®
CoRayVac
Custom Engineered,
Gas-Fired, Low-Intensity
Infrared Heating System
CRV-B-2
CRV-B-4
CRV-B-6
CRV-B-8
CRV-B-10
CRV-B-12
CRV-B-12A
Design Manual
All designs must be installed in strict accordance with the CORAYVAC®
Installation, Operation and Service Manual (P/N 127102NA).
Roberts-Gordon LLC
1250 William Street
P.O . B o x 44
Buffalo, New York 14240-0044
Telephone: 716.852.4400
Fax: 716.852.0854
Toll Free: 800.828.7450
CRV-B-9
© 2009 Roberts-Gordon LLC
www.rg-inc.com
www.radiantheaters.com
www.corayvac.com
P/N 127500NA Rev D 05/09
© 2009
Roberts-Gordon LLC
All rights reserved. No part of this work covered by the copyrights herein may be reproduced
or copied in any form or by any means - graphic, electronic, or mechanical, including
photocopying, recording, taping or information storage and retrieval systems - without the
written permission of Roberts-Gordon LLC.
TABLE OF CONTENTS
SECTION 1: Concept ..............................................................1
SECTION 2: The CRV-Series System.....................................2
2.1 Safety...........................................................................2
2.2 Zero Regulator ............................................................. 2
2.3 Fuel Savings and Comfort ...........................................4
SECTION 3: Clearances to Combustibles.............................5
3.1 Required Clearances to Combustibles.........................5
SECTION 4: Sizing and Design Considerations...................9
4.1 Radiant Adjustment to Heat Loss ................................9
4.2 Radiant Height Adjustment Factor...............................9
4.3 Selecting the Burners ................................................ 10
4.4 Radiant Distribution ................................................... 10
SECTION 5: Flow Loading.................................................... 12
5.1 Radiant Branch Flow .................................................12
5.2 Pump Capacity ..........................................................14
5.3 Tailpipe Flow.............................................................. 14
SECTION 6: Radiant Tube and Tailpipe............................... 15
6.1 Radiant Tube Length.................................................. 15
6.2 Tailpipe.......................................................................15
6.3 Design Parameters .................................................... 16
6.4 CRV-Series Design Methods ..................................... 16
6.5 Tailpipe Design Method ............................................. 18
SECTION 7: Example CRV-Series System Layouts............21
7.1 Example System Layout (Option 1) ............................ 21
7.2 Example System Layout (Option 2) ............................ 22
7.3 Example System Layout (Option 3) ............................ 22
7.4 Example System Layout (Option 4) ............................ 23
7.5 Example System Layout (Option 5) ............................ 23
7.6 Example System Layout (Option 6) ............................ 24
7.7 Example System Layout (Option 7, 8 and 9)............... 25
SECTION 8: Control Methods .............................................. 26
8.1 ROBERTS GORDON
(P/N 02770002) .........................................................26
8.2 ROBERTS GORDON® ULTRAVAC™..........................26
8.3 SPST Transformer Relay (P/N 90417600K)...............27
8.4 DPST Transformer Relay (P/N 90436300).................27
8.5 Pressure Switch .........................................................27
SECTION 9: Air Supply System ...........................................28
9.1 Pressurized................................................................28
9.2 Non-Pressurized ........................................................ 28
9.3 Outside Air System Design Requirements.................28
SECTION 10: ROBERTS GORDON
Requirements.................................................31
SECTION 11: CRV-Series Equipment Specifications......... 32
11.1 Burner and Burner Controls......................................32
11.2 Equipment ................................................................32
®
System Control
®
ULTRAVAC™ Design
Printed in U.S.A.
TABLE OF FIGURES
Figure 1: Assembly Overview (Two Branch System Shown).....3
Figure 2: Standard Reflector .....................................................6
Figure 3: One Side Reflector.....................................................6
Figure 4: Two Side Reflectors ...................................................6
Figure 5: Universal Shield, Position 1 .......................................7
Figure 6: Universal Shield, Position 2 .......................................7
Figure 7: Universal Shield, Position 3 .......................................7
Figure 8: 2-Foot Deco Grille......................................................8
Figure 9: Barrier Shield .............................................................8
Figure 10: Protective Grille........................................................8
Figure 11: Radiant Distribution (Average Coverage)............... 11
Figure 12: Radiant Distribution (Increased Coverage) ............ 11
Figure 13: Radiant Distribution (Heavy Coverage).................. 11
Figure 14: Burner Flow Units .................................................. 13
Figure 15: Vacuum Loss Curve for 4" Shared Tailpipe...........14
Figure 16: Tube Length vs. Efficiency...................................... 16
Figure 17: Possible Damper Coupling Locations ....................20
Figure 18: Example System Layout (Option 1)....................... 21
Figure 19: Example System Layout (Option 2)....................... 22
Figure 20: Example System Layout (Option 3)....................... 22
Figure 21: Example System Layout (Option 4)....................... 23
Figure 22: Example System Layou
Figure 23: Example System Layout (Option 6)....................... 24
Figure 24: Example System Layout (Option 7)....................... 24
Figure 25: Example System Layout (Option 8)....................... 24
Figure 26: Example System Layout (Option 9)....................... 25
Figure 27: Air Supply System Capacity by Duct Length and
Diameter ................................................................28
Figure 28: Outside Air Blower .................................................29
Figure 29: Sample Layout for Pressurized Outside Air
Systems..................................................................30
t (Option 5).......................23
LIST OF TABLES
Table 1: CORAYVAC® Design Parameters ............................12
Table 2: Pump Capacity..........................................................14
Table 3: Pump Exhaust Requirements ...................................14
Table 4: Allowable Tailpipe Lengths .......................................17
Table 5: Operating Characteristics; Condensing or
Non-Condensing ......................................................18
SECTION 1: CONCEPT
The concept of CRV-Series is easy to understand.
However, it means discarding old ideas because CRVSeries is a different kind of heating system.
CRV-Series is a gas-fired, vacuum-operated, low-
intensity infrared heating system incorporating a patented incremental burner system.
Gas-Fired means it uses clean-burning Natural or
Propane gas.
Vacuum-Operated means that the pump draws all
the products of combustion through the system and
expels them outdoors.
Low-Intensity means the radiant surfaces of the
tubes do not glow red; instead they operate at a lower
temperature (less than 900° F or 482.2° C) and radiate
heat at lower intensity per square foot of radiating sur-
face. Area coverage is provided by long runs of 4" (10
cm) O.D. tubing which hang from the ceiling or roof
supports. Reflectors direct the radiant heat downward
to occupied areas.
SECTION 1: CONCEPT
Radiant refers to the heat radiated by the CRV-Series
system. Because this heat is in the form of infrared
rays, it does not directly heat the air. Instead, the rays
heat objects such as floors, people, walls, cars,
machines, tools, etc. The warm objects, in turn, heat
the air throu
gh convection.
Incremental Burner System means that several
burners can operate in-series and fire into the same
run of steel tube that carries the combustion gases
from upstream burners. Each of these burners in a
radiant branch may have different firing rates; also, the
space between burners may vary. This allows the
designer to match heat gain to heat loss for each area
of the building. Firing burners in-series provides higher
thermal and radiant efficiency.
In a properly designed low-intensity radiant system,
the occupants should be barely aware of the radiant
heat when the system is firing. They will feel little or no
change when the thermostat is satisfied and the system is not firing. This combines with warm floors,
warm walls and draft-free operation to improve the
mean radiant temperature of the space. This is the key
to the exceptional comfort and fuel efficiency provided
by the CRV-Series system.
1
CRV-SERIES DESIGN MANUAL
SECTION 2: THE CRV-SERIES SYSTEM
A CRV-Series system consists of one pump, a control
system, and a number of burners, see Page 3, Figure
1. It also includes an extended tube surface (4" (10
cm) steel tubing) covered by highly efficient reflectors
to direct the radiant heat downward to the floor. The
tubing nearest the burners radiates with the most
intensity and is called radiant tube. This should be
located over areas with the greatest heat loss. The
rest of the tubing surface (located between the radiant
tube and the pump) radiates with less intensity and is
called tailpipe. This can be located in areas with
lower heat loss.
While it is important to locate radiant tubes over areas
with high heat loss, such as the perimeter of the build-
ing, it is not essential to cover all areas directly with
radiant heat. Center areas (away from external walls)
and other areas of low heat loss can be adequately
heated without direct coverage as long as the input of
the system is adequate for the total building heat loss.
However, to achieve the highest degree of comfort and
fuel savings, it is recommended that the CRV-Series
system be located to provide as complete and even a
distribution as is practical. In addition, several different
reflector and shield configurations are available to
direct the radiant heat to or away from desired areas.
With CRV-Series, all equipment and controls are
C.S.A. design certified, both as individual parts and
also as a complete heating system. Also, individual
electrical component parts are listed as applicable.
