Genuine questions, as I genuinely am puzzled. Although I have had night heaters fitted in some motors, I have never actually had to use them.
I have seen in several threads that they can flatten the batteries. But I am/was under the understanding, (or I read somewhere), that they (or some versions at least) work by a small diesel engine that provides heating, and trickle charges the batteries while in use.
Is this just one type of heater? If so, how do they generally work? Are they just little 24v fan heaters? Does the type of heater I mentioned exist? I have no idea where I got it from, but remember a diagram so I guess I read it somewhere.
I found (last night) the heater was too good on a low setting so turned it off, the one I have has a timer so theoretically you could set it for every hour or two if yours has that function.
I was just chuffed to suss out the on off button then got technical with temp settings 
Night heaters all work the same way. A small combustion chamber is heated by burning diesel (or petrol) from the vehicles fuel tank. The warm air is blown into the cab by an electric fan, fumes are blown through an exhaust to the outside. The fuel is initially ignited by a spark, also from the battery.
All these heaters are supposed to have a control that prevents them from working when the battery voltage drops, thus leaving enough charge to start the engine.
Hi Santa, you need a certificate from nasa to work the remote on mine.
I did okay with my certificate from the European Space Agency 
(I delivered there )
Every night heater I ever used in the UK never drained the battery unless the vehicle had faulty batteries that is. On Fed Ex I would leave mine on 65 degrees all weekend with no problems. Truck batteries are more reliable than most think, we only have 12v systems in trucks here but I can leave my fridge, TV and floor lights on sometimes up to 16 hours a night without it flattening the batteries.
The night heater on my volvo FH is easy press the switch turn the temp dial and leave it, 2 nights out last weekend left it on for 12 hours lovely and warm 
Jeff
When diesel night heaters start up they don’t use a spark but a glow plug- a wound heating element that glows red hot until the combustion is stable after 3-4 mins. They also get activated during shutdown of the heater to make sure no unburned fuel is left in the combustion chamber.
The glow plugs draw quite a current when on- and it’s this that can be an issue- hence why some people say having them on low can cause issues with them coming on and off constantly. Never had an issue myself but if you have weak batteries…
Set mine to come on at 03:00 Monday, cab will be nice and warm and windows defrosted when I get in at 03:45
Well the one in my actros is crap just keeps you warm and no more, I checked air intake vent if that blocks it sometimes fails but seams clear will need to get into merc as winter is a coming!
Fallmonk:
Well the one in my actros is crap just keeps you warm and no more, I checked air intake vent if that blocks it sometimes fails but seams clear will need to get into merc as winter is a coming!
You having a cheeky night out last night? Seen you parked round the corner at 4am.
I used to have a little webasto one that was great, had it on full bollox when out the cab for evening meal then set thermostat a bit lower so it didn’t wake me up too much, could reach up in the morning an switch it on before i made a brew.
Opened window a fraction for some fresh air just in case of fume build up.
Fuse used to keep blowing though and always turned my engine on for a couple of minutes before bedtime, probably not neccesary just for piece of mind.
Dipper_Dave:
Fuse used to keep blowing though and always turned my engine on for a couple of minutes before bedtime, probably not neccesary just for piece of mind.
I wouldn’t bother, the power drained by starting the engine will be more than will be recharged in just a few minutes of idling.
Can anyone tell me how to keep the axor night heater on all it does is keep turning off after A few hours and will not kick in even when freezing. The computer thing is akin nightmare
topmixer11:
Can anyone tell me how to keep the axor night heater on all it does is keep turning off after A few hours and will not kick in even when freezing. The computer thing is akin nightmare
leave the key in the radio position on the ignition and it stays on all night
Night heaters have a glow plug inside a heat chamber.When you fire one up a small pump pressurises diesel which is sprayed on to the glow plug,Around the heat chamber is a tube with an induction fan called the heat exchanger.As air from outside the truck gets drawn in it passes over the heat chamber,picks up heat and is blown into the cab.Most have a thermal cut out in case the flow of air gets restricted.The glow plug usualy draws about 15 amps to give a heater of about 300 to 400 watts.
Never run one on bio fuel as they go buggerd in no time as it screws up the glow plug.
A thermostat is usually mounted somwhere in the cab roof lining.