Thermatic® Electric Fans
In 1971, belt-driven fans were the only option for automotive cooling. Searching for a more efficient method, Australian engineers Daryl Davies and Bill Craig created the Thermatic® / Electric Fan.
Davies, Craig was formed to manufacture the new electric fans, and has since developed a comprehensive range, covering most makes of vehicles. Its innovation in electric cooling has now become a standard feature on most of the world's new cars.
A Davies, Craig Fan is suitable for both condenser and radiator cooling and provides constant air flow, increased fuel economy, better air conditioning performance, cooler engine running, and increased engine power. Our fans are fully reversible blades and polarity for mounting either side of the heat exchanger. (Except 11" & 14" Brushless Fans)
All Davies Craig fans are built in Upstream (Pusher) configuration. For downstream applications the fan blade must be removed and turned over, always check that the fan blade rotates in the direction shown by the arrows on the blade before making a permanent wiring connection.
All Davies, Craig Thermatic® / Electric Fans are packaged with fan assembly (motor, fan blade, shroud and mounting feet). Fan fitting / mounting hardware sold separately. (See below)
Davies Craig backs the quality of its fans with an unprecedented 2 Year Manufacturer Warranty
THERMATIC® / ELECTRIC FAN RANGE
UNIVERSAL FAN FITTING KIT
The Davies, Craig Universal Fan Fitting Kit includes all parts necessary for mounting and wiring any 12- and 24-volt electric fans
– all Davies, Craig Thermatic® Fans and other electric fan models.
What size Thermatic® Fan do I need?
If your car make is not listed in our Model Selection Guide (see the Davies, Craig website, www.daviescraig.com.au/catalogues) we suggest the following:
- Measure your radiator core dimensions (width, depth and clearance - refer diagram below) and refer to “Fan Models” to check which fan/s will fit your core.
- Davies Craig Thermatic® Fans are reversible (Ex: Brushless models) which means they can be mounted upstream or downstream, as illustrated below.
- In general, one large fan will have better airflow than two smaller fans. Where radiator is rectangular there may be no choice but to fit two smaller fans; choose the largest that can be accommodated in space available. The fan can also be mounted offset from centre to clear engine components when mounted in the downstream position.
Note: Fans should not be fitted on opposite sides of radiator core unless these are offset such that the airflow of one is not interfering with the airflow of the other.
- If you require advice, please contact Davies, Craig for assistance.
Fan Mounting Direction
BENEFITS OF A DAVIES CRAIG THERMATIC® FAN
As a primary cooling source electric fans provide:
- Economical replacement for failed original equipment.
- 5-10% increase in engine power and fuel saving when replacing fan clutch and fan assemblies
- Reversible blades for pusher (upstream) or puller (downstream) applications
- Compatibility with all electric fan controls
- Coverage for a wide variety of applications
As an add-on cooling source electric fans provide:
- Constant air flow regardless of vehicle speed constant air flow across the condenser
- Increased air conditioning performance due to constant air flow across the condenser
- With the conversion from R12 to R-134A refrigerant there is a need for additional condenser cooling to ensure the overall improved efficiency of the cooling system
- Increased fuel economy All of our electric fans kits are packaged complete with instructions and mounting hardware for quick and easy installation
CAUSES OF OVERHEATING IN ORDER OF LIKELIHOOD
- Fan facing wrong direction.
- Fan rotating wrong direction.
- Fan wired to coil or alternator (only 8 Volts.)
- No condenser fan.
- Temperature gauge faulty - disagrees with thermometer in radiator.
- Towing a heavy caravan.
- Inadequate kit fitted.
- Oil cooler obstructing ram air.
- Insect screen obstructing ram air.
- Driving lights obstructing ram air.
- Number plate obstructing race air.
- Battery not up to 13 Volts.
- Insufficient water in radiator.
- Radiator need5.cleaning.
- Radiator cap faulty allowing water to boil at 100°C.
- Thermostat faulty.
- Electric motor faulty.
- Fan not in hot corner of radiator.
- Engine out of tune or idling too fast.
UPSTREAM (PUSHER) OR DOWNSTREAM (PULLER)?
Davies Craig Electric Thermatic Fans can be simply set up to either push air through the radiator or pull air through it. A upstream (pusher) fan sits flush up to the front of the radiator core. A downstream (puller) fan on the other hand sits right behind and flush with the rear of the radiator core. The downstream puller fan pulls air through the radiator and has less impact on airflow at high speeds than a upstream pusher fan since it is behind the radiator.
A downstream puller fan is slightly more efficient than a upstream pusher fan. A puller draws the air in at any angle and around obstacles like a vacuum, pulling the hot air from the radiator at a constant wind force, known as CFM, Cubic Feet per Minute. A upstream pusher fan will push air through the radiator and, on occasions this may cause some bounce and as a consequence may lose some of its flow. When pushing air the fan will commence with a certain CFM but then as the air hit the fins and tubes and creates turbulence you may lose some air flow. Also, once the vehicle reaches around 60 kph the stronger ram air takes over and the electric fans become superfluous. Hence an uninhibited frontal radiator area offers greater cooling efficiencies at highway speeds.
Now, what is vital is the size and indeed the strength (wind velocity known as CFM) of an Electric Fan. If space is an issue between the rear of the radiator and front of the engine then install the largest Electric Fan possible at the front of the radiator.
The more air flow, being pushed or pulled through a radiator, which is usually related to the size (diameter) of the electric fan and the strength of the electric motor, the better. Hot air extracted from a radiator, known as heat exchange, either being pushed or pulled should exit the rear of the engine bay essentially uninhibited/unobstructed.
Finally, Davies Craig Thermatic Electric Fans are manufactured in Australia and offer reverse polarity which means they can be mounted as either a ‘pusher/upstream fan’ or ‘puller/downstream fan’ by simply reversing the wiring and turning the blade over on the shaft. All Davies Craig Electric Thermatic Fans are accompanied by a 2-year unconditional warranty.
Straight vs. Curved Fan Blades - Dispelling the Myth!
The relative merits and technology of curved vs. straight fan blades, has been debated for some time. Davies, Craig conducted an extensive research program to formulate the design of fans in which several design types including curved blades with and without a ring were considered. Curved blades generated less noise but at the expense of a significant loss in performance caused by the fact that curved blades stall at a lower static pressure than straight blades. If a fan moves less air, then, simply you can expect less noise. As shown in the performance curves below, Davies, Craig Thermatic Fan outperforms its competitor across the full pressure range:
Noise Control: Most fan noise is generated from a blade passing a shroud strut. The noise level is higher when the whole length of a blade overlaps/passes a shroud strut and if all the blades pass all the struts of a shroud at the same time, NOISE IS AT ITS WORST. Some manufacturers have chosen to curve the blades and keep the struts straight. Since this approach significantly affects performance, Davies, Craig has proven it's best to adopt the reverse approach of having straight blades and curving the struts.
Our investigations also found that when air flowed in layers (laminar flow), it breaks up into counter rotating airflow vortices (whirlwinds): Figure 2
These vortices consume energy and therefore reduce the airflow. It was found that by inserting triangular protrusions near the leading edge of the blade, the air is tripped into going into vortices earlier but they were much smaller and removed much less energy therefore making the blade more efficient (Figure 3).
The idea of a ring around the blade tips was also researched and rejected since the performance suffered due to the increased energy required to propel the blade with the extra weight at the tips. While the purpose of a ring is to reduce losses from air passing from the high-pressure side of the blade to the low-pressure side as shown, Davies, Craig managed to achieve this by adding winglets to the blade tips without energy loss.
When all aspects of blade design are considered, straight blades with tips, winglets and the correct shroud is the optimum, test-proven combination for efficient fan operation.