Winterizing Genset & Boiler Fuel Systems: Tips for Facility Managers

It’s never too late (or too early) to winterize! Facilities managers need to ensure that their backup power and heating systems can withstand freezing conditions. Gensets and boiler fuel systems, which often rely on diesel fuel, are vulnerable to cold weather issues like fuel gelling and ice formation. This article discusses some common challenges associated with cold weather, strategies for winterizing these systems to avoid those challenges, and best practices for management of your systems as cold weather approaches.

The Challenges of Cold Weather Diesel Fuel
Diesel fuel, particularly ultra-low sulfur diesel (ULSD), faces a unique set of problems in low temperatures. When the temperature drops below the fuel’s cloud point, wax crystals start to form, leading to fuel gelling. This can cause clogged filters, plugged strainers, and lead to equipment failure. ULSD can begin forming wax crystals at 12°F, making it essential to keep fuel above this threshold.

Additionally, ULSD holds less water in cold conditions, leading to fuel separation – water being pushed out of the fuel in small droplets. This separation allows the water droplets to freeze in temperatures below 32°F – leading to ice crystals that can clog filters, or if water accumulates at the bottom of fuel tanks, it can freeze suction lines.

Strategies for Winterizing Fuel Systems

Keep Your Fuel Warm

1. Consider Location

Keeping fuel warm is critical for preventing issues like gelling and ice formation during cold weather. Facilities managers should consider several strategies for maintaining optimal fuel temperature to ensure uninterrupted operation of gensets and boilers.

One of the most effective ways to keep fuel warm is to use underground storage tanks (USTs) and piping, which benefit from natural insulation provided by the earth. The ground retains heat better than air, meaning USTs can withstand long periods of cold weather without the fuel freezing. Additionally, USTs help protect fuel from extreme heat during the summer, making them a year-round solution for consistent fuel temperature.

In contrast, outdoor fuel systems are far more vulnerable to cold weather. Above-ground piping and tanks are exposed to freezing temperatures, and wind chill can exacerbate heat loss, leading to faster gelling of diesel fuel. Wind exposure speeds up the cooling process, making these systems particularly challenging to manage in winter conditions. Outdoor systems are also more difficult to maintain in freezing weather, complicating repairs and diagnostics.

To mitigate these risks, facilities managers should consider placing generators and day tanks indoors where they are shielded from the elements. NFPA regulations allow for up to two 660-gallon day tanks to be installed indoors without requiring a fire-rated room, though local codes may permit even larger capacities.

2. Insulation

Insulating above-ground piping and storage tanks can significantly reduce heat loss in cold weather. While insulation doesn’t generate heat, it slows down the rate at which heat escapes, buying time during short cold spells. However, insulation alone won’t be enough for prolonged freezing temperatures, so it should be combined with other heat-maintenance strategies. It’s important to evaluate insulation thickness and materials based on the system’s specific exposure to cold.

3. Oil Heating

There are several options for heating your system, some more effective than others. Generally, tank immersion heaters are not recommended as they are not effective without circulation. Suction stub heaters are effective in some situation, as they can keep the oil around the suction tube warm and pumpable. Heat tracing, when used with proper insulation, can be effective in keeping fuel lines warm but won’t add enough heat for an entire fuel system.

For more comprehensive protection, a thermopump system can be installed to actively maintain fuel temperature. A thermopump system circulates fuel through an oil heater to maintain a stable temperature. These systems use ambient temperature sensors to trigger the heater when outdoor temperatures drop, ensuring that fuel stays warm even in extreme cold. By circulating warm oil through the system, thermopumps can prevent gelling in tanks, pipes, and day tanks. This method provides consistent fuel temperature maintenance, even in sub-zero conditions, making it an essential component of a robust winterization strategy.

Fuel Polishing and Water Removal

Water contamination in diesel fuel is always a concern, but it becomes even more critical in cold weather when it can freeze and form ice, clogging filters and freezing suction lines. Installing a fuel polishing system can help remove both water and particulate matter from the fuel before it causes issues.

Fuel polishing is a process that removes water and particulate matter from diesel fuel, ensuring that it remains in optimal condition. A dedicated fuel polishing system continuously circulates fuel through filters and water separators, effectively cleaning the fuel and removing contaminants before they can cause problems.

Polishing systems work by drawing fuel from the bottom of the tank, where water and sludge tend to settle. By running the fuel through a series of filters, the system removes water and debris, returning clean fuel to the tank. Regular use of fuel polishers helps prevent ice formation in cold weather and extends the overall life of the fuel, making it a critical part of winterization.

Improve Your Fuel’s Performance

Another strategy for winterizing genset and boiler fuel systems is to improve your fuel’s performance, by either using a different fuel, or using additives that improve winter performance of your fuel.

1. Winter Blends

Winter blends are a common and effective solution in colder climates. These fuel blends mix No. 1 diesel (or kerosene) with No. 2 diesel to reduce the fuel’s cloud point, making it more resistant to freezing temperatures. Arctic blends, for example, can lower the cloud point to as much as -40°F, which is sufficient for even the most extreme winter environments.

Winter fuel blends are widely available in regions with severe winters, such as the Northern United States. In these areas, fuel suppliers typically switch to winter blends from November through March. However, in warmer regions like Texas, winter blends may not be readily available. This is a crucial factor for facilities managers to consider when planning for winterization, as relying on winter blends alone may not be feasible in all areas. In these cases, other solutions like fuel heating or additives may be necessary.

2. Fuel Additives

Fuel additives are another option. Fuel additives are available that are designed to prevent wax formation and improve the cold flow properties of diesel fuel. Some additives can lower the cloud point enough to avoid gelling in moderate cold conditions. Additives can also break up large water droplets so they can be more effectively removed by filters.

It is important to follow manufacturer recommendations for dosage and application. The effectiveness of additives depends on proper mixing and fuel temperature at the time of application.

Best Practices for Facility Managers
For facility managers preparing for winter, the following best practices can help ensure their genset and boiler systems remain operational:

• Regular Maintenance: Schedule preventive maintenance before the onset of cold weather. This should include inspecting filters, strainers, and heaters, and testing the fuel for water and contaminants.
• Fuel System Testing: Periodically test the fuel for water and gelling. Take bottom samples from tanks to check for water and sludge accumulation.
• Exercise Equipment: If you are in an area that must switch from natural gas to oil in the winter, do regular oil test-runs on gensets and boilers to prevent issues in the winter months. The VA hospitals in Texas, for example, require its boilers to run on oil for at least eight hours each month, which helps operators stay familiar with oil systems.
• Prepare for Emergencies: In cold weather emergencies, having a genset running can generate warm fuel that can be used to heat other parts of the system. Plan for manual operations to circulate warm fuel throughout the system in case of automatic control failures.

By taking proactive steps to winterize genset and boiler fuel systems, facilities managers can avoid costly downtime and ensure reliable performance during cold weather. Implementing solutions that are appropriate for your area’s needs, like fuel polishing, heat tracing, thermo pump systems, and/or winter blend fuels is essential for protecting fuel systems in freezing conditions. With these measures in place, facilities can continue to run smoothly, even when temperatures plummet.

David Eoff, a B.S.M.E. with over 30 years of engineering expertise, serves as VP of Sales and Service at Preferred Utilities. With a robust background, he adeptly navigates projects, from low NOx burners to controls, fuel oil handling, and tank design, ensuring systems are reinforced and regulation-compliant.