Slab-on-Grade
This method is for designs with light to moderate
vertical load requirements across the slab. With
under slab and edge insulation, the heated slab is
isolated from high movement of energy from the
slab to the surrounding frozen soil. Response time
is fairly quick and ideal for residential application.
When to use: This installation is applicable for driveway and sidewalks.
How to install: The base layer must be properly compacted prior to installing the insulation and tubing. The tubing is then laid down on a high-density insulation board. Modern products have securing pucks molded on the insulation board. Securing pipe to mesh is no longer required. Install vertical insulation along the entire edge down to the depth of the horizontal under-slab insulation. The insulation creates a thermal break between the heated slab and the frozen ground. The concrete slab is then poured on top of the tubing about 2-3″ thick or as per design. This system is pre-pressurized during this process.
Control Strategy: We recommend using a semi- or fully automatic strategy with this installation method. Full automatic is preferred.
Brick Pavers
Pavers Over a Compactable Soil/Sand Bed
This method is for designs with light vertical load
requirements. With insulation, the heated area is
isolated from high movement of energy from the
snow and melting system to the surrounding
frozen soil. Response time is fairly quick and ideal for residential applications.
When to use: This installation is applicable for driveway and sidewalks.
How to install:
The tubing is installed on high-density insulation. Not shown above,
modern insulation products have securing pucks molded on the insulation board. Securing pipe to mesh is no longer required. Install vertical insulation along the entire edge
down to the depth of the horizontal insulation. The
insulation creates a thermal break between the
heated area and the frozen ground.
After installing the tubing, cover with a compactable
soil/sand bed (typically 2 to 3 inches) prior to
applying pavers or bricks.
Control Strategy: We recommend using a semi- or fully automatic strategy with this installation method. Full automatic is preferred.
Asphalt
Asphalt Pour Over a Compactable Soil/Sand Bed
This method is for designs with light vertical load
requirements. With insulation, the heated area is
isolated from high movement of energy from the
snow and melting system to the surrounding
frozen soil. Response time is fairly quick and ideal for residential applications.
When to use: This installation is applicable for driveway and sidewalks.
How to install The tubing is installed on high-density insulation. Not shown above,
modern insulation products have securing pucks molded on the insulation board. Securing pipe to mesh is no longer required. Install vertical insulation along the entire edge
down to the depth of the horizontal insulation. The
insulation creates a thermal break between the
heated area and the frozen ground.
After installing the tubing, cover with a compactable
soil/sand bed (typically 3 inches) prior to applying
the asphalt pour. Cold water is flushed through pipes during placement of asphalt to keep the pipes cool. Under 200°F (93°C)<.p>
Control Strategy: We recommend using a semi- or fully automatic strategy with this installation method. Full automatic is preferred.
Stairs
Stairs Installation
Stairs can be very hazardous during the winter.
They are also the most expensive and time consuming area for manual snow and ice removal.
Stairs Installation The most critical portion of the step is the leading
edge formed by the tread and the step riser. This
area has the greatest exposure to air temperature
and wind effect with the least heated mass to
counter these effects.
As shown above, install the tubing parallel
to the edge of the step tread. Run supply on the
leading edge of the treads. Secure the tubing to the
reinforcing bar within the stair structure. Tubing
bend supports can assist the install in making the
required tight turns.
Control Strategy Unless specific circumstances warrant the stairs to be on a separate zone or it’s a single SIM area. We recommend the same control strategy as the main SIM area.
Design Consideration
Snow and Ice Melting Performance
Snow and ice melting systems must be designed
to perform to the customer’s needs and
expectations. There are many ways to design a
snow and ice melting system. They vary in the
spacing of tubing, the BTU/h required, how the
area is insulated, the depth of the concrete and
the controls selected to run the system.
Snow and ice
melting systems are typically designed to melt
snow at 0°F with a 10-mph wind. Local conditions
may require higher or lower design temperatures.
There is a point at which a design may become
financially difficult to justify for operation in Class 1
and some Class 2 applications. In those situations,
we can program the controls
with a cold weather cut-off (CWCO) temperature.
This allows the owner to automatically turn the
system off at a desired temperature. The system
automatically restarts as soon as the outdoor
temperature rises above the CWCO temperature.
Snow and ice melting designs fall into one of three
classification levels (1, 2, 3). The higher the
classification, the higher the BTU/h/ft2 load. The
on-center recommendations shown with each class
are subject to a reduction in on-center distance as
the climatic conditions become more severe or the
end-user’s requirements become more stringent.
- Class 1 — Residential driveways, sidewalks or
other non-critical surfaces. Tubing can
be installed up to 12 inches on center.
- Class 2 — Commercial public-use driveways,
sidewalks or other public-use surfaces.
Tubing usually installed 9 inches
on center.
- Class 3 — Helipads, emergency entrances or other
critical-use surfaces. Tubing usually
installed 6 inches on center.
Always use an under-slab rated product, as
standard fiberglass insulations will not meet the
insulating value once it is compressed. Be sure
that the insulation selected meets local code and
building requirements.
We recommend a minimum thickness of
2-inch high-density board for use as perimeter
and horizontal insulation. Typically, this gives an
R-value of 10.0 (check manufacturer information),
and provides a durable surface to walk on while
installing the tubing. There are new options for
insulation entering the market. Ensure that these
products meet the vertical load and compression
requirements for under slab installations. Refer to
the project engineer for guidance.
Remember, the heat loads (BTU/h/ft2
) in snowmelting systems are much greater than typical home
heating systems. Using a higher R-value insulation
reduces the energy lost to areas around and below
the snow-melt area.
It is important to consider the placement of hydronic manifolds. Many SIM system installations will require hydronic manifolds exterior of the home. It’s best to pre-plan for this placement as holes need to be pre-dug with water proof poured concrete shells or large plastic irrigation boxs will need to be installed to protect the manifolds and allow for future access.
Control Strategies
Control Strategies
Constant Idle:
Use this type of control strategy in commercial
applications such as the heated aprons before and
after a car wash entrance. The slab is maintained
above freezing at all times to eliminate the build-up
of ice from water dripping off the cars.
Semi Automatic:
Systems can be designed to be semi-automatic.
What differentiates this strategy from a constant
idle system is that the start of the melting cycle
happens with user interaction, or by pressing the
on/off switch. The run cycle ends via a “time-out”
feature where the user sets the specific time
interval. The setup or programming is more
extensive than the constant idle scenario, but it
provides additional benefits and safety features
for the user. The system automatically shuts off
as programmed, which eliminates any wasted
fuel consumption.
This type of control uses a slab sensor that
provides temperature data feedback. Set the
control to a temperature to melt snow. Once the
desired slab temperature is achieved and the time
interval has ended, the control automatically ends
the heat demand. This keeps the slab from overheating, so it operates more economically. For
example, set the control at a 38°F slab temperature
and a four-hour run cycle. To start the melting
process, press the button on the control. Once the
system reaches 38°F on the sensor, the timer
begins. The heat plant continues to cycle and add
heat, keeping the slab at 38°F. The snow-melting
operation automatically ends after four hours.
Automatic:
A fully automated system requires user input to
program the control. Once powered up, the control
takes over from there. Automatic controls eliminate
human intervention to start and stop the snowmelting system. These systems incorporate a disk
or sensor at the surface level of the snow-melting
area. These types of sensors offer increased
capabilities over conventional slab sensors. For
example, they provide outdoor temperature
feedback, current slab temperature and detect the
presence of moisture (snow or ice at temperatures
below 32°F). Most advanced automated controls
provide snow and ice detection, the ability to idle
the system (considered as a slab low limit) and
react to outdoor ambient conditions. The ability to
sense outdoor temperatures offers the option of
locking out a heat demand when it is too warm or
too cold. These features optimize fuel
consumption. Conditions may exist where it is
either too cold for snow to fall or too warm for
snow to accumulate due to solar exposure
There is a difference between idle setpoint
temperature for the slab and the snow-melt
setpoint temperature. To idle a slab under the
automatic control strategy, maintain the slab at a
setpoint temperature until activated by the control
to accelerate into the snow-melt mode. The control
then targets the snow-melt setpoint temperature
as its new slab temperature. Supply fluid
temperatures are adjusted by the mixing control
to support this new, higher setpoint temperature.
Often the idling setpoint temperature is just under
freezing (28 to 30°F). This allows the system to
respond quicker to a call for snow melt than if
the slab was allowed to cool down to ambient
temperatures. At other times, the specification
may require that the slab should not freeze. In
this situation, the idle setpoint temperature is
maintained above freezing (34 to 36°F). This
setpoint is often used in Class 3 snow-melt
applications or when the surface condition of the
slab is critical, such as an emergency helipad.