CleaverBrooks CFC 1500, CFC 3300, CFC 1000, CFC 750, CFC 500 User Manual

Model CFC ClearFire Condensing Boiler

MODEL CFC FEATURES AND BENEFITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

MODEL CFC PRODUCT OFFERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

DIMENSIONS AND RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

PERFORMANCE DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

ENGINEERING DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

STACK/BREECHING SIZE CRITERIA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

CB FALCON CONTROLLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

AluFer Inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Fireside Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Premix Burner Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Model CFC Heat Flow and Component Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

ClearFire Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Model CFC Dimensional Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Competitive Condensation Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Emissions Data Clearfire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16-19

Pressure Drop Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22-25

Condensate Piping Direct To Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Optional Condensate Treatment Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Condensate Piping for Multiple Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Condensate Treatment Tank for Multiple Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Gas Piping Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Gas Header Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Model CFC Minimum Room Clearance Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

CFC Seismic Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

No Primary Loop with Domestic Water and 2-Way Divert Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Two Boilers and Three Variable Temperature Zones (No Primary Loop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Two-Pipe Primary/Secondary Piping with Domestic Hot Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Two-Pipe Primary/Secondary Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

No Primary Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Domestic Water Heating, No Primary Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Domestic Water with On/Off and 3-Way Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Piping ‘Hybrid’ Boilers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

‘Hybrid’ Boilers with Domestic Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

2 Pipe System, Typical (reverse-return) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Table of Contents

List of Figures

1 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Zoning with Zone Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Domestic Water with 2 Boilers and 2 Coils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49

Two Opening Outside Wall Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Two Opening Ducted Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

One Opening Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Two Opening Engineered Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

Optional Direct Vent Combustion Kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Horizontal through the wall venting using inside air for combustion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

Horizontal flue through-wall with direct vent combustion intake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Inside Air - Vertical Vent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Vertical Stack with Direct Vent Combustion Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Electrical Connections CFC 500-2500 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Electrical Connections CFC 3300 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

CFC Rear Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

CB Falcon pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

U.S. Standard Dimensions Model CFC Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Metric Dimensions Model CFC Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Model CFC Boiler Ratings (Sea Level to 2000 Feet) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Altitude Correction for Input Capacity at Various Altitude Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

ClearFire Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 - 15

Noise Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

CFC Flow Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

CFC Flow Rates (Metric) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Model CFC Minimum Over Pressure Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Model CFC Boiler Safety Valve Information @ 125 PSIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Model CFC Boiler Safety Valve Information @ 60 PSIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Model CFC Water Chemistry Requirements in accordance with ABMA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Glycol Application Guidelnes - Model CFC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Max Firing Rate vs. Glycol Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

HF Speed Settings vs. Glycol Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Model CFC Maximum Condensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

CFC capacities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Model CFC Minimum and Maximum Gas Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Model CFC Minimum Required Gas Pressure Altitude Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Stack design (single boiler) using room air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

Stack sizing using outside air for combustion (direct vent combustion) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61

Operating Conditions - Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

Operating Conditions - Display/Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

CB Falcon burner sequence (Central Heat) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68

List of Tables

2 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

MODEL CFC FEATURES AND BENEFITS

Compact Firetube
Design

The Model CFC boiler is a single pass,
vertical down fired durable firetube
boiler. The internal extended-heating
surface tubes provide very high levels of
performance in a compact space,
offering over 10 square feet of heating
surface per boiler horsepower, providing
many years of trouble free performance.

Figure B5-1. AluFer Inserts

Advanced
Technology

Advanced
Construction

Tubes and tube sheets are constructed from UNS S32101 duplex stainless steel.
Tubes feature AluFer tube inserts for optimal heat transfer.

The extended heating surface design provides the ideal solution for the demands of
a condensing boiler and helps to recover virtually all the latent heat of the flue gas.
Each tube consists of an outer stainless steel tube (waterside) and the AluFer
extended surface profile on the flue gas side.

High Efficiency With the extended heating surface tubes the CFC boiler will provide fuel to water

efficiency of up to 99% at low fire and 97% at high fire with 80 degrees F return
water temperature.

Ease of Maintenance The powder coated steel casing is designed for easy removal and re-assembly. As

shown in Figure B5-2, the burner is hinged and is provided with hydraulic pistons
for simple opening for service of the spark electrode, inspection of the burner
cylinder, tubes and tube sheet on Models CFC1000 and larger. (On the CFC500 and
750, the burner is hinged only). A front mounted service platform is provided for
easy access to the burner components and controls.