2.2 Zero Regulator
CRV-Series uses a 100% pre-mix burner with the input
dependent on system vacuum. With no vacuum, the
zero regulator prevents gas flow. When vacuum is
present, the burner fires and input increases as vac-
uum increases. As the input increases, the amount of
air also increases. Over the normal range of operating
vacuum, the gas/air ratio is essentially linear.
This unique and patented feature provides optimum
combustion conditions at all times. Combustion condi-
tions are unaffected by fluctuations in fuel pressure,
vacuum, dirty air filters, changes in atmospheric pressure, wind velocity or other climate conditions.
Page 3, Figure 1 illustrates the components of a typi-
cal CRV-Series system. The system shown is a four
burner system composed of two branches. A branch
consists of a single run of tubing, including an end
burner, followed by any burners downstream. A
branch ends at a tee or a cross (where other branches
connect). For a single branch system, the branch ends
at the pump.
2.1 Safety
Safety is a prime consideration of CRV-Series. First,
there is a pre-purge of the complete tube network prior
to flame ignition. Then, to ensure that there will be no
gas flow unless the pump is operating, a pressure
switch located at the pump must activate prior to igni-
tion. After the pressure switch has closed, there are
two valves in-series in each burner that must be ener-
gized, as well as a zero regulator. Additionally, slow
opening gas valves provide smooth ignition and
enhance reliability. Once the thermostat has been satisfied, the burners turn off and the pump continues to
run for two minutes to purge the entire system of flue
gases.
2
FIGURE 1: Assembly Overview (Two Branch System Shown)
Pump
End
Vent
Combustion
Chamber
End Burner
Radiant
Tube
Coupling
Reflector
End Cap
Reflector
Support
Burner
Tube &
Reflector
Hanger
Reflector
Reflector
with Hole
End Vent
Exhaust to
Outside
Shared Tailpipe
End Burner
Tailpipe
Tailpipe
1. Radiant tubing between burners, and 20-50' (6-15 m)
downstream of the last burner is normally hot rolled steel or
heat-treated aluminized steel. All tailpipe tubing must be por-
celain coated steel or heat-treated aluminized steel.
2. Damper couplings are required when layout has unequal
branches. Unequal branches are achieved by unequal
geometry, burner quantity or burner firing rates.
3. Plain couplings are used to connect combustion chambers
to radiant tubing and radiant tubing to tailpipe tubing. All
tailpipe couplings must be lined.
SECTION 2: THE CRV-SERIES SYS TEM
3
CRV-SERIES DESIGN MANUAL
2.3 Fuel Savings and Comfort
Space heating can be accomplished with less input
capacity when a radiant heating system is utilized,
rather than with a conventional convective heating
system. Why is this so?
A conventional, convective heating system, such as a
unit heater or central furnace works by heating the air,
which then indirectly heats the area and
occupants. CRV-Series utilizes infrared energy to heat
objects, people and surfaces directly, not the air. The
warm objects and floor create a heat reservoir, which
then re-radiates to the surroundings and also heats
the air by convection.
The radiant energy received by the occupants, directly
from the heater or indirectly from the
surroundings via re-radiation, serves to increase the
mean radiant temperature (MRT) of the space. In a
manner similar to direct sunlight, the increased MRT
allows the occupant to perceive a comfort condition at
a reduced air temperature. The resulting reduced air
temperature within the space provides the
following fuel-saving advantages:
• Reduced stratification of air in the space.
• Reduced transmission heat loss due to lower temperature inside than assumed design
condition.
• Redu
ced air change heat loss, to the extent that
exfiltration through cracks or openings near the
roof will be decreased because of decreased
stack effect.
• Decreases the actual degree days experienced.
4
SECTION 3: CLEARANCES TO COMBUSTIBLES
WARNING
Fire Hazard
Keep all flammable objects, liquids and
vapors the minimum required clearances to
combustibles away from heater.
Some objects will catch fire or explode when
placed close to heater.
Failure to follow these instructions can result
in death, injury or property damage.
3.1 Required Clearances to Combustibles
Clearances are the required distances that combusti-
ble objects must be away from the heater to prevent
serious fire hazards. Combustibles are materials,
which may catch on fire and include common items
such as wood, paper, rubber, fabric, etc. Maintain
clearances to combustibles at all times for safety.
Clearances for all heater models are located on the
burner assembly and on Page 6, Figure 3 through
Page 8, Figure 10 in this manual. Check the clear-
ances on each burner for the model heater being
installed to make sure the product is suitable for your
application and the clearances are maintained. Read
and follow the safety guidelines below:
• Keep gasoline or other combustible materials
including flammable objects, liquids, dust or
vapors away from this heater or any other appli-
ance.
SECTION 3: CLEARANCES TO C OMBUSTIBLES
• Hang heater in accordance to the minimum sus-
pension requirements.
• If the radiant tubes must pass through the building
structure, be sure that adequate sleeving and fire
stop is installed to prevent scorching and/or fire
hazard.
•
The stated clearances to combustibles represents
a surface temperature of 90° F (32° C) above
room temperature. Building materials with a low
heat tolerance (such as plastics, vinyl siding, canvas, tri-ply, etc) may be subject to degradation at
lower temperatures. It is the installer’s responsibility to assure that adjacent materials are protected
from degradation.
• Maintain clearances from heat sensitive
equipment and workstations.
• Maintain clearances from vehicles parked below
the heater.
• Maintain clearances from swinging and overhead
doors, overhead cranes, vehicle lifts, partitions,
storage racks, hoists, building construction, etc.
• In locations used for the storage of combustible
materials, signs must be posted to specify the
maximum permissible stacking height to maintain
required clearances from the heater to the combustibles. Signs must be posted adjacent to the
heater thermostat. In the absence of a thermostat, signs must be posted in a conspicuous location.
• Consult local Fire Marshal, Fire Insurance Carrier
or other authorities for approval of proposed
installation when there is a possibility of exposure
to combustible airborne materials or vapors.
5
CRV-SERIES DESIGN MANUAL
B
C
D
A
A
B
C
D
A
B
C
D
NOTE: 1. All dimensions are from the surfaces of all tubes, couplings, elbows, tees and crosses.
2. Clearances B, C and D can be reduced by 50% after 25' (7.5 m) of tubing downstream from
where the combustion chamber and the tube connect.
FIGURE 2: STANDARD REFLECTOR
Model A B C D A B C D
CRV-B-2 4 20 48 20 11 51 122 51
CRV-B-4 4 20 48 20 11 51 122 51
CRV-B-6 4 20 48 20 11 51 122 51
CRV-B-8 4 20 48 20 11 51 122 51
CRV-B-9 4 36 60 36 11 92 153 92
CRV-B-10 4 366036119215392
CRV-B-12 4 36 60 36 11 92 153 92
CRV-B-12A 4 36 60 36 11 92 153 92
.
(inches) (centimeters)
FIGURE 3: ONE SIDE REFLECTOR
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 12 56 20 11 31 143 51
CRV-B-4 4 12 56 20 11 31 143 51
CRV-B-6 4 12 56 20 11 31 143 51
CRV-B-8 4 12 56 20 11 31 143 51
CRV-B-9 4 12 60 42 11 31 153 107
CRV-B-10 4 12 60 42 11 31 153 107
CRV-B-12 4 12 60 42 11 31 153 107
CRV-B-12A 4 12 60 42 11 31 153 107
FIGURE 4: TWO SIDE REFLECTORS
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 12 56 12 11 31 143 31
CRV-B-4 4 12 56 12 11 31 143 31
CRV-B-6 4 12 56 12 11 31 143 31
CRV-B-8 4 12 56 12 11 31 143 31
CRV-B-9 4 12 60 12 11 31 153 31
CRV-B-10 4 12 60 12 11 31 153 31
CRV-B-12 4 12 60 12 11 31 153 31
CRV-B-12A 4 12 60 12 11 31 153 31
6
NOTE: 1. All dimensions are from the surfaces of all tubes, couplings, elbows, tees and crosses.
C
A
B
D
C
A
B
D
C
A
B
D
2. Clearances B, C and D can be reduced by 50% after 25' (7.5 m) of tubing downstream from
where the combustion chamber and the tube connect.
