Справочник Пользователя для Roberts Gorden CTHN-60

33

See Page 33, Figure 21 through Page 34, Figure 22 
for diagrams of T and Fork layouts. The T and Fork 
layouts have a tee or cross (called the "last tee" or 
"last cross") where the combustion gases in the 
system enter the tee or cross with directly opposing 
flow directions, which creates an added source of 
pressure drop in the system.  This additional source 
of pressure drop requires some difference in how the 
allowed manifold length is calculated. In this case, 
we have to differentiate manifold tube that is located 
between the radiant pipe and the last tee (or cross) 
from manifold tube that is located between the last 
tee (or cross) and the pump.

First determine the length of manifold tube between 
the radiant tube end and the last tee (or cross). Do 
not count any tube length twice. Now refer to Page 
30, Table 10 and find the maximum manifold tube 
length for each burner. Add together the maximum 

manifold tube length on the table for each burner in 
the system, this is the maximum manifold tube length 
for the entire system.  

To determine the maximum manifold tube allowed 
between the last tee (or cross) and the pump:  
Subtract the manifold tube length between the 
radiant tube and the last tee (or cross) from the 
maximum manifold length for the entire system, then 
divide that number by 1.5.

Example: Consider a T layout with two CTHN-100 
burners. See Page 33, Figure 21. Assume that 15' 
(4.5 m) of manifold was used from each radiant tube 
end to the last tee.  Page 30, Table 10 indicates that 
each CTHN-100 burner can have a maximum of 45' 
(13.5 m) of manifold tube. Therefore the maximum 
manifold tube length amount allowed between the 
last tee and the pump in this case is 
([45' + 45']-[15' x 2])/1.5 = 40' or in metric, 
([13.5 m + 13.5 m]-[4.5 m x 2])/1.5 = 12 m.

Pump

Manifold tube between joining tee

and pump.

Last Tee

Burner

One pair of burners.