Figure B5-2. Fireside Access

Quality Construction ISO 9001:2001 certified manufacturing process ensures the highest degree of

manufacturing standards are always followed.

ASME Code construction ensures high quality design, safety, third party inspection,
and reliability, and is stamped accordingly.

Premix Technology The burner utilizes "Premix" technology to mix both gas fuel and combustion air prior

to entering the burner canister, with air "leading" during burner firing transitions.

3 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Combined with a variable speed fan, this technology provides very low emission
levels, exceptionally safe operation, and nearly 100% combustion efficiency.

Full Modulation The variable speed fan provides modulated firing for reduced on/off cycling,

excellent load tracking, and reduced operating costs. The burner does not require
mechanical linkage connections between the fuel input valve and air control.
Instead, the microprocessor control positions the fan speed in accordance with
system demand, and this determines the fuel input without mechanical device
positioning - that is, linkage-less fuel/air ratio control. This eliminates linkage
slippage, minimizes burner maintenance, and provides control repeatability. This is
shown schematically in Figure B5-3.

Figure B5-3. Premix Burner Technology

Designed For
Heating
Applications

The pressure vessel is designed for 125 psig MAWP (Max. Allowable Working
Pressure) and is constructed of durable ASTM Grade Steel and Stainless Steel
materials. Figure B5-4 shows the counter flow heat exchanger design that gives
optimal heat transfer. The design also prevents hot spots, does not require a
minimum flow for thermal shock protection, and does not require a minimum return
water temperature. In fact, the design carries a 20-year thermal shock warranty.

Because of its design characteristics, the Model CFC is well suited for applications
utilizing indoor/outdoor reset controls, radiant floor heating, snow melt systems,
ground source heat pump systems and systems that utilize variable speed
circulating pumps. It may also be employed in standard hot water systems that
require higher heated water at colder outdoor temperatures but then require
minimum temperatures during warmer heating days, realizing fuel efficiency savings
over traditional hot water boilers.

While the design does not lend itself to the direct supply of potable water, a separate
storage tank with an internal heat exchanger can be employed, as the
microprocessor control permits domestic water programming. Therefore, the Model
CFC can service both hydronic heating and domestic water source heating.

Dual Return Two return pipes - high and low temperature - allow condensing performance with

as little as 10% return water at condensing temperature.

4 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Combustion Fan and

Premix Gas Valve

Safety Relief Valve

Air Vent Connection

Hot Water

Outlet

High Temp.
Return

Assembly

Burner

Canister

Control

Panel

“Finned” High

Efficiency AluFer

Tubes

Low Temp.
Return

Flue Gas

Outlet

Figure B5-4. Model CFC Heat Flow and Component Orientation

MODEL CFC PRODUCT OFFERING

Information in this section applies to condensing hot water boiler sizes ranging from
500,000 Btu input through 3,300,000 Btu input for operation on Natural Gas or
LP Gas only. Installation is for indoor use only.

Dimensions, ratings, and product information may change to meet current market
requirements and product improvements. Therefore, use this information as a guide.

ASME Code

Pressure Vessel

5 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Standard Equipment Equipment described below is for the standard boiler offering:

1. The Boiler
A. Each boiler size is designed for a Maximum Allowable Working Pressure

(MAWP) of 125 psig (8.6 Bar), constructed in accordance with the ASME
Code Section IV and bear the "H" stamp.

B. The insulated boiler is mounted on a base and powder coated steel casing

provided.

C. A drain valve connection is provided at the front bottom for field piping of a

boiler drain valve, which can be furnished as an option.

2. Boiler Trim and Controls

• The following items are furnished:

• Probe Type Low Water Cutoff control, manual reset.

• Excess Water Temperature Cutoff, manual reset.

• NTC (negative temp. coefficient) sensor for hot water supply temperature.

• NTC sensor for hot water return temperature.

• ASME Safety Relief Valve set @ 125 psig. (8.6 Bar)

• Combination Temperature/Pressure Gauge.

3. Burner Control
A. The CB Falcon is an integrated burner management and modulation control

with a touch-screen display/operator interface. Its functions include the
following:

• Two (2) heating loops with PID load control.

