Is PEX Tubing the Best Way to Snowmelt?

June 15, 2017


Radiant heating and cooling systems are designed to achieve the singular goal of transferring heat between two masses, these masses being a glycol solution and a pavement of some sort. Not all radiant systems are created equal, and there's a good reason for that. The medium of heat exchange is what differentiates hydronic radiant systems and there are basically two different categories: tubing and panel systems. The design parameters and desired performance of the system should guide the decision making process in terms of which type of system should be installed. Proper navigation of the decision making process requires knowledge of the differences between these systems and which applications each is suitable for.


Mechanical Components


Mechanical room for a snowmelt system



Before I get into which system is best for different hardscapes I want to explain the slight differences in the mechanical portion of a tubing and ThermaPANEL system. If you were to compare the mechanical room for a tubing snowmelt system and the mechanical room for a ThermaPANEL snowmelt system, they would look almost identical. The only differences with a ThermaPANEL system would be in the type of circulator used and the presence of a glycol feeder.


Traditional tubing systems require a circulator with higher flow and lower head. The higher flow is to create more energy transfer through the loops, and lower head requirements are due to the lower comparative pressure drop of the tubing. ThermaPANEL systems require circulators with higher head and lower comparative flow. This is due to the design of the panel and how the rows are constructed. ThermaPANEL loops see much more pressure drop as a result of the flow channels, but they require less flow because these flow channels create more energy transfer. The different flow dynamics and pressure drop simply means that a different type of circulator is required. For ThermaPANEL systems, we do the system engineering in-house and specify pump requirements to allow installers to purchase their preferred brand of circulators. 


The glycol feeder is something that may exist on a tubing system, however we require it for all ThermaPANEL systems. This is because our panel system holds a lot of air, much more than tubing. During operation this air slowly works its way out of the system via the air eliminator. Having a glycol feeder ensures that the air is worked out and that fresh glycol is introduced into the loop. Furthermore, if for any reason the pressure in the systems rises above the specified operating level, a pressure relief valve will blow off into the feeder.


Many tubing systems are filled with glycol after installation and have a freshwater feed. The glycol is checked seasonally to ensure that it doesn't get diluted to an unsafe level. This can be a dangerous practice for a few reasons. If the glycol concentration isn't properly regulated, the system could become too diluted and freeze. Fresh water can also carry minerals and chemicals that can cause corrosion, or nullify the protective barrier(s) in tubing.


Poured Concrete Slab


Radiant heating systems in a poured concrete slab leave little room for error. Installers need to make sure the system is absolutely leak free before the slab is poured. Fixing a leak after the slab is set would require tearing the whole thing up and starting over. Tubing is the preferred system for most radiant systems in a poured concrete slab. Partially due to cost, but mostly due to the fact that most installers have been installing tubing in slab for years. They know it, they trust it, and, for the most part, it works. 


ThermaPANEL will heat a slab wonderfully. However, the panel does expand as it heats up. This could cause issues if not properly accounted for during installation. In many situations, tubing makes sense in a poured slab. ThermaPANEL is more suitable for features like stairs, where slabs or treads can be thick. In this case a lot of energy is needed to adequately snowmelt and tubing can't perform.


Interlocking Pavers on a Compacted Base


 Interlocking pavers installed atop a ThermaPANEL System



Settling of pavers occurs when the base is not prepared properly. This could be due to using the wrong materials, not compacting properly, or using too much bedding sand to set pavers. Improper installation methods can lead to undulation in the paver surface, as well as cracks, heaves, ruts, gaps, and more. The assembly method for traditional radiant tubing snow melting systems in a sand bed can also cause these issues.


The Interlocking Concrete Paver Institute (ICPI) publishes guidelines for installation specifications, which many paver manufacturers use as standards. These guidelines state that bedding sand should be screeded to a nominal 1" (25 mm) thickness and should not exceed 1.5" (40 mm) thickness. Installation of tubing snowmelt systems in a sand bed beneath pavers requires 2-3 inches of sand to adequately cover any wire mesh, rebar, and the tubing while also providing enough sand to set the pavers. This installation method steps outside of the ICPI guidelines and could even void the manufacturer's warranty of the pavers.


ThermaPANEL systems lay atop the compacted base and provide a solid sub-base for the bedding sand and pavers. The amount of bedding sand remains within ICPI guidelines. This can help prevent the pavers from settling over time. Also, ThermaPANEL systems can withstand high compressive force so there is no need to worry about heavy vehicles crushing the system below the pavers.


Permeable Pavement


Permeable pavements are becoming a popular option for driveway and walkways. This hardscape system allows water to return directly to the ground instead of flowing to a drain. Permeability is created by using layers of different sized stone as base and filler materials instead of gravel and sand. The stone, even when compacted, has voids which allow water to trickle back down into the ground below. 


Tubing systems are not adequate for most permeable hardscapes. Their installation method is not very compatible with permeable systems. Furthermore, they cannot transfer enough heat through the stone and into the surface to efficiently melt snow.


The modularity of ThermaPANEL paired with it's durability makes it an ideal candidate for permeable hardscape systems. The panels can be spaces apart beneath the stone allowing plenty of flow through to the bottom layers. Furthermore, the panels will transfer enough heat through the crushed stone to melt snow and will not be crushed by any vehicle traffic.


Supported/Pedestal Pavers


 Pedestal pavers installed atop a ThermaPANEL system



If you are unfamiliar with supported or pedestal pavers, we have a great reference post that will teach you everything you need to know. Pedestal pavers are a unique challenge when it comes to heating and cooling. Because they are suspended and decoupled from the roof, they retain a lot of heat in the summer and require more energy to heat in the winter. Radiant tubing systems cannot adequately heat pedestal pavers. There have been attempts to accomplish this feat with tubing but they are difficult to install and don't perform as intended. 


To properly heat or cool supported or pedestal pavers, the radiant system needs a modular design, needs to be self-insulated, and needs to be quick to install. This is where ThermaPANEL takes the cake. A custom built solution for every project delivered directly to the installing contractor. These systems are engineered and designed in-house for the architects and engineers. To learn a bit more about exactly how ThermaPANEL systems work, and what our process looks like, check out these videos


If you have a specific project in mind, and are unsure which solution is the right one, contact us today and we will work with you to understand exactly what you need and how we can help.


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Portsmouth, NH 03801


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