MIL-HDBK-1003/8A
Change 2, 30 December 1991
2.3.6.2
Heat Loss and Cost Relationship. To optimize the costs the designer
must calculate the total owning and operating cost of different sections of
the system, assuming use of one particular type of system configuration with
various thicknesses of insulation. Only one type of system configuration
needs to be considered because the optimum heat loss rate in a particular set
of circumstances is not significantly different for different types of system
configurations. As illustrated in Figure 1, the total owning and operating
cost of a system is represented by a "U" shaped curve when cost is plotted
against heat loss which is a function of insulation thickness. The curve is
the sum of three other curves: the owning cost curve, which increases as heat
loss increases; the maintenance cost curve, which is constant within limits
regardless of heat loss; and the operating cost curve, which is directly
proportional to the heat loss. The lowest point of the total cost curve is
the minimum total owning and operating cost for the system, and the heat loss
for the point is the optimum heat loss for the system. When total cost curves
are generated for various types of system configurations for a particular
site, the point of optimum heat loss is approximately the same for all the
system configurations even though the total cost of owning and operating the
different systems is different, as illustrated in Figure 2. Therefore, it is
not necessary to calculate the insulation requirements for all types of system
configurations.
2.4
Federal Agency Approved System Suppliers. The following list
contains all approved system suppliers issued Federal Agency Letters of
Acceptability required in NFGS-02694, Exterior Underground Heat Distribution
System.
2.4.1
Class A, B, C, and D Ground Water Conditions.
a)
Intergy Systems, Brecksville, OH
b)
Perma Pipe, Niles, IL
c)
Rovanco Pipe, Joliet, IL
d)
E. B. Kaiser Company, Glenview, IL
e)
Pittcon Preinsulated Pipes, Inc., Syracuse, NY
f)
U. S. Polycon Corporation, Panama City, FL
g)
Nova Group, Inc., Napa, CA
h)
Thermacor Process, Inc., Fort Worth, TX
i)
Sigma Piping Company, Inc., Incline Village, NV
2.4.2
Class B, C, and D Ground Water Conditions.
a)
Thermal Pipe Systems, Media, PA
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