Ferroli PREXTHERM User manual

06/97
WELDED STEEL BOILER
from 86.000 to 860.000 kcal/H - from 100 to 1000 kW
from 341.000 to 3.410.000 BTU/HR
PREXTHERM
INSTALLATIONS
AND OPERATING INSTRUCTIONS

PREXTHERM
3
Contents
1. Dimensions and technical data
2. Installation
3. Operation
4. Maintenance

PREXTHERM
4
1. DIMENSIONS AND TECHNICAL DATA
A B C D E F G H L M a1 - a2 a3 a4 a5
100 970 760 1110 235 215 145 540 470 660 400 DN 50 1" 1/4 200 160
125 970 760 1260 235 365 145 540 470 810 400 DN 50 1" 1/4 200 160
150 970 760 1410 235 465 195 540 470 960 400 DN 50 1" 1/4 200 160
200 1060 850 1452 306 415 205 585 515 930 480 DN 65 1" 1/4 250 160
250 1060 850 1652 306 515 305 585 515 1130 480 DN 65 1" 1/4 250 160
300 1060 850 1852 306 615 405 585 515 1330 480 DN 65 1" 1/4 250 160
350 1230 1040 1832 484 405 395 670 600 1250 540 DN 80 1" 1/2 300 210
400 1230 1040 2032 484 605 395 670 600 1450 540 DN 80 1" 1/2 300 210
470 1230 1040 2232 484 805 395 670 600 1650 540 DN 80 1" 1/2 300 210
Output kW Input kW Water capac. Pressure drop Working press. Weight
Min. Max. Min. Max. m3dm3*Flue gas mbar **Water mbar bar kg
100 60 100 65 109 0,083 120 0,6 4 5 270
125 75 125 82 136 0,102 142 0,9 7 5 290
150 90 150 98 163 0,124 162 1,1 10 5 320
200 120 200 131 218 0,174 214 0,8 7 5 430
250 150 250 163 272 0,204 247 1,1 10 5 490
300 180 300 196 327 0,241 283 1,4 16 5 560
350 210 350 229 381 0,286 528 1,8 11 5 830
400 240 400 262 436 0,332 598 2,7 15 5 910
470 282 470 307 512 0,378 667 3,6 19 5 980
comb. chamber
volume
Legend
1Boiler shell
2Door
3Burner mounting plate
4Casing
5Door insulation
6Control panel
a1 Flow connection
a2 Return connection
a3 Safety valve tapping
a4 Flue outlet
a5 Burner flange
PREXTHERM 100-470
PREXTHERM
PREXTHERM
FERROLI F
a4
a2
100
B
A
100
40
G
D E F
a1 a3
H
a5
C
FLUE CONDENSE
Ø 3/8
DRAIN OFF Ø 1
50
1
4
23
56
L 240
M
Fig. 1
*technical dates for oil-fired heating; for gas heating you must decrease of 15%
** ∆ t considered: 15 ° C

PREXTHERM
5
Fig. 1b
min 250
a5
DEF 55
C
a3 a1a2
a4
H
H
DRAIN OFF Ø 1"
FLUE CONDENSE
Ø 3/8"
B
A110
12 3
45
6
max G
0 000
L
Ø M
PREXTHERM 550-1000
Output kW Input kW Water capac. Pressure drop Working press. Weight
Min. Max. Min. Max. m3dm3*Flue gas mbar **Water mbar bar kg
550 330 550 359 598 0,574 852 2,2 14 5 1150
620 372 620 404 674 0,647 936 2,8 19 5 1240
800 480 800 522 870 0,867 1060 2,8 18 5 1580
1000 600 1000 652 1087 1,083 1290 4,2 30 5 1830
PREXTHERM
comb. chamber
volume
Legend
1Boiler shell
2Door
3Burner mounting plate
4Casing
5Door insulation
6Control panel
a1 Flow connection
a2 Return connection
a3 Safety valve tapping
a4 Flue outlet
a5 Burner flange
PREXTHERM A B C D E F G H L M a1 - a2 a3 a4 a5
550 1400 1230 2363 746 500 500 340 720 1600 700 DN 100 DN 40 350 240
620 1400 1230 2563 746 700 500 340 720 1800 700 DN 100 DN 40 350 240
800 1540 1365 2570 782 525 620 360 790 1850 800 DN 125 DN 65 400 270
1000 1540 1365 3020 782 975 620 360 790 2300 800 DN 125 DN 65 400 270
*technical dates for oil-fired heating; for gas heating you must decrease of 15%
** ∆ t considered: 15 ° C

