Vertical Tubeless Steam Boiler -...

CBTVertical Tubeless Steam Boiler

Boiler Book02/2020

BOILER BOOK CBT

Table of ContentsFEATURES AND BENEFITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3PRODUCT OFFERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3DIMENSIONS AND RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9ENGINEERING DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11PERFORMANCE DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

List of Tables

Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Dimensions Model CBT Full Modulating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10CBT Steam Boiler Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11CBT Steam Boiler Safety Valve Outlet Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11Lifting Lug Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Steam Volume and Disengaging Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Recommended Steam Nozzle Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Blowdown Tank Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Minimum Required Gas Pressure at Entrance to Standard Gas Trains . . . . . . . . . . . . . . . . . . . . . . . . . . .13Gas Pressure Correction Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Required Water Quality Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Feedwater Flow Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14Natural Gas, Estimated Emission Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Predicted Sound Levels at High Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Predicted Fuel-to-Steam Efficiencies-Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

List of Figures

CB Falcon Display/Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6CB Falcon Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Model CBT Dimensional Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9Lifting Lugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Rigging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Boiler Room Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

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BOILER BOOK CBT FEATURES AND BENEFITS

FEATURES AND BENEFITS• Robust vertical tubeless pressure vessel designed for reliability and longevity• Large steam volume for exceptional dry-quality steam – both high- and low-pressure operation• High efficiency; up to 84% efficient and 5:1 fully modulating turndown• 15 psig low pressure steam and up to 150 psig high pressure steam• Flexible burner options:

Natural gas or propane Low-emission premix, <20 ppm NOx

• Full-modulation premix burner includes PID set-point control with built-in lead-lag functionality and touchscreen interface

• Side-mounted burner for ease of serviceability• UL Listed (US and Canada)• Control trim and gas train are ASME CSD-1 compliant• Available in skid-mounted steam system solutions

PRODUCT OFFERINGThe CBT is available in 9.5, 10, 15, 20, 25, 30, 40, and 50 HP sizes.

The boilers are constructed in accordance with the ASME Boiler Construction Code, Section I for high pressure steam boilers and Section IV for low pressure steam boilers. High pressure steam boilers are stamped with the ASME “S” symbol. Low pressure steam boilers are stamped with the ASME “H” symbol.

Full ModulationUtilizes a premix burner with a self-regulating gas valve-venturi system, ECM variable regulating gas valve, variable speed blower, and Fecralloy metal fiber burner canister.

• Full modulation is provided using the integral variable speed combustion air fan and Falcon control.• The low temperature, surface combustion burner flame provides low emissions and optimum combustion

efficiency.• Direct spark ignition with UV flame detection.• At maximum firing rate, the sound level of the burner is less than 70 dBA, measured in front of the boiler at

a distance of 3 feet. At reduced firing rates, sound levels are even lower.• Provision is made for optional direct vent combustion air connection.• Combustion Air Proving Switch standard.• Combustion air filter is standard.

Full modulation boilers use the CB Falcon steam boiler control, an integrated burner management and modulation control with a color touch-screen display/operator interface.

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BOILER BOOK CBT PRODUCT OFFERING

Standard EquipmentThe equipment listed below applies to the standard boiler package offering. Optional items areavailable to meet specific projects when required.

A. The Boiler

• Each boiler (pressure vessel) size is designed and built for a Maximum Allowable Working Pres-sure (MAWP) of 15 psig in accordance with ASME Section IV (bearing the “H” stamp) or 150 psig (100 psig for 9.5 HP) in accordance with ASME Section I (bearing the “S” stamp).

• The vessel is insulated with a minimum 2” thick blanket and mounted on a structural steel base. A painted 18 gauge steel casing covers the insulation.

• Vessel connections are furnished for:Steam outletBottom drain or blowoffSurface blowoffFeedwater makeupHigh water level overflow

• For waterside inspection, handholes are provided.• Two lifting lugs are provided for rigging purposes.• The combustion exhaust is located at the top rear.

B. Boiler trim and controls

• Water column with primary low water cutoff and pump control (probe type).• Water column gauge glass and gauge glass drain valve.• Water column drain valve.• Auxiliary low water cutoff (probe type), manual reset.• Operating limit pressure control, auto reset.• High steam pressure limit control, manual reset.• Pressure transmitter for burner on/off and modulation.• Steam pressure gauge.• ASME safety relief valve.

