Have more questions about FrostBoss® fans?

Read our Frequently Asked Questions

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Ask us how we can help you achieve your frost protection goals.

1. How does a frost fan work?

When frost sets in, it can damage crops during the growing stages, causing cell damage, wilting, deterioration, flower and fruit damage or stunted growth. This can affect development of the crops and lead to reduced yield, and partial or complete loss of the crop.

Frost fans circulate air across the crops during a frost. They re-distribute warmer air which has been radiated from the soil and crops and risen into the inversion layer during the night, and blow it down across the crops to raise the temperature. This prevents cold air settling near the ground and reduces the risk of frost getting a chance to form. 

FrostBoss® fans blow in an elliptical fashion on a 360 degree axis, and are placed to maximise the coverage area and allow for any katabatic drift which may present. 

Frost fans can be manually started or automatically set to turn on before reaching critical temperatures for frost damage. They can also be supplemented by additional frost protection such as heaters in particularly severe conditions.

2. Are your frost fans noisy?

Our frost fans have been designed with noise, efficiency and fuel consumption in mind. Frost fans move large volumes of air over a large area, so they do produce some noise, however our aerodynamic blade shape works to increase the airflow without the thumping Iroquois-type ‘chopping’ sound some other fans make.  It is this chopping sound neighbours find most annoying on still nights, akin to someone playing music really loud and all you hear is the bass.

Our greater blade areas also allow for both the fan and the engine to be run at a slower speed without reducing performance or the blades stalling, further reducing the noise generated or fuel consumed. This results in our fans rated at just 51dB at a 300m distance for the 4-blade C49, and 50dB for the 5-blade C59. 

Consideration of natural and fixed obstacles such as hills and buildings is important during fan placement to minimise sound amplification.

3. Do the fans need to stay on all the time?

No, our frost fans only need to stay on during a frost to protect the budding crop. Once temperatures rise and the frost risk reduces, the fans can be switched off.

When they’re not running, FrostBoss® frost fans easily spin when an ambient wind hits them to turn themselves out of the wind, and avoid the shock loading and damage a 2-blade fan may experience.

4. What powers them?

FrostBoss® frost fans come with either Perkins or John Deere engines. These are powerful, high performing engines, built for durability and reliability in low temperatures, with the John Deere rated at 170Hp at 2500rpm, and the Perkins at 150Hp at 2200rpm.

The fan runs on diesel fuel, with a 490 litre lockable fuel tank with sensor to prevent the engine running the fuel tank dry, and includes the FrostBoss® clutch and intelligent controller for starting the fan manually or automatically at preset temperatures. The controller will also stop the fan in winds above 10kph and restart when the wind speed drops to 8kph (if still within the preset temperature range). Fans are equipped with the hardware required for FrostSmart® monitoring via a web app (annual monitoring subscription applies).

5. Can they be used to generate power?

Our current range of FrostBoss® fans are diesel-powered, and designed solely for protecting orchards, so they’re not connected to a power supply, and unable to generate power. With greater demand for alternative power sources and supporting the climate, our future frost fan development could see our frost fans equipped with the ability to do both.

6. Why does the blade shape look so different?

The C49 and C59 fan blades are twisted from the tip to the root and give them a distinctive 3 dimensional shape, especially towards the blade root. This, combined with the progressive increase in blade width, the rounded blade tips, and the greater number of blades, gives much improved performance to 2 and 3 blade fans with a more uniform wind momentum, and they look striking in the field.

When comparing our machines to others, at the equivalent fan speed (rpm), we believe we have the best performing machine on the market based on these 3 parameters – noise, fuel-efficiency and coverage.

7. What are the blades made out of?

FrostBoss® composite blades are manufactured with the latest Resin Transfer Moulding (RTM) technology, and are an advanced technology composite structure. They are statically balanced for smooth running, have optimal structural detailing for improved fatigue strength and have significantly thinner tips to reduce noise.

The aerodynamic design has been engineered for efficiency and noise reduction at low operating engine speeds of 1750-1800rpm.

8. What crops will they protect?

FrostBoss® frost fans are capable of protecting virtually any crop type which may be susceptible to frost damage, including apples, grapes, cherries, olives, kiwifruit, citrus, stonefruit, almonds, avocados and more.

9. What is better – wind volume or wind speed?

Neither – the most important aerodynamic property of a frost fan is the momentum of the wind stream it generates. This 'wind momentum' is the product of the wind flow rate, the wind speed and the air density. The more momentum the wind stream has, the further it penetrates into the orchard or vineyard.

10. How powerful are FrostBoss® fans?

Power of a frost fan can be determined by the uniform wind momentum and, the area it covers. Our 4 and 5 blade frost fans have been specifically designed to give the greatest coverage for the lowest fuel consumption of other leading brands of frost fan. They operate at slower speeds, use less fuel and produce less turbulence or noise disturbance without affecting overall performance.

In continental climates like Australia with large temperature inversions and low katabatic wind speeds, FrostBoss® frost fans can cover approximately 10ha. The same fan in an island climate like New Zealand, and in a cold valley with strong katabatic drift and small temperature inversion, may reach approximately 6-7ha.

It’s important to remember, the coverage, or effectiveness, of any frost fan depends not only on the machine’s ability to move air, but also the warmth of the inversion temperature and the degree of frost present.

11. What area does a fan cover?

Coverage is typically 6 - 8 hectares depending on the conditions, climate and the location of obstacles, natural topography and katabatic drift.

12. What is the coverage pattern of a frost fan?

Frost fans cover an elliptical shape rather than a circle. This is due to the katabatic drift, so before we recommend correct positioning of the fans, it’s important to understand the direction of the drift.

