Third-party testing put a stamp of approval on boilers and baseboard.

The Hydronic Institute's I=B=R ratings program gives contractors an extra level of assurance that a boiler will do what it says it will once installed.

"We're the Good Housekeeping Seal of Approval," says John Woodworth, consultant and retired technical director of the Hydronics


Earlier this century, testing done by one of HI's predecessors, the Institute of Boiler and Radiator Manufacturers, virtually eliminated the "credibility" problem at a time when there were no national standards for boilers. Back then, each manufacturer assigned its own Btu output. Ethical producers tended to assign conservative ratings, while others used exaggerated ratings.

Since then, HI's I=B=R ratings program has expanded to test baseboard radiation and finned tube radiation, and provides authorization for the use of I=B=R ratings for those products, as well.

While the testing procedures is a great benefit to installers and end users, Woodworth says the program keeps manufacturers on their toes, too.

"It doesn't happen often, but occasionally we get a product that doesn't make it," he explains. "It's a wakeup call to the quality control staff. Boilers have hundreds of 'pins' that account for the bulk of the heat transfer. If the castings aren't right, you may end up with abbreviated pins or missing pins. Pretty soon, the boiler won't have the heating surface it should, and it will fail the test."

Each January, HI publishes its I=B=R Ratings Book, which contains the I=B=R ratings for cast-iron, steel and copper boilers; baseboard and finned tube radiation. The ratings have been determined under the provisions of HI's "Testing and Rating Standard for Heating Boilers," "Testing and Rating Standard for Baseboard Radiation" and "Testing and Rating Standard for Finned Tube Radiation." For boilers under 300,000 Btu input, the HI standard also includes the requirements of the Department of Energy.

Boiler Testing

The "Testing and Rating Standard for Heating Boilers" itemizes specific methods and procedures to assure accuracy and uniformity of testing.

The tests determine the ratings in terms of "Heating Capacity" or "Gross Output," the former referring to boilers under 300,000 Btuh input, and the latter to larger sizes. The size distinction is based on the Department of Energy's test procedures for small boilers, published in the CFR 10, Part 430 and ASHRAE Standard 103-1993.

The boiler test standard has the following basic requirements in order for a model to be certified and licensed by HI. Every boiler must meet ASME standards for construction and for safety devices. Every commercial boiler must meet a minimum steady state efficiency of 75 percent, although most are much higher. Every residential boiler must meet a minimum of 80 percent AFUE except natural gas, and steam, which must meet at least 75 percent AFUE.

Steady state efficiency tests for commercial and residential boilers are essentially the same. However, in 1978, the U.S. Department of Energy mandated that residential boilers up to 300,000 Btu input are to have an additional test for Annual Fuel Utilization Efficiency (AFUE), as a guide for homeowners to ascertain the relative efficiencies of various brands. The added test includes a "heat-up" and "cool-down" cycling test, which provides an estimate of the annual cost of operation for that model.

Under the DOE regulations, manufacturers are responsible for testing to determine the efficiency ratings of residential boilers and reporting the ratings to the Federal Trade Commission. HI conducts one pre-certification test on each series to assure the accuracy of the manufacturer's testing. Then annually, HI conducts verification tests on samples randomly selected from the manufacturer's stock to assure the continued accuracy of the ratings. The number of tests conducted is related to the number of models listed for the manufacturer.

"Essentially, we're saying that when the boiler is running properly, the AFUE is the annual efficiency a consumer may get, just like the EPA's gas mileage for cars," Woodworth adds.

During tests, photographs are taken and dimensions are recorded, to assure the specific model is the one being listed in the manufacturer's catalog. The catalogs are reviewed in detail after publication to ensure they agree with the product tested.

Besides tests on new models, verification tests are performed on existing models on a planned cycle, annually for residential boilers, and five years for commercial size, as long as that model is being offered on the market.

Baseboard Testing

An I=B=R baseboard rating is the output, determined under the strict limitations and conditions set forth in the "I=B=R Testing and

Rating Standard for Baseboard Radiation," plus 15 percent. This added percentage is credited to the baseboard unit because this type of radiation is usually installed at low levels where heating effect results.

The testing procedures also include the following provisions:

  • Water Flow Rate: All baseboards are rated at a water flow rate of 500 lbs. per hour (1 gpm). This rating must be used where the water flow rate through the baseboard is not known. An I=B=R rating at a water flow rate of 2,000 lbs. per hour (4 gpm) is also approved, when requested by the manufacturer. This 2,000 lbs. per hour rating is limited to installations where the water flow rate through the baseboard is equal to or greater than 2,000 lbs. per hour.

  • Active Length: All I=B=R baseboard ratings are based on active length. Manufacturers are required to publish in their literature the difference between active and total length.

  • Pressure Drop: Manufacturers are required to publish the pressure drop per linear foot applicable to 500 lb./hour water flow rate, and if ratings are approved at 2,000 lb./hour water flow rate, the pressure drops per linear foot applicable to that flow rate.

  • Periodic Testing: In addition to testing baseboard for initial approval, annual periodic tests are conducted at the I=B=R Laboratory to assure that current production will deliver the output originally approved. The production samples tested are selected from the manufacturer's stock by HI personnel.

    Finned Tube Testing

    While the terms "baseboard radiation" and "finned tube radiation" are often used interchangeably, for the purposes of the I=B=R testing, HI defines finned tube as the following:

    "Finned Tube (Commercial Radiation) is a finned tube element; one, two or three tiers high designed for installation bare, or with open type grilles, covers or enclosures having top, front or inclined outlets. (Usually used for buildings other than residential.)"

    The I=B=R ratings are steam ratings in Btuh per foot of active length at 215 degrees F steam and 65 degrees F inlet air. The steam ratings are based on the condensation capacity determined by laboratory test as prescribed in the I=B=R standard, but include an added percentage, ranging up to 15 percent depending on the height and type of cover or enclosure. When the unit is installed, as specified in the listings, no adjustment to the listing ratings is required. If the unit is to be installed at a different height than recommended, the I=B=R Rating Book offers methods to calculate the needed adjustments. The guide also offers various correction factors for water flow rate, flat top cover and expanded metal covers.