Updated September 30, 2020
Historically, steam has been a powerful resource for space heating in homes and commercial buildings. Steam has proven extremely effective at providing controlled, consistent heat to distribute throughout a building without the need for pumps by simply using a durable steam boiler. In fact, the heating effectiveness of steam still makes it a staple heat source after more than a century.
Over the past 50 years, however, the use of steam for providing regular comfort (space) heating has declined, as many businesses employ newer technologies. Yet, specific industries and applications such as breweries, distilleries, dairy production and scientific laboratories are all increasing the demand for steam heating and enjoying a myriad of benefits as a result.
Low Pressure Steam Heating Overview
Generally speaking, engineers and homeowners like steam heating because it’s quiet and there isn’t air flow stopping and starting. These systems are also capable of delivering a lot more heat, warming spaces more quickly and thoroughly while providing more of a choice of areas to heat. Steam piping can also act as an alternative to expensive radiant floor heating.
How do low pressure steam boilers work
Low-pressure steam heating is just what it sounds like: the steam from the boiler is pushed out to the building at a low pressure as opposed to high. Low-pressure boilers generally stay between 10 and 15 psi and the temperature is maintained under about 300 degrees F. This type of boiler is generally used in buildings where a somewhat consistent temperature works for all spaces and no rapid changes are required.
Difference between low-pressure vs. high-pressure
When comparing low- and high-pressure boilers, we start with the sometimes-surprising fact that low-pressure steam travels faster—much faster—than high-pressure steam when the load is the same. High-pressure steam is essentially squeezed more tightly. So, to transfer the same load, the steam doesn’t have to move as quickly through the pipes.
Steam heating is available from high- and low-pressure steam boilers, allowing businesses to match equipment to their unique needs. Many industries that may have traditionally opted for high-pressure steam are now realizing the benefits they can achieve with low-pressure steam applications.
The operating pressure of steam boilers should match the temperatures required for each specific application – such as pasteurizing beer or yogurt. It is a common misconception, however, that low-pressure steam boilers are not suited for process heating. In fact, many businesses running high-pressure steam boilers could likely satisfy heating needs with low-pressure steam boilers and achieve the same results, while saving on both equipment purchases and operating costs.
Low-pressure steam is limited to 15 PSI (pounds per square inch). High-pressure steam applications require more than 15 PSI. However, with high pressure steam, complex and costly regulations set in. Owning and operating high-pressure steam systems may require staff to undergo specific training and certification, and require that staff be present 24 hours per day. Businesses must purchase additional, specialized insurance coverage specific to high-pressure steam. Therefore, opting for low-pressure steam when it satisfies the process requirements reduces regulatory burden, increases staffing flexibility and reduces overall insurance costs.
In addition, high-pressure steam systems can be more expensive to purchase, install and repair. High-pressure steam systems often call for expensive, specialized welding during assembly or repairs, adding to cost of ownership.
While many steam heat applications can easily be accomplished with either low or high-pressure systems, some processes are better suited for high-pressure technology. For example, high-pressure steam is ideal for extremely large facilities with high heat demands, such as hospitals with sterilization and in autoclave requirements. These applications need much higher pressure – 60 PSI and above.
Benefits of steam heating
Many businesses require precise levels of heat to achieve a desired outcome. For example, in food production industries, it is tremendously important for all production to maintain consistent quality. This can be difficult to achieve with some other heating technologies, such as direct fired heating. Direct fired heating requires management of extremely high temperatures that can fluctuate and scorch products to yield varying results.
Steam heating, on the other hand, generates the same large heat loads but in a more controlled form, creating greater consistency and resulting in higher product quality.
Most low-pressure steam boiler systems are highly configurable to match the unique needs of different applications. Furthermore, many low-pressure boiler systems can be built into existing systems or designed for new installations – ensuring consistency and efficiency for each individual application.
Further underscoring their versatility, low-pressure commercial steam boilers come in a variety of sizes and run on several different fuel sources. High-quality options can operate on natural gas, propane, oil or a dual fuel option, while ranging in size from 48 lb/hr to 8,800 lb/hr in a single boiler.
Modern Day Low-Pressure Steam Applications
There are many growing industry applications in the U.S. that embrace low-pressure steam heat for its cost-efficiency and versatility.
Food and beverage
Pasteurization, in particular, requires products to be heated to very specific temperatures to eliminate certain harmful pathogens, without overheating and impacting taste.
An increasing number of small craft brewers, micro-pubs, and micro-distilleries are enjoying the low costs associated with low-pressure steam heat while achieving consistent batches and reducing waste. In addition, food and beverage industries such as dairy production can use their steam boilers to create hot water through a steam-to-water heat exchanger for cleaning and other sanitizing needs.
Laboratories
Another unique application of low-pressure steam heat is demonstrated in scientific laboratory buildings. Labs on college campuses utilize a tremendous amount of exhaust air when conducting experiments and tests. To make up for the large amount of exhaust air, the laboratories bring in an equal amount of outside air, which can be extremely cold in the winter, and require a significant amount of heat to warm up to neutral conditions. When the air is below freezing point, other forms of heating the building – such as hot water coils – may be more susceptible to freezing and damage. Low-pressure steam, however, is much less vulnerable to this risk and provides large heat capacities.
Lumber Kilns
Low-pressure steam heat also is proving very useful in kiln drying of specialty lumber. Mills often house a variety of specialty hardwoods used for making furniture, or cedar planks used for cooking, that require drying in a kiln. Using a low-pressure steam boiler enables mills to perform this function safely and effectively for standardized results, increasing the quality of the wood. The manageability and consistency of low-pressure steam heat make it ideal for these and other growing industries.
As food and beverage industries such as brewery distilleries and dairy production adopt low-pressure steam heat systems at an increasing rate, other sectors are just starting to familiarize themselves with the application opportunities and benefits of the technology. Chemicals or cosmetics manufacturers, for example, are discovering they can swap a high-pressure system for a low-pressure steam application to obtain the same results at a reduced installed cost as well as lower operating costs.
Factors to consider
When selecting a low-pressure steam boiler, buyers should take inventory of their business’ needs and facility amenities before making a selection.
- Determine what is required for optimal production first and then build a system to match to avoid unnecessary costs.
- Sizing the boiler so that it can efficiently heat the building is crucial for preventing fuel loss and excessive cycling. For example, low-pressure boilers should be capable of adjusting to a region’s most extreme weather.
- For businesses with limited demands, there are simple atmospheric burners available at low costs. For higher-demand operations, power burner models allow for greater capacity and flexibility.
- Controls for the burners also are customizable to enable varying levels of precision in temperature regulation throughout the system. Burner control ranges from:
- Good: Simple on/off functionality
- Better: Low/high/low – offers low-stage to more closely match lighter loads and reduce energy consumption
- Best: Full modulation – offers precision heating and variable controls
- Businesses with complex heating requirements may opt for a multiple boiler control system to run larger operations more efficiently.
Finally, businesses should choose a low-pressure steam boiler after consultation with a professional in the industry with expert knowledge on specifying the best boiler to meet steam system operational needs. An industry expert can explain the different steam piping designs available to ensure the product fits the application seamlessly and achieves optimal performance. Weil-McLain, a leading U.S. manufacturer of efficient boilers for more than a century, offers several models for low-pressure steam applications including EGH, LGB, Series 80, Series 88 and Series 94.