FIGURE 5: UNIVERSAL SHIELD, POSITION 1
Model A B CDABCD
CRV-B-2 4 12 12 12 11 31 31 31
CRV-B-4 4 12 12 12 11 31 31 31
CRV-B-6 4 12 12 12 11 31 31 31
CRV-B-8 4 12 12 12 11 31 31 31
CRV-B-9 8 18 24 18 21 46 61 46
CRV-B-10 8 18241821466146
CRV-B-12 8 18 24 18 21 46 61 46
CRV-B-12A 8 18 24 18 21 46 61 46
SECTION 3: CLEARANCES TO C OMBUSTIBLES
(inches) (centimeters)
FIGURE 6: UNIVERSAL SHIELD, POSITION 2
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 24 48 24 11 61 122 61
CRV-B-4 4 24 48 24 11 61 122 61
CRV-B-6 4 24 48 24 11 61 122 61
CRV-B-8 4 24 48 24 11 61 122 61
CRV-B-9 4 36 48 36 11 92 122 92
CRV-B-10 4 36 48 36 11 92 122 92
CRV-B-12 4 36 48 36 11 92 122 92
CRV-B-12A 4 36 48 36 11 92 122 92
FIGURE 7: UNIVERSAL SHIELD, POSITION 3
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 12 56 30 11 31 143 77
CRV-B-4 4 12 56 30 11 31 143 77
CRV-B-6 4 12 56 30 11 31 143 77
CRV-B-8 4 12 56 30 11 31 143 77
CRV-B-9 8 12 60 42 21 31 153 107
CRV-B-10 8 12 60 42 21 31 153 107
CRV-B-12 8 12 60 42 21 31 153 107
CRV-B-12A 8 12 60 42 21 31 153 107
7
CRV-SERIES DESIGN MANUAL
A
B
C
D
C
A
B
D
A
B
C
D
NOTE: 1. All dimensions are from the surfaces of all tubes, couplings, elbows, tees and crosses.
2. Clearances B, C and D can be reduced by 50% after 25' (7.5 m) of tubing downstream from
where the combustion chamber and the tube connect.
FIGURE 8: 2-FOOT DECO GRILLE
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 12 48 12 11 31 122 31
CRV-B-4 4 12 48 12 11 31 122 31
CRV-B-6 4 12 48 12 11 31 122 31
CRV-B-8 4 12 48 12 11 31 122 31
CRV-B-9 4 18 56 18 11 46 143 46
CRV-B-10 4 18 56 18 11 46 143 46
CRV-B-12 4 18 56 18 11 46 143 46
CRV-B-12A 4 18 56 18 11 46 143 46
FIGURE 9: BARRIER SHIELD
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 12 12 12 11 31 31 31
CRV-B-4 4 12 12 12 11 31 31 31
CRV-B-6 4 12 12 12 11 31 31 31
CRV-B-8 4 12 12 12 11 31 31 31
CRV-B-9 - UNAPPROVED - - UNAPPROVED -
CRV-B-10 - UNAPPROVED - - UNAPPROVED -
CRV-B-12 - UNAPPROVED - - UNAPPROVED -
CRV-B-12A - UNAPPROVED - - UNAPPROVED -
FIGURE 10: PROTECTIVE GRILLE
(inches) (centimeters)
Model A B CDABCD
CRV-B-2 4 20 48 20 11 51 122 51
CRV-B-4 4 20 48 20 11 51 122 51
CRV-B-6 4 20 48 20 11 51 122 51
CRV-B-8 4 20 48 20 11 51 122 51
CRV-B-9 4 36 60 36 11 92 153 92
CRV-B-10 4 36 60 36 11 92 153 92
CRV-B-12 4 36 60 36 11 92 153 92
CRV-B-12A 4 36 60 36 11 92 153 92
8
SECTION 4: SIZING AND DESIGN CONSIDERATIONS
Given a building with a calculated heat loss of
350,000 (Btu/h), what is the installed capacity
required of a CORAYVAC
®
system mounted at
30' (9 m)?
CORAYVAC
®
Installed Capacity = Heat Loss x
Radiant Adjustment x Height Adjustment
For CORAYVAC
®
systems, a .80 radiant adjust-
ment factor is used.
The height adjustment is 1% per foot over 20'
(3% per meter over 6 meters), or 1.10.
∴CORAYVAC
®
Installed Capacity = 350,000
(Btu/h) x .80 x 1.10 = 308,000 (Btu/h)
A 12% reduction in installed capacity vs. a
conventional heating system.
The building heat loss must be calculated in accor-
dance to accepted energy load calculation methods.
ASHRAE (American Society of Heating, Refrigeration
and Air-Conditioning Engineers) offers in-depth information that is useful in calculating energy loads. The
CRV-Series system input is determined in concert with
the required radiant adjustment to heat loss and height
adjustment factors.
4.1 Radiant Adjustment to Heat Loss
The practice of applying an adjustment factor to heat
loss calculations for radiant heating systems is well
known within the radiant heating industry, having been
used by manufacturers for over 25 years. A number of
studies have been conducted to identify the values of
the adjustment factor in the range of 0.8 to 0.85
depending on efficiency (higher efficiency uses lower
factor). This adjustment can be more thoroughly
understood when considering the following radiant
effect issues:
• Infrared energy heats objects, not the air.
• Lower ambient temperatures reduce the amount
of air infiltration.
• Less air stratification with radiant heat.
heating system. The ability of a radiant system to provide the advantages of these radiant effects rests
largely with the ability of this system to establish a
reserve heat capacity in the floor. Without this reserve
capacity, radiant comfort cannot be achieved. (The
exception is station heating/spot heating applications
where sufficiently high levels of direct radiation are
received from the heater.) The height adjustment factor is a means to insure adequate floor level radiant
intensity to “charge” the floor heat reservoir.
Proportionately larger wall surfaces also remove
energy from the floor to a larger degree, decreasing
the heat reservoir.
The increased input capacity recommended by a
height adjustment factor is not extraneous as compared to the heat loss calculation. Rather, it is a realization that in order to maintain radiant comfort
conditions (and the economic benefits), a minimum
radiant level must be maintained at the floor.
It is recommended that an adjustment to the heat loss
of 1% per foot (3% per meter) for mounting heights
above 20' (6 m), be added up to 60' (18 m). Above this
height, additional correction overstates the BTU
requirement as determined by the heat loss.
• Lower ambient air temperatures reduce the trans-
EXAMPLE 1:
mission heat loss through walls and roof.
SECTION 4: SIZING AND DESIGN C ONSIDERATIONS
• Elevated floor temperature provides a thermal
reserve capacity.
• Increased mean radiant temperature allows occu-
pants to perceive thermal comfort at the reduced
air temperature.
Each of these issues impacts favorably on the reduc-
tion of the installed capacity of the radiant heating system. This fact, together with the realization that the
standard ASHRAE heat loss calculation methods
(particularly the transmission heat loss coefficients)
have been developed specifically for conventional hot
air systems, demonstrates the need for the heat loss
adjustment factor.
• In general, a .80 adjustment factor should be
used for CRV-Series systems.
4.2 Radiant Height Adjustment Factor
As discussed above, the installed input capacity of
radiant heating systems is typically reduced as compared to the calculated heat loss due to the radiant
effects associated with a properly designed radiant
9
CRV-SERIES DESIGN MANUAL
Given a building with a calculated heat loss
of 500,000 Btu/h, what is the installed capacity required of a CRV-Series system mounted
at 50' (15 m)?
CORAYVAC
®
Installed Capacity = Heat Loss x
Radiant Adjustment x Height Adjustment.
For CORAYVAC
®
systems, a .80 radiant adjust-
ment factor is used.
The height adjustment is 1% per foot over 20'
(3% per meter over 6 meters), or 1.30.
∴ CORAYVAC
®
Installed Capacity = 500,000
(Btu/h) x .80 x 1.30 = 520,000 (Btu/h).
EXAMPLE 2:
Note in Example 2, if equipment had been conventionally sized based on thermal output only, a nearly identical input requirement would result. For mounting
heights above 60' (18 m), no further correction is generally necessary if the floor level radiant intensity is
sufficient to establish a reserve capacity (hence, radiant comfort), and the heat loss
requirement is satisfied based on thermal output.
Due to the complexity of installations with mounting
heights over 60' (18 m), it is advisable to contact Roberts-Gordon for further information regarding the specific application.
4.3 Selecting the Burners
The number of burners and input for each must be
specified in the design layout. The following
factors should be considered when selecting burner
input:
• Heat gain and distribution required.
• Mounting height.
• Flow loading restrictions.
• Length of radiant branches.
• Distance required between burners.
• Desired radiation intensity.
In general, lower burner inpu
ts can be used for lower
mounting heights and where lower heat gains are
required. Higher burner inputs are used primarily with
higher mounting heights and where high heat gain is
required.
The number of burners required can be calculated by
dividing the input rating of the selected sizes into the
10
calculated CRV-Series system required installed
capacity.
4.4 Radiant Distribution
Radiant heat distribution at occupant level must be
considered in the burner and design selection
process.
Distribution of heat between radiant branches at floor
level is more critical at the perimeter of buildings. This
is where the heat loss is highest. Therefore, it may be
possible to combine different applications of distribu-
tion within the same building. The following figures
show three different applications of rules to determine
distribution.