The FrostBoss® C49 (4-blade) fan rotates around the tower every 6 minutes, 40 seconds and for the FrostBoss® C59 (5-blade) fan every 7 minutes.

13. How much fuel do they use?

Operating at our standard speed of 1760rpm, the C49 uses 21 litres per hour, and the C59 consumes 20 litres per hour operating at 1800rpm.

14. Can I paint it?

We don’t recommend painting the tower or the blades. Performance has been designed down to minute detail, and the extra weight and width of additional paint layers could unbalance the fan, and reduce its efficacy and efficiency.

The steel towers are hot dipped galvanised providing corrosion protection to both the exterior and interior of the tower.

15. What’s the lifespan of a frost fan? 

With regular servicing, fans can be expected to last well over 20 years.

FrostBoss® Frost Fans are guaranteed against defects in materials and workmanship for a period of four years from the date of installation when operated under normal conditions, provided annual maintenance has been carried out by an authorised FrostBoss® service agent. This is an easy-to-understand, no-nonsense, non-diminishing Manufacturer’s Warranty overing parts and labour. There are no carve-outs, with all machine components covered under the warranty (excluding standard service consumables).

16. Are frost fans cheaper than a helicopter or irrigation?

When considering any method of frost protection, it’s important to consider all factors in addition to the initial cost, such as labour costs, availability of resources, impact on the environment, equipment and installation cost, accurate weather predictions, size of your property, and effectiveness in protecting your crops.

Irrigation is quiet, however is labour and resource intensive, is reliant on a reliable and plentiful water source and may be subject to water restrictions or drought. There’s also a high risk of overwatering, creating ice or disease if the crops remain too wet. Helicopters can cover a large area quickly, and get air around obstacles, but they are noisy, can be expensive, and are subject to availability, and guesswork to get them in the air at the right time.

A frost fan has a per unit cost, with fuel, monitoring and servicing as ongoing cost, and with built-in temperature sensors and easy operation to turn the fan on manually or automatically, there’s no guesswork required or extensive labour costs.

17. What’s the difference between 4 and 5 blade fans, and fans with fewer blades?

The main difference is the design and how they perform. Typically, the more blades, the greater the volume of air which can be moved across your property and circulated around your crops to provide a uniform wind momentum to keep the plants’ temperatures higher.

Noise from the frost fan can be generated from the engine, the speed of the blade rotations and from the design of the blades. We have designed our blades to be quieter without losing performance, with an aerodynamic shape to produce wind to match the maximum torque of the engine. Because of this, the engine and fan can both operate at a lower speed (1700-1900rpm) and achieve better coverage and fuel economy, with less noise than 2 and 3 blade fans.

Our 5 blade C59 fans operate at a lower fan speed (rpm) than our 4 blade C49, and cover a greater area at even lower noise levels.

18. Is thrust important in measuring the performance of a fan?

Thrust is used to measure the performance of a propeller on an aircraft, and isn’t a good measure of the capability of a frost fan. The best measure of performance is the uniformity of the wind momentum.

A uniform wind momentum is best achieved with a blade angle pitched progressively from the tip to the root, which allows air to flow uniformly across the fan diameter, and creates a uniform blast of wind.

If there isn’t sufficient pitch variation (called twist), the blade tips create the wind momentum, which mixes with the slower air in the middle of the fan blast. This dilutes the momentum of the wind stream before it can drive out into the orchard or vineyard.

The C49 fan has over 20 degrees of progressive pitch in the blade. This compares to only 5 degrees of pitch between the tip and the root of the blade of some 2 blade fans.

19. Where are they made?

FrostBoss® frost fans are manufactured in our modern purpose-built factory in Hawke’s Bay, New Zealand, where we make the fan blades, fabricate the steel towers, and build the engine units ready to ship to you.

We also have a significant research and development programme onsite and in the field focusing on improving the efficiency and reliability of the FrostBoss® fans and FrostSmart® monitoring web app to give you the best value for your investment.

We have distributors around the globe, and can ship our fans worldwide.

20. Can I upgrade the blades on my old machine?

Whether your aim is to save fuel, become noise compliant, or improve your coverage area – we have an upgrade package for most makes and models of frost fan.

Where existing gearbox ratios won’t allow an upgrade to our C49 four blade system, we can usually upgrade 2 blades to our C39 three blade system.

21. Does the price include installation?

The price covers shipping to your property, a concrete pad and installation of the fan onsite. It doesn’t cover the cost of consents which may be required, or the removal of any existing structures or crops to allow the fan to be positioned, or to allow the truck access to the site.

22. What consents are needed?

These vary for each region. We can advise what’s required by your local council and when you need to have the application submitted. The consent process can be the biggest lead time to having your fans installed when you need them, so it pays to get any consent applications underway as soon as possible.

23. Will it blow the cold air or debris onto my neighbour’s property? 

We work with you to position the machines to reach the largest area of your property possible, to ensure your crops are benefiting, rather than your neighbour’s land. There may be a small amount of wind disturbance as the fan turns on its 360 degree axis, but this should be minimal.

24. Will it scare livestock?

All animals have the potential to be scared by something new – different noises, strange sights, new arrivals. 

However, livestock is generally not affected by noise that they are accustomed to.  If you have your own stock, you’ll best understand their capacity for change and how to introduce them to something new.

If your neighbours have animals, have a chat to them first, and discuss ways you could introduce the animals slowly as the fan is installed.

25. There isn’t a local distributor near me. Can I still purchase?

Yes, you can! Reach out to us, and let’s chat about how we can make this happen.

Supplying fans globally.