C. Falcon Control System

• Control Description - The Falcon control is an integrated burner management and modulation control with a touch-screen display/operator interface.

• Functionality - The controller incorporates the following functions:PID load control.Burner sequencing with safe start check, pre-purge, direct spark ignition, and post purge.Electronic ignition.Flame Supervision.Safety shutdown with time-stamped display of lockout condition - last 15 lockouts stored in memory.Variable speed control of the combustion air fan.Supervision of low and high gas pressure, air proving, stack back pressure, and low water.Alarm outputRemote enable & remote modulation or set point.First-out annunciator.Diagnostics.Real-time data trending (w/ standard System Display).(3) pump/auxiliary relay outputs.Built-in Lead LagWarm/hot standby (minimum temperature) control

4


Modbus communication.Outdoor temperature reset.Anti-short-cycling modeTime-of-day (night setback) operationThree levels of access to control configuration:

End-userInstaller/Service Engineer (password protected)OEM Manufacturer (password protected)

• Main Electrical Connection - 115V/single phase/60Hz• Demand switch - Local/Remote/Off• Combustion Air Proving Switch• Gas Pressure Switch - Gas pressure switches for low gas pressure and high gas pressure prevent

the burner from being activated if either is open. Each switch is a physical manual reset device, requiring physical depression of the reset button if either switch is not closed prior to burner start or during burner operation. Monitored in Interlock (ILK) Circuit.

• System Configuration - CB Falcon configuration is grouped into the following functional groups:

• CB Falcon Control Access - There are three levels of access to the CB Falcon controller:

Table 1: Operating Conditions

Temperature RangeOperating 32 F to 122 F (0 C to 50 C)Storage -22 F to 140 F (-30 C to 60 C)

Humidity 85% max. relative humidity

CB FALCON BURNER SEQUENCE

1. Heat request detected (Setpoint minus On Hysteresis); LCI limits and steam demand detected (terminals J6 3 and J8 3).

2. The CH pump is switched on (relay contact closes).3. After a system Safe Start Check, the Blower (combustion air fan) is started4. After the ILK input is energized - 10 sec. allowed for IAS input (combustion air proving) to energize - and the

purge rate proving fan RPM is achieved, prepurge time is started. 5. When 30 sec. purge time is complete, the fan RPM is changed to the lightoff speed.6. Trial for Ignition (4 sec for direct ignition; 10 sec for pilot ignition burner).7. The ignitor and the gas valve are energized.8. The ignitor is turned off at the end of the trial for ignition period. 9. The fan is kept at the lightoff rate during the stabilization time.10.Release to modulation (Run).11.At the end of the CH-heat request the burner is switched off and the fan stays on until post purge is complete

(15 sec.). Boiler enters standby mode.

• System Identification and Access• Central Heat Configuration• Outdoor Reset Configuration• DHW - Domestic Hot Water Configuration• Modulation Configuration• Pump Configuration• Statistics Configuration• High Limits• Stack Limit• Other Limits

• Anti-condensation Configuration• Frost Protection Configuration• Annunciation Configuration• Burner Control Interlocks• Burner Control Timings & Rates• Burner Control Ignition• Burner Control Flame Failure• System Configuration• Fan Configuration• Lead Lag Configuration

5


End User Level - read or view parameters; change setpoints. No password required.

Installer/Service Level - read all parameters; enables changing of most parameters. This access level is used to configure the CB Falcon for a particular installation, and is password-protected.

OEM Level - read/change all parameters; for factory configuration of boiler-specific parameters. Password-protected and restricted to CB or factory authorized service personnel.

For additional information regarding service and setup of the burner controller, refer to CB manualpart no. 750-295.

Figure 1. CB Falcon Display/Operator Interface

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Figure 2. CB Falcon Pinout

D. Forced draft burner

• The burner is a “Pre-mix” design consisting of a unitized venturi, single body dual safety gas valve, blower, and burner head (canister).

• Full modulation is accomplished with a variable speed fan for up to 5:1 turndown ratio.• For near flameless combustion, the burner utilizes a Fecralloy metal fiber head (canister).• Noise level at maximum firing is less than 70 dBA regardless of boiler size.• When boiler is operating on natural gas, NOx emissions will be less than 20 PPM regardless of

boiler size; certified for California and Texas low emissions requirements.