PREXTHERM
6
1
2
3
45
6
Key
1Boiler shell
2Door with burner mounting plate
3Flue hood
4Control panel
5Casing
6Insulation
PREXTHERM 100-470
Fig. 2a
Fig. 2b
3
2
451
PREXTHERM 550 -1000
Key
1Boiler shell
2Door with burner mounting plate
3Flue hood
4Casing
5Insulation

PREXTHERM
7
1.01 PACKING AND SHIPMENT
PREXTHERM 100 - 470
The boilers are supply in N°3 pieces:
1 - Boiler shell with door and flue hood
2 - Casing
3 - Control panel
PREXTHERM 550 - 1000
The boilers are supply in N°2 pieces:
1 - Boiler shell with door and flue hood
2 - Casing and control panel
Fig. 3

PREXTHERM
8
Legend
1Boiler shell
2Door
3Flue outlet cover plate
4Control panel fitted with:
4.1 Control thermostat
4.2 High low thermostat
4.3 Limit thermostat
4.4 Thermometer
4.5 Hours run indicator low fire
4.6 Run indicator high fire
4.7 Burner run light
4.8 On/off switch
4.9 Burner connections (electrical)
5Casing (for assembly, see next page)
6Burner door plate
7Combustion chamber sight glass
8Combustion chamber pressure test point
9Pressure gauge and thermostat pocket
10 Thermal insulation
Fig. 4a
PREXTHERM 100-470

PREXTHERM
9
Casing assembly instructions
- Attach the cover supports 21 in their right positions
- Place the coupling clips pos. 23-23.1-23.2 and pins/washers/nuts pos. 22-22.1-22.2 as indicated
- Attach plate 1 with two bolts and nuts M5X16 pos. 20
- Insert the cable collars 2 in the slit in plate 1 resting the panel 4 on the boiler
- Mount the sidings 3 so that they fit over the seat in plate 1
- Open the panel 4, take out the screws 5 and attach the sidings 3 with 6 self-threading screws pos. 6
- Insert the bulbs 9 into sleeves 8, tighten the end of the thermohydrometer 7 into the gauge tap 10
- Attach the back cover 11 togheter with the two cable collars 12 using 8 self-threading screws pos. 6.1
- Mount left cover 13 and right cover 14
- Mount right padded door 16 using 2 self-threading screws pos. 6.2, mount left padded door 15
- Take out of the document envelope the technical specifications label 18 and attach it on siding 2
- REMEMBER to take the cleaning accessories 19 out of the combustion chamber
Fig. 4b
PREXTHERM 100-470
SLIT
SIDING SEAT
23
22

PREXTHERM
10
8
6
78
21
10
9
4
5
3
4.9 4.4 4.6 4.5
4.7
4.8
4.1
4.2
4.3
PREXTHERM 550-1000
Fig. 5a
5Casing (for assembly, see next page)
6Burner door plate
7Combustion chamber sight glass
8Combustion chamber pressure test point
9Pressure gauge and thermostat pocket
10 Thermal insulation
Legend
1Boiler shell
2Door
3Flue outlet
4Control panel fitted with:
4.1 Control thermostat
4.2 High low thermostat
4.3 Limit thermostat
4.4 Thermometer
4.5 Hours run indicator low fire
4.6 Run indicator high fire
4.7 Burner run light
4.8 On/off switch
4.9 Manometer

