® CoRayVac Custom Engineered, Gas-Fired, Low-Intensity Infrared Heating System CRV-B-2 CRV-B-9 CRV-B-4 CRV-B-10 CRV-B-6 CRV-B-12 CRV-B-8 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. Box 44 Buffalo, New York 14240-0044 Telephone: +1.716.852.4400 Fax: +1.716.852.0854 Toll Free: 800.828.7450 © 2012 Roberts-Gordon LLC www.robertsgordon.com www.rg-inc.
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.
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 .......................................
SECTION 1: CONCEPT 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, lowintensity 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.
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.
Coupling Reflector Support Burner 3. Plain couplings are used to connect combustion chambers to radiant tubing and radiant tubing to tailpipe tubing. All tailpipe couplings must be lined. 2. Damper couplings are required when layout has unequal branches. Unequal branches are achieved by unequal geometry, burner quantity or burner firing rates. 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.
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.
SECTION 3: CLEARANCES TO COMBUSTIBLES SECTION 3: CLEARANCES TO COMBUSTIBLES 3.1 Required Clearances to Combustibles Clearances are the required distances that combustible 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.
CRV-SERIES DESIGN MANUAL 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.
SECTION 3: CLEARANCES TO COMBUSTIBLES 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.
CRV-SERIES DESIGN MANUAL 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.
SECTION 4: SIZING AND DESIGN CONSIDERATIONS SECTION 4: SIZING AND DESIGN CONSIDERATIONS heating system. The ability of a radiant system to proThe building heat loss must be calculated in accorvide the advantages of these radiant effects rests dance to accepted energy load calculation methods. ASHRAE (American Society of Heating, Refrigeration largely with the ability of this system to establish a reserve heat capacity in the floor.
CRV-SERIES DESIGN MANUAL EXAMPLE 2: 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 adjustment 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).
SECTION 4: SIZING AND DESIGN CONSIDERATIONS FIGURE 11: Radiant Distribution (Average Coverage) H= mounting height 3H 90° H FIGURE 12: Radiant Distribution (Increased Coverage) H= mounting height 2H 90° H FIGURE 13: Radiant Distribution (Heavy Coverage) H= mounting height y= height above the floor level where overlap of radiant output will occur x=2H-2y x H 90° y 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.
SECTION 5: FLOW LOADING FIGURE 14: Burner Flow Units B-10 Burner #1 End Burner End Vent Air B-10 Burner #2 B-10 Burner #3 Combustion Gas Combustion Gas Downstream Burner + 20 Flow Units Combustion Gas Downstream Burner + 10 Flow Units + 10 Flow Units Total Flow Units 20 + 10 + 10 + 10 = 50 Flow Units + 10 Flow Units Coupling Burner 1 Burner 2 Burner #2 Flow Units Burner 3 Burner # Burner Firing Rate Btu/h End Vent Flow Units 1 2 3 20,000 20,000 20,000 6 2 2 2 12 1 2 3 40,000 4
CRV-SERIES DESIGN MANUAL 5.2 Pump Capacity number of flow units carried in the tube. 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). See Figure 15.
SECTION 6: RADIANT TUBE AND TAILPIPE 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 downstream burner. Tailpipe is defined as all tubing between the radiant tube and the pump.
CRV-SERIES DESIGN MANUAL FIGURE 16: Tube Length vs. Efficiency ip e ip e n e ip P t Ma xim um Ra Ra di ina l No m 2.0 di a an tP nt P dia Ra 2.5 Mi nim um Length of Tailpipe per Flow Unit (feet) 3.0 1.5 1.0 83% 84% 85% 86% 87% 88% 89% 90% Steady State Thermal Efficiency (%) NOTE: Thermal efficiency values shown do not include the contribution due to condensing conditions when operating in cyclic fashion.
SECTION 6: RADIANT TUBE AND TAILPIPE 4. Select pump model series for total system flow 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: Radiant Tube Length Burner After Each Burner 1 + 2 + 3 + 4 + 5 + 6 + Total Radiant Tube Length in Branch = Repeat this calculation for each branch in the system. 7.
CRV-SERIES DESIGN MANUAL EXAMPLE 3: B-10 Radiant Tube vs. Tailpipe Length 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'.
