Gas Technology: Floor heating finds new friends

Radiant Systems Ideal for Industrial Environments

By Plant Engineering August 10, 2011

For most of the U.S. and all of Canada, it is necessary to provide heat for indoor manufacturing areas and much of the warehouse space. Winter temperature control is needed not only for worker comfort and efficiency, but also to protect products and maintain calibration on process machinery. Numerous types of heating systems have been used in the past. Today, many owners are discovering the benefits of in-floor radiant heat.

Warm Liquid Circulates Beneath Floor

An ideal way to achieve warm floors is to circulate a heated liquid through tubing beneath the concrete floor. Today, high-strength plastic tubing makes installation much easier and more reliable than earlier metal pipe heat distribution schemes. The tubing material is cross-linked polyethylene, sometimes called PEX or XLPE. This tough, durable material has been used for decades for in-floor radiant systems in Europe, and is quickly gaining in popularity in North America.

Today’s highly efficient natural gas-fired boilers and modern heat transfer products make these systems more efficient than ever. Most in-floor systems use a water-glycol circulating fluid designed to protect the system in the event of a freeze-up. An expansion tank adjusts for volume variations with heating.

The working fluid is pumped through a heat exchanger where it can also be heated by a variety of other sources. These might include process waste heat water, process steam, heat from onsite engines or gas turbine electric generation, along with a dedicated high efficiency boiler. Often, a combination of these sources is used, with the dedicated boiler being used when other heat sources cannot meet heating needs.

Heat Where It’s Needed

Part of the reason for this newfound popularity is the growing recognition that these systems provide even heat where it is needed most – at the working level. Most workers and machinery are near floor level, even in high-bay manufacturing and warehouse facilities. Yet forced air systems tend to make the space near the ceiling the warmest. Energy is wasted in heating areas that are not occupied.

One of the major suppliers of PEX-based radiant floor systems is Uponor. This firm supplies the full range of tubing, connectors and supplies. Mark Huboda from Uponor is the Senior Product Manager, Radiant Heating and Cooling. He was recently a speaker at a Technology & Market Assessment Forum, sponsored by the Energy Solutions Center. Huboda states, “Awareness of the comfort and energy efficiency provided by radiant heating continues to grow. This is being fueled by recent increases in energy costs. Specifications of radiant systems for commercial sites have nearly doubled since 2005.”

Suitable for a Variety of Floors

With floor systems, the heated floor is only a few degrees above ambient air temperatures, but the heat radiates upward and keeps workers and machinery in their most efficient working range. According to Huboda, even carpeting or floor mats can be used with radiant floor systems. “Radiant floor heating systems can almost always be designed to accommodate the characteristic of different flooring materials.”

The durability of PEX tubing is proven, and manufacturers offer long-term warranties. Huboda emphasizes, “Standard concrete cracks and floor movements will not harm Uponor PEX tubing. Over four decades, more than 12 billion feet of Uponor PEX tubing has been installed worldwide, with in-slab installations being commonplace. Uponor PEX tubing is backed with a 30-year warranty and independent testing shows it will last far longer than that.”

Manufacturer Support Available

It is important that system designers and installers receive factory training in the use of this material. Companies such as Uponor provide design and technical services to assist engineers, contractors and customers. Special tools and fittings are needed for installation.

One of the beauties of in-floor heat is that it can be zoned to allow for different heating levels. Examples might be lower heating levels in warehouse areas, and higher heat density near outside doors or in high-occupancy manufacturing or administrative areas. Huboda also points out, “Zoning provides improved energy efficiency and comfort by controlling the temperatures in different areas or zones.“

For example, if only a couple of rooms are being used in a building, the heating energy directed at other zones can be reduced or eliminated. Radiant zoning provides the ability to control the different amounts of heat required by each room to maintain the optimal comfort within each zone.

Zoning Provides Operating Flexibility

Heat output can be controlled both by the spacing of heating tubes and thermostatic control of heat outputs by zone. Zone-by-zone thermostat control is especially useful in manufacturing areas that are frequently re-arranged, or where there are seasonal variations in floor usage. Manufacturers such as Uponor offer a variety of thermostats with different features to accommodate a wide variety of applications and user preferences.

An example of a successful installation of radiant flooring is in a 50,000 square foot distribution center operated by Henri Studio, a designer and manufacturer of case stone fountains and statuary in Wauconda, Illinois. One of the owners of the company, Dennis Prosperi, says, “The facility serves as the hub of our business, so it must run as efficiently as possible. When designing it, one of our main concerns was finding the right heating system. Research led me to hydronic heating systems.”

Rapid Heat Recovery Attractive

Prosperi points out, “A forced air system makes no sense in a warehouse with 30-foot ceilings and numerous windows. You can’t beat the rapid heat recovery in the shipping area where doors are opened and closed constantly.” Preliminary data revealed that the company could save about $11,000 with the radiant floor system. Actual savings were nearly $19,000, paying for the system in as little as two years.

These are the kinds of experiences customers are discovering with radiant floor heating systems. If your company is considering building or remodeling a manufacturing or distribution center, this option should be carefully considered.

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Hydronics Industry Alliance

Radiant Design Institute