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.
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 sat- isfied, the burners turn off and the pump continues to run for two minutes to purge the entire system of flue gases.
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 pres- sure, wind velocity or other climate conditions.
