Roberts Gorden CRV-B-4 - Manual (Page 8)

CRV-S ERIES D ESIGN M ANUAL
2
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.