• Burner sequencing with safe start check, pre-purge, direct spark ignition (pilot
ignition CFC-3300), and post purge.

• Electronic ignition.

• Flame Supervision.

• Safety shutdown with time-stamped display of lockout condition.

• Variable speed control of the combustion fan.

• Supervision of low and high gas pressure, air proving, stack back pressure, high
limit, and low water.

• First-out annunciator.

• Real-time data trending.

• (3) pump/auxiliary relay outputs.

• Modbus communication capability.

• Outdoor temperature reset.

• Remote firing rate or setpoint control

• Setback/time-of-day setpoint

• Lead/Lag for up to 8 boilers

6 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

LWCO RESET

FALCON DISPLAY / OPERATOR INTERFACE

DEMAND SWITCH

Figure B5-5. ClearFire Control Panel (1500/1800 shown)

4. Forced Draft Burner
A. The burner is a "Pre-mix" design consisting of a unitized venturi, single body

dual safety gas valve, blower, and burner head.

B. Full modulation is accomplished with a variable speed fan for 5:1 turndown

ratio.

C. For near flameless combustion, the burner utilizes a Fecralloy-metal fiber

head.

D. Noise level at maximum firing is less than 70 dBA regardless of boiler size.

E. Operating on Natural Gas, NOx emissions will be less than 20 PPM

regardless of boiler size and the boiler is certified for California and Texas for
Low NOx emissions.

F. As an option, the burner is capable of direct vent combustion.

G. Ignition of the main flame is via direct spark, utilizing high voltage electrodes

and a separate electrode for flame supervision (CFC-3300 uses gas pilot
ignition and UV scanner for flame supervision).

H. To ensure adequate combustion air is present prior to ignition, and to ensure

the fan is operating, a combustion air proving switch is furnished.

I. A High Air Pressure Switch is provided to ensure burner lockout if excessive

back pressure due to a blocked stack occurs.

J. For ease of maintenance and inspection, the burner is furnished with

hydraulic rods and easy opening lockdown nuts, which permit the burner to
swing up (except 500 and 750, which are hinged only). This provides full
access to the burner and electrodes, as well, to the tube sheet and tubes.

5. Burner Gas Train

The standard gas train is equipped in accordance with UL certification and complies
with ASME CSD-1. Each burner gas train includes:

7 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

• Low Gas Pressure Interlock, manual reset.

• High Gas Pressure Interlock, manual reset.

• ASME CSD-1 Test Cocks.

• Downstream manual ball type shutoff cock.

• Single body dual safety shutoff gas valve.

Optional Equipment For option details, contact the local authorized Cleaver-Brooks representative. In

summary, here are some of the options that can be provided with the boiler:

A. Dual gas train for quick and easy fuel switchover.
B. Reusable air filter.
C. Condensate neutralization tank assembly - consists of neutralizing media, filter, and PVC

condensate holding tank with integral drain trap. This assembly can be mounted beneath

the boiler.
D. Outside air intake for direct vent combustion.
E. Outdoor temperature sensor for indoor/outdoor control.
F. Header temperature sensor for multiple boiler Lead/Lag operation.
G. Auxiliary Low Water Control (shipped loose) for field piping by others into the system piping.
H. Alarm Horn for safety shutdown.
I. Relays for output signal for burner on, fuel valve open.
J. Stack Thermometer.
K. Stack temperature limit-sensor.
L. Auto air vent.
M. Boiler drain valve.

DIMENSIONS AND RATINGS

For layout purposes, the overall dimensions for the Model CFC are shown in Table
B5-1 (US Dimensions) and Table B5-2 (Metric Dimensions) including the various
pipe connection sizes for supply and return water, drain, and vent. The performance
ratings for the boiler are shown in Table B5-3.

Altitude Relative to the ratings shown, installation of the boiler above 2000 feet elevation

will result in input capacity reduction. Please refer to Table B5-4 for input ratings of
the boiler at various elevations.

PERFORMANCE DATA

Efficiency The Model CFC is a "full condensing" boiler realizing efficiency gain at variable

operating conditions. It is designed to extract the latent heat of condensation over a
greater range than other designs. This can be seen in Figure B5-7, which depicts
nominal stack temperatures of the boiler versus other designs. The nominal point of
condensation is approximately 132
efficient heat transfer design and lower stack temperature, is able to capture the
latent heat of condensation over a broader range.

