I'm planning a load of modifcations to the motorhome i'm building, one of them is to fit a second diesel tank (done) and have the back tank to hold greasle (cooking oil) The engine is a TDI, so i'll need to start her on diesel, then switch over to greasle when warmed up, i've got no problems with that.
The fuel tanks are plastic, and very easy to get at (4 bolts and it's off the chassis rail) so i'll be fitting a heating coil into the rear tank to heat the cooking oil in the cold weather (easy to add, i'll plumb it in so the connections are at hte top of the tank, using bulkhead fittings like i did when i added a breather for the new filler etc)
I'll be running a coolant line fron the engine, halfway back the van and then back to the engine, this line will be a loop, and i'll Tee off it at the end of the loop to fit a second heater matrix and fan to heat the living area of the van as i drive along, this will be a self contained unit, having a water flow valve and fan speed controll on the front cover,
As the coolant line to this heater will run past the fuel tanks, i'll just Tee off from the main line again and run the pipes to the tanks heater coil,
However i'm a little worried about heating the oil up a bit too much, the enging runs at 80 degrees C almost all the time, but has been upto 98 degrees C in the middle of summer, this is not a problem when cooking oil is in the tank, but when i go abroad i'll be putting regular road diesel in both tanks (as it can be got for about 40 pence per litre, there's no point farting about with cooking oil)
then i don't really want to be heating the diesel in the tank up past it's flash point (45 degrees C) so a simple cable operated valve could be put in the coolant line going to the tanks heater coil to shut the heater coil down in summer and when i have diesel in that tank,
however i'd rather be able to controll the temperature of the tank's contents a bit better,
Certian cars now have electronic controlls for the heater, i.e you set the dash display to xx degrees C, and it'll adjust the water valve as needed to get the heater to give out the correct ammount of heat.
i know most modern cars use a flap, the heater matrix is on all the time, but i know that certian slightly older cars had an electricaly controlled valve, and some even had a mechanical thermostaticaly controlled valve, i think certian volvo's had this system,
Can anyone give me any pointers to what cars deffinately have a electricaly controlled heater valve, in them, so i can see about getting one and either getting the temperature controll parts too, or building my own, i'd like to have the thermocouple inside the tank, reading the fluid's temperature, and idealy have a small temp display on the vans dash, with an adjustment knob so i can alter the temp of the fuel in the rear tank as required.
i'm having a bare bones computer in the van, and it'll run a GPS system, process a couple of camera's for reversing and parking as well as recording any people who get too near to the van, and this will display on a small screen in the dash, also i'll want to have engine data on that screen.. so i'll need to run some form of dyno type software, and have the relevent engine sensors to give the signals to the computer (oil temp, egt, oil pressure, turbo boost, voltage, current etc, so maybe adding a fuel temp, and having hte computer controll the valve to set the temp could be a posibility??)