The Hotline Newsletter

Summer 2005

Cambridge Space Heaters vs. Infrared Heaters

Heating an insulated building with large open spaces doesn't sound very difficult. However doing it effectively at the lowest total cost is now a bigger challenge due to rising energy costs and growing concerns about indoor air quality.

Question: What type of heater is normally best for large warehouses, manufacturing plants, automobile dealership service areas, aircraft hangers, boat storage, indoor recreational facilities and other large commercial and industrial buildings?

Answer: A direct gas-fired, high efficiency, Cambridge Blow-Thru® Space Heater. If that answer is a surprise because others have told you a gas-fired infrared (radiant) heater is always the best choice, then look at the comparison shown below.

Energy Efficiency
Infrared heating is promoted as being more energy efficient than forced air heating. The comparison study on above confirms this is not always true. Building studies and customer testimonials document 40% to 70% energy savings for Cambridge Space Heaters versus all types of industrial heating systems, including infrared heaters as shown below:

Many different types of radiant heaters are available. Low intensity, tube style infrared systems are the most common choice to heat large open spaces in commercial and industrial buildings. This design burns gas inside a long tube, radiating heat from the hot tube surface. A polished reflector directs radiant heat to the floor.

Published seasonal infrared heating efficiency is 80% to 92%, based on moderate tube length and mounting heights 15 to 18 feet above the floor. Shorter tube lengths, higher mounting heights, dirty reflectors and negative air pressure problems reduce operating efficiency below 70%.

Indirect gas-fired heating equipment like infrared heaters, unit heaters and air turnover systems require some method of heat transfer, such as a heat exchanger or radiant tubes, which lower overall efficiency. A flue is also required to vent products of combustion (and heat) outside the building. Claims of higher energy efficiency for infrared heaters are based on comparisons with unit heaters or other indirect gas-fired air heating equipment and with low temperature rise, draw-thru direct gas-fired heating equipment.

Today, the high temperature rise, direct gas-fired Cambridge Blow-Thru® Space Heater is recognized as the most energy efficient way to heat large insulated buildings that require some form of ventilation.

Total Cost of Ownership
The total cost to heat a building includes "first installed costs", "operating costs" and "impact costs". First installed cost for small buildings that require only a few infrared heaters is relatively low. However infrared heaters have the highest first installed cost of any industrial heating system for larger buildings due to the high number of gas burners, extensive gas pipe runs and the many flue stacks (roof penetrations) required for large facilities.

High gas bills, maintenance of numerous gas burners, cleaning dirty reflectors and expensive spare parts for proprietary systems make infrared heaters expensive to operate. More energy efficient, Cambridge heaters use less gas and are virtually maintenance free because the Blow-Thru® design keeps critical components out of the hot air stream.

Infrared Heating System

Infrared heaters must be mounted close to the floor to maintain their efficiency. However they cannot be installed too close to any object that either blocks the path of its radiant heat or could possibly reach a combustible temperature. These mounting restrictions create impact costs for the building owner or tenant. Examples include: lost vertical racking space for storage, interference with overhead cranes, relocation of tall equipment and objects suspended from the ceiling. Cambridge Space heaters can be mounted thru-the-wall, on the roof, under the roof and along inside or outside walls to maximize the building's floor and vertical racking space.

Ventilation and Indoor Air Quality
Infrared systems provide spot heat but don't provide forced air movement or ventilation to improve indoor air quality (IAQ). When an exhaust system is used, a building heated with just infrared can be starved for make-up air. This creates IAQ and negative air pressure problems. Either a constant path of cold air drafts results when dock doors open or the exhaust system is rendered ineffective when the building is closed up tight. Dock door air curtains that reduce air infiltration/cold drafts and makeup air heating systems are often added to buildings with infrared heaters to solve these problems. However, for most applications, the best solution is to eliminate the use of infrared heaters, air curtains and make-up air units by just using intermittently controlled, Cambridge Blow- Thru® Space Heaters. They will heat just the right amount of fresh outside air required to address the building's air infiltration, make-up air and space heating needs.

Cambridge Blow-Thru® Space Heater

In conclusion, heating and ventilating an insulated building with a large open space is not so simple after all. Many selection factors must be considered before determining the best and lowest total cost heating system that will both minimize energy costs and address concerns about indoor air quality. Cambridge Engineering has over 40 years experience heating large commercial and industrial buildings from 10,000 to over three million square feet. Our current Blow-Thru™ Space Heater Technology is the direct result of that unique experience. So if you have a commercial, industrial or warehouse space heating application over 10,000 sq. ft., give us a call before you specify or purchase infrared or any other type of industrial space heating equipment.