Fans, spreaders and tech augment Fast Dry system

Aggressive early harvest means better grades and retained moisture that can later be used for blending low moisture grain. Careful management of fans and burners is more cost-effective than using a dryer, according to Dave Wall. | Wall Grain photo

The choice of grain dryer is important but how it is used might be even more important.

Good dryer management can lower capital costs while boosting the number of bushels dried.

There’s no secret to making the most of grain bins and a dryer, according to Dave Wall of Wall Grain. The combine, bins, dryer and trucks all play their roles.

“The process is very simple. It’s called Fast Dry. We’ve shown hundreds of farmers how to extract more money from their crops using Fast Dry,” said Wall in a phone interview.

He introduced prairie farmers to the concept in a Farming Magazine story in 2000 as a cost-effective way to convert bins into grain dryers.

“Since that article we’ve added four key factors that increase the dryer efficiency by 20 to 30 percent.

“Fast Dry speeds up natural air drying in the bin by using heat. You can dry grain in seven days or less instead of weeks or months. The beauty of the concept is that bins can be designed for later addition of accessories like a continuous flow dryer.”

The four new factors in the system are roof fans, multiple fans, self-adjusting grain spreaders and technology coaching.

Roof fans

In mid-September and on cooler nights, dripping water creates a mess on the bin walls and reduces the amount of moisture removed. Wall Grain designed a roof fan that reduces dripping.

This helps push moisture out of the space under the roof. More importantly, it keeps the roof at a constant temperature so moisture doesn’t condense. Later in fall, cold conditions can still cause some dripping.

Multiple fans

Wall says that as bins got bigger, his engineers began installing multiple fans. Two 25 horsepower motors now allow drying 25,000 to 35,000 bushels in bins of cereal or canola. In five to seven days, each bin is dried.

Self-adjusting grain spreader

With bin diameters up to 54 feet, the grain peak can be high and should be level for consistent drying. This can be done by taking a load or two out of the bin, but that’s a lot of work. A self-adjusting grain spreader can handle augers up to 16 inches. It has self-adjusting springs that allow constant feed on the spreading arms/pans. Having a “lumpy” spread rather than a peak means less over-dried grain that needs to be blended.

The spring-loaded self-adjusting grain spreader can handle augers up to 16 inches. | Wall Grain photo

Technology and coaching

Knowing how much water must be removed helps manage the batches. Wall Grain has developed a calculator for cereals and canola, working with seven fan combinations. Advisors coach customers on what works and help match fans to each operation.

Moisture and temperature cables help monitor the bins. GrainX Command for fan automation and monitoring makes it easier to learn what is happening in the bin. GrainX Command also comes with coaching and weekly reporting at harvest time. Wall Grain works with GrainX Command representative Calvin Boisjoli in designing systems.

Wall Grain designed a roof fan that pushes moisture out of the space under the roof. It reduces wall dripping by keeping the roof at a constant temperature so moisture doesn’t condense inside. | Wall Grain photo

“Grain drying isn’t complicated. Simply warm up the grain to a certain temperature and it’s dry. The faster we do it the more effective we can be,” says Wall. “We use the acronym HATT (heat, airflow, time, timing).”

Size matters

Size the right burner with a fan. The sizing formula is:

  • CFM x temperature rise (in Fahrenheit) x 1.05 = BTU required

For example:

  • A 10 h.p. @ 1,750 rpm fan delivers 11,000 CFM
  • 60F – 110F outside temperature yields a 50 degree temperature rise
  • 11,000 x 50 x 1.05 = 577,500 BTU
  • Therefore a 600,000 to 1,000,000 BTU unit is required, using natural gas, liquid propane or other heat.

Caution: If the burner is not big enough, drying time can double and result in over-dried grain.

The 1.05 multiplier is used because combustion of gas creates water that is burned off by adding a few BTUs to have “dry air” maximum. The most effective burner is a downstream unit that fits between the fan and the transition.

Upstream burners can also be used, adding to existing fans. Modulating burners are standard on bigger units versus thermostats, which make for better burner ignition. Cost of burners varies from $4,000 to $6,000 for single phase. Three-phase units are slightly more. Spreaders and roof fans are extra.


How long will it take to dry a bin? The ideal Fast Dry target is six to seven days, removing about a half point of moisture per day.

This is full-on heat for 24 hours a day regardless of weather. A popular single-phase design is a 36-foot bin with 10 hp, 1,750 rpm fan.

So 15,000 to 18,000 bushels of wheat at 18 percent will take five to six days to dry. In colder conditions, add an extra day to allow for warming the grain.

A popular three-phase design is a 48-foot bin with a 25 hp fan turning at 1,750 rpm. This dries 26,000 bushels of wheat in five to six days or 20,000 to 25,000 bushels of canola in four days.

The charts at the top of the page show the length of drying time using different fans. Blue colors indicate single phase.

Capacity can be doubled with three phase. If it is not available, consider buying a gen set, finding a different location or buying a variable frequency drive converter. The grain requires one day to warm and a half day or less to cool before moving it out.

A calculator for wheat and canola with the seven most common fan combinations can be found on the Wall Grain website.


Combining sooner can make Fast Dry more effective. It’s easier to bin dry in August or early September than in late September or October when grain temperatures are colder and nighttime temperatures even lower.

Using roof fans in September reduces dripping. Self-adjusting spreaders can reduce the amount of over-dried grain on the sides when the middle is still wet.

GrainX Command gives temperature and moisture monitoring cables to indicate what’s happening in bins. Monitoring makes it easier to blend on the farm or with the terminal. At times it’s better to over-dry a batch to blend with other bins.

“The Fast Dry system does not fit all situations. There are a number of points a farmer should keep in mind. And there comes a time when Fast Dry will not fit your farm. That’s when it’s time to invest in a more common continuous-flow dryer,” says Wall.

Other considerations

  • Full-floor bins dry grain six or seven times faster than hopper bins. Most hopper bins have only 40 sq. feet of screen for drying. A 36-foot bin has 1,000 sq. feet of floor area. Drying in a hopper bin can turn grain to “popcorn” giving extremely over-dried grain.
  • There has been limited success in hopper bins, even with a good air system. In a hopper, the hot air tends to channel, taking the path of least resistance. This makes for extremely over-dried grain in one area but totally wet grain in most areas.
  • Stir augers can help mix or blend the grain, but they do not speed up the drying process much. Because of higher maintenance costs, it’s more economical to add burners to more bins. The longer stir augers break too often.
  • Burners are often not sized properly to handle the amount of moisture to be removed.
  • When a wet year like 2019 comes along, there’s not enough drying capacity and bins get overfilled. This badly disrupts the Fast Dry bin drying plans.
  • Corn dries too slowly to be used in the Fast Dry system.

Fast Dry Check List

  • Design for future expansion. Plan the site so it’s easier to move grain from Fast Dry bins.
  • It’s work, but dry grain must be moved away from any kind of dryer in any system.
  • Add roof fans for the late harvest so no moisture sticks to the walls.
  • Add adjustable spreaders for more even drying and less work.
  • Know how much water must be removed, using the calculator and charts. Talk to others who have successfully adapted the system.

Visit or call Dave Wall at 844-744-9255.

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