Blow-Thru Technology
Saves Energy And Reduces Heating Costs

BY KEN WILLIAMS
DIRECTOR OF MARKETING
CAMBRIDGE ENGINEERING INC.

Cutaway view of a Cambridge direct gasfired heater with Blow-Thru™ burner design.

Heating insulated metal buildings, with large open spaces, may not seem difficult. However, doing it effectively and providing the lowest total cost of ownership is now a bigger challenge due to rising energy costs and growing concerns about indoor air quality. So what type of heater is best for these commercial and industrial applications? The answer is a direct gas-fired, high efficiency, Blow- Thru™space heater.

It seems like every heater manufacturer has jumped on the bandwagon promoting energy efficiency. Who do you believe? Does anyone have documented proof of actual energy savings versus all other types of heating systems?

Direct gas-fired space heaters with high temperature rise, Blow-ThruTM technology have been used to heat thousands of buildings and over a billion sq. ft. in recent years. Today, this technology is recognized as the best and most energy efficient way to heat large insulated metal buildings that require some form of ventilation. Typical applications include warehouses, manufacturing facilities, assembly plants, car dealerships and service areas, aircraft hangars, boat storage and indoor sports facilities. Building studies and customer testimonials document 40% to 70% energy savings versus all other types of indirect and direct gas-fired heating systems, as shown in TABLE 1.

 
 

DIRECT vs. INDIRECT GAS-FIRED
HEATING SYSTEMS

Energy Efficiency:

  • Direct gas-fired air heating has gained popularity because there is no wasted energy. 100% of the heat goes into the building.

  • Indirect gas-fired heating equipment, like boilers, unit heaters, air turnover and even tube-style infrared heaters require some method of heat transfer, such as a heat exchanger or radiant tubes, which lowers overall energy efficiency. A flue is also required to vent products of combustion (and heat) outside the building.
  • Indoor Air Quality (IAQ):

  • Direct gas-fired heaters utilize outside air to provide ventilation, improve IAQ and help eliminate negative air pressure problems.
  • Indoor Humidity And Condensation Problems:
    Many sources can create excessive moisture in a building. When improperly applied, either indirect or direct gas-fired heaters can be part of the problem, or, when properly applied, either heating system can be part of the solution. Unfortunately, direct gas-fired heaters are often blamed for excessive humidity problems by some contractors/engineers that don’t understand the technology. Improperly applied heaters can cause problems if the facility is not vented to avoid over pressurization for very tight buildings. Cambridge Engineering has conducted actual building studies showing the same humidity levels for both nonrecirculating direct gas-fired heaters and indirect gas-fired heaters (including the air turnover/thermo-rotating type). These studies confirm both heating systems react the same way to the effects of outdoor temperature/humidity.

    DIRECT GAS-FIRED HEATERS:

    Not all direct gas-fired air heaters are alike. In fact, three different types are used in metal buildings as summarized in TABLE 2.

  • Conventional direct gas-fired heaters use a low temperature rise, draw-thru design where the blower is downstream of the burner. This older technology is used for both make-up air (MUA) and recirculation heater (Pressurization) type designs.

  • Blow-Thru™ Space Heaters have the burner downstream of the blower. This more advanced technology provides superior comfort levels and improved IAQ with the least amount of energy usage. The Cambridge S-Series design uses a proprietary burner to achieve the highest BTU/CFM ratio and the industry’s highest temperature rise/discharge temperature rating of 160°F. This crucial maximum rating results in smaller, but more powerful heating units. This translates into lower horsepower motors, less required outside air to heat a building and much lower energy costs. Locating the blower upstream of the burner also increases service life and heater reliability by keeping critical components out of the hot air stream.
  • Testimonials

    "We used unit heaters and infrared heaters in other sections of our air museum. They interfered with aircraft displays and we could not always get the heat where we wanted it. A more effective and efficient technology was needed to heat our new 20,000 sq. ft. B-29 bomber exhibit. The answer was a Cambridge direct gas-fired space heater installed thru-the wall of our metal building. We are very pleased with the results."
    Mike Speciale - Executive Director
    - New England Air Museum at Bradley International Airport
    "We are the largest privately held flat-rolled steel service center network in the U. S. I have been specifying and using Cambridge direct gas-fired space heaters for the past 12 years to heat metal building that range 50,000 to 500,000 sq.ft. I like the high temperature rise, Blow-Thru™ heaters because they seem to dry the air and prevent high humidity problems. In fact we have been replacing our unit heater and air turnover heating sytems with these heaters to save the floor space, improve indoor air quality, reduce energy costs and prevent flash rust problems on our steel products."
    Gene Hubbard - Chief Engineer - Heidtman Steel
    "Our company does design and layout work for all types of warehouse facilities. Over 40 years of experience has convinced me that Cambridge direct gas-fired, Blow-Thru™ space heaters now offer the most economical form of warehouse heating. No heat exchangers to waste heat. No holes in the roof for flues. I've cut heating costs in half with these heaters. Believe me it works.
    Bob Goldwasser - President - R. A. Goldwasser, LLC