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| Before Calling
our Technical Support Team, it is useful 'background information'
for you to know that... |
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Heat Trace manufacture
a wide selection of heating cables - and sell thousands of kilometres
a year. As a result, we do not manufacture a 'standard heating
cable' (we wish it was that easy) - so we won't know what type
of heating cable you're using.
Amongst our vast range of heating tapes, we offer a range of
parallel Self-Regulating heating
tapes, a range of parallel Constant
Wattage heating tapes, and a range of Series
Resistance heating tapes. The most common type is Self-Regulating,
and the least common is Series Resistance. |
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| 1. |
Can
I cut the heating tape anywhere? |
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Only
if it is a parallel type - so you’ll need to identify the
type of heating tape that you have. You can identify any ‘type’
of heating tape by simply looking at the end of the heating
tape. If you have a self-regulating heating tape, you will see
two wires (sometimes referred to as ‘buswires’ or
‘conductors’), surrounded by a narrow, black material
(a semi-conductive core). The two conductors act as your ‘live’
and ‘neutral’ wires - it doesn’t matter which
one you use as which. Surrounding that will be either a RED,
BLUE or BROWN insulation. You may then have one (or two) further
‘layers’ depending on the other options taken when
ordering. If this describes what you’re looking at, you
have a self-regulating heating tape.
However, if you have a constant wattage heating tape, there
are a number of styles available. The choices available from
Heat Trace are i) a ‘flat foil’ heating tape, and
ii) a ‘spirally wound’ heating tape. Both work on
the same principle. However, on either style, you will have
two conductors. If you look at the end of a spirally wound,
constant wattage heating tape, you will notice two round buswires
- fairly close together. Surrounding these wires will be a jacket
providing insulation. Spirally wound around this jacket will
be a fine wire heating element. If you can see all of this,
you have a Spiral Wound Constant Wattage heating tape. If you
don’t see any of these, it sounds as though you’ve
got a ‘flat foil’ constant wattage heating tape. If,
when looking at the end of heating tape you see three equal
‘conductors’, you have a Series Resistance heating
tape. You must not cut this type of heating tape to length without
reference to Heat Trace Ltd. If in any doubt, call us.
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| 2. |
Where do I cut
it? |
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Now that you have
identified the type of heating tape that you have, you’ll
be pleased to know that you can cut a self-regulating heating
tape anywhere. If, however, you have a constant wattage heating
tape, you will need to know how it has been constructed. Basically,
your spiral-wound constant wattage heating tape has ‘nodes’
cut-out of it. Nodes are points along the heating tape where
the fine wire heating element make contact with each of the
two conductors in turn along the heater. The nodes are cut-out
approximately every metre, on alternate buswires. Each section
between two alternate nodes is a heating zone. If you cut between
the nodes, the distance between your cut and the next node is
designed not heat-up (this acts as your ‘cold-lead’
into your junction box). A ‘flat-foil’ heating tape
will have been riveted through the foils. The heating element
is a flat, glass-woven ‘layer’ underneath the foils.
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| 3. |
Do I join the
bus wires together? |
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No, you must NOT
do this. The current in an parallel circuitry heater does not
flow down one conductor, and back up the next - but across from
one conductor to the other. If you join them together, you will
cause a ‘short-circuit’. The heating tape has ‘live’
and ‘neutral’ buswires and, as you would not join
‘live’ and ‘neutral’ wires under any circumstances,
you should not do this with heating tape either. |
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| 4. |
Do I spiral
the heating tape onto the pipe, or do I run it along the pipe?
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Your heating tape
will have a ‘Watts per Metre’ (W/m) rating. Your pipework
has heat losses that are measured in W/m. If your heating tape
gives more W/m than the pipework loses heat, you can run the
heating tape along the length of the pipework - ideally in the
4 O’Clock, or 8 O’Clock positions - but not, if you
can help it, along the very bottom of the pipe. The person/computer
program that selected your heating tape will be able to offer
advice on spiraling the heating tape should you need it. If
you can straight-trace, we recommend that a ‘snake’
or a turn or some other pattern is applied at regular intervals
to limit the possibility of all the expansion effects gathering
at one point. |
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| 5. |
I’ve just
opened my box and I see black cap at the end of the heating
tape. What is it for? |
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It is simply a
protective covering and should be discarded. |
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| 6. |
Do I need to
use thermal insulation? |
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Yes. Insulation
is a critical component of any heat tracing installation. Without
it, your heating tape will not have the desired effect. Heating
tape simply complements insulation - it is not a replacement
for it. Without insulation, there is no application for heating
tape. |
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| 7. |
How do I fix
the heating tape to the pipe/vessel? |
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Adhesive fixing
tape is available for use up to 200 Deg C, whilst plain glass
fabric tape is available for higher temperatures. Contact your
local Heat Trace representative for further details. |
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| 8. |
Do I need a
thermostat? |
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You don’t
always need a thermostat - but it is advisable. If your heat
tracing system has been calculated to have a ‘stabilised
design’ (ie. if, on a hot summer day it can be proved (using
mathematics) that your heating tape will not (potentially) get
too hot for the pipework/lagging/liquid or substance in your
pipe), then you do not need one. However, without a thermostat,
your heating tape will remain switched ON - all the time. This
could prove to be uneconomical. A thermostat would allow the
heating tape to switch off when it’s not needed. |
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| 9. |
How much heating
tape can I take out of the thermostat? |
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Ideally, you should
not terminate a heating tape directly into a thermostat - but
via a junction box. However, you are restricted only by the
maximum ampacity of the thermostat you are using. You can calculate
the load that your heating tape will use by multiplying the
Power Output (W) x Total Metres of Heating Tape (m), and dividing
by the voltage (V). |
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| 10. |
Can I join the
heating tape together? |
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Yes you can. Splicing
kits are available for a selection of our heating tapes - but
not all. If we cannot provide a splice kit, you must use a junction
box/termination kit method of joining the heating tapes. |
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For further reading
please ask for our 'Installation, Testing and Maintenance guide
(reference IMEHT010). |
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