The Vow2 is an inline 90oC 12volt fuel heater.
* * * * * All Vow2 Heaters are fully automatic 90oC or 70oC fuel heaters * * * * *
(Means
that anybody can drive the car without needing to know about oil or switching.
Get in and drive)
First
a bit about the heater.
The Vow2 is an inline glow plug fuel heater originally designed for a 2L Turbo Diesel. The Vow2 has been built with the aid of expert mechanics and engineers. The original Idea was to design a heater so that anybody could fit it with a screwdriver, pair of pliers and a bit of common sense. It must also work with 100% diesel (Achieved by switching it off) and not require the driver to do anything else.
The current design evolved over a number of tests to become the Vow2. The first was an indirect heater that sadly just couldn't get the oil hot enough. The Vow2 has been extensively tested for over 3 years with only 2 serious problems. In both cases it overheated due to sensor faults. Sensors are now modified to ensure this doesn't happen again. Yes I know its the unknown problems that are a concern. There is no doubt that the initial cold start will increase wear on the pump and engine. There is also no doubt that Straight Vegetable Oil SVO has better lubricity than Diesel when heated. So the question becomes, does one outweigh the other ???? In tests so far, which includes 3 engine strip downs, the opinion is that it does. It must also be noted that Lucas and HDis don't convert well on a single tank and are better suited to twin tanks.
The Vow2 is probably the most
effective electric fuel heater currently available for the money. Cheaper than
the German alternative but made from the same high quality components and just
as reliable. It is a 12volt
heater that unlike some other inline heaters reaches a high temperature quickly.
This is possible by having the NGK plug in direct contact with the fuel. The
small size also ensures rapid heating. The body of
the heater heats up and helps to heat oil at high fuel flows to reduce the risk
of shock cooling. No need to have difficult starting or wait to switch over after
waiting for water temp with other heat exchangers. By the time your normal glow
plugs have heated the engine the fuel temp should be sufficient for starting.
Ideal for a single tank conversion and short journeys.
With the new + plug fitting the unit is simpler than ever to maintain. Off the shelf NGK 924J plugs can be used. Fitting is a simple matter of unscrewing the plug with a 12mm spanner and refitting the new plug.
The unit fits inline before or after the fuel filter and heats the fuel up to around 80-90oC, this is dependant on fuel flow rate and starting temp. Fuel heat should not exceed 90oC. Fits 8 and 10mm fuel lines. Size of the units varies depending on which unit.
So what are my options in order of best for the car...For and against.
1 Use Bio Diesel. No need to convert the car.
Easy to do but you pay for every litre which makes it as expensive as dino diesel. No real quality
control yet but that will come. Might need a Standyne 10oC heater in the widdle of minter. Bio isn't as
green as it looks due to the production.
2 Twin tanks, switchover valves and water heaters.
Kits can be £300 to £500 and £1200 fitted. Self fitting can be quite difficult. Allows 100% veg oil to be
used so will save £££ on fuel. You still need to use diesel so it's not really 100% especially if you only
use the car once or twice a day for short trips.
3 Twin tanks, switchover valves and electric heaters.
As with option 2 but it will heat faster so not as much diesel needed and starts paying off with the
shorter trips too.
4 Single tank with electric and water heaters.
You can pay £100 to £200 and you will get 80-95% oil depending on the car, pump ect. You still need a little diesel. Stresses the pump
a little at startup. Quite easy to fit.
5 Single tank with electric heating.
This is your cheapest option at £30 to £150 and 70-90% oil can be used depending on the car, pump ect. Quick and easy to fit. Pump is
stressed more at startup but only lasts 120 seconds before hot oil is delivered.
Well there you are. If you use less than 2500L no duty to pay. You can spend 56p a litre on clean oil or filter (5 Micron) dirty oil. My heaters address 3 ,4 and 5. They can also be used on option 1 in the middle of winter.
Be selective about the dirty oil you use as water and high acid contents may damage the engine.
Direct contact heating V indirect heating.
It has been claimed that indirect heating of veg oil is both safer and as effective as direct contact heating. This just isn’t the case. The Vow1 was an indirect heater but was discontinued due to poor performance. It failed to heat oil for cold starting and failed to give adequate heating under high fuel flow conditions. This indirect heater was never sold due to it's poor performance.
Indirect heating
As the fuel is only heated by the surface of the bore while it is passing through the block the heat exchange potential is very limited. The oil will not start to heat until the block has started to get quite warm. Only the oil in contact with the surface of the bore will heat and the fuel in the center of the flow will still be cold. The oil at high fuel flows will spend such a short time in the block it will hardly be heated at all. This will become more evident in the winter months. No matter how well fitting the plugs are in an indirect heater there will be air around the plug. A glow plug in air will fail very quickly. The speed at which an indirect heated block can get fuel up to 90oC under low load conditions on a 1.9 TD was about 10 mins. Under higher load conditions fuel fell back to 30oC.
Direct heating.
The fuel absorbs all the heat from the plug as it passes through the unit. The unit absorbs heat from the fuel in order to heat up. Once up to temp the fuel has a much bigger and hotter surface area where it can absorb heat. As the plug passes through the middle of the fuel flow oil in the center of the flow is heated. Oil touching the surface of the heater will also be heated. At high fuel flows the direct heating unit will maintain a much higher average fuel temp. This is because the plug is still in direct contact with the fuel and the fuel is in contact with the surface of the heater. As the plug is immersed in liquid all the heat is absorbed. In this way the plug never reached the very high temps that cause plug failure. The speed at which direct heating can raise fuel to 90oC under the same test conditions was 180 seconds. Under high load conditions temperature of the fuel fell back to 70oC.
Safety
It has been indicated that the direct heating of oil is not as safe as indirect heating. This simply isn’t true. Both ways of heating use a sensor to turn of the plugs. Both turn of before 100oC. Cooking oil has to be a lot hotter than this before it ignites. Ask you wife the next time she makes chips how hot the oil needs to be. Deep fat fryers use indirect or direct heating depending on the design and both have passed safety tests. I use both direct an indirect on the twin chamber models. The indirect is suitable as a pre heater while direct is more suitable for heating before the pump.
Reliability
I use an over rated relay and cable for each glow plug. We use top quality NGK glow plugs. On the twin plug unit’s twin relays, Cables and fuses are used. In this way a level of redundancy is included to ensure if one system fails the other will continue to heat until it is repaired. As the plugs are immersed they will last much longer than indirect heating plugs.
Control
You can control the units in any way that suits your application. The gray ignition live wire can be connected to an ignition live for fully automatic use. If manual control is also needed adding a switch to the gray gable gives full manual control as well. I do not supply this switch as every car has a different type of fascia. You can select a button that suits your application for a couple of pounds.