When Pittsburgh Architect Peter Brown began designing a sizeable home addition for a client, among his considerations was the best way to heat this additional space. The project consisted of a large family room and, below it, a garage.

After considering several systems of heating for the new structure, Brown reached the conclusion that radiant floor heat would be best.

"Radiant heat is the next wave of heating products available today. Radiant heat is comfortable, efficient, quiet and cleaner then any forced air system on the market today."
- Mark Marini, Zurn Plumbing Products Group, Mid-Atlantic Regional Manager

"Radiant heat is really the most comfortable type of heat that I'm aware of," said Brown. "Also, it is more economical in the long run than other heating systems. Actually, a radiant heat system is easy to design, but it takes some effort to become familiar with the concept and with the equipment that is available today."

Radiant panel heating has been around for centuries. The Romans heated the floors of their baths with underground fireboxes and long, efficient flues under the floors. The famous American architect Frank Lloyd Wright was a big believer of radiant heat, piping hot water through the floors of many of the buildings he designed.

In the 1950's many houses were built in the United States with radiant heat using primitive controls, copper, or steel pipe. These systems showed the promise of radiant heat in delivering comfort, but had many problems with control and longevity of materials. New controls and the use of PEX tubing have perfected radiant heating, making it a reliable, long lasting method for heating. This has been demonstrated by the vast use of radiant heat in Europe using similar technology over the past 30 years, and also by the rapid growth in the USA and Canada for this same application.

Unseen. Unheard. Unmatched. The pure compfort of in-floor heat.

Most people who own radiant floor heating feel that the most important advantages are comfort, efficiency, and quiet operation. Radiant floor systems promote even heating throughout the whole floor, not just in localized spots as with forced-air. The room heats from the bottom up, warming the feet and body first. Radiant heat also eliminates the draft and dust problems associated with forced-air heat.

The system is more comfortable because heat energy follows the path of tubing embedded within the radiant panels. The designer is able to route the tubing precisely to the regions that require heat, distributing more heat or less heat, depending on the properties of the room. This is done by controlling individual under floor "loops" in the system, which allow energy to be placed where or when it is needed. A "loop" is nothing more than the strategic routing of PEX tubing below the floor, in the slab, etc., which carries hot water as the heat source.

No other heat system is capable of this measure of control. Radiant heat has more even floor-to-ceiling temperatures than any other system. It warms the closest and coldest mass, which radiates heat throughout that space evenly. Radiant heat goes from hot to cold from the ground up and forced-air goes from hot to cold from the ceiling down. This means radiant heat provides warmth and comfort at ground level and it does not waste energy on heating the ceiling.

"There's no better way to condition a house better than radiant heat. It's the most comfortable, economic and reliable heating system available today."
- Richard Navari, Jr. and John Sembower, Sembower-Mikesell, Inc. / Mr. Waterheater

Stroll along the beach on a sunny day (you'll have to leave Pittsburgh for this) and feel the warmth of the sand beneath your feet. You have just experienced the theory of radiant heating. Objects absorb radiant heat until they are the same temperature as the heat source, after which the heat escapes and radiates to whatever mass is colder and closer. Radiant heat in your home will evenly and comfortably heat the floor, tables, chairs, curtains…and you.

RADIANT HEAT vs. FORCED AIR:
A room with radiant heating will have a very uniform temperature from the ceiling to the floor, even in basement applications. If you've lived in a house with forced air, you can crank up the heat, but the basement floors are still chilled. The warmest air in rooms that are heated with a forced-air furnace will be near the ceilings. This is what keeps the floors cold. Although the air may be heated-way up at the ceiling-the floors and lower portions of the room will be chilled and uncomfortable.