PREXTHERM
11
8
16 10
13
12
3
3.1
18
20
5
7
8
9115
14
5
21
19
6.1
17 11
6
2
5
4.1
7
4
1
55
7
7
77
5
1
5
5
18
1
1
555
1
- Install the clips 1on side panels 2 and 11, on the front panel 3, on the left back panel 4, and on the jacket support 9.
- Installtheclips5 onthe frontpanels 3and 3.1,on therear panel4.1, onthe sidepanels atthe rearside 6,on theside panelson thefront 6.1(with protection).
- Install springs 7 on the top panels 8, on the front panel 7.1 and on rear panel 4.1.
- Install the control panel 7.1 10 and the cable support 2.1 on the front side panel 11 with 8 self taping screws 12. The control panel is fixed with 2 self tapping
screws 13.
- Install the temperature sensing bulbs 14 in socket 15 and connect the pressure gauge 16 connection to the apposit sensing point.
- Install the cable clamps 17 and wire the electrical connections to the control panel.
- Sequence installing jacket: - side panels 11.2 - top panels 8 - front panel 3 and 3.1 - side panels 6 and 6.1 - top and bottom covers 18 - rear panel 4 and 4.1
- ake out the data badge from the documents envelope 19 and place it on side panel 11
- DON'T FORGET to remove the cleaning tools 20 from the combustion chamer
- NE PAS OUBLIER d'enlever du foyer les accessoires pour le nettoyage 20.
Fig. 5b
PREXTHERM 550-1000
57
1

PREXTHERM
12
2. INSTALLATION
Strictlyadheretoalllocalrulesandregulationsregardingboilerlocation,installation,firefightingdevicesand
personal safety. For best operation of the boiler follow the suggestions listed below.
2.01 Stack
Whenattachedtoasystemofpressurizedcombustion,thestackdoesnotfunctionasdraftactivatorbutonly
as a conveyor of flue gas. Still it must create low pressure conditions and must therefore be designed
appropriately. Low pressure is required for safety reasons, to avoid the infiltration of fumes into areas that
for some reason have not been sealed off. The lifting force of the hot gas must overcome the resistance of
thestackandoftheflueleadingfromtheboiler,whilethegaspressure-dropthroughouttheboilerisprevented
by the thrust of the burner.
The boiler must be installed in accordance with these instructions and the local Regulations with materials
which resist to the expected temperatures and corrosion.
The connection between boiler and flue must be without leakage and sufficient isolated, with a slope of 45°
to the chimney if possible.
The draught must be min. 0 mbar with boiler in operation.
Ifthedraughtishigher,adraughtregulatorshouldbeinstalledsuchthatthedraughtontheboilerconnection
is 0 mbar, such to reduce stand-bye losses.
Fig. 6
PREXTHERM

PREXTHERM
13
2.02 Burner assembly (fig. 8)
Theburnermustbeofthetwo-stagepressurizedtypeandequippedwithanintermediateflangeforattaching
the door 4 to the burner plate 3. Due to the length of the combustion chambers it is recommended to use
nozzles with a spray angle of 30°to 45°to produce a long and narrow flame. It is also suggested to use the
shortest nozzles listed in the table below, so as to avoid a rapid inversion of the flame with the consequent
rise of flue gas temperature and reduced boiler efficiency.
NOTE - topreventoverheatingthedoornearthe burnerplate, thegapbetweentheburnershellandthehole
in the door should be filled with insulating material 2. The flexible pipes 8 should be long enough to allow
opening the door by 90°with the burner mounted.
* In gas burners, decrease the combustion chamber pressure by 15%
For ignition pressures, consider about 2.5 times the normal operation pressure.
Legend
1 Combustion chamber sight glass
2 Insulating rope
3 Burner plate
4 Front door
5 Burner
6 Turbulators
7 Boiler shell
8 flexible oil lines
Fig. 7
CHECK FOR CORRECT POSITION
MREHTXERPepyT 001 521 051 002 052 003 053 004 074 055 026 008 0001
mmA 042042042042042042042042042043043063063
mmB 061061061061061061012012012042042072072
rabm.sserprebmahc.bmoC* 6,09,01,18,01,14,18,17,26,32,28,28,22,4
h/gketarwolflioleuF 2,95,118,314,819,226,721,238,632,344,058,654,377,19
metarsaG
3
h/0,117,314,610,224,729,233,838,345,155,062,861,880,011
mmC 011011011031061061061061061002002052052