3

1

4

2

FLAMESTRENGTH

LOCALMODBUSA B C

LEAD LAGMODBUSA B C

POWER

FLAME

ALARM

RESET

PIM

1

2

3

4

5

6

STEAMCONTROL

J1 J2

J3ECOMD R C

L1

L2 FOR 120VAC OR 24VAC RETURN (OPTOS)

EGND

BLOWER/HSI

EX. IGNITION

ALARM

MAIN VALVEPILOT VALVE

ANNUN 1/IASANNUN 2

ANNUN 3ANNUN 4ANNUN 5ANNUN 6

PRE IGN INTLK

INTERLOCK

P

P

P

LCI

PUMP A

{{

{

{

PUMP B

PUMP C

ANNUN 7 HFSANNUN 8 LFS

24 VAC24 VAC RTNS

STEAM PRESSURESENSOR

4-20 mA

STACK TEMP ASTACK TEMP RTN

STACK TEMP B

TODREMOTE RESET

0 - 10 VDC MA /VDC RTN

4 TO 20 MAV

I

BUILDINGAUTOMATION

SYSTEM

FUTURE System Display

TACHOMETERPWM OUT

FAN POWER (25 VDC)FAN GND

GLOBALMODBUSLOCALMODBUSLEAD LAG MODBUS

++–

FUTURE

UVBLUE

WHITE

STAT+–+–

EXTERNALLY POWERED PRESSURE SENSOR (0-15 PSI OR 0-150 PSI).1

1

FALCON STEAM CONTROLPLUG CONNECTORS

J4

J5

J6

J7

J8

J9

J10

J11

121110 9 8 7 6 5 4 3 2 1

7654321

87654321

7654321

123456789

101112

1234567

12345678

1234567

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• As an option, the burner can utilize direct vent combustion air.• Ignition of the main flame is via direct spark, utilizing high voltage electrodes and a separate

electrode for flame supervision.• To ensure adequate combustion air is present prior to ignition, and to ensure the fan is operating,

a combustion air proving switch is provided.• For ease of inspection and maintenance, the burner is hinged for easy swing away from the boiler

permitting full inspection of the burner components, front tube sheet and furnace.• A flame observation port is located in the burner door.

E. Burner Gas Train

The standard gas train is equipped in accordance with UL 795, ASME, CSD-1, XL-GAPS, and FM.Each burner gas train includes:

Low gas pressure interlock, manual resetHigh gas pressure interlock, manual resetASME CSD-1 test cocksDownstream manual ball type shutoff cockSingle body dual safety shutoff gas valveGas pressure regulator for maximum of 1 psig inlet pressure

F. Boiler control panel

A standard NEMA 1A type panel enclosure is located at the front of the boiler. This panel enclosesthe CB Falcon operating control, water level circuit boards, transformers, electrical terminals, andfuses. Terminals are provided for contractor connections.

Optional EquipmentFor option details, contact the local authorized Cleaver-Brooks representative. In summary, here aresome of the options that can be provided with the boiler package:

• Bottom blowdown valves, shipped loose or mounted and piped• Surface blowoff valve, shipped loose or mounted and piped• Feedwater stop and check valves, shipped loose or mounted and piped• Surface blowoff skimmer tube• Steam stop valve• ASME hydro test of boiler piping• Modbus communications• Alarm horn• Direct vent combustion air provision• High water alarm• Conductivity control, automatic surface blow-off• Steam system accessories and packaged skid solutions• ProtoNode Gateway (protocol translator)• Boiler Monitor (remote monitoring)

8

BOILER BOOK CBT DIMENSIONS AND RATINGS

DIMENSIONS AND RATINGSFor layout purposes, the overall dimensions for the Model CBT are shown below including the variouspipe connection sizes for steam outlet, feed water, blowoff, drain, fuel, and vent. The performanceratings for the boiler are shown in Table 4.

Figure 3. Model CBT Dimensional ViewsQP

D

E

M N

L

C

B

A

V

R

STU

(4) Ø5/8" HOLES

WG

H J

K

X

Y

F

DIMENSIONS, RATINGS, AND PRODUCT INFORMATION MAY CHANGE DUE TO MARKET REQUIREMENTS OR PRODUCT ENHANCEMENTS. THE INFORMATION CON-TAINED HEREIN IS A GUIDE FOR GENERAL PURPOSES ONLY.

