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Thermal Insulation
Commission Testing
An installed heating circuit should be thermally insulated im-
mediately to provide protection from damage from ongoing
work. Things to remember about insulating:
• Insulate the equipment being heat traced as soon as pos-
sible after the heating cable is installed. This will protect
the cable from possible physical damage.
• The type and thickness of thermal insulation specified on
the design drawing must be used. If you use another type
or thickness, the heater cable type or amount may have
to be changed.
• Never install wet insulation. Both the piping and the insu-
lation must be dry when thermally insulating a circuit. Wet
insulation may cause start-up or operational problems.
• Properly weatherproof the thermal insulation. All places
where valve stems, conduits, pipe supports, connection
housing, thermal capillary tubes, etc. extend outside the
insulation jacketing must be sealed with a suitable com-
pound to keep water out.
• Insulate valves fully up to, and including, the packing
gland.
• Heat trace and fully insulate the face of all non-diaphragm
pressure instruments.
• Insulation must be covered by a weatherproof barrier,
such as an aluminum jacket.
• If you are using metal jacketing and sheet metal screws,
be sure the screws are not long enough to penetrate the
thermal insulation and damage the heater cable.
• Again, perform the megger test on the circuit immediately
after the thermal insulation is installed to detect if any me-
chanical damage may have occurred.
• When the insulation and the weatherproofing is complete,
attach “Electric Traced” labels on the outside of the in-
sulation. These should be installed where they are vis-
ible from normal operations, usually on alternating sides
about every 10 feet. It is also useful to mark the location
of any connections buried under the insulation.
Additional requirements for rigid thermal insulations:
• In the standard single heater cable installation, rigid insu-
lations do not need to be oversized. However, they should
be carved so there is no gap in the insulation.
• In case of redundant or multiple heater cables, rigid insu-
lations which are 0.500 inches oversized should be used.
1. Again, visually inspect the piping, insulation, and connec-
tions for the heater cable to make sure no physical dam-
age has occurred since the installation and start-up.
2. Megger the system again to determine if damage not
readily visible has occurred.
3. Turn all branch circuit breakers to the OFF position.
For systems controlled by ambient
sensing thermostats:
1. If the actual ambient temperature is higher than the de-
sired thermostat setting, turn the thermostat setting up
high enough to turn the system ON or (some models) turn
the selector switch to the ON position.
2. Turn the main circuit breaker ON.
3. Turn the branch breakers ON one-by-one until all are on.
4. Allow system to run at least four hours in order to let all
pipes reach steady-state.
5. Measure the amperage draw, ambient temperature and
pipe temperature for each circuit and record in the in-
stallation log. This information may be needed for future
maintenance and troubleshooting.
6. When the system is completely checked out, reset the
thermostat to the proper temperature.
For systems controlled by line sens-
ing thermostats:
1. Set the thermostat to the desired control temperature.
2. Turn the main circuit breaker ON.
3. Turn ON the branch circuit breakers controlled by the
thermostat.
4. Allow the pipe temperatures to be raised to the control
point. This may take up to four hours for most circuits
(large full pipes may take longer).
5. Measure the amperage draw, ambient temperature, and
pipe temperature for each circuit and record in the in-
stallation log. This information may be needed for future
maintenance and troubleshooting
For redundant systems:
Follow the procedure above for the type of control system
you have, but commission the systems one at a time. Start
up the primary system, qualify it and shut it down. Then start
up the backup system, qualify it and shut it down
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