Fuel-to-water efficiency is relative to specific operating conditions. Operating
efficiency will be greater in the "condensing" mode of operation as noted above, yet
with its inherently greater heat transfer surfaces and superior pre-mix burner, the
ClearFire’s efficiency under "traditional" hot water conditions is also outstanding.
Table B5-6 through Table B5-9 show the guaranteed efficiencies at various
operating conditions and firing rates for Natural Gas. It should be noted that the
efficiency is exceptional at high fire and low fire versus other designs where high
efficiency is realized only with low fire or minimal firing rates and low temperature
returns.

 F (55.5 C). The ClearFire, due to its more

8 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

I

Figure B5-6. Model CFC Dimensional Views

9 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Table B5-1. U.S. Standard Dimensions Model CFC Boiler

ITEM DIMENSIONS (inches) 500 750 1000 1500 1800 2500 3300

A Overall Height 71.8 71.8 75.7 81.6 81.6 82.2 85.0

B Overall Width 32.3 32.3 36.6 43.7 43.7 50.8 61.3

C Overall Depth 48.8 48.8 62.6 65.6 65.6 72.6 86.3

D Width Less Casing 26.8 26.8 31.1 38.2 38.2 45.3 55.5

E Gas Connection to Top of Casing 8.1 8.1 9.5 12.5 10.2 9.4 10.0

F Gas Connection to Floor 63.7 63.7 66.2 69.1 71.4 72.8 75.0

G Side of Casing to Gas Connection 2.3 2.3 4.3 3.4 5.2 4.7 5.1

H Boiler Centerline to Air Inlet Centerline 4.0 4.0 4.0 4.9 7.1 7.1 7.1

I Floor to Bottom of Base 10.3 10.3 10.3 10.3 10.3 10.3 10.3

J Floor to Top of Stack Connection 18.6 18.6 18.1 19.1 19.1 20.9 21.4

K Centerline to Centerline of Stack Stub 15.4 15.4 16.9 21.0 21.0 28.1 35.8

L Rear of Boiler to Centerline of Stack

Stub

M Front of Boiler to Rear of Casing 38.8 38.8 49.4 49.5 49.5 56.5 67.0

N Control Panel Projection 4.1 4.1 4.1 4.1 4.1 4.1 4.3

O Casing Height 56.2 56.2 60.0 65.4 65.4 65.4 67.0

P Air Vent Line Projection from Rear of

Casing

Q Floor to Centerline of Lower Return 19.5 19.5 19.6 20.7 21.3 22.4 24.1

R Floor to Centerline of Upper Return 28.2 28.7 30.5 20.3 32.3 33.8 35.5

S Floor to Centerline of Supply Connec-

tion

T Floor to Centerline of Air Vent 59.9 59.9 62.3 63.1 63.1 63.6 66.4

AA Boiler Adjustment Foot Height 2.5 2.5 2.5 2.5 2.5 2.5 2.5

Height Above Boiler for Burner Service 14.0 14.0 14.0 14.0 14.0 14.0 18.0

5.4 5.4 7.5 8.1 8.1 8.6 10.0

7.8 7.8 7.3 8.1 8.1 8.7 4.7

54.3 54.3 56.2 57.1 56.2 56.2 59.1

CONNECTIONS

U Water Supply/Return, 150# RF Flg 2-1/2" 2-1/2" 2-1/2" 3" 4" 5" 5"

V Boiler Air Vent, NPT 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2"

W Electrical Conduit, left or right 1.6" 1.6" 1.6" 1.6" 1.6" 1.6" 1.6"

X Boiler Drain, NPT 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2"

Y Flue Gas Nominal OD, Left or Right

option

Z Combustion Air Option 4" OR 6" 4" OR 6" 4" OR 6" 6" OR 8" 6" OR 8" 8" 8"

BB Gas Connection, NPT 1" 1" 1" 1-1/2" 1-1/2" 1-1/2" 2"

CC Condensate Drain, FPT 3/4" 3/4" 3/4" 3/4" 3/4" 1" 1"

Relief Valve outlet @ 125 # Setting 1" 1" 1" 1" 1" 1" 1"

Voltage Fan Motor 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 208-240/

Voltage Control Circuit 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60

6" 6" 8" 10" 12" 12" 12"

