Thread: Cheap Ebay diesel heaters

Doesn't look like it has a muffler, but if it needs one, I'll sort that later. It won't be used while we're asleep or anything so that's not an issue but no idea how loud the exhaust is to be honest.

Linky here - 12V 5KW Diesel Air Heater Tank 2 x Vent, Duct, Thermostat Caravan Motorhome RV | eBay

Use Promo code 'Awesome' and it knocks $32 off.

Originally Posted by Homestar

Doesn't look like it has a muffler, but if it needs one, I'll sort that later. It won't be used while we're asleep or anything so that's not an issue but no idea how loud the exhaust is to be honest.

Noise can be greatly reduced with intake and exhaust silencