PAVERS, THIN BRICK/STONE AND THIN VENEER
A new and sustainable technology that assists in the design, installation and functionality of spaces
By Max DesMarais
Hardscape installers are not usually tasked with the installation of hydronic or electric cable pavement heating systems. However, they do need to be involved with the scheduling of the trades that install these systems, and quite often work hand in hand with the mechanical or electrical contractor to allow for a clean and seamless installation.
The most important step is to decide what the customer requirements will be for a safe, comfortable, year-round use of the paved areas. It is common to think only about whether an area should be snow melted or not. What also needs to be considered is how the hardscape can be managed for safety, comfort, ecological and economical use year-round.
Thanks to new Therma-HEXX product technologies, customers have the option to heat and cool the paver surface, whether it is a pedestal or on-grade paver installation. The paver mass can act as an invisible thermal solar collector that can heat swimming pool or domestic water, while cooling the paver surface in the warm months and snow-melting the surface in the winter months.
The Faults of Hydronic Tube Systems
One of the most common snow-melt systems has been tubing embedded in a concrete slab (preferably insulated) that is connected to a heat source (boiler, geothermal) and a pump that circulates a glycol water mixture throughout the system. This type of system has had less than perfect results when used with segmented paving due to installation requirements. It can also create cracked or spalling surfaces in poured concrete slabs or other paver surfaces due to uneven heating between the tubes.
In order for hydronic tubing to stay in place during installation, the paving contractor must provide a wire mesh or rebar grid laid out over the prepared structural sub-base. The mechanical contractor then ties the tubing to the grid with wire or plastic ties in a pre-engineered pattern; pressure tests it, and then releases the site back to the paver installer to lay the bedding sand and pavers. The problem arises when the tube is tied to the rebar, totaling 1.5–2 in., requiring a layer of sand that is too thick for ICPI guidelines. When the pavers are set and compacted, they want to settle between the tubes and rebar. This creates a very weak and undulating paver surface over time, resulting in endless callbacks to the hardscape installer and potential failure of the tubing. The tubing quite often is also not installed as specified by the engineer, causing further uneven heating. On top of this, the pavers are no longer under warranty due to ICPI guidelines.
All of this adds up to why ThermaPANEL is a better option.
Modular Panel Systems
ThermaPANEL units circulate a water and glycol mixture with turbulent flow that aids in efficient heat transfer. With 95 percent of a paver’s surface in contact with the panel, even heat transfer is accomplished across the entire paver surface. Warm fluid is pumped through the panels in the winter to melt snow. In the summer, the thermal energy from the sun is extracted from the pavers, transferred to the fluid running through the panels, and then used to heat a pool, spa or domestic water.
Standard ThermaPANEL units are 23.5 x 23.5 x 1.4 in. They are made from high-density polyethylene (PE-RT) specifically engineered by Dow Chemical Co. for hydronic applications. The units come in bundles with 1-in.-thick 60 psi or 100 psi density EPS foam insulation mounted to the back of the panels.
Therma-HEXX engineers will design the layout, piping and system specs for each installation. Each panel is permanently labeled with the section, zone and row number for easy installation and repair. The panels can be cut to fit in the direction of the flow.
The panels are factory connected in rows up to 48 feet long using fusion welding technology and 0.5-in. PE-RT tubing. Utilizing “living hinge” technology, they are folded into 7-foot-long boxes for shipping directly to the jobsite.
Operation and Installation
On-grade installations are required to have an ICPI-approved sub-base, with a thin 0.25-in. layer of sand on top of the base to fill any voids in the rough base material. The panels are laid out at one end and are simply unfolded into place, hooked up to the pre-installed and tested manifold row by row, until the entire zone is connected and pressure tested. Then the hardscape installer applies the 0.5- to 1-in. bedding sand, pre-tamps sand into any voids or spaces and then screeds the area to the correct depth. Pavers are then set and compacted as usual.
The ThermaPANEL system provides structure to the base (acting as a second sub-base) and adds full support to the paver array. It is advisable to pre-compact the sand into the joints and crevices between the panels. This can be done using a vibraplate with a plastic base or a hand tamp.
When using a grate-type support system, such as Pierdex or Silca System mounted on a wood-framed deck or pedestals, any type or size of paver, brick or stone can be applied over the system.
Wood-framed decks can also be configured to support ThermaPANEL units with just the framing, and then wood, PVC or other synthetic decking can be applied over the panels and fastened to the framing located between the panels.
The ThermaPANEL system can also be applied beneath artificial turf for all the same reasons as pavements: solar energy collection, cooling of the surface and snow-melting. There are also recent installations with the panels incorporated in geothermal systems.
ThermaPANEL Benefits
- Remains within ICPI guidelines.
- 95 percent surface contact results in better heat transfer, and no spalling or cracking.
- Panel becomes added support and prevents settling.
- 2.5X more efficient than PEX tubing.
- Capable of snow-melting, patio cooling and solar pool heating.
- Easy installation and repairs when necessary.
- Lower operating temperatures due to high efficiency.
ThermaPANELs are made entirely in the U.S. and utilize the latest in bimodal copolymer plastic resin technology to produce a durable, easy-to-install heat exchange system. Panels are joined to form parallel rows with fusion-welded PE-RT tubing, eliminating the need for any mechanical connections that would be susceptible to leaking.
Contact Therma-HEXX to discuss your next project. Email contact@therma-hexx.com or call (603) 319-8815. Or simply check out their website, www.therma-hexx.com.
Max DesMarais can be reached at maxd@therma-hexx.com.