Burnham Series 8H/8HE Boiler Manual De Propietario

4.1    General – Breeching ducts and water pipes are 

generally less flexible in design location than are gas 

pipes.  To avoid conflicts for a given location, design 

and layout breeching ducts and water piping before 

proceeding with gas piping in this section.

4.2    Gas Piping Design and Layout – On a scaled drawing 

of the boiler room locate the boiler modules as 

planned in SECTION 2.  Locate the gas meter on the 

drawing.  Observe that the opening in the module 

jacket for gas piping is on the top surface at the right 

side front corner.  The gas connection to the module 

gas train is inside the module vestibule and on the 

right side 12” above the floor.

4.2.1  Using Figures 4-1 and 4-2 decide on the simplest 

piping arrangement for the module layout.  The 

location of the gas meter in relation to the modules 

has a large effect on the length and size of the gas 

piping.  Long mains with many fittings should be 

avoided as the minimum pipe size required increases 

as the length of pipe and number of fittings increases.  

For this reason it is desirable to ask the gas supplier 

to set the gas meter as close to the boiler room as 

possible.

4.2.3  On the plans, draw the gas piping using the shortest 

possible route from meter to modules while observing 

the need to keep passageways open around all 

modules for servicing.  It is highly recommended that 

the gas main be located horizontal, at the ceiling level 

of the boiler room, and directly over the front base 

line of the modules.  The branch lines from the main 

should be vertical and direct to the modules.

4.2.4  On the plans, measure the total distance, including 

vertical runs, from the gas meter to the furthest 

module, and count the main fitting ells in that furthest 

run.  (Straight flow through a tee is not counted as a 

fitting)

4.2.5  Obtain from the gas supplier the following 

information:

a)  type of gas (natural or propane)

b) specific gravity

c) heating value

4.3   Gas Pipe Sizing (Preferred Method)
4.3.1  Figure 4-3 may be used for sizing pipes and fittings if 

all of the following conditions are met:

a)   the distance from the gas meter to the furthest 

module is no more than fifty feet and has no more 

than three ells, and

b)   the maximum supply gas pressure at the meter is 

0.5 psig, and

c)   the maximum supply gas pressure drop is 0.3 

inches water column, and

d)   the specific gravity of the gas is between 0.64 and 

0.70 for natural or 1.50 and 1.63 for propane, and

e)   the heating value of the gas is either 1000 Btu/Ft

3

 

for propane.

4.3.2  The procedure for sizing using Figure 4-3 is as 

follows:

1)   Total the Input MBH (from figure 2-3) of all 

modules to be supplied by the gas pipe (and/or 

fitting) to be sized.

2)   Locate this value in the left column.

3)   Move to the right to the appropriate gas column, 

either Natural or Propane.

4)   Read the pipe and/or fitting size.  Record this on 

the gas pipe drawing.

5)   The size of individual module supply piping -A, 

and the manual valve-B, should correspond to the 

Gas Connection size as tabulated in Figure 2-3.  

Record these sizes on the gas pipe drawing.

 

  Example #1:  Eight 809HE modules are to be piped in 

line, similar to Figure 4-1, on natural gas.  

 

  Size the piping:

1)   A check of the conditions for this job shows the 

measured length of pipe from the gas meter to 

the furthest module is 45 ft with 3 ells.  The gas 

supplier says that his system will deliver 4224 

cubic feet at 0.5 psig at the meter, and his gas has 

0.65 specific gravity and 1000 Btu/Ft

3

 heating 

value.  Figure 4-3 can be used.

2)   The piping (D

8

) between the gas meter and the first 

module take-off (C

8

) serves eight modules.  From 

Figure 23, each 809HE module requires 460 MBH 

Input.  8 x 460 = 3680.  MBH- Total Input thru D

8

.

3)   Enter the left column in Figure 4-3 with 3680 total 

input MBH, which falls between the figure values 

of 3630-5610.

4)   Read across to the “Natural Gas” column and pick 

off a pipe/fitting size of 4”.  Record this on the gas 

pipe drawing as D

8

.