School Addition Goes Green with Radiant Heat

By Todd Fratzel on Heating

Radiant Heat Keeps School Comfortable and Healthy

Radiant heat has long been classified as a Green Construction method for several reasons. Most importantly is the elimination of duct work which potentially creates poor air quality. Additionally radiant heat is considered by many to be a much more efficient heating system.

We recently designed and built a two story 3,500 sq. ft. addition for a non-profit Montessori School. One of the main goals for the new addition was taking advantage of Green Construction techniques that would ultimately reduce operating expenses and provide for a healthier more comfortable learning atmosphere. With that goal in mind the preferred heating solution for the project was radiant heat. The radiant heating system had to be installed in a concrete slab (lower level) and under a traditional wood sub-floor adjacent to engineered lumber joists.

Uponor Radiant Heating Systems

Thanks to a very generous donation by Uponor the new addition will include radiant heat. Uponor is one of the leading manufacturers of PEX tubing used for radiant heating systems. In fact, Uponor has been manufacturing PEX tubing for over 35 years with over 12 billion feet of PEX tubing installed worldwide. With a history like that these folks know radiant heat!

Our project included two different radiant heat types; the lower level of the school has radiant heat tubes embedded in the concrete while the second level of the school includes radiant heating tubes secured below the wood sub-floor. This type of design is fairly common among residential homes and light commercial buildings.

Project Heating Design – Flexibility

This project presented some unique challenges including little room for a new boiler and construction work beginning during the school year. Because of those constraints the design included a small mechanical closet in the new addition to house the radiant heat manifolds. This design allowed hot water from the existing boiler to be supplied through supply lines into the new closet and distributed from there through manifolds.

From the new mechanical closet the two different radiant levels are fed from several manifolds. As you can see in the adjacent photo radiant heat tubes from the concrete slab enter the bottom and radiant tubing from the upper level enter the top. The design also included several zone valves that allow each classroom to have it’s own thermostat.

This design really simplified the installation of tubing. Instead of having to run each piece of radiant tubing back through the existing building to the old mechanical room we were able to terminate it all in the new closet. This resulted in only having to run two 3/4 inch heat pipes (one supply and one return) through a small ceiling opening in the hold building back to the mechanical room. A traditional forced hot air system would have required significant duct work openings and a great disturbance to the existing classrooms.

Another benefit with the Uponor Radiant Heating System is it’s flexibility. Their system can be installed under many different flooring types. In fact for our project the system is installed under carpet (both on top of concrete and wood sub-structure) and under vinyl composite tile (VCT). It can be installed under ceramic tile, wood, carpet, stone and most any floor covering.

Joist Trak Speeds Installation – Improves Effeciency

When installing radiant heat tubes on the underside of traditional wood framed floors it’s important to create an even transfer of heat to avoid hot spots and improve the efficiency of the system. Uponor has developed Joist Trak™ panels which help evenly transfer the heat and also speed up installation.

Installation is much easier with the Joist Trak Panels. Many radiant heat systems involve stapling radiant tubing to the underside of a wood sub-floor. Not only is that method time consuming but many times tubes are punctured with the staples and must be spliced. With Joist Trak you simple screw it to the sub-floor and then snap the PEX tubing into the receiver slot.

For this particular job we noticed a labor savings of approximately 20% compared to a stapled tubing application. In addition to that a normal job typically results in several spliced tubes which can always lead to a long term maintenance liability.

Comfort Factor

We’ve been huge fans of radiant heat for years now and build most of our residential homes with it and a growing number of commercial buildings with it. Ultimately the comfort that radiant heat provides along with it’s energy efficient savings makes it a great heating system.

For this particular school the comfort of radiant heat is an added bonus. With their Montessori curriculum many of the lessons for young students are done while sitting on the floor. Here in New England with winter days in the single digits or lower a nice warm floor is sure to keep everyone’s spirits high.

Learn About Uponor and Radiant Heating Systems

If you’d like to learn more about Uponor and their Radiant Heating Systems please check out their website. We’ve been using Uponor products for years with great success and rely on their expertise and quality products.

About the author

Todd Fratzel

I'm full time builder for a large construction company in New Hampshire. I run their design-build division that specializes in custom homes, commercial design-build projects and sub-divisions. I'm also a licensed civil and structural engineer with extensive experience in civil and structural design and home construction. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. I'm also the Editor-in-Chief and Founder of Tool Box Buzz. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site.

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  1. Frank Wells says:


    I recently moved to Central NY and purchased a home that was built in 2003. I have no experience with biolers or radiant heating. This house has radiant heating through out powered by a propane boiler. The “boiler room” looks like a 3 year old threw spaghetti everywhere. Red tubing going this way and that, in no way does it look like your photos. The boiler is filled with Eythlglycol? or a mixture of water and glycol? Is that normal? Especially since my hot water heater is a boiler transfer style.(Big blue cylinder, hot liquid heats water from the well)


    • Todd says:


      There are certainly lots of levels of craftsmanship out there when it comes to mechanical work. We pride ourselves in making sure our mechanical subcontractors do neat and organized work. Having said that I’ve seen so many “ugly” PEX jobs that you are not alone.

      Typically glycol is used when a portion of the radiant system is exposed to freezing temperatures. It’s actually quite common especially when basements are heated, garages, walkways, things of that nature. The only thing I don’t like about it is your can’t get as much efficiency out of the boiler.

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