PREXTHERM
14
TRSTB
TA
220V-50Hz
hours run indicator
circulation pump
run light
recirculation pump
smoke lock-gate
BURNER BLOCK
PT
57
BZ1
5453
TR2ST
58
220V-50Hz
56 39
5244 38 46 48 49
TR TR2ST
BZ2SL
STB BZ1
F6,3A
35 36
45
BZ2
50
37
25
47
22 26 2723
1210 13 20 11 14 21 15 1918 24 16 17
33
31
9
5
L
34
PW1
7
3228 3029
51
M
NS
41 BZ1
55
241
AGWSLP.GAS 2ST1 BZ2
3N6
SL
40
N
43
L
42
L1
N
8
1
43
2
second stage
BURNERS CONNECTION WITH
TERMINAL BOARD
(without female connections)
BURNERS THREE-PHASE CONNECTION
(main P.C.B. exclusion)
P.H
2
O
Fig. 8
Connection diagram
The PREXTHERM 100÷470 boiler harness is required for single-phase burners at 230 V with female
connections. In case of burners with terminal board, the terminal board will have to be connected
according to enclosed drawing.
The connections of three-phase burners are possible if on exclude the main P.C.B..
PW3

PREXTHERM
15
2.03 Fitting the door
In all pressurized boilers the door may be set to open towards either sides.
Opening
To prepare the door to open to a chosen side, turn on the desired side of the door the lock nuts 3 towards
4 and the lock nuts 5 in the other direction. In order to move the lock nuts 3 and 5 and invert the sides of
opening, proceed as follows; keep three bolts 4 tightened, loosen the fourth, take out lock nuts 3 and 5 and
tightenthefourthbolt4.Insertandtightenthelocknuts3and5ontheoppositesideandrepeattheprocedure
with lock nuts 6 and 7.
Sealing
Loosen the lock nuts 3 and 5; tighten bolt 4 as needed; then tighten lock nuts 3 and 5.
Positioning
Afterassemblingtheburneritmightbenecessarytoadjustthedoorposition.Thismaybedonebyloosening
thedowel 8and turningbolt 9.This shouldbe doneto assurethat thesealinglayerispressedevenlyagainst
the rebate.
Fig. 10
1256
3
4
12
5
6
34
PREXTHERM
100 - 470 PREXTHERM
550 - 1000
Fig. 9

PREXTHERM
16
2.04 Location of boiler
the introduction of the Ferroli boilers in the boiler house is very simple given their small size in relation to
capacity.Theboilermustbewellventilatedandroomtemperatureduringoperationshouldnotexceed35°C.
Air should be allowed into the room through an opening, which is not sealed when shut, the size of 1/30th
of the room floor area or more, but not smaller than 0.5 m2. Location, should be arranged so as to avoid the
transmission of noise outside. The room should be built in accordance with current safety rules. Before
operating the boiler, you should make sure that the front door carrying the mounted burner can rotate 90°
in the chosen direction of opening, to accommodate a full inspection and cleaning of the tube nest. For this
purpose it is also recommended to leave an open space in front of the boiler, not less than the length of the
flue. Under normal conditions, the boiler, not less than the length of the flue. Under normal conditions, the
boilermaybeplaceddirectlyonthefloor,asitisequippedwithitsownbasemadeofmetalbeams.However,
when the room is very humid, we suggest adding a cement block 8-10 cm thick.
Fig. 11
O SPAZIO ESTRAZIONE TUBI
MIN. 600 MIN. 600
MIN. 1700 E MIN. 1000
Clearence to remove turbulators

PREXTHERM
17
3. OPERATION
3.01 Fuels
For PREXTHERM 100÷470 kW is admited to use of gas or low-sulphur fuel oil is particularly for the small
capacityboilers,astheyimprove the thermal efficiency, decreasemaintenancecostandreduce condensa-
tion buildup in the stack.
Forhigheroutputisadmittedfluidoilfuel(3÷5°Eto 250°C)orsemi-fluidoilfuelprovidedthatyouuseemulsion
burners.
3.02 Fuel flow rate
Fuelflowratemustbedeterminedaccordingtoboilercapacity(paragraph2.02).Butflowrateshouldproduce
a minimum flue gas temperature, to avoid possible acid condensation.
So attention during the prolonged start up a lower flame. The lowest limits for temperature of smokes are:
for gases: 130°C
for gas oil: 140°C
for oil fuel: 160°C
3.03 Functioning at low capacity
Any time the heating system is required to slow down, as it normally would be in winter and fall, the Ferroli
boiler would operate in high efficiency also at low capacity. To ensure proper operation, you should extract
fromthe boilerpipesallthemetalturbulenceactivatorsandset theburnertoworkwithasingleflame,orwith
two smaller flames. After performing this small operation the boiler will work in low capacity at a high rate of
efficiency. After completing this operation, you should also check the flue gas temperature in the stack, and
make sure it does not be higher 220°C for good output and it does not be lower indicated limits.
3.04 Boiler water temperature
Toeliminatepossiblecorrosionoftheboilertubenestitisimperativetokeepthetemperatureoftheoutflowing
water above 65°C, by using fuels containing 3% or less of sulphur. Lower water temperature might cause
the flue gas to reach the dew point and form acid compounds on the surfaces of the fume duct. This in turn
wouldreducethelifeexpectancyofthetubenest.Tokeeptheboilerwateratahightemperature,regardless
of the system temperature, you should install a 4-way mixing valve (Fig. 12).
Fig. 12