SECTION 6: RADIANT TUBE AND TAILPIPE Table 5 for the burner model to ensure that the resulting 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 coupling is placed in every branch except for the longest branch.
20 Damper Zone 1 Damper Coupling NOTE: Damper setting will vary Zone 1 Damper Coupling Zone 2 Zone 2 Damper Coupling Zone 1 End Vent Zone 3 Damper Coupling Pump Damper Zone 3 Zone 2 End Vent Zone 3 End Vent CRV-SERIES DESIGN MANUAL FIGURE 17: Possible Damper Coupling Locations
SECTION 7: EXAMPLE CRV-SERIES SYSTEM LAYOUTS SECTION 7: EXAMPLE CRV-SERIES SYSTEM LAYOUTS FIGURE 18: Example System Layout (Option 1) Systems that are symmetrical are preferred because 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.
CRV-SERIES DESIGN MANUAL FIGURE 19: Example System Layout (Option 2) 40' (12 m) 10' (3 m) 40' (12 m) FIGURE 20: Example System Layout (Option 3) 30' (9 m) 20' (6 m) 40' (12 m) 40' (12 m) 30' (9 m) 30' (9 m) 40' (12 m) 40' (12 m) 50' (15 m) 6" Tailpipe 40' (12 m) 7.2 Example System Layout (Option 2) 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.
SECTION 7: EXAMPLE CRV-SERIES SYSTEM LAYOUTS FIGURE 21: Example System Layout (Option 4) FIGURE 22: Example System Layout (Option 5) 30' (9 m) 40' (12 m) 30' (9 m) 40' (12 m) 30' (9 m) 40' (12 m) 70' (21 m) 30' (9 m) 30' (9 m) 30' (9 m) 40' (12 m) 6" Tailpipe 10' (3 m) 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.
CRV-SERIES DESIGN MANUAL Layout to provide minimum system efficiency. Adjust the lengths as necessary for different input systems and to increase the efficiency levels. This layout method is often used effectively in heatloss and perimeter heating applications.
SECTION 7: EXAMPLE CRV-SERIES SYSTEM LAYOUTS FIGURE 26: Example System Layout (Option 9) Layout to provide condensed radiant output and good uniformity of distribution. Layout will exhibit minimum system efficiency. 30' (9 m) 30' (9 m) 10' (3 m) 30' (9 m) 10' (3 m) 6" Tailpipe 30' (9 m) 30' (9 m) 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.
CRV-SERIES DESIGN MANUAL SECTION 8: CONTROL METHODS 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.
SECTION 8: CONTROL METHODS CORAYVAC® Modulating system. The system will modulate based on the temperature sensed at the modulating thermostat, not outdoor temperature. The modulating controls offer many features like 7 day programmability, four time periods per day (2 occupied, 2 unoccupied), temporary temperature setpoint override, keypad lockout security and more. Remote sensors or outdoor sensors are optional, not required. Remote sensors will allow for zone temperature averaging, if required. 8.3.
CRV-SERIES DESIGN MANUAL 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: DON® ULTRAVAC™ or relay transformer, a separate 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.
SECTION 9: AIR SUPPLY SYSTEM 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.
CRV-SERIES DESIGN MANUAL FIGURE 29: Sample Layout for Pressurized Outside Air Systems Branch A 20 8 8 8 6" duct 4" duct 15' (4.5 m) 110' (33 m) B 10' (3 m) max.* 50' (15 m) (44) 4" duct Branch B 15 6 6 6 P (33) (22) 4 4 4 10 Branch C 4" duct 100' (30 m) *NOTE: up to 10' (3 m) max. from blower inlet can be neglected for pressure drop calculations.
SECTION 10: ROBERTS GORDON® ULTRAVAC™ DESIGN REQUIREMENTS 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. -ORCRV-Series systems with recommended radiant tube length shall have 1.2' - 1.5' per flow unit of tailpipe length.
CRV-SERIES DESIGN MANUAL SECTION 11: CRV-SERIES EQUIPMENT SPECIFICATIONS The total heating system supplied shall be design cer- 11.2 Equipment tified by the CSA International per American National 11.2.1 Burner Standard ANSI Z83.20/CSA 2.34 (latest edition). Each burner assembly shall consist of heavy-duty 11.1 Burner and Burner Controls cast-iron burner heads, pre-wired gas controls with 11.1.