4.4.1 Radiant Distribution (Average Coverage)
The aim of this distribution is to provide average or
lighter than average radiant intensity and works well
for general b
uilding heating. See Page 11, Figure 11.
The distance between radiant branches can vary
between 2.5 to 4 (or more) times the mounting height.
This distribution is commonly used in applications
such as warehouses and lower heat loss areas of a
building.
Lighter coverage can be used in areas where occu-
pant traffic is low.
4.4.2 Radiant Distribution (Increased Coverage)
The aim of this distribution is to provide continuous
radiant intensity. See Page 11, Figure 12. The
distance between radiant branches is about 2 times
the mounting height.
This distribution is commonly used in areas bordering
high heat loss areas or areas requiring increased radi-
ant intensity to achieve occupant comfort.
4.4.3 Radiant Distribution (Heavy Coverage)
The aim of this distribution is to provide increased radiant intensity in areas that range from sedentary work
to spot heating for loading docks. See Page 11, Figure
13. The y dimensions in the diagram is the height
above floor level where overlap of the radiant output
will occur.
In practice, y = 6' (1.83 m) is commonly used in areas
where occupant comfort doing sedentary work is an
important factor. In loading bays, spot heating and
areas of high heat loss, the horizontal distance (x)
between branches can be as little as 0.5 times the
mounting height.
FIGURE 11: Radiant Distribution (Average Coverage)
H
90°
3 H
H= mounting height
2 H
H
90°
H= mounting height
H
90°
y
x=2H-2y
x
y= height above the
floor level where
overlap of radiant
output will occur
H= mounting height
FIGURE 12: Radiant Distribution (Increased Coverage)
SECTION 4: SIZING AND DESIGN C ONSIDERATIONS
FIGURE 13: Radiant Distribution (Heavy Coverage)
11
CRV-SERIES DESIGN MANUAL
SECTION 5: FLOW LOADING
The patented CRV-Series burner system allows a
number of burners to be installed in-series, in the
same radiant tube, resulting in a long, continuous radiant emitting surface to give even heat distribution
within the building.
To enable the burners to be correctly located within the
system, to maintain system operating vacuum and
obtain design flue gas temperatures at the pump, the
design layout is based on a simplified flow principle
using a “flow unit.”
The flow unit is defined as the amount of fuel/air mixture for a heat input of 10,000 (Btu/h). This corresponds to a flow rate of 1.83 cfm at 65-70°F.
For the purpose of design, flow units enter the CRVSeries system in one of two ways:
• Through the burner.
• Through the end vent plate.
Flow units exit the system as spent produ
cts of com-
bustion via the pump.
The purpose of the end vent air is to dilute the hot
combustion gases at the burner, thereby promoting
uniform heating of the tube while avoiding excessive
heating of the combustion chamber.
For the end burner, the burner inlet flow consists of the
end vent air and combustion air. For all other
burners, the burner inlet flow consists the of the total of
the end vent air plus the combustion gases from all
upstream burners.
The requirement for minimum burner inlet flow is met if
the total flow units entering the combustion chamber
meets or exceeds the minimum as shown on Page 12,
Table 1.
5.1 Radiant Branch Flow
The flow in a radiant branch consists of the end vent
flow units plus the flow units of combustion air from all
burners. Page 13, Figure 14 shows a representation
of flow
units for various types of branches.
The limiting factor for maximum flow in the radiant section has been determined experimentally in terms of
the maximum burner inlet flow units that can be tolerated without degradation of combustion characteris-
tics at the last downstream burner. If more than the
maximum number of burners are installed per radiant
branch, the vacuum loss across the additional burners
will increase appreciably.
This maximum flow in the radiant branch can be
expressed for each burner firing rate by either a maximum number of burners per branch or the maximum
number of flow units. See Page 12, Table 1.
Table 1: CORAYVAC® Design Parameters
Burner Model B-2 B-4 B-6 B-8 B-9* B-10 B-12A B-12
Input (Btu/h) x (1000) 20 40 60 80 90 100 110 120
Flow Units per Burner 2 4 6 8 9 10 12 12
Flow Units per End Vent
(minimum flow units entering combustion chamber)
Maximum Number of Burners per Branch 6 4 4 4 2 4 3 3
Maximum Number of Flow Units per Branch 18 26 39 52 33 60 56 56
Radiant Tube Length (average distance between burners)
Minimum (ft) 10 12.5 20 20 20 30 35 35
Recommended (ft) 15 20 25 30 30 40 50 50
Maximum (ft) 20 25 35 45 50 60 70 70
Minimum Distance from Burner to Downstream Elbow (ft) 5 5 10 10 10 15 15 15
Suggested Minimum mounting Height (ft) 8 8 8 10 10 15 15 15
6 10152015202020
* CRV B-9 requires first downstream tube from burner to be aluminized heat-treated.
12
FIGURE 14: Burner Flow Units
B-10 Burner #1
End Burner
End Vent Air
+ 20 Flow Units
Combustion Gas
+ 10 Flow Units
Coupling
B-10 Burner #2
Downstream Burner
Combustion Gas
+ 10 Flow Units
B-10 Burner #3
Downstream Burner
Combustion Gas
+ 10 Flow Units
Burner 1
Burner 2
Burner 3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
1
2
3
1
2
3
1
2
3
End Vent
Flow Units
Burner Firing Rate
Btu/h
Burner #
Burner #1
Flow Units
Burner #2
Flow Units
Burner #3
Flow Units
Total Flow
Units
6
20,000
20,000
20,000
40,000
40,000
40,000
60,000
60,000
60,000
80,000
80,000
80,000
90,000
90,000
100,000
100,000
100,000
120,000 (or 110,000)
120,000 (or 110,000)
120,000 (or 110,000)
120,000
100,000
80,000
10
15
20
15
20
20
20
2
2
2
12
4
4
4
22
6
6
6
33
8
8
8
44
9
9
33
10
10
10
50
12
12
12
56
12
10
8
50
Total Flow
Units
20 + 10 + 10 + 10
= 50 Flow Units
SECTION 5: FLOW LO ADING
13
CRV-SERIES DESIGN MANUAL
NOT OK
OK
SIDE
10
20
30
40
50
60
70
80
90
100
120
130
Length of Tailpipe Section (feet)*
Maximum Flow Units per Single Tailpipe Section
30
40
50 60 70
80
90 100
110
120
5.2 Pump Capacity
The flow unit capacity of the pump is indicated on
Page 14, Table 2, as a function of installed altitude.
When the CRV-Series system is designed in accordance with this set of instructions and is in proper
operating condition, a vacuum from 2-3" w.c. will be
obtainable at each end vent (i.e. at all burners).
Table 2: Pump Capacity
Installed Altitude Maximum Flow Units
Feet Above
Sea Level
' - 2000'
0
2001' - 3000'
3001' - 4000'
4001
' - 5000'
5001' - 6000'
6001' - 7000'
7001
' - 8000'
8001' - 9000'
Meters Above
Sea Level
0 m - 609 m 66 112 224
610 m - 914 m 63 105 215
915 m - 1219 m 60 100 206
1220 m - 1524 m 57 95 197
1525 m - 1828 m 54 90 188
1829 m - 2134 m 51 84 180
2135 m - 2438 m 48 80 170
2439 m - 2743 m 45 75 161
EP-100
EP-200
Series
EP-300
Series
number of flow units carried in the tube.
See Figure 15. Readings for length and flow when
plotted on the graph must fall on OK side to avoid
excessive vacuum losses.
FIGURE 15: Vacuum Loss Curve for 4" Shared
Tailpipe
There are a number of design requirements which, if
not met, will reduce the vacuum obtainable and
thereby the effective flow capacity of the pump. These
include:
• Minimum Length of Tailpipe - If less than the
minimum length of tailpipe is provided per radiant
branch, there will be insufficient cooling of the com-
bustion gases and improper operation of the pump.
• Line Loss Check for Tailpipe is applicable to
sections of tailpipe which are common to two or
more radiant branches (i.e. shared lengths). See
Page 14, Figure 15.
• Excessive back pressure on discharge line of
pump can be caused by partial blockage or too
much flow for length. See Section 5.3.1
• More than maximum number of burners or flow
units per radiant branch. See Page 14, Table 2.
• Excessive number of elbow or tee fittings
which increases vacuum loss.
5.3 Tailpipe Flow
Excessive flow loading in a single section of tailpipe
can cause low vacuum and lower effective pump
capacity. For the pump to develop the proper vacuum,
the length of tailpipe m
14
ust not be excessive for the
NOTE: For 6" (15 m) tailpipe, length is limited to a
maximum of 100’ (30 m). See Page 16, Section 6.3
for more details.
Lengths shown include allowance for 1 elbow every
50' (15 m); deduct 15% of length for each additional
elbow used per 50' (15 m) length.
