
1
/2”
D2256
D2257
D7641 (A)
A1
B
E
F
M
L
C
H
I
G D A
D7639
(C)

5
FIRING RATES (A)
During operation, burner output varies between:
• MAXIMUM OUTPUT, selected within area A,
• MINIMUM OUTPUT, which must not be lower than
the minimum limit in the diagram.
RS 28/M = 198 MBtu/hr 58 kW
RS 38/M = 266 MBtu/hr 78 kW
RS 50/M = 321 MBtu/hr 94 kW
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 24 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) D2259
Combustion chamber pressure
“WC
Combustion chamber pressure
“WC
Combustion chamber pressure
“WC
(B) D2918
Length (feet)
Diameter (inches)
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
• Burner operating at maximum output
•A= Gas ring 2)(B)p.8 adjusted as indicated in dia-
gram (C)p. 8.
•B= Gas ring 2)(B) adjusted to zero.
Calculate the approximate maximum output of the
burner as follows:
- 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 1A or B of the table for the burner in question.
- Read off the corresponding output on the left.
Example - RS 28/M:
• Maximum output operation
• 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
A maximum output of 795 MBtu/hr shown in Table RS
28/M corresponds to 1.57” WC pressure, column 1A.
This value serves as a rough guide, the effective deliv-
ery must be measured at the gas meter.
(A)
RS 28/M
RS 38/M
RS 50/M
MBtu/hr kW
p (“ WC)
1
AB
624
699
795
891
986
1078
1174
1232
183
205
233
261
289
316
344
361
0.98
1.22
1.57
1.85
2.17
2.48
2.76
2.95
0.98
1.3
1.69
2.05
2.28
2.68
3.07
3.58
MBtu/hr kW
p (“ WC)
1
AB
870
979
1099
1211
1327
1440
1552
1665
255
287
322
355
389
422
455
488
1.02
1.22
1.46
1.69
1.89
2.13
2.36
2.6
1.02
1.38
1.77
2.28
2.72
3.11
3.54
4.21
MBtu/hr kW
p (“ WC)
1
AB
1099
1249
1402
1552
1706
1856
2006
2197
322
366
411
455
500
544
588
644
0.87
1.14
1.42
1.69
1.97
2.2
2.48
2.83
0.87
1.3
1.61
2.01
2.36
2.76
3.15
3.78
D2786
(B)

7
INSTALLATION
BURNER MOUNTING (A)
Drill the combustion chamber mounting plate as shown
in (A).
The position of the threaded holes can be marked using
the 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 (inches), is as follows:
Blast tube 10): RS 28/M RS 38/M RS 50/M
• short 8
1/2”8 1/2”8 1/2”
• long 13 13/16”13
13/16” 13 13/16”
For boilers with front flue passes 13) or flame inversion
chambers, protective insulation material 11) must be
inserted between the boiler refractory 12) and the blast
tube 10).
This protective insulation must not compromise the
extraction of the blast tube.
For boilers having a water-cooled front, the insulation
11)-12)(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 sen-
sor probe is correctly set in position, as shown in (C).
Now detach the combustion head from the burner,
fig.(B):
- Remove screw 14) and withdraw the cover 15).
- Disengage the swivel coupling 4) from the graduated
sector 5).
- 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 9)(B) to the boiler plate, inserting the
head gasket 6)(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 the 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 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
not energized.
- 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)
inch ABC
RS 28/M 69/32“8
13/16“3
/8W
RS 38/M 69/32“8
13/16“3
/8W
RS 50/M 69/32“8
13/16“3
/8W
D455
(A)
(D)
Probe
Electrode
D2260
(B)
D2292
Ignition pilot
D2261
(E)
MB - Burner terminal strip
D2317

8
COMBUSTION HEAD ADJUSTMENT
Installation operations are now at the stage where the
blast tube and sleeve are secured to the boiler as shown
in fig. (A).
There are two possible cases:
A - The MIN burner output is not in the values of
table (D).
In diagram (C), depending on the MAX output, 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 screw 1)(B) and turn ring 2) until the notch iden-
tified is aligned with index 3).
Tighten the screw 1) fully down.
Example:
the burner RS 38/M varies its output between: MIN =
378.7 and MAX = 1288 MBtu/hr.
The MIN output of 378.7 MBtu/hr is not found in the val-
ues of table (D) and therefore diagram (C) is valid, from
which it results that for a MAX output of 1288 MBtu/hr
the gas and air adjustments are done on notch 3, as in
fig. (A) and (B).
In this case the pressure load loss of the combustion
head is given by column 1A page 6.
Note
Diagram (C) shows the ideal settings for the ring 2)(B). If
the gas supply pressure is too low to reach the max out-
put operation 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/M with output of 1288 MBtu/hr a
pressure of approximately 1.81” 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.
B - The MIN burner output is found in the values of the
table (D).
Air adjustment
The same as the previous case: follow diagramm (C).
Gas adjustment
The gas ring 2)(B) is always adjusted to position 0, irre-
spective of the MAX burner.
In this case the pressure load loss of the combustion
heads is given by column 1B page 6.
Once you have finished setting up the head, refit the
burner 4)(E) to the slide bars 3) at approximately 4” from
the sleeve 5) - burner positioned as shown in fig.(B)p.7 -
insert the 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.(E).
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).
Reconnect the swivel connector 8) to the graduated sec-
tor 7).
Connect gas train and pilot train as shown in fig. (A)
page 9.
Important
When fitting the burner on the two slide bars, it is advis-
able to gently draw out the high tension cable and flame
detection probe cable until they are slightly stretched.
(A)
(C)
(B)
(E)
Notches (Air = Gas)
Burner max output
(D)
MODULATION MINIMUM OUTPUT: when the MIN output is within the value range given
below, the gas ring 2)(B) is adjusted to zero.
RS 28/M 198 - 280 MBtu/hr 58 - 82 kW
RS 38/M 266 - 375 MBtu/hr 78 - 110 kW
RS 50/M 321 - 488 MBtu/hr 94 - 143 kW
D2315
D2263
D2262

9
GAS PIPING
• The main gas train must be connected to the gas
attachment 1)(A), using flange 2), gasket 3) and
screws 4) supplied with the burner.
• The main gas train can enter the burner from the right
or left side, depending on which is the most conven-
ient, see fig.(A).
• Gas safety shut-off valves 5)-6)(B) must be as close
as possible to the burner to ensure gas reaches the
combustion head within the safety time range.
• The pilot gas train must be connected to the gas
attachment 5)(A) and can enter the burner from the
right or left side.
GAS TRAIN (B)
It must be type-approved according to required local-
standards and is supplied separately from the burner.
Note
See the accompanying instructions for the gas train lay-
out.
KEY (B)
1 - Gas input pipe
2 - Manual valve
3 - Pressure regulator
4 - Low gas pressure switch
5 - 1st safety shut off valve
6 - 2nd safety shut off valve
7 - Standard issue burner gasket with flange
8 - Gas adjustment butterfly valve
9-Burner
(A)
(B)
TYPICAL UL SCHEMATIC GAS PIPING
GAS PILOT LINE
MAIN GAS LINE
D2293
D2294
1
3
2
4