The heat capacity of water makes it a vastly more efficient medium than forced air for the delivery of heat. Water has 3000 times more heat capacity per cubic foot than air. Small energy efficient pumps are used for routing water through tubing, rather than large blowers for forced-air through duct work. The entire surface of the floor radiates about the same amount of heat that the human body does, always keeping the occupant warm. This allows you to set a thermostat several degrees lower, relative to other heating systems. When a radiant panel achieves its optimum temperature, it stores the heat within the panel resulting in the system not having to work as hard to achieve the optimum temperature. Because radiant heat actually stores energy and does not lose heat as fast as forced-air, it can save you 15% to 20% on utility bills.

Radiant heat systems are quiet. There is no noise from fans or forced air units. Radiant heat does not blow dust and pollen around a house. This is great for people with allergies because it helps prevent irritation occurring from stirred up dust and pollen. It also does not dry the skin like forced-air can. Yet another advantage of radiant heat is that it is "invisible." There are no heat registers or radiators to obstruct furniture arrangements or interior design plans.

Radiant heat systems are quiet, clean, efficient and comfortable for all home-heating needs.

PEX:
The basic tubing that carries heated water in a radiant system is a product called PEX. This is a flexible polyethylene pipe (PE), which is "cross-linked" (that is what the "X" in PEX stands for). Cross-linking this material is what gives it its tremendous properties of strength, as well as its amazing heating and pressure abilities. Plus, it's easy to work with and install. These properties make PEX the catalyst in a good radiant heat system. These properties are also what give the installer the ability to use PEX in the floor, in the wall, in the ceiling, embedded in concrete, and so forth.

PEX was developed to replace rigid and non-corrosion resistant fluid distribution materials such as steel pipe, copper tubing, and CPVC. Over the past 30 years, it has become the predominant tubing used for radiant heating worldwide.

The following are advantages of PEX over rigid piping systems:

• Long life expectancy and high temperature ratings
• Encrustation resistant - no mineral and lime build-up like other materials
• Corrosion resistant - tubing can be installed directly in concrete
• Resistant to electrolysis and poor water quality
• Freeze damage resistant - able to expand to avoid costly ruptures
• Water hammer resistant - absorbs water hammer in flexible pipe walls
• Quieter than copper and CPVC systems - does not amplify noise
• Pricing is very stable (unlike copper)
• Can be used for radiant heat, drinking water systems, potable water systems, and snow melt systems

As complex as this large Radiant Heat application seems, it is quite simple

A key component to any radiant heat system is the manifold system. A manifold directs the flow of heated water to the zones or loops in each room to distribute the heat where you want it, so that optimum comfort is achieved in each room in your house. Products such as The Zurn QuickZone Manifold allow the setting of flow rates and temperature to any room or zone through adjustable/settable flow gauges called balancing valves. It is designed to take system-balancing guesswork out. Balancing the system is achieved by turning the valve until the desired flow rate is achieved. This is critical to the control temperature to each room in the house.

The methods to install radiant heat are numerous. They can be separated into three main categories: radiant floors, ceilings, and walls. Within these three main categories there are several sub-categories. The vast majority of radiant heat is designed around the use of radiant floors. Radiant floors are separated into two main categories: those that are placed in concrete, and those that are placed on or under a suspended floor. Within these categories the methods will vary significantly depending on the designer and homeowner's comfort level and preference.

Architect Peter Brown designed the large garage to use radiant heat with the tubing embedded, or poured into, the concrete floor. The family room would have the PEX tubing in the sub-floor, below the hardwood flooring.

One of the advantages of radiant heating is that the tubing can be installed in the joists, embedded in concrete, sandwiched in a sub-floor, suspended below, above, etc. The room can then be finished by using any type of floor covering on the market today. This efficient system works perfectly with tile, marble, carpet, hardwood, "floating" floors, linoleums, and even multiple layers such as area rugs over hardwood.

Some offshoots to residential radiant room heat are becoming common as consumer awareness of these systems grows and the building industry embraces them for all the right reasons. These include snowmelt systems, for people who hate to shovel snow (who doesn't?). In snowmelt, PEX tubing is arranged and then poured into the concrete slab of the driveway and walkway of a home or business. The system can then be manually turned on when the weatherman calls for snow. More sophisticated systems employ embedded moisture sensors, barometer sensors and other goodies, which automatically turn on the system, heating the driveway and walkways when snowfall seems imminent.