PREXTHERM
18
3.05 Temperature difference between inflow and outflow
Thetemperaturedifferencebetweentheboilerflowandreturnshouldnotexceed20°C.thisdifferentialmust
be maintained both during normal operation and during ignition. Greater temperature differentials might
cause serious damage to the structure of the boiler. The installation and the pumps will be provided for
conformity.
Important-Itisimperativetostartthewatercirculationpumpspriortoswitchingontheburner.Youmaymake
sureofthatby using an automaticprioritysystem.Should you be requiredtoturnon a secondary coldwater
circuit during operation, please do so gradually.
3.06 Characteristics of the boiler water.
Itisrecommendedtouse properly treated waterfortheheatingsystem, to prevent encrustationintheboiler
- caused by hard water or corrosion produced by aggressive water.
Notethatevenencrustationsofonlyfewmillimetresinthicknesscause,duetotheirlowthermalconductivity,
a considerable overheating of the sheeting. Such phenomenon produces different rates of expansion in
various points in the boiler which causes damage to the sheeting and weldings.
A correct inflow of water TOTAL HARDNESS ppm 10
should be as follows: ALKALINITY mg/l CaCO3750
PH 8,5 ÷11
SILICON DIOXIDE ppm 100
CHLORIDES ppm 3500
It is imperative to treat the heating system water in the following cases:
• Very large systems.
• Very hard water.
• Frequent system water replenishing.
Ifapartialortotalflushingofthesystemiscalledfor,itisrecommendedtorefillthesystemwithtreatedwater.
3.07 Starting up the boiler
The first time you operate the boiler and the system, you should inspect the following:
Check that the thermostats function properly. To enhance instrument sensitivity, it is recommended to add
mineral oil in the sleeves housing the sensory bulbs.
Check that the flue and stack fit properly: seal all gaps, if any, with high temperature resistant sealant.
Checkthatthefrontdoorsitsproperlyinplace;makesuretheburnerismountedsothatfumescannotescape.
Checkthewaterlevelintheexpansiontank.Thelevelmustbewithinthespecifiedtolerance;ifthereisaneed
for continuous water replenishing, you should look for the causes (leaks, insufficient volume of expansion
tank,etc.)andeliminatethem.Acontinuouswaterrefillingincreasesthedangerofcorrosionandoflimestone
deposits in the boiler.