10 Rev. 05-2012

3/60

Model CFC ClearFire Commercial Boilers

Table B5-2. Metric Dimensions Model CFC Boiler

Boiler Size

ITEM DIMENSIONS (mm) 500 750 1000 1500 1800 2500 3300

A Overall Height 1824 1824 1923 2073 2073 2088 2159

B Overall Width 820 820 930 1110 1110 1290 1557

C Overall Depth 1240 1240 1590 1666 1666 1844 2192

D Width Less Casing 681 681 790 970 970 1151 1410

E Gas Connection to Top of Casing 206 206 241 318 259 239 254

F Gas Connection to Floor 1618 1618 1681 1755 1814 1849 1905

G Side of Casing to Gas Connection 58 58 109 86 132 119 130

H Boiler Centerline to Air Inlet Centerline 102 102 102 124 180 180 180

I Floor to Bottom of Base 262 262 262 262 262 262 262

J Floor to Top of Stack Connection 472 472 460 485 485 531 544

K Centerline to Centerline of Stack Stub 391 391 429 533 533 714 909

L Rear of Boiler to Centerline of Stack Stub 137 137 191 206 206 218 254

M Front of Boiler to Rear of Casing 986 986 1255 1257 1257 1435 1702

N Control Panel Projection 104 104 104 104 104 104 109

O Casing Height 1427 1427 1524 1661 1661 1661 1702

P Air Vent Line Projection from Rear of Casing 198 198 185 206 206 221 119

Q Floor to Centerline of Lower Return 495 495 498 526 541 569 612

R Floor to Centerline of Upper Return 716 729 775 516 820 859 902

S Floor to Centerline of Supply Connection 1379 1379 1427 1450 1427 1427 1501

T Floor to Centerline of Air Vent 1521 1521 1582 1603 1603 1615 1687

AA Boiler Adjustment Foot Height 64 64 64 64 64 64 64

Height Above Boiler for Burner Service 356 356 356 356 356 356 457

CONNECTIONS (inches)

U Water Supply/Return, 150# RF Flg 2-1/2" 2-1/2" 2-1/2" 3" 4" 5" 5"

V Boiler Air Vent, NPT 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2"

W Electrical Conduit, left or right 1.6" 1.6" 1.6" 1.6" 1.6" 1.6" 1.6"

X Boiler Drain, NPT 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2" 1-1/2"

Y Flue Gas Nominal OD, Left or Right option 6" 6" 8" 10" 12" 12" 12"

Z Combustion Air Option 4" 4" OR 6" 4" OR 6" 6" 6" 6" OR 8" 8"

BB Gas Connection, NPT 1 "1 "1 "1-1/2 "1-1/2 "1-1/2 "2"

CC Condensate Drain, FPT 3/4 "3/4 "3/4 "3/4 "3/4 "3/4 "1"

Relief Valve outlet @ 125 # Setting 1 "1 "1 "1 "1 "1 "1"

Voltage Fan Motor 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 208-240/

Voltage Control Circuit 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60

3/60

11 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Table B5-3. Model CFC Boiler Ratings (Sea Level to 2000 Feet)

Description Units 500 750 1000 1500 1800 2500 3300

Input Max. BTU/Hr. 500,000 750,000 1,000,000 1,500,000 1,800,000 2,500,000 3,300,000

KCAL/Hr. 126,000 189,000 252,000 378,000 453,600 630,000 831,600
Natural Gas (1000 Btu/ft3) FT3/Hr 500 750 1000 1500 1800 2500 3300
Propane (2500 Btu/ft3) FT3/Hr 200 300 400 600 720 1000 1320
Natural Gas M3/Hr 14.2 21.2 28.3 42.5 50.9 70.8 93.4
Propane M3/Hr 5.7 8.5 11.3 17.0 20.4 28.3 37.4

Output at 104/86 F [40/30 C] 100% Firing BTU/Hr. 480,000 720,000 960,000 1,440,000 1,728,000 2,400,000 3,168,000

KCAL/Hr. 120,960 181,440 241,920 362,880 435,456 604,800 798,336

BHP 14.3 21.5 28.7 43.0 51.6 71.7 94.6

KW 141 211 281 422 506 703 928

Output at 176/140 F [80/60 C] 100% Firing BTU/Hr. 435,000 652,500 870,000 1,305,000 1,566,000 2,175,000 2,871,000