5.3.1 Pump Exhaust Length Requirements
The tube length on the exhaust side of the pump is
considered excessive if not within the following condi-
tions:
Table 3: Pump Exhaust Requirements
Pump Series Exhaust Tube Length Exhaust Tube Diameter
EP-100 Up to 25' (7.6 m) 4" 3 Elbows
EP-100 Up to 50' (15 m) 5" 3 Elbows
EP-200 Up to 10' (3 m) 4" 0 Elbows
EP-200 Up to 25' (7.6 m) 5" 3 Elbows
EP-200 Up to 50' (15 m) 6" 3 Elbows
EP-300 Up to 10' (3 m) 6" 1 Elbows
EP-300 Up to 25' (7.6 m) 7" 3 Elbows
EP-300 Up to 50' (15 m) 8" 3 Elbows
SECTION 6: RADIANT TUBE AND TAILPIPE
The main purpose of the tailpipe and the radiant tube
is to provide sufficient tube surface to transfer the heat
from the flue gases to the tube wall where it radiates
from the tube. Radiant tube is defined as the tubing
between burners firing in a radiant branch, plus the
radiant tubing immediately following the last down-
stream burner. Tailpipe is defined as all tubing
between the radiant tube and the pump.
Most of the radiant heat supplied by each burner is
released from the radiant tube; the balance is released
by the tailpipe. The placement of radiant tube to correspond to areas of major heat loss is the key to providing uniform comfort levels. The use of adequate
tailpipe is the key to high combustion efficiency and
proper operation of the pump.
6.1 Radiant Tube Length
The considerations in the selection of the length of
radiant tube include the following:
SECTION 6: RADIANT TUBE AND TAILPIPE
Page 16, Figure 16 relates the effect on system thermal efficiency of variations in radiant and tailpipe
lengths. The chart was created based on test data
obtained in accordance with methodology developed
by the National Bureau
of Standards (NBSIR 80-2110)
and recommendations on flue loss calculation contained in ANSI Z83.20/CSA 2.34 (latest edition).
Actual installation variables (gas BTU content, air temperature and operation cycle, etc.) may effect efficiencies (positively or negatively). Page 16, Figure 16 is
presented as a guide to the designer for information
only.
NOTE: When accounting for the required tailpipe
lengths during the design process, it is important to
verify that the tailpipe for each branch is at least equal
to the specified minimum.
6.1.1 Minimum Radiant Tube Length
Provides for the highest level of intensity per length of
radiant tube and good radiant heat uniformity between
b
urners. More tailpipe length is required to maintain
operating efficiency and pump capacity.
6.1.2 Maximum Radiant Tube Length
Provides the lowest level of intensity per length of radi-
ant tube, and consequently the largest span between
burners. The radiant intensity will be reduced slightly
for the last 5'-10' (2-3 m) of radiant tube before the
next burner.
The length of radiant tube required varies according to
the burner input. Consideration has been given to the
use of a standard 10' (3 m) length of tube or lengths
that can be cut from same without waste. See Page
12, Table 1.
When positioning radiant tube to give the required
radiant distribution, it is important to consider:
• Clearances to combustible materials.
• Lighting equipment and other suspended objects.
6.2 Tailpipe
Tailpipe provides a low level of radiant intensity per
length. The length of tailpipe for systems can be varied
according to the flow units in the system and the
designed radiant length. Longer lengths of tailpipe will
attain higher operating efficiencies and therefore condensation will occur.
15
CRV-SERIES DESIGN MANUAL
Length of Tailpipe per Flow Unit (feet)
3.0
2.5
2.0
1.5
1.0
83% 84% 85% 86% 87% 88% 89% 90%
Steady State Thermal Efficiency (%)
M
a
x
i
m
u
m
R
a
d
i
a
n
t
P
i
p
e
M
i
n
i
m
u
m
R
a
d
i
a
n
t
P
i
p
e
N
o
m
i
n
a
l
R
a
d
i
a
n
t
P
i
p
e
NOTE: Thermal efficiency values shown do not include the contribution due to condensing conditions when
operating in cyclic fashion. To estimate cyclic efficiencies, add 2-3% to the values obtained from the graph.
Flow Units Per Branch
Branch 1 +
Branch 2 +
Branch 3 +
Branch 4 +
Branch 5 +
Branch 6 +
To t a l S ys te m
Flow Units =
FIGURE 16: Tube Length vs. Efficiency
6.3 Design Parameters
When designing branches of 4 B-8 or larger burners
in-series, the following limitation to the pump capacity
applies:
Pump Model Series
Maximum Loading
EP-100:Not Allowed
EP-200:1 Branch of 4 burners
EP-300:2 Branches of 4 burners
For systems that are designed above 90% pump
capacity, the following limitations of shared tailpipe
apply:
• 4" (10 cm) tailpipe: limited to maximum of 2 combined branches and length limited to maximum of
20' (6 m). See Page 14, Figure 15 for all other
tailpipe considerations.
• 6" (15 cm) tailpipe limited to maximum of 4 combined branches and length limited to maximum of
100' (30 m).
• When calculating required tailpipe length 1' (.3 m)
of 6" manifold tube is equivalent to 1.3' (.4 m) of 4"
tailpipe.
in insufficient vacuum to burners.
6.4 CRV-Series Design Methods
1. L ay o ut the system to suit the BTU input
required.
2. Calculate the system design for each branch
individually.
3. Calculate the number of flow units per branch of
burners. Add the flow units for each branch
together to get the total system flow units. See
Page 12, Table 1 for the r
model. See Page 13, Figure 14 for example flow
unit calculations.
ules for each burner
Failure to comply with the above parameters will result
16
4. Select pump model series for total system flow
Burner
Radiant Tube Length
After Each Burner
1+
2+
3+
4+
5+
6+
Total Radiant Tube
Length in Branch =
Average Radiant
Length Per Burner =
units:
EP-100: up to 66 flow units
EP-200: up to 110 flow units
EP-300: up to 224 flow units
5. See Page 14, Table 2 for altitudes greater than
2000'.
6. For each branch, add the length of radiant tube
after each heater:
SECTION 6: RADIANT TUBE AND TAILPIPE
Repeat this calculation for each branch in the
system.
7. Divide the total radiant tube length in the branch
by the number of burners in the branch to get
the average radiant length per burner.
Repeat this calculation for each branch in the
system.
8. Using the average radiant length per burner
(Calculated in Step 7) See Page 17, Table 4 to
select the allowable tailpipe lengths per flow
unit.
Table 4: Allowable Tailpipe Lengths
Radiant Tube Length (average distance between burners)
Minimum (ft) 10 12.5 20 20 20 30 35
Recommended (ft) 15 20 25 30 30 40 50
Maximum (ft) 20 25 35 45 50 60 70
Tailpipe length per flow unit
Minimum (ft)* 1.2 1.2 1.2 1.2 1.2 1.2 1.2
Recommended (ft) 1.5 1.5 1.5 1.5 1.5 1.5 1.5
Maximum (ft) 2.5 2.5 2.5 2.5 2.5 2.5 2.5
Maximum (ft) for EP-100 only 1.7 1.7 1.7 1.7 1.7 1.7 1.7
*Minimum tailpipe lengths can only be used if radiant tube length is recommended or greater.
B-2 B-4 B-6 B-8 B-9 B-10 B-12/B-12A
Burner Model
17
CRV-SERIES DESIGN MANUAL
For a B-10 burner system of 200 flow units and an average of 40' radiant tube length per burner, See
Page 17, Table 4 for the tailpipe lengths per flow unit that can be used and the corresponding
operating characteristic.
From Table 4, we can use between 1.2' per flow unit and 2.5' per flow unit when the average radiant length
per B-10 burner is 40'. By multiplying the number of flow units in the system (200 flow units) by the mini-
mum tailpipe length from the chart (1.2' per flow unit), we see that we will need a minimum of 240' of tailpipe
for this system. Likewise, by multiplying the number of flow units in the system (200 flow units) by the maxi-
mum tailpipe length from the chart (2.5' per flow unit), we see that maximum system, tailpipe length is 500'.
Tailpipe length range for a B-10 burner system with 200 flow units and an average radiant tube length of 40’
is 240'-500'. The length of the tailpipe will determine whether the system is condensing or non-condensing.
Given a certain radiant tube length and tailpipe length, the operating characteristic can be determined
u
sing Table 5.
Total tailpipe ' (includes 1 elbow / 50').
Total tailpipe - 10' = Optimum unshared
tailpipe per branchNumber of branches
Total system tailpipe
= Tailpipe ft/flow unit
To t a l f l ow units
EXAMPLE 3: B-10 Radiant Tube vs. Tailpipe Length
Table 5: Operating Characteristics; Condensing or Non-Condensing
Radiant Tube Length (average distance between burners)
Minimum N/A NC Borderline C
Recommended NC Borderline C C
Maximum Borderline C C C
N/A=Not Allowed NC=Non Condensing C=Condensing
Minimum Recommended 1.7 ft/flow unit Maximum
Tailpipe Length per Flow Unit
6.5 Tailpipe Design Method
Given the overall length of tailpipe for the system, the
following section provides the method for ensuring the
design will function correctly.
the section of tailpipe.
