Radiant Heat: A Primer for Plumbers

Here’s a crash course in designing efficient and dependable radiant heating systems
Radiant Heat: A Primer for Plumbers

Interested in Residential Plumbing?

Get Residential Plumbing articles, news and videos right in your inbox! Sign up now.

Residential Plumbing + Get Alerts

Perhaps you’ve been thinking about adding radiant heat to your list of plumbing services. Doing so can be a good way to differentiate your business from the competition. But where do you begin? 

Two simple entry points are electrical and hydronic radiant heat. Unlike whole-house hydronic systems, electrical radiant heat is best suited for small areas, such as bathrooms, kitchens, basements and garage floors. 

“Electric radiant is actually a pretty cool product,” says John Barba, residential training manager for hydronic-based components manufacturer Taco Inc. in Cranston, Rhode Island. 

One such product is STEP Warmfloor, a low-voltage 12-inch-wide plastic heating mat that can be covered with tile, stone, hardwood, laminate or carpet. 

Another hydronic radiant heat product is the Taco X-Pump Block (control and heat exchanger with built-in pumps) that connects to an existing tank-type water heater. The system generates 20,000 to 40,000 Btus. 

“The other option would be to use a 6-gallon electric water heater instead of the existing water heater,” Barba says. “Check the wattage to make sure it produces enough Btus for what you need. But if you’re just warming floors it doesn’t take much.” 

Back to basics
Hydronics, in its simplest form, uses fluid rather than air to transfer heat and cold. However, designing an efficient and dependable system involves more than soldering pipes together. 

Today’s ever-changing hydronics technology requires a basic understanding of low-temperature heat sources (120-degree water or less), solar thermal, biomass and other renewable energy sources, as well as water-to-air heat exchangers, ductless heating and cooling systems, space-saving hydronic appliances, electronically commutated motor or “smart” pumps and Btu metering. 

“It’s not something to dabble with,” Barba says. “You either do it or you don’t. A lot can go wrong when you start dealing with combustion, carbon monoxide and things that can kill people. There’s a responsibility to learn how to do it the right way. I don’t mean to scare anybody off, but if you’re going to do it, do it the right way.” 

Barba, a licensed plumber who has 20 years of training experience, says before you start you should learn as much as you can from as many people in the industry as possible. And get a good background in electronics. 

“Learn about boiler selection and combustion, heat loss and sizing pipe properly for the correct fluids,” he says. “You’re going to want to learn about how to select the proper circulator, the differences in circulators and what they do and what they don’t do. The basics from soup to nuts: design, selection and dynamics — what happens when zone valves close?”

Hit the books
Taco offers a FloPro University that includes free eLearning programs where you can learn at your own pace through long-format classes (about an hour).

“Each class is broken up into small five- to seven-minute segments with a quiz at the end of each one,” Barba says. “You take the quiz, pass the segment and go on to the next one. There’s a final exam at the end.” 

Contractors can take the classes as many times as they want. Taco also offers monthly educational webinars, field training programs and two-day factory training programs.

Once you have a grasp of the basics, consider a simple installation.

Like most first-time projects, problems are likely to occur. The worst is the system doesn’t heat. “In that case, be sure you can call your wholesaler expert or local sales rep to help you out,” Barba says.

Another common problem is system oversizing, which leads to reduced overall efficiency. “It can also shorten the life of components if the system cycles too much,” he says. “And it’s wasteful.” 

Other first-time issues are mistakes in calculating circulator sizing. 

“You have the flow part right but because you missed a mixing valve the circulator can’t handle the head loss,” Barba says. “Or you put in a steep-curved pump where a flat-curved pump might be more appropriate. Those are some of the common problems we see.” 

The biggest concern when installing a hydronic system is combustion. 

“Bad venting kills people,” he says. “If someone is going to get involved in hydronics, learn everything you can possibly learn about venting, combustion and carbon monoxide — be safe.” 

When it comes to specialty tools, a combustion analyzer is critical, Barba says. A multi-meter for diagnosing low-voltage electronics is another handy item to have, along with tools for connecting PEX (cross-linked polyethylene) tubing, most commonly used in hydronic systems.  


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.