KCAL/Hr. 109,620 164,430 219,240 328,860 394,632 548,100 723,492

BHP 13.0 19.5 26.0 39.0 46.8 65.0 85.8

KW 127 191 255 382 459 637 841

MAWP PSI 125 125 125 125 125 125 125

BAR 8.6 8.6 8.6 8.6 8.6 8.6 8.6

Operating Temp., Max. °F 194 194 194 194 194 194 194

°C 90 90 90 90 90 90 90

Water Content Gallons 51 51 90 113 99 126 209

Liters 193 193 341 428 375 477 791

Weight w/o Water Pounds 1,160 1,160 1,795 2,225 2,505 3,640 4,835

Kg 526 526 814 1009 1136 1651 2193

Operating Weight Pounds 1,585 1,585 2,545 3,165 3,325 4,685 6,570

Kg 719 719 1154 1436 1508 2125 2980

Weight, Shipping Pounds 1,210 1,210 1,850 2,300 2,600 3,725 5,000

Kg 549 549 839 1043 1179 1690 2268

Fireside Heating Surface ft2 185 185 307 445 596 937 1,258

m2 17.1 17.2 28.5 41.3 55.4 87.0 117

Standby Heat Loss BTU/Hr 1,206 1,639 1,912 2,459 2,561 3,415 4,620

Watts 353 480 560 720 750 1000 1353

Fan Motor Size Watts 335 335 335 750 1,200 1,200 2,200
Operating Voltage, Fan Volts/Ph/Hz115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 208-240/

Control Circuit Volts/Ph/Hz115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60 115/1/60

Current Draw, Fan Amperes 4 4 4 8.5 12 12 6.9
Current Draw Cont. Ckt. Amperes 1.5 1.5 1.5 1.5 2 2 2.3

Condensate Quantity Firing Nat. Gas & operat­ing @ 104/86 F.

Condensate Value PH 4.5 - 5.5 4.5 - 5.5 4.5 - 5.5 4.5 - 5.5 4.5 - 5.5 4.5 - 5.5 4.5 - 5.5

Gal/Hr. 4 5 6.5 10 12 16.5 22

l/Hr. 15 19 25 38 45 62 83

3/60

Flue Gas Mass Flow @ 100% Firing (Natural
Gas)

Flue Gas Temp. Oper.
176/140 F [80/60 C]

Flue Gas Temp. Oper.
104/86 F [40/30 C]

lb/hr 557 835 1,113 1,670 2,004 2,783 3674
kg/h 253 379 505 758 909 1262 1667

°F 155 180 160 170 170 160 160
°C 68 82 71 77 77 71 71
°F 105 125 110 108 108 110 110
°C 41 52 43 42 42 43 43

12 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Table B5-4. Altitude Correction for Input Capacity at Various Altitude Levels

Natural Gas

700' ASL 2000' 4000' 6000' 8000' 10000'

CFC 3300 3300 kBTU/h 3300 3300 3300 3057 2930

CFC 2500 2500 2418 2245 2083 1930 1850

CFC 1800 1800 1800 1800 1666 1544 1480

CFC 1500 1500 1500 1500 1415 1311 1257

CFC 1000 1000 1000 1000 943 874 838

CFC 750 750 750 750 707 655 628

CFC 500 500 500 490 454 421 404

Ratings assume 35% excess air, 80F combustion air.
Blower speed adjustments should be made to match performance and local conditions accordingly.
For minimum gas supply pressures see Table B5-24. Altitude corrections for supply pressure should be made per Table B5-25.
Natural gas heating value of 1000 BTU/SCF assumed.

LP Gas

700' ASL 2000' 4000' 6000' 8000' 10000'

CFC 3300 3300 kBTU/h 3300 3300 3300 3057 2930

CFC 2500 2500 2500 2339 2169 2010 1927

CFC 1800 1800 1800 1800 1704 1579 1514

CFC 1500 1500 1500 1500 1500 1390 1332

CFC 1000 1000 1000 1000 1000 926 888

CFC 750 750 750 750 750 695 666

CFC 500 500 500 500 481 445 427

Ratings assume 40% excess air, 80F combustion air.
Blower speed adjustments should be made to match performance and local conditions accordingly.
For minimum gas supply pressures see Table B5-24. Altitude corrections for supply pressure should be made per Table B5-25.
LP (propane) gas heating value of 2500 BTU/SCF assumed.