If flow units entering a shared tailpipe system exceed
90% of pump capacity, the length of 4" diameter
tailpipe must not exceed 20'.
System with EP-300 Series Pump
6.5.1 Rule of Thumb Unshared Calculations
For shared tailpipe up to 115 flow units, 4" diameter
tailpipe can be used. See Page 14, Figure 15 for max-
imum permissible length of tailpipe for the number of
flow units entering the section of tailpipe.
Select a pump discharge location and plan the route of
the tailpipe. For example system layouts See Page 21,
Figure 18 through Page 25, Figure 26 for different
pump and system efficiency requirements. If these layouts are not suitable, it is necessary to customize the
layout for the CRV-Series system to the individual
building requirements.
For multiple branch systems, always plan to connect
the unshared tailpipe together as close to the pump as
possible for better system efficiency.
6.5.2 Shared Tailpipe Calculation
System with EP-100 or EP-200 Series Pump
Shared tailpipe greater than 115 flow units use 6"
diameter tube. Note that all tailpipe lengths for the pur-
poses of calculation are expressed in terms of 4"
diameter tube.
Effective length: 10' (3 m) of 6" (15 cm) diameter
tube = 13' (4 m) of 4" diameter tube.
6.5.3 To Calculate the Total System Tailpipe
To ta l unshared tailpipe + shared 4" branch tailpipe +
effective length of shared 6".
6.5.4 To Check Performance Criteria
See Page 14, Figure 15 for maximum permissible
length of tailpipe for the number of flow units entering
Compare the results to Page 17, Table 4 and Page 18,
18
Table 5 for the burner model to ensure that the result-
ing tailpipe lengths maintain intended operating characteristic.
6.5.5 Damper Couplings
Damper couplings are needed:
• In any tailpipe branch that carries less flow units
than other tailpipe branches connected to the
same pump
• In unsymmetrical layouts with branches having
the same number of flow units, the damper cou-
pling is placed in every branch except for the
longest branch.
The purpose of the damper coupling is to adjust the
end vent vacuum down to the desired level. These are
to be placed in the tailpipe section and not the radiant
branch. The recommended location is before the first
tee fitting or 10'-40' from the end of the radiant pipe.
See Page 20, Figure 17; Page 23, Figure 21, Page
24, Figure 25, and Page 25, Figure 26 for placement
examples.
SECTION 6: RADIANT TUBE AND TAILPIPE
19
CRV-SERIES DESIGN MANUAL
Damper Coupling
Damper
NOTE: Damper setting
will vary
Zone 1
Zone 2
Zone 3
Zone 1
End Vent
Zone 3
End Vent
Zone 2
End Vent
Zone 1
Damper
Coupling
Zone 2
Damper
Coupling
Zone 3
Damper
Coupling
Pump
Damper
FIGURE 17: Possible Damper Coupling Locations
20
SECTION 7: EXAMPLE CRV-SERIES SYSTEM LAYOUTS
CORAYVAC
®
Burner
LEGEND
Pump
Damper
Radiant Tube
Tailpipe
6" Tailpipe
30'
(9 m)
30'
(9 m)
30'
(9 m)
20'
(6 m)
20'
(6 m)
20'
(6 m)
10' (3 m)
Systems that are symmetrical are preferred because
FIGURE 18: Example System Layout (Option 1)
the vacuum available in the system branches are balanced as a function of design (damper couplings are
not needed).
Where radiant tube lengths are variable in a single
branch, the average length shall be used to determine
the total radiant tube length. Tailpipe will begin after
the last radiant tube following the last burner in the
branch.
CRV-Series is most effective when there are at least 3
burners in the radiant branch.
To assist with the selection of burners and system
designs, the following figures show system layouts that
have been used extensively with CRV-Series since
1962. Designing systems using these layouts will
mean altering the dimensions to suit the individual
building.
SECTION 7: EXAMPLE CRV-SERIES SYSTEM L AYOUTS
Generally, shared tailpipe reduces the available system vacuum. See Page 14, Section 5.3 for shared
tailpipe design rules.
7.1 Example System Layout (Option 1)
Six B10 burners at minimum radiant tube length and
2.5 ft/flow unit tailpipe, the recommended pump for
this system is an EP-200 Series p
ump.
This system provides maximum radiant intensity on
the left and right and adds supplemental radiant
effects through the center creating very even radiant
effects over the coverage area.
Layout to provide high system efficiency, condensed
radiant output and good uniformity of distribution.
Adjust the lengths as necessary for different input systems and to change the efficiency levels.
21
CRV-SERIES DESIGN MANUAL
40'
(12 m)
40'
(12 m)
40'
(12 m)
40'
(12 m)
40'
(12 m)
20' (6 m)
10' (3 m)
30'
(9 m)
30'
(9 m)
40'
(12 m)
40'
(12 m)
30'
(9 m)
50'
(15 m)
6" Tailpipe
FIGURE 19: Example System Layout (Option 2)
7.2 Example System Layout (Option 2)
FIGURE 20: Example System Layout (Option 3)
Six B10 burners at recommended radiant tube length
and 1.2'/flow unit tailpipe, the recommended pump for
this system is an EP-200 Series pump.
Layout will minimize up front equipment cost of tubing
by implementing minimum tailpipe length.
Layout will exhibit minimum system efficiency. Adjust
the lengths as necessary for different input systems
and to increase the efficiency levels.
7.3 Example System Layout (Option 3)
Twelve B10 burners at minimum radiant tube length
and 1.56'/flow unit tailpipe, the pump for this system is
an EP-300 Series Pump.
All shared tailpipe is 6" diameter.
Layout will provide maximum radiant intensity
between burners.
Layout will exhibit minimum system efficiency. Adjust
the lengths as necessary for different input systems
and to increase the efficiency levels.
22
SECTION 7: EXAMPLE CRV-SERIES SYSTEM L AYOUTS
30'
(9 m)
40'
(12 m)
30'
(9 m)
40'
(12 m)
40'
(12 m)
40'
(12 m)
30'
(9 m)
6" Tailpipe
70'
(21 m)
10'
(3 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
FIGURE 21: Example System Layout (Option 4)
FIGURE 22: Example System Layout (Option 5)
7.4 Example System Layout (Option 4)
Nine B10 burners at recommended radiant tube length
and 1.58'/flow unit tailpipe, the pump for this system is
an EP-300 Series Pump.
All shared tailpipe is 6" diameter.
Layout will exhibit nominal system efficiency. Adjust
the lengths as necessary for different input systems
and to increase the efficiency levels.
7.5 Example System Layout (Option 5)
Six B10 burners at minimum radiant tube length and
1. 5 ' / f l o w unit tailpipe, the pump for this system is an
EP-200 Series pump.
23
CRV-SERIES DESIGN MANUAL
100'
(30 m)
10' (3 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
10' (3 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
negligible
180'
(55 m)
10' (3 m)
30'
(9 m)
30'
(9 m)
30'
(9 m)
10' (3 m)
Layout to provide minimum system efficiency. Adjust
the lengths as necessary for different input systems
and to increase the efficiency levels.
This system is generally accompanied by an additional system, as shown, so that the radiant output of
the additional system supplements the lack of radiant
intensity from the tailpipe of the first system. This layout method is used in high heatloss and perimeter
heating applications.
FIGURE 23: Example System Layout (Option 6)
This layout method is often used effectively in heatloss
and perimeter heating applications.
FIGURE 24: Example System Layout (Option 7)
7.6 Example System Layout (Option 6)
Six B10 burners at minimum radiant tube length and
2.3'/flow unit tailpipe, the pump for this system is an
EP-200 Series pump.
FIGURE 25: Example System Layout (Option 8)
Layout to provide high system efficiency, condensed
radiant output and good uniformity of distribution.
Adjust the lengths as necessary for different input systems and to change the efficiency levels.
24
SECTION 7: EXAMPLE CRV-SERIES SYSTEM L AYOUTS
30'
(9 m)
30'
(9 m)
10'
(3 m)
30'
(9 m)
10'
(3 m)
30'
(9 m)
30'
(9 m)
6"
Tailpipe
FIGURE 26: Example System Layout (Option 9)
Layout to provide condensed radiant output and good
uniformity of distribution. Layout will exhibit minimum
system efficiency.
7.7 Example System Layout (Option 7, 8 and 9)
These systems are for B9 burners only, this burner is
specially rated for 2 burners in-series applications in
the systems shown.
Option 7 is a 180' (55 m) straight system connected to
an EP-100 pump.