9

BOILER BOOK CBT DIMENSIONS AND RATINGS

Table 2: Dimensions Model CBT Modulating

DIMENSIONS IN INCHES unless noted Boiler HorsepowerDimension 9.5 10 15 20 25 30 40 50

LENGTHSOverall A 53.3 59 59 68 68 70 77.5 82Center To Drain / Blowdown B 24.5 27 27 31 31 32 33.5 33.5Center To Front C 29 32 32 37 37 38 44 48.5Center To Feedwater D 22 25 25 30 30 30.5 33 33Center To Base E 21 21 21 25 25 26.5 28.25 28.25Center To Stack Outlet F 18 22 22 28 28 28.5 32 32Center To Gas Train G 23 26 26 31 31 32.5 38 39Base End to Bolt Hole H 1 1 1 1 1 1 1 1Bolt Hole to Bolt Hole J 40 40 40 49 49 51 54.5 54.5Base Channel K 42 42 42 51 51 53 56.5 56.5WIDTHSOverall L 34.5 37 37 47 47 49 55.5 55.5Center to Lagging M 14 18 18 23 23 24.5 27.75 27.75Center to Water Column N 20.5 19 19 24 24 25 27.75 27.75Center To Feedwater P 9.5 12 12 15.5 15.5 16.5 19 19Center To Drain / Blowdown Q 9.5 12 12 15.5 15.5 16.5 19 19Center To Gas Train R 16.5 17 17 13.5 13.5 15 17 17.5Base, Inside of Channel S 10 9 9 19 19 22 34 34Base Bolt Hole to Bolt Hole T 16 15 15 25 25 28 40 40Base, Outside of Channel U 22 21 21 31 31 34 46 46HEIGHTSOverall - Steam Nozzle V 85.5 83 83 87 87 90.5 100 100Base to Gas Train W 28.5 24 24 25 25 28.5 34.25 29.5Base to Blowdown / Feedwater X 7.5 7 7 7 7 7 7.5 7.5Base to Stack Outlet Y 70.5 68 68 73 73 75.5 84 84BOILER CONNECTIONSFeedwater AA 0.75 0.75 0.75 1 1 1 1 1Drain / Blowdown BB 1 1 1 1 1 1 1.25 1.25Surface Blowoff CC 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75Steam Outlet (150 psig only) DD 2* 2 2 2 2 2 3 3Steam Outlet (15 psig only) EE 3 3 4 4 4 6 6Combustion Air Inlet FF 4 NOM 4 NOM 4 NOM 4 NOM 4 NOM 6 NOM 6 NOM 8 NOM

Gas Train Inlet GG 1 1 1 1 1 1.25 1.25 1.25Stack O.D. HH 6 OD 6 OD 6 OD 6 OD 6 OD 8 OD 8 OD 8 ODWEIGHTS - LBSWater Weight (150 psig Normal Level) 270* 450 450 1190 1190 1515 2550 2550Water Weight (15 psig Normal Level) 475 475 1135 1135 1475 2490 2490Approx. Dry Weight (150 psig) 2,000* 2,350 2,350 3850 3850 4350 5150 5150Approx. Dry Weight (15 psig) 2,150 2,150 3675 3675 4175 4850 4850*9.5 HP is 100 psig design pressure

Table 3. ClearancesCLEARANCES inches

FRONT 36BACK 18SIDES 18ABOVE BOILER 18

10

BOILER BOOK CBT ENGINEERING DATA

Table 4: CBT Steam Boiler Ratings

ENGINEERING DATA

Boiler H.P. 9.5 10 15 20 25 30 40 50

Ratings

Rated capacity - steam (lbs-steam/hr from & at 212°F) 328 345 518 690 863 1,035 1,380 1,725

Output (1000 Btu/hr) 318 335 502 669 837 1,004 1,339 1,674

Approximate Fuel Consumption At Rated Capacity

Natural gas input (CFH) - 15 psig SteamA 398 598 797 996 1,195 1,594 1,992

Natural gas input (CFH) - 150 psig SteamB 397C 413 620 826 1,033 1,240 1,653 2,066

Power Requirements (Single Phase, 115 VAC, 50/60 Hz)

Blower motor size (watts)D 240 335 335 335 335 335 750 1,200

Minimum overcurrent protection 10A 10A 10A 10A 10A 10A 15A 20A

Heating Surface

Total waterside (ft2) 25 39 39 60 60 73 98 98

Total waterside (m2) 2.3 3.6 3.6 5.6 5.6 6.8 9.1 9.1

Total fireside (ft2) 41 61 61 94 94 107 155 155

Total fireside (m2) 3.8 5.7 5.7 8.7 8.7 9.9 14.4 14.4

Notes:

A. Input calculated at nominal 84% efficiency for 1000 Btu gas content.B. Input calculated at nominal 81% efficiency for 1000 Btu gas content.C. 9.5 HP is 100 psig design pressure.D. For altitudes above 1500 ft, contact your local C-B authorized representative for derates.