13 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Competitor 1

Competitor 2

Clearfire

ClearFire
Efficiencies

Firing Rate

100 96.0 94.6 92.0 89.0 88.5 88.4 87.9

Firing Rate

100 94 92.7 90.5 88.5 87.8 87.0 86

Figure B5-7. Competitive Condensation Analysis

The Tables below depict the operating efficiencies of each size Model CFC boiler,
including radiation losses. As the Model CFC is a fully condensing boiler, maximum
efficiency is obtained when operating within the condensing mode, utilizing the latent
heat of condensation.

Table B5-5. CFC 500 ClearFire Efficiency

%

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)

20 99.0 98.8 97.5 94.8 92.0 88.5 88.0
50 97.4 96.2 95.0 92.2 90.5 88.5 88.0
75 97.0 95.6 93.0 90.5 89.0 88.5 88.0

Return Water Temperature F

0

(C)

Table B5-6. CFC 750 ClearFire Efficiency

%

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)

20 98.3 97.1 93.6 91.7 90 88.0 87.5
50 96.5 95.3 91.8 89.9 88.5 88.0 87.5
75 96 94.9 91 89 88 87.5 86.5

Return Water Temperature F

0

(C)

14 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Table B5-7. CFC 1000 ClearFire Efficiency

Firing Rate

%

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)
20 99 97.8 94.3 92.4 90.1 88.5 88
50 98.5 96.5 93.5 90.8 89.5 88.5 87.5
75 97.5 96.2 92.5 89.5 88.3 88 87.3

100 96.5 95.8 91.5 88.9 88 87.5 87

Return Water Temperature F

Table B5-8. CFC 1500 ClearFire Efficiency

Firing Rate

%

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)
20 99 98 96.2 94 91 88.7 88.2

50 98.2 97.5 94.3 92 90 88.5 88.2
75 98 96.5 92.1 91 89 88.5 88.2

100 97 95.3 91.5 90 88.1 87.8 87.5

Return Water Temperature F

0

(C)

0

(C)

Table B5-9. CFC 1800 ClearFire Efficiency

Firing Rate

%

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)
20 99 98 96.5 94 91 88.5 88

50 98.3 96 93.8 91 89.8 88.5 87.6
75 98 95 93 89.5 88.9 88.3 87.3

100 97.2 94 91.5 88.9 88 87.5 87

Return Water Temperature F

0

(C)

Table B5-10. CFC 2500 ClearFire Efficiency

Firing Rate

%

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)
20 99 99 97.5 95 92 88.5 88

50 99 98.5 96 93 91 88.3 88
75 98 97 95 92 89 88 87.5

100 98 97 94 91 88.5 87.6 87

Return Water Temperature F

0

(C)

Table B5-11. CFC 3300 ClearFire Efficiency

Firing Rate

%

Return Water Temperature F

0

(C)

68 80 100 120 130 140 160

(20) (27) (38) (49) (55) (60) (72)
20 99 98 95.7 93 90.2 88.5 88

50 98.6 97.5 94.1 92 89.6 88.5 88
75 98 96.5 93.5 91 89.2 88.5 87.9

100 97 95 93.1 89.8 89 88.3 87.8

15 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Emissions The Model CFC Boiler has been tested by an independent testing lab for Low NOx

certification in California under the requirements of South Coast Air Quality
Management District (SCAQMD) Rule 1146. Meeting the requirements of SCAQMD
also qualifies the boiler for meeting the NOx requirements in the state of Texas.

By means of the Pre-mix burner, the Clearfire boiler provides environmentally
friendly emissions when firing natural gas; emission data are shown in Figure B5-8
through Figure B5-13.

Figure B5-8. Emissions Data Clearfire Model CFC 500

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Model CFC ClearFire Commercial Boilers

Figure B5-9. Emissions Data ClearFire Model CFC 750

Figure B5-10. Emissions Data ClearFire Model CFC 1000

17 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Figure B5-11. Emissions Data ClearFire Model CFC 1500

Figure B5-12. Emissions Data ClearFire Model CFC 1800

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Model CFC ClearFire Commercial Boilers

Figure B5-13. Emissions Data ClearFire Model CFC 2500

Figure B5-14. Emissions Data ClearFire Model CFC 3300

19 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

Noise Level The Model CFC is extremely quiet at all operating levels, does not require any sound

level modifications to provide ultra low noise levels, and is virtually vibration free.
Thus, it is very suitable in applications that demand low noise levels.