A radiant heat system can be used in other applications as well. For example, a "loop" can be directed away from the floor application and run behind a bathroom mirror to make it fog free (at least during the heating season).

Installing radiant heat on special heat transfer panels: Zurn's thermal track.

THE SYSTEM:
Radiant heat is not a do-it-yourself weekend project. The most efficient systems are carefully planned to deliver the most efficient heating at the best possible cost.

Generally, the system consists of basic components: PEX tubing (lengths are determined by the areas and properties of the rooms to be heated); the manifold to distribute the heated water to each loop and each room (the manifold sends the water out to the rooms, and accepts it back at the end of the loop); and the hot water supply (usually a boiler, but sometimes on smaller applications, a standard water heater; and various installation and assembly aids).

From an economic perspective, a boiler can cost more than a residential water heater. However, this cost is offset by the greater efficiency and comfort of the system overall. As mentioned above, radiant systems do not require duct work and registers to supply heat; but practically speaking, there will still be some duct work in the home for distribution of cooled (air-conditioned) air. Still, the long-range benefits of cost savings will be realized quite quickly.

There are a growing number of contractors proficient in the design and installation of such systems. This growth is driven by the benefits of radiant heating, the greater visibility and consumer awareness, and the desire of contractors to be on the "cutting edge" of technology.

In an article in the June 2005 edition of Plumbing Engineer Magazine entitled "Radiant - deceptively simple," Larry Drake, executive director of the Radiant Panel Association, says it's important to have your system professionally installed, although it's not essential:

"The new systems today allow homeowners to vary temperatures for all types of flooring; hardwood; marble; ceramic tile; stone; concrete or carpet, and even set up zones in the house to provide separate thermostats for individual control."
- Paul T. DeHart, President BOLSTER - DeHART INC. Heating & Air Conditioning

"At first glance, radiant heating looks like a simple process of installing some tubing in, or under, a floor and circulating hot water at the call of the thermostat. The average plumber, mechanical contractor or engineer often looks at it and says, 'Hey, I can do that. What's the big deal?'

Fortunately, radiant heating can be pretty forgiving if installed within certain boundaries. The result of not knowing those boundaries is a lot of poorly performing radiant systems out there installed with good intentions. The good news is that often times even a poorly performing radiant system is more comfortable than the conventional alternative."

The climate of Western Pennsylvania, with its too long winters, too short springs and too cool falls, makes it a perfect area for this growing method of home heating. In fact, some heating contractors have worked hard to develop their radiant business in order to become the contractor of choice for builders and consumers who are addressing their heating needs.

In Erie, PA, a town with a reputation of being overly cold and snowy, one such contractor is Ollinger Plumbing and Heating.

"We have been doing radiant heat applications for 15 years or better," says owner Chuck Ollinger. "The majority are new houses and home additions such as sunrooms. As far as comfort goes, radiant heat cannot be matched by anything else. For warming naturally cold surfaces such as concrete or tile, it is second to none."

Although radiant heat is certainly a primary heat source, it has some other unique and practical applications as well. For example, a home can employ traditional forced-air heating, with radiant heat used to augment the primary heat source to help warm up specific rooms or segments of a room.

"We have used radiant heat just to warm ceramic tile on a bathroom floor," said Ollinger. "We have installed it to heat indoor pool areas, to keep the deck nice and warm, which, in turn, allowed it to dry more quickly."

Despite its ancient roots, new materials and technologies have made radiant heat systems a very modern and efficient technology. The next time you have the opportunity to decide on which heating system to employ in new construction, additions or specialty applications, the consideration of today's radiant heat should be a must.

This article was written by R.J. Blum (Triangle Sales) who is a manufacturer's representative in the heating and plumbing industry. For additional information, he can be reached at 412-257-2300 or via email at rjblum@trainglesales.net.