PREXTHERM
19
4. MAINTENANCE
4.01 routine maintenance
In general, it is difficult to offer precise recommendations for periodic maintenance as each boiler-burner
complex has its own unique functioning characteristics (type, operation cycles, type of fuel oil, etc.).
Intervals between cleaning operations must be determined by each customer according to his experience
with individual systems.
Itisagoodhabittoopenthefrontdoorandinspecttheboilerinterioronceaweek,topreventless-than-optimal
functioning for longer periods of time.
Whendoingso,itisrecommendedtoremovelongitudinallyalltheturbulenceactivatorstopreventtheirbeing
clogged by unavoiable deposits of soot.
Normal operations of routine maintenance are:
1. Thorough cleaning of the combustion chamber.
2. Thorough cleaning of the tube nest: open the boiler front door completely and take all the turbulence
activators out of the pipes using the appropriate extractors • Proceed to thoroughly clean the tube nest with
atube-brush •Removesootdepositsfromtherearsmokechamber,usingtheappropriatesmalldoor •Brush
and scrub clean the combustion chamber to remove sulphur deposits and other solid substances • Check
the nozzles and the burner combustion head for carbon deposits, clean if necessary.
4.02 Maintenance at end of season or before long periods of inactivity
It is recommended to keep the boiler and system completely filled with water. After performing the routine
maintenance,useaclothdippedinalkalinesolutionofcausticsodatocoverallmetalsurfacesthathavebeen
in contact with the combustion gas in order to prevent acid corrosion caused by sulphur compounds. It is
especially important to thus protect the tube nest. When the interior of the boiler is dry, lubricate the tubes
andthecombustionchamberwithfueloilorlightnaphthatoprotectthemfromhumidity.Itisadvisabletoplace
inthe combustionchamberaboxofcausticlimetoabsorbthehumidityandkeeptheboilerinteriorwalls dry.
Finally you should close the door and the opening to the stack .
4.03 Descaling the boiler
It is extremely important, especially where water is very hard, to perform periodic descaling, or better, to
introduceacontinualanti-encrustationtreatment.Thisperiodicorcontinualoperationsprolongtheboilerlife
expectancy, prevent localized overheating of the sheeting, different expansion rates and thermal shocks. It
isadvisablethereforetoperform,atleastafterthefirstseasonofoperation,athoroughdescaling.Thisshould
be repeated at the end of each heating period. In case a continual anti-encrustation is performed, it is
importanttouseasafeandpositivelynon-corrosiveproducts.Itisalsoimperativetoperiodicallydrawoffmud
that deposits in the boiler.
4.04 Check the fit of door
In case there are leaks of combustion gas along the door, you should adjust the appropriate screws to
increase the pressure of the seal against the rebate in the area where the leak has been detected.
Iftheleak ofcombustiongas isdetectedall around,youshouldtighten thefoursupporting doorscrewsafter
having loosened the lock nuts, which must be tightened again when you are done.
4.05 Danger of freezing
The best safeguard during periods of icy weather is to keep the boiler and user facilities running, so that the
whole system is working. You may also add antifreeze solution to the system water, at the ratio suggested
by the supplier according to the lowest expected room temperature.

PREXTHERM
20
Electric diagram
PREXTHERM 100 - 470
TR First stage regulator thermostat
TR2ST Second stage regulator thermostat
NS Lighted switch
STB Safety thermostat
SL block-spy
BZ1 First stage consumption meter
BZ2 Second stage consumption meter
PW1 Electronic plate
PT Test button
TA Room thermostat
AGW Flue thermostat
TA
SL
recirculation pump
circulation pump
smoke lock-gate
burner burner
second stage
BZ2
TR1 PT
S3 B4
NT2
T1
L1 B5T6T7T8
BZ1
1716 18 212019
N
AGW
46 48
PGAS
50
7
5452
65
F 6,3A
43
L
98
3837
34
NS
33 393644 35
28 3029 31 32
22
43
1211
49
4
4745
10 14 23
13 15
55
NL
M
220V-50Hz
L1 N
2
41
1
3
STB
N
40
42
58
27
57
262524
12
51 56
L
53
TR2STPH
2
O2ST1
Fig. 13

PREXTHERM
21
Connection diagram
PREXTHERM 100 - 470
TR First stage regulator thermostat
TR2ST Second stage regulator thermostat
NS Lighted switch
STB Safety thermostat
SL block-spy
BZ1 First stage consumption meter
BZ2 Second stage consumption meter
PW1 Electronic plate
PT Test button
TA Room thermostat
AGW Flue thermostat
TR
STB
TA
circulation pump
recirculation pump
burner
smoke lock-gate
burner second stage
PT
57
N
T2
L1
B4
T1
S3
BZ1
5453
TR2ST
58
220V-50Hz
56 39
5244 38
46 48 49
F6,3A
T7
T6
B5
35 36
45
BZ2
50
37
25
47
22 26 27
23
1210 13 20
11 14 21
15
T8
1918 24
16 17
33
31
9
5
L
34
PW3
7
3228 3029
51
M
NS
41 BZ1
55
24
1
AGW
SL
P.GAS 2ST1 BZ2
3
N6
SL
40
N
43
L
42
L1
N
8
1
43
2
PH
2
O
Fig. 14