Roberts Gorden CRV-B-4 - Manual (Page 22)

CRV-S ERIES D ESIGN M ANUAL
16
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 com-
bined 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 com-
bined 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.
Failure to comply with the above parameters will result
in insufficient vacuum to burners.
6.4 CRV-Series Design Methods
1. Layout 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 rules for each burner
model. See Page 13, Figure 14 for example flow
unit calculations.
Length of
Tailpipe per Flo
w Unit (f
eet)
3.0
2.5
2.0
1.5
1.0
83% 84% 85% 86% 87% 88% 89% 90%
Steady State Thermal Efficiency (%)
M
ax
im
um
Ra
dia
nt
Pip
e
M
in
im
um
Ra
di
an
t P
ip
e
No
m
in
al
Ra
di
an
t P
ip
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 +
Total System
Flow Units =