I tried to watch a Google video of a Diesel Heater but the guy talked extremely fast with a strong (down under) accent.
I guess the heater burns diesel fuel maybe in an engine and the muffler gets hot. Users hope that it does not leak carbon monoxide. My car heater uses the engine liquid cooling system.
Hey! Maybe the diesel heater also uses the engine liquid cooling system?

Some ads for a Diesel heater mention AIR. Maybe the engine has a fan and uses air cooling that can be used to heat a tent?

 

I suspect it works like the kerosene heaters used by construction workers in cold climates. Simply atomizes the fuel, mixes it with air, and burns it, blowing the heated air into the room. Seems a bit dangerous CO wise.

 

I have a 12v 8kw diesel heater

Just how is the 12V used? Fan/blower power? Diesel fuel pump to an atomizer? Both? Where did you get the 20A rating from? Is there a circuit diagram or equipment diagram available? My kerosene heater is unpowered and could run on diesel... Is this a "Salamander/Torpedo" heater? All we have to work on is it needs 12V/20A (for what). It either produces or requires 8kW. It heats with diesel fuel? Or heats a diesel engine? If you are simply looking for a 12V/20A power supply, I'd get one capable of producing more than the 20A required to give it some headroom instead of running at its limit nonstop. I'd go for 25A to 30A capacity if that is the case.

 

8 Kw @ 12VDC is almost 700Amps.

 

After some confusion we have learned that the 8KW is the heat output from burning fuel, not the electrical input to run fans and atomizer.

 

12V 20A is 240W. But you said the heater was 8000W.

One of those better be wrong or you’ve got a problem.

8 Kw @ 12VDC is almost 700Amps.

Yeah, I gotta agree. 8kW ÷ 12V = 666.6 2/3 amps. Something is obviously wrong with the description. Been re-reading the posts and it appears we're talking about a heater and not an engine warmer. I can't see using 8kW to heat a Diesel engine. Not unless you want to fry the oil and potentially burn down the house.

Some have suggested using a 30A power supply on a 20A system. Others suggest that a 20A supply is sufficient. In my limited experience with engineering I'd opt for 1 1/3 to 1 supply to demand. If you draw 20 amps then a 30 amp supply is more than enough. 30A is actually 1 1/2 to 1 supply to demand ratio. My reasoning and experience is that 133% supply to demand is good commercial practice. 150% supply to demand is common in defense, medical and automotive where mission/life critical equipment is of consideration. I've worked all four manufacturing arena's, commercial, medical, defense and automotive fields. When I worked at JPL it was not uncommon to see engineering of both 200% and 101%. Why so low in some cases? Because of weight and power. Satellites require very low power. Consequently their engineered with devices that can be ESD sensitive down to 50 volts static. And they do that with regular success. Back in the 70's and 80's they leaned toward over-engineering (200%).

If weight and space is not a major concern then I'd recommend 30A supply. I have a 12V blower that one day I hope to connect it to a fireplace to bring heat into the room while exhaust gasses go up the chimney. Those are plans that seem to never come to fruition. But the blower is connected to a 30A fuse. My plan is for a variable speed control. Space is not a concern.

 

Here's one type of heater the TS might be discussing. This one is battery powered using 20V batteries. Not suggesting anyone buy this heater, just highlighting it because kerosene and diesel fuels are rather similar.
https://www.lowes.com/pd/DEWALT-90000-BTU-Forced-Air-Indoor-Outdoor-Kerosene-Heater/5002158871
Notice this heater is 90,000 BTU. Don't know what that would cross over to in converting BTU to kW's. I'm now wondering if the TS is talking about an 8000 BTU diesel heater.

 

12V 20A is 240W. But you said the heater was 8000W.

One of those better be wrong or you’ve got a problem.

Maybe the heat output of the diesel heater is 8kW, but the electrical supply that it needs to run it is rather less than that.

 

Maybe the heat output of the diesel heater is 8kW, but the electrical supply that it needs to run it is rather less than that.

Maybe. But in nearly every high powered heating system I've seen them rated in BTU's. My wife's hair dryer is rated at 1500 watts, my radiant heater is rated at 1800W. But my furnace, which runs on a fuel, this case natural gas, is rated in BTU's. Off hand I don't recall what it's rating is but I do know it's in BTU's.

 

We still don't know the purpose of the 12VDC power supply. Maybe it is to power the blower?

 

I've seen engines rated in kW instead of horsepower but the guy is in the UK so I'd expect the heater to be rated in British Thermal Units instead of kWs.

 

Until we "know" - we don't.

 

Maybe it is to power the blower

I'm pretty sure what he has is a Salamander, also called a Torpedo, electrically blown heater that uses diesel as the flame fuel for heating. It may also have a small electric pump to push fuel through an atomizer jet. But, most of those have line powered electronics inside. I don't think I've ever heard of a 12V powered unit but I learn something new every day...

 

We still don't know the purpose of the 12VDC power supply. Maybe it is to power the blower?

Seemed obvious to me that he was talking about some sort of engine heater.

Why not stop bashing the OP?

 

Seemed obvious to me that he was talking about some sort of engine heater.

unlikely, more likely one of these
https://www.machinemart.co.uk/c/diesel-paraffin-heaters/?Brand=clarke

 

I suspect that the 12V at 20A is used for the starter motor on the diesel engine. The tent probably does not have a furnace or fireplace.

 

No. I am going with a 12VDC RV, camper or trailer heater.

 

No. I am going with a 12VDC camper or trailer heater.

Which he actually said eventually.

 

Hi,
The way the TS describes the project is that the 12V 20A heater is to raise the temperature of the diesel oil tank from say freezing to a combustible fluid for burning in the 8kWatt heater furnace.

E
Use your history lessons from the WW2 regarding the diesel vehicles on the Russian front

 

https://uk.vevor.com/diesel-heater-...itch-for-truck-boat-trailer-rr-p_010680521746
if you look down in the Questions and Answers the first reply says that it needs. 12V 20A supply.
Seems a lot to me, but a domestic oil-fired boiler needs 170W.
You would end up with a motor home with a flat battery in no time.