Table 5: CBT Steam Boiler Safety Valve Outlet Size

VALVE SETTING

15 PSIG STEAM 150 PSIG STEAM

BOILER HP NO. OF VALVES REQ'D

OUTLET SIZE (IN.) NO. OF VALVES REQ'D

OUTLET SIZE (IN.)

9.5 1* 3/4*

10 1 1-1/2 1 3/4

15 1 1-1/2 1 3/4

20 1 1-1/2 1 3/4

25 1 2 1 1

30 1 2 1 1

40 1 2-1/2 1 1

50 1 2-1/2 1 1-1/4

Valve manufacturers are Kunkle, Consolidated, or Conbraco, depending on availability. Contact your local Cleaver-Brooks representative for alternate safety valve set points and sizes.

*9.5 HP is 100 psig steam

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Notes:

*Based on normal water level(A)Based on 150 psig design pressure (100 psig for 9.5 HP)(B)Based on 15 psig design pressure

Table 7: Steam Volume and Disengaging Area*

BOILER HPSteam Volume CU-FT Steam Disengaging Area SQ-IN

HIGH PRESSURE LOW PRESSURE HIGH PRESSURE LOW PRESSURE(A) (B) (A) (B)

9.5 1.6 18610 3.4 3.6 424 42415 3.4 3.6 424 42420 7.0 8.0 868 86825 7.0 8.0 868 86830 8.4 9.6 1032 103240 11.9 13.6 1468 146850 11.9 13.6 1468 1468

Table 6: Lifting Lug Locations (see Fig. 4)

BOILERA inches B inches

HP9.5 78 1210 77 1915 77 1920 82 2625 82 2630 85 2440 93 3450 93 34

60° min.

Figure 4. Lifting Lugs Figure 5. Rigging

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NOTES:1. Steam nozzle sizes given in inches.2. Recommended steam nozzle sizes based on <5000 fpm steam velocity for 99%+ steam quality.

NOTE: Quantity of water removed from boiler by lowering normal water line 2”.

NOTE: For altitudes above 700 feet, refer to Table 11 below.*Maximum pressure without step-down gas regulator.

Table 8: Recommended Steam Nozzle Size

OPERATING PRESSURE BOILER HPPSIG 9.5 10 15 20 25 30 40 50

6 3 3 4 4 4 4 615 2-1/2 2-1/2 3 3 3 4 430 2 2-1/2 3 3 3 3 440 2 2 2-1/2 2-1/2 2-1/2 3 350 2 2 2 2 2-1/2 2-1/2 3 3

60-80 2 2 2 2 2 2 3 3100 2 2 2 2 2 3 3125 2 2 2 2 2 3 3

Table 9: Blowdown Tank Sizing

BOILER HP WATER (GAL)9.5 1.810 3.615 3.620 7.625 7.630 9.040 13.050 13.0

Table 10: Minimum Required Gas Pressure at Entrance to Standard Gas Trains

BOILERHP

INLET PIPESIZE

(inches)

MINIMUMHEADER SIZE

(inches)

PRESSURE REQUIRED NAT. GAS PRESSURE REQUIRED LP GASMIN

(“WC)MAX*(“WC)

MIN(“WC)

MAX*(“WC)

9.5 1 1.5 7 14 11 1410 1 1.5 7 14 11 1415 1 2 7 14 11 1420 1 2 7 14 11 1425 1 2 7 14 11 1430 1.25 2.5 9 14 11 1440 1.25 2.5 8 14 11 1450 1.25 2.5 9 14 11 14

Table 11: Gas Pressure Correction Factors

Correction factor for mini-mum required gas pressure

700’ ASL 2000’ 4000’ 6000’ 8000’ 10000’

1.00 1.07 1.16 1.25 1.35 1.45

BLOWDOWN: As steam is produced, unwanted solids areleft behind in the water and become concentrated within thevessel. If these constituents are allowed to adher to the heattransfer surfae they will impede the flow of energy. Theirremoval requires proper blowdown - either bottom, surface,or both. The table at left shows the recommended blowdowntank requirements for bottom blowdown. The surface blow-down requirement is relative to the level of TDS controldesired by the water treatment specialist. Local codes willdictate the manner of treating blowdown effluent.