Option 8 is a system connected to an EP-200 Series
pump.
Option 9 is a system connected to an EP-300 Series
pump.
These layouts show minimum allowed lengths. Addi-
tional tubing may be added. The distance between the
burners can be varied from 30' (9 m) to 20’ (6 m), but
the overall system lengths must remain the same.
Layout will minimize upfront equipment cost of tubing
by implementing special shortened minimum tailpipe
lengths.
25
CRV-SERIES DESIGN MANUAL
DANGER
Electrical Shock Hazard
Disconnect electric before service or
maintenance.
More than one disconnect switch may be
required to disconnect electric to the unit.
Control must be properly grounded to an
electrical source.
Failure to follow these instructions can
result in death or electrical shock.
WARNING
Explosion Hazard
Turn off gas supply to heater before service.
Failure to follow these instructions can result
in death, injury or property damage.
SECTION 8: CONTROL METHODS
Electronic 24 Vac thermostats and mechanical thermostats with heat anticipator can be used. The system control offers a 24 Vac power supply to power
electronic thermostats.
Roberts-Gordon offers a selection of low voltage
thermostats approved for use with the system
control.
A System Control operated system has two minutes
post purge pump operation to completely exhaust
products of combustion from the system. A system
control provides indication of power to the pump and
zones and indicates the status of the pressure switch
with lights.
The System Control is ETL listed in accordance with
UL873 – Standard for Temperature Indicating and
Regulating Equipment.
8.2 ROBERTS GORDON
®
ULTRAVAC
™
The ROBERTS GORDON® ULTRAVAC™ is a micro
processor based control package designed for modu-
lating control of CRV-Series heaters based on outdoor
temperatures. The controls offer full modulation
between 60% and 100% of system maximum rated
input.
There are several methods of controlling CRV-Series
systems. The options are as follows:
8.1 ROBERTS GORDON
®
System Control (P/N
02770002)
®
The ROBERTS GORDON
System Control is an
electronic controller designed for the control of
CORAYVAC
systems.
®
and VANTAGE® NP (multiburner only)
The System Control is capable of giving four zones of
burners' temperature control and power. The control
will also give power output to as many as two pumps,
provided that the load is not greater than 20 A and 1
Ø. For additional electrical specifications see the
System Control Installation, Operation and Service
manual (P/N 10091601NA).
This controller is capable of giving control outputs to
one pump and three heating zones. The controller
also features inputs which are used for indoor and out-
door signal condition monitoring.
System status and settings are viewed and altered
from a PC (not supplied) running ROBERTS GOR-
®
DON
ULTRAVAC™ Software.
®
ROBERTS GORDON
a PC (not supplied) running Windows
with a Pentium
®
class processor and at least 64k of
ULTRAVAC™ Software requires
®
95 or higher,
RAM.
Special design requirements apply for CRV-Series
®
systems using the ROBERTS GORDON
™
VAC
Controller, See Page 31, Section 10.
ULTRA-
26
SECTION 8: CONTROL METHODS
Buildings today demand all sorts of control options
based on the user’s preference. ULTRAVAC™
controls offer a host of communication options for
integration with controls’ networks to best serve
individual needs:
BACnet
®
: Interface ULTRAVAC™ with other building
management control platforms with our BACnet
option.
TCP/IP (LAN): Connect to ULTRAVAC™ via your
local area network of computers. Load ULTRAVAC™
software onto any computer on the network and
control and view your heating system from your
computer.
MODEM: Dial into ULTRAVAC™ from anywhere in
the world via modem. Supplied as standard on all
central controllers!
RS-485: Hard wire ULTRAVAC™ directly to your
computer.
There are references in this manual to various trademarks. All
trademarks mentioned herein, whether registered or not, are the
property of their respective owners. Roberts-Gordon is not
sponsored by or affiliated with any of the trademark or registered
trademark owners, and make no representations about them,
their owners, their products or services.
Roberts-Gordon LLC is not sponsored by or affiliated with
BACnet®.
indication of operating conditions. The transformer
relay wiring diagram is shown in the CORAYVAC
®
Installation, Operation and Service Manual (P/N
127102NA).
8.5 Pressure Switch
A pressure switch is required to confirm pump operation on all systems.
A pressure switch is also required on the inlet duct of a
non-pressurized air supply.
8.3 SPST Transformer Relay (P/N 90417600K)
The transformer relay can be used to control an EP100 or EP-201 pump CORAYVAC
®
system. The single
pole relay can only be used to control one zone of
burners. The electrical circuit is a 120 V AC (20 A)
supply. The transformer 24 V AC output for the thermostat is rated at 40 V A. Thermostats used with the
transformer must not exceed this power requirement.
A transformer relay operated system will not give any
post purge pump operation to completely exhaust
products of combustion from the system or provide
indication of operating conditions. The transformer
relay wiring diagram is shown in the CORAYVAC
®
Installation, Operation and Service Manual (P/N
127102NA).
8.4 DPST Transformer Relay (P/N 90436300)
The transformer relay can be used to control an EP100 or EP-201 pump CORAYVAC
®
system. The double
pole relay can only be used to control two zones of
burners. The electrical circuit is a 120 V AC (20A) sup-
ply. The transformer 24 V AC output for the thermostat
is rated at 40 VA. Thermostats used with the trans-
former must not exceed this power requirement. A
transformer relay operated system will not give any
post purge pump operation to completely exhaust
products of combustion from the system or provide
27
CRV-SERIES DESIGN MANUAL
140
120
100
80
60
40
20
0
0 50 100 150 200 250
Flow Units
Straight Duct Length (feet)
4"
5"
6"
7"
NOTE: For capacity requirements larger than shown, use 8" duct.
Duct Diameter
SECTION 9: AIR SUPPLY SYSTEM
An air supply free of dust and corrosive contaminants
is essential for proper operation and best life expectancy with any heating system. With CRV-Series, there
are two alternatives available to the designer for providing the air supply. These are:
• Room air, a filter is standard for each burner.
• Outside air system to duct air from an uncontami-
nated source. The outside air system can be
designed as a pressurized or non-pressurized
system.
The first alternative above is usable when the dust
load is not excessive and there is no usage of corrosive contaminants such as solvents or vapors inside
the building.
The outside air system must be used in all applica-
tions where corrosive contaminants may be present in
the air even in trace amounts (few parts per million).
It is important for designers and owners of heating
systems to note that the presence of contaminants in
the combustion air supply will greatly accelerate the
rate of corrosion on tube surfaces and will shorten the
useful life of the heating system. This is true regard-
less of whether the heating system is CRV-Series,
other infrared systems or conventional gas or oil-fired
equipment such as u
nit heaters, central boiler plant,
etc.
With the unique vacuum powered burners, the fuel/air
mix remains constant, even if combustion air filters are
dirty. It can be expected that the use of an outside air
system will reduce but not eliminate the potential for
corrosion due to contamination.
®
ULTRAVAC™ or relay transformer, a separate
DON
load relay package is required. Wire the control for the
relay in parallel with the pump. The outside air blower
must have a separate 20 A, 120 V power supply.
9.2 Non-Pressurized
For a non-pressurized outside air supply, a 4" O.D. single wall pipe duct may be attached to the burner and
end vent. For length and duct sizing requirements See
Section 9.3. To prevent condensation, insulate the
outside air duct.
9.3 Outside Air System Design Requirements
9.3.1 Non Pressurized
• 6" diameter duct must not exceed 90' (27 m)
• 4" diameter duct must not exceed 90' (27 m)
• Elbows are equivalent to 10' (3 m) of duct length.
• See the CRV-Series Installation, Operation, and
Service Manual (P/N 127102NA) for ducting
installation details.
9.3.2 Pressurized Systems
• 6" diameter duct must not exceed 120' (36 m) total
per system.
• 4" diameter duct must not exceed 120' (36 m) per
radiant branch.
• See the CRV-Series Installation, Operation, and
Service Manual (P/N 127102NA) for ducting
installation details.
FIGURE 27: Air Supply System Capacity by Duct
Length and Diameter
In a way similar to the CRV-Series pump system, the
design of the air supply system also involves considerations of total flow units and acceptable combinations
of duct lengths (and diameters) versus flow units car-
ried. In certain circumstances, it may be desirable to
introduce an outside air blower to pressurize the system. A small positive pressure is desirable and necessary to prevent the system from drawing in
contaminated air.
9.1 Pressurized
For pressurized outside air supplies, the outside air
blower motor has a pressure switch that must be used.
Wire this switch in-series with the pu
switch. When using an outside air blower with a ROB-
ERTS GORDON
28
®
System Control, ROBERTS GOR-
mp pressure
9.3.3 Pipe sizing
To size each section of pipe proceed as follows:
• Calculate the required flow units at each outlet of
the supply system.