Table B5-11 shows the noise levels of the Clearfire at various firing rates.

20% Firing 60% Firing 100% Firing
CFC 500 39 48 60
CFC 750 41 51 62
CFC 1000 43 57 66
CFC 1500 40 50 64
CFC 1800 45 56 66
CFC 2500 45 57 68
CFC 3300 63 73 78

Table B5-11. Noise Level (dBA) measured 3 feet in front of boiler

ENGINEERING DATA

Boiler Information The Model CFC boiler is designed for service in any closed hydronic system and can

be used to augment any hot water system. It can be put into operation as a single
stand-alone unit with 5:1 turndown or in multiple units for larger turndown and
capacity.

Flow Rates and
Pressure Drops

System Operating
Parameters

Clearfire boilers may be utilized in water heating systems with temperatures from
40

 F (4.4 C) to 195 F (90.5 C); ideal for ground water source heat pump

applications, etc. Because the Clearfire is a full condensing boiler, low water
temperature (below the dewpoint) restrictions do not apply. In fact, the lower the
return the better the fuel savings.

Variable temperature differentials can be designed to make use of changing outdoor
conditions and thus, the Clearfire is not restricted to a nominal 20

 F (10 C)

differential. The boiler is designed to withstand thermal stresses with supply and
return temperature differences up to 100

 F (55 C), without the use of a boiler-

circulating pump, blend pump or minimum water flow.

Note: The Clearfire does not require a minimum flow or continuous flow through it during operation.

However, the load imposed on the boiler must be considered when sizing the system flow so that
the flow does not exceed the capacity of the boiler or the demand.

To maintain rated capacity of the boiler, recommended flow rates should not be
exceeded as the flow will remove the heat beyond the capacity of the boiler. Table
B5-12 through Table B5-13 can be used to determine the full boiler output relative
to system temperature drop and the maximum recommended system pump flow.
Knowing the flow rate, the pressure drop through the boiler can be found in Figure
B5-14 through Figure B5-19.

To prevent water flashing to steam within the boiler or system, hot water boilers
must operate with proper over-pressure. System over-pressure requirements are
shown in Table B5-14.

Note: The ASME Code Section IV limits the maximum setting of the excess temperature control to

210 F (98.9 C) for boilers constructed with stainless steel. This is to ensure that water
temperature will not reach the boiling point (steaming) and therefore, so as not to exceed the
maximum limit of this control and in compliance with the Code, the operating limit of 195 F

20 Rev. 05-2012

Model CFC ClearFire Commercial Boilers

(90.5 C) is set for normal boiler operation.

While proper overpressure is required, a means to relieve excess pressure at or
beyond the design pressure of the boiler must be provided. As boiler water is
heated, expansion occurs. And this expansion must be accounted for either with an
expansion tank (air filled) or with a bladder type tank. These devices permit the
water pressure to expand outside of the boiler and not impact the pressure vessel or
pressure relieving device. But, in accordance with Code, each boiler is equipped
with an ASME approved safety relieving device should pressure build-up occur (See
Table B5-16 and Table B5-15).

Air Venting The elimination of entrained air is required. It is recommended that each unit be

piped to an expansion tank. If this is not possible, then an auto air vent should be
provided on the vent connection of the boiler. The caveat in using an auto vent is
that free oxygen can be introduced to the vesel as the boiler cools, or in some
instances the vent can become plugged.

Table B5-12. CFC Flow Rates

System Temperature Drop 0 F

10 20 30 40 50 60 70 80 90 100 110 120

Boiler

Size

500 95 48 33 24 19 16 12 11 10.5 9 8 7

750 131 66 44 33 26 22 19 16 15 13 12 11

1000 176 88 59 44 35 29 25 22 20 18 16 15

1500 260 130 87 65 52 43 37 33 29 26 24 23

1800 351 176 117 88 70 59 50 44 39 35 32 30

2500 470 235 157 118 95 79 67 59 52 48 43 39

3300 620 310 207 155 124 103 89 78 69 62 56 52

Flow rate as a function of Delta T at 94% efficiency and maximum firing capacity

Flow Rate GPM

21 Rev. 05-2012