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Figure 4. Boiler Room Spacing

Table 12: Required Water Quality Parameters

Constituent Maximum LevelOxygen <0.005 ppmCO2 0 ppm

Hardness <2.0 ppmSuspended Solids <300 ppm

pH 8.5 - 10.5Sulfite >50 ppm

Fe <0.1 ppmSilica <150 ppm

Total Alkalinity <700 ppmDissolved Solids <3,000 ppm

Table 13: Feedwater Flow Rates

BHP Gallons/Hour9.5 39.310 4115 6220 8325 10330 12440 165.350 206.7

Clearances around boiler are for service, inspection, and mainte-nance access.

NOTES:

1. Recommended minimum distance between boiler and wall is 18"

2. Recommended minimum distance between boilers is 18"

3. Clearance above top of boiler is 18"

4. Recommended clearance at rear of boiler is 18"

14

BOILER BOOK CBT PERFORMANCE DATA

PERFORMANCE DATA

*Corrected to 3% O2†High pressure 9.5 HP values are for 80# operating pressure

Table 14: Natural Gas, Estimated Emission LevelsPOLLUTANT UNITS

CO ppmA 10lb/MMBtu 0.007

NOx ppmA 20lb/MMBtu 0.024

SOx ppmA 1lb/MMBtu 0.001

HC/VOCs ppmA 4lb/MMBtu 0.0016

PM ppmA -lb/MMBtu 0.01

A. ppm levels are given on a dry volume basis and corrected to 3% oxygen (15% excess air)

Table 15: Predicted Sound Levels at High Fire

BHP Sound Level-dbA9.5 6310 6715 6720 6825 6830 7040 7050 70

Table 16: Predicted Fuel-to-Steam Efficiencies-Natural Gas*

BHPOPERATING PRESSURE = 10 psig OPERATING PRESSURE = 125 psig

% OF LOAD % OF LOAD

25% 50% 75% 100% 25% 50% 75% 100%9.5 83.0† 82.4† 81.8† 81.1†10 85.2 84.8 84.5 84.2 82.4 82.2 82.1 81.9

15 84.9 84.1 83.5 82.8 82.0 81.5 81.0 80.620 85.1 84.6 84.1 83.7 82.3 82.0 81.7 81.5

25 84.9 84.2 83.6 83.0 82.1 81.6 81.2 80.830 84.8 83.9 83.1 82.4 81.9 81.3 80.7 80.140 84.8 84.0 83.4 82.7 82.0 81.5 81.0 80.4

50 84.6 83.5 82.6 81.7 81.7 81.0 80.2 79.4

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Venting

Stack/Breeching Criteria

General - Under ANSI Z21.13 the Model CBT boiler can operate as a Category III or IV boiler as deemed appropriate for the application. The CBT boiler is nominally a Category III appliance (i.e. positive pressure, non-condensing).

Proper design and installation of the flue gas venting is critical to efficient and safe operation of the boiler. The vent should be designed with proper supports and clearances from combustible materials. Use insulated vent pipe spacers where the vent passes through combustible roofs and walls.

The design of the stack and breeching must provide the required draft at each boiler stack connection as proper draft is critical to safe and efficient burner performance.

Although constant pressure at the flue gas outlet is not required, it is necessary to size the breeching and stack to limit flue gas pressure variations. Consideration of the draft must be given whenever direct combustion air ducting is utilized and lengthy runs of breeching are employed. Please note: The allowable draft tolerance is negative 0.25" w.c. (-62 Pa) to a positive 0.10" w.c. (+25 Pa) for proper light offs and combustion. NOTE: This pressure range does not pertain to the boiler room; that is, the boiler room must be neutral or slightly pos-itive, never negative when using air from the boiler room for combustion.

For best performance, Cleaver-Brooks recommends individual stacks for multiple boiler installations.

For multiple CBT boilers in a common vented flue system, boiler flue isolation dampers are required. The com-mon flue system must maintain a negative draft condition at all times. In some cases, an active draft inducer system and/or modulating draft damper control may be necessary to ensure proper draft at each boiler's flue outlet.