• Measure the longest run of pipe from the blower
to the most remote outlet. Use only this distance
in Figure 27 (or the next longer distance if the
exact distance is not shown). This is to provide
assurance that the pressure drop to the most
remote outlet will not exceed 0.25" w.c. when all
outlets are supplied.
• See Figure 27, find the intersection point on the
graph for the appropriate duct length and number
of flow units. The duct size above this intersection
point indicates what size duct work should be
used. Proceed in a similar manner for each outlet
and each section of duct. For each section of
duct, determine the total flow unit capacity sup-
plied by that section.
SECTION 9: AIR SUPPL Y SYS TEM
Duct Design Rules
• System should be designed so that the blower is
positioned closest to the highest flow require-
ments (end vents).
• When a duct is carrying more than 40 flow units, it
must be at least 6" diameter.
Blower (P/N 90707501) Performance 112 Flow
Units:
One outside air blower is required per each EP-100 or
EP-200 series pump and two outside air blowers may
be required for each EP-300 series pump. Outside air
blowers cannot be shared between two separate
CRV-Series systems.
FIGURE 28: Outside Air Blower
29
CRV-SERIES DESIGN MANUAL
*NOTE: up to 10' (3 m) max. from blower
inlet can be neglected for pressure drop
calculations.
4
4
4
10
20 8
8
8
110'
(33 m)
(44)
15 6
66
(22)
(33)
P
100'
(30 m)
15'
(4.5 m)
B
50'
(15 m)
10'
(3 m)
max.*
4" duct
4" duct
Branch A
Branch B
Walls
Branch C
4" duct
6" Duct
4" Duct
6" duct
FIGURE 29: Sample Layout for Pressurized Outside Air Systems
30
®
SECTION 10: ROBERTS GORDON
ULTRAVAC™ DESIGN REQUIREMENTS
CRV-B-2 and CRV-B-4 are not available for use with
ROBERTS GORDON
®
ULTRAVAC™ controls.
CRV-Series systems designed with minimum
radiant tube lengthshall have 1.5' - 2.0' per flow unit of
tailpipe length.
-OR-
CRV-Series systems with recommended radiant tube
length shall have 1.2' - 1.5' per flow unit of tailpipe
length.
SECTION 10: ROBERTS GORDON® ULTRAVAC™ DESIGN R EQUIREMENTS
31
CRV-SERIES DESIGN MANUAL
SECTION 11: CRV-SERIES EQUIPMENT SPECIFICATIONS
The total heating system supplied shall be design cer-
tified by the CSA International per American National
Standard ANSI Z83.20/CSA 2.34 (latest edition).
11.1 Burner and Burner Controls
11.1.1 Burners shall be designed to operate simulta-
neously in series without adverse effects from com-
11.2 Equipment
11.2.1 Burner
Each burner assembly shall consist of heavy-duty
cast-iron burner heads, pre-wired gas controls with
electronic, three-try direct spark ignition and combus-
tion air filter.
bustion gases from upstream burners.
11.2.2 Pump
11.1.2 Burners shall be capable of firing on:
Natural Gas, or LP Gas.
11.1.3 Burners shall be supplied to fire at any one of
the input firing rates as specified:
CRV-B-2-20,000 (Btu/h)
CRV-B-4-40,000 (Btu/h)
CRV-B-6-60,000 (Btu/h)
CRV-B-8-80,000 (Btu/h)
CRV-B-9-90,000 (Btu/h)
CRV-B-10-100,000 (Btu/h)
CRV-B-12A-110,000 (Btu/h)
CRV-B-12-120,000 (Btu/h)
When using ROBERTS GORDON
®
ULTRAVAC™ controls, burner rates will modulate between 60% and
100% rated input (CRV-B-2 and CRV-B-4 are not available for use with ROBERTS GORDON
®
ULTRAVAC™
controls).
11.1.4 The design of burners supplied shall provide
for maintaining a constant proportion of fuel gas to filtered combustion air. These conditions are met for
burners in which the pressure of both the fuel gas
and the combustion air are introduced at zero (atmospheric) pressure and the flow of each is established
by a vacuum on the downstream side of the flow
The pump model supplied will vary with the capacity of
the system. See the pump technical specification
sheet or the installation, operation and service manual
for product description and specification.
The pump shall be acoustically isolated from the system with a flexible connector with temperature rating of
350°F minimum. The motor in the vacuum pump shall
be secured with rubber mounts for acoustical isolation.
11.2.3 Heat Exchanger
Radiant tubing (between burners and 10’ - 70’ down-
stream of last burner) shall be of 4" O.D. steel or heat
treated aluminized tubing.
As an option, the balance of the tubing shall be 4"
O.D. steel tubing w
of acid-resistant porcelain.
All heat exchanger (tubing) connections shall be made
with stainless steel coupling assemblies. Standard
couplings will be used in radiant sections. Lined cou-
plings will be used in tailpipe sections.
11.2.4 Outside Air
When specified, in contaminated environments, the
system shall be capable of supplying air from the out-
side to each burner and end vent for the support of
combustion.
metering orifices.
11.1.5 To as s ure a high degree of fail-safe operation,
the design shall preclude flow of gas if any or all of
the following abnormal conditions occur in the non-
firing mode:
ith an internal and external coating
1. Main valve fails in open position.
2. Vacuum pump motor fails to operate.
3. Power fails.
11.1.6 To further assure a high degree of safety, the
system will be under negative pressure at all times
during operation to preclude the possibility of the
escape of combustion gases inside the building.
11.1.7 The burner control assembly will include a zero
regulator.
11.1.8 All bu
rners shall be pre-wired with a grounded
electrical cord and plug.
32
Infrared Heating
Maintain clearance
to the side and
clearance below
the heater from vehicles
and combustible materials.
www.rg-inc.com Printed in U.S.A. P/N 91037912 Rev. H
Attach this information to a wall near the ROBERTS GORDON
®
heater.
Read the Installation, Operation, and Service Manual thoroughly before installation, operation, or service.
Know your model number and installed configuration.
Model number and installed configuration are found on the burner and in the Installation, Operation and Service Manual.
Write the largest clearance dimensions with permanent ink according to your model number and configuration in the open spaces below.
OPERATING INSTRUCTIONS
1. STOP! Read all safety instructions on this information sheet.
2. Open the manual gas valve in the heater supply line.
3. Turn on electric power to the heater.
4. Set the thermostat to desired setting.
1. Set the thermostat to off or the lowest setting.
1. Set the thermostat to off or the lowest setting.
2. Turn off electric power to the heater.
3. Turn off the manual gas valve in the heater supply line.
4. Call your registered installer/contractor qualified in the
installation and service of gas-fired heating equipment.
IF THE HEATER WILL NOT OPERATE, TO ENSURE YOUR SAFETY,
FOLLOW THESE INSTRUCTIONS TO SHUT DOWN YOUR HEATER
Fire Hazard
Keep all flammable objects, liquids and vapors the minimum
required clearances to combustibles away from heater.
Some objects will catch fire or explode when placed close to
heater.
Failure to follow these instructions can result in death, injury
or property damage.
TO TURN OFF THE HEATER
Service Telephone: +44 (0)121 506 7709
Service Fax: +44 (0)121 506 7702
E-mail: uksales@rg-inc.com
E-mail: export@rg-inc.com
Roberts-Gordon LLC
1250 William Street
P.O. Box 44
Buffalo, NY 14240-0044 USA
Telephone: 716.852.4400
Fax: 716.852.0854
Toll Free: 800.828.7450
WARNING
Roberts-Gordon Europe Limited
Unit A, Kings Hill Business Park
Darlaston Road, Wednesbury
West Midlands WS10 7SH UK
Telephone: +44 (0)121 506 7700
Fax: +44 (0)121 506 7701
®
Installation Code and Annual Inspections:
All installation and service of ROBERTS GORDON® equipment must be performed by a contractor qualified in the installation and service of equipment sold and supplied by Roberts-Gordon and
conform to all requirements set forth in the ROBERTS GORDON
®
manuals and all applicable governmental authorities pertaining to the installation, service and operation of the equipment. To help
facilitate optimum performance and safety, Roberts-Gordon recommends that a qualified contractor conduct, at a minimum, annual inspections of your ROBERTS GORDON
®
equipment and
perform service where necessary, using only replacement parts sold and supplied by Roberts-Gordon.
Further Information: Applications, engineering and detailed guidance on systems design, installation and equipment performance is available through ROBERTS GORDON® representatives.
Please contact us for any further information you may require, including the Installation, Operation and Service Manual.
This product is not for residential use.
© 2009 Roberts-Gordon LLC All rights reserved. No part of this work covered by the copyrights herein may be reproduced or copied in any form or by any means – graphic, electronic, or mechanical, including photocopying,
recording, taping, or information storage and retrieval s
ystems – without written permission of Roberts-Gordon LLC.
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