Under Floor Heating FAQ
We hope you find the answers to the following
'frequently asked questions' useful. For a complete
understanding of the product, they should be read in
conjunction with the specification and installation
data.
BN Thermic offers three under floor
heating systems, which one is right for me?
ECK
is for use with stone or ceramic floors. Being a cable
based system it is ideal for use in irregular shaped
areas.
EHM
is also for use with stone or ceramic floors, but
being a mat based system is quicker and easier to
install. It is particularly suitable to regular shaped
areas.
LH
elements are designed to be installed under laminate
or wooden floors.
ECK and EHM
Application
Is an EHM or ECK underfloor heating
system designed to warm a floor or heat a room?
The primary use of an EHM or ECK underfloor heating
system is to maintain a comfortable temperature on the
surface of a ceramic or stone floor. In performing this
function, the EHM system will make a significant
contribution to the air temperature within the room. In
many instances the system will produce enough warmth to
mean that additional heating is not required. As a
general rule an EHM system will be sufficient as a sole
source of heat in buildings constructed according to
current regulations. In older buildings, supplementary
heating may be required.
Selecting a Kit
How do I select a mat for my
room?
Firstly you must calculate the area of floor to be
heated. This will be the total floor area minus the area
occupied by fixtures such as cupboards, sinks, baths
etc. If you are using an ECK cable kit, refer to the
schedule of kits and ensure that the minimum ‘area to
heat’ shown is no greater than your calculated area.
For EHM mats, refer to the schedule of mats to find
the mat with a square area slightly lower than your
calculated figure. This is likely to be the mat for
you.
To double-check your selection, draw a sketch of the
free area. Leaving a space of 50mm between mat runs and
80mm between the mats and the wall, draw the mat runs
onto your sketch. Remember you can cut the mat at any
point along its length but you cannot alter its
width.
If you are unsure whether there is quite enough space
to install a particular EHM mat you should consider
using a slightly smaller mat. Remember although you can
cut the mat at any point you must not cut the heating
cable.
Installation
Who should install an EHM or ECK
system?
EHM and ECK are designed to be installed by a
suitably qualified, professional trades-person. They are
not a ‘Do it Yourself’ products.
Can I install EHM or ECK on an
asphalt sub-floor?
No. We do not recommend the installation of EHM or
ECK directly onto an asphalt sub-floor.
Should I insulate the
floor?
Insulation below the heating mat, whilst not
essential, will greatly enhance the efficiency and
economy of the system. If the mat is to be installed
directly on to a layer of insulation, it must be a rigid
foil-backed board (foil side up). Under no circumstances
should insulation be installed above the heating
cable.
How thick should the adhesive layer
be?
The layer of adhesive should be thick enough to
completely cover the cable.
Can I cut the heating
cable?
NO! Under no circumstances should the heating cable
be cut. There are three reasons.
1. Cutting the cable
will break the electrical circuit that enables the cable
to function.
2. Repairs are possible but are
difficult to execute and become a potential cause of
future failure.
3. If a section of cable is removed
and discarded and the circuit reconnected the remaining
cable will operate above design temperatures and would
be prone to premature failure.
Can EHM or ECK be used under
carpets?
We would not recommend the use of EHM or ECK under a
carpeted area.
How long should I wait before
energising my EHM or ECK system?
From the date that the surface of the floor has been
laid, you should wait 28 days before energising the
system. This will ensure that the adhesive is completely
dry. NEVER USE THE WARMTH FROM THE CABLE TO DRY THE
ADHESIVE.
What do I do if my under floor
heating stops working?
If the system stops working, call a qualified
electrician who should make the following checks.
1. Check the supply to the system. The solution maybe
as simple as resetting a circuit breaker.
2. Check
whether there is an ‘error code’ on the controller, if
there is the controller may need replacing.
3.
Disconnect the controller probe from the controller
terminal block and using an ohmmeter, check that there
is a circuit through the probe. If there is no circuit
the probe will need replacing.
4. Disconnect the
heating cable from the controller and, using an
ohmmeter, check the resistance reading is consistent
with the nominal output of the heater. If there is no
circuit through the cable, the circuit has been broken
and you should check for structural cracking in the
floor or for places where screws, bolts or other such
fixings have been driven through the floor damaging the
cable.
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Is my EHM or ECK system
guaranteed?
Assuming correct installation, Warm Tiles will give
many years of satisfactory service. In the unlikely
event of a malfunction resulting from faulty
manufacture, Warm Tiles is guaranteed for 12 months from
date of purchase. The guarantee covers the full purchase
price but not the cost of repairing or replacing the
heating cable in the floor.
An Installation
Record Form is supplied with each kit. This should
be completed at the time of installation and posted to
BN Thermic within 60 days of installation.
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LH Elements
Application
Is an LH underfloor heating
system designed to warm a floor or heat a room?
LH elements have been developed as a room heating
system. In properties constructed according to current
regulations LH elements can usually be relied upon as a
sole source of heat. In poorly insulated properties
supplementary heating may be required.
Under what floor surfaces can
LH elements be installed?
LH elements can be installed under laminate floor
systems and timber floors with a maximum thickness of
20mm.
Selection
How do I select the correct
LH elements for my room?
Draw a plan of the floor identifying areas occupied
by fixed furniture such as kitchen cabinets (elements
should not be installed in these areas). Draw the
heating elements side by side onto the plan leaving a
minimum gap of 50mm between the wall and the edge of the
heating element. Whenever possible keep the element ends
fitted with the live and neutral cables along one wall.
This should also be the wall on which the thermostat is
mounted.
Installation
Who should install an LH
system?
LH elements must be installed by a suitably
qualified, professional trades-person. This is not a ‘Do
it Yourself’ product.
Should I insulate the
floor?
A layer of suitable insulation must be placed below
the LH element, we recommend Depron. This will provide
the necessary thermal insulation and sound
deadening.
Can I install an LH system
onto a wooden sub-floor?
LH element can be installed on a wooden sub-floor
provided a layer of Depron installation is placed below
between the LH element and the sub-floor.
Is an adhesive or screed
required?
No. LH elements are designed to be installed without
requiring bedding compounds of any type.
Can I cut the cold
leads?
Yes. The cold leads can be cut or extended to suit
the application.
Can I cut an LH
element?
Yes. If required the length of an LH element can be
reduced. The width of an LH elements should not be
altered.
Can I use LH elements under
carpet?
We do not recommend LH elements be used under a
carpeted area.
Operation
What does the F18C controller
do?
The F18C controller has the facility to monitor both
floor and air temperature. The controller is
programmable and allows the system to maintain a
selected comfort temperature when a room is likely to be
used and a lower set-back temperature at other times
How long will an LH system
last?
The key to this question is correct installation.
Assuming the elements are installed in accordance with
the instructions and are not subjected to mechanical
damage, they will have a life span similar to standard
mains carrying electrical cable.
What should I do if my
underfloor heating stops working?
If your system stops working, call a qualified
electrician who should make the following checks.
1. Check the supply to be system. The solution may be
as simple as resetting a circuit breaker.
2. If the
controller is fitted with batteries, check whether they
need replacing.
3. Check whether there is an ‘error
code’ controller. If there is, the controller may need
replacing.
4. Disconnect the controller probe from
the controller and using an ohmmeter, check that that
there is a circuit through the probe. If there is no
circuit the probe will need replacing.
5. Disconnect
the heating system from the controller and using an
ohmmeter check that the ohms reading is consistent with
the nominal output of the system. If there is no circuit
through the system the connections in the junction box
should be checked.
Is my LH system
guaranteed?
Assuming correct installation, an LH underfloor
heating system will give many years of satisfactory
service. In the unlikely event of a malfunction
resulting from faulty manufacture, the system is
guaranteed for 12 months from date of purchase. The
guarantee covers the full purchase price but not the
cost of repairing or replacing the heating elements in
the floor.
An Installation Record Form is supplied
with each system. This should be completed at the time
of installation and posted to BN Thermic within 60 days
of installation
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