Consult your local Cleaver-Brooks authorized representative for specific venting requirements.

Combustion Air - The burner must be supplied with adequate volume of uncontaminated air to support proper combustion and equipment ventilation. Air shall be free of chlorides, halogens, fluorocarbons, construction dust or other contaminants that are detrimental to the burner or boiler heating surfaces.

Combustion air can be supplied by means of conventional venting, that is, with combustion air drawn from the area immediately surrounding the boiler (boiler room is neutral or slightly positive pressure), or with a direct vent to outside the boiler room where air is drawn directly from the exterior of the building. Regardless of the method, all installations must comply with NFPA54 (the National Fuel Gas Code - NFGC) for U.S. installations and CAN/CSA B149.1 and B149.2 for Canadian installations.

Note: A boiler room exhaust fan is not recommended as this type of device can cause a negative pressure in the boiler room if using conventional air intake.

In accordance with NFPA 54, the required volume of indoor air shall be determined in accordance with the “Standard Method” or “Known Air Infiltration Rate Method”. Where air infiltration rate is known to be less than 0.40 Air Changes per Hour, the Known Air Infiltration Rate Method shall be used. (See the NFPA Handbook for additional information).

Engineered Design - When determining boiler room air requirements for an unconfined space the “Engineered Design” method may be used. Following this method, consideration must be given to the size of the room, air-flow and velocity of air as follows:

A. Two permanent air supply openings in the outer walls of the boiler room are recommended. Locate one at each end of the boiler room, preferably below a height of 7 feet. This allows air to sweep the length of the boiler

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B. Air supply openings can be louvered for weather protection, but they should not be covered with fine mesh wire, as this type of covering has poor air flow qualities and is subject to clogging with dirt and dust.

C. A vent fan in the boiler room is not recommended as it could create a slight vacuum under certain conditions and cause variations in the quantity of combustion air. This can result in unsafe burner performance.

D. It is forbidden to have the total area of the air supply openings at less than one square foot.

E. Size the openings by using the formula (Area in ft2 = cfm/fpm), where cfm = cubic feet per minute of air; fpm = feet per minute of air.

F. Amount of air required (cfm):

1.Combustion Air = Maximum boiler horsepower (bhp) times 8 cfm.2.Ventilation Air = Maximum boiler horsepower (bhp) times 2 cfm.3.Total Air = 10 cfm per bhp (up to 1000 feet elevation, add 3% more per 1000 feet of added elevation).

G. Acceptable air velocity in the boiler room (fpm):

1.From floor to 7 feet high = 250 fpm.2.Above 7 feet from boiler room floor = 500 fpm.

Example of required air openings (Engineered Method):

Determine the area of the boiler room air supply openings for (2) 30 horsepower Model CBT boilers at 750 feet elevation. The air openings will be 5 feet above the floor level.

Total boiler horsepower (bhp): 30 x 2 = 60 bhpFrom F.3 above, total air required = 60 bhp x 10 = 600 cfm.Air Velocity: From G.1 above = 250 fpm.Area required: From the formula in E above, 600cfm/250fpm = 2.4 square feet total.Area/Opening: 2.4 divided by 2 = 1.2 ft2 per opening (2 required).

Consult local codes, which may supersede these requirements.

Direct Vent Combustion Air - If combustion air will be drawn directly from the outside by means of a duct connected to the boiler enclosure (“direct venting”) or directly to the burner air intake (“sealed combustion”), use the following guidelines:

1. Install combustion air duct in accordance with local codes and the boiler operating and maintenance man-ual.

2. Provide for adequate ventilation of the boiler room or mechanical equipment room.3. Duct material can be PVC or metallic vent material. It should be air tight to prevent in leakage of air during

operation.4. Maximum pressure drop for the duct shall not exceed 0.25" w.c. negative. If this pressure drop is exceeded

a larger size duct is recommended.5. Multiple boilers may be connected to a single duct with take-offs to each boiler.6. If the duct will run horizontally to an outside wall, it is recommended that the duct have a slight downward

slope away from the burner intake to prevent collected moisture from draining into the burner connection.7. If the outside air is dust-laden or the installation is near a heavily traveled roadway, it is recommended that

an air filter be installed to prevent intake of contaminants that could accumulate on the burner canister.

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e-mail: [email protected] Address: http://www.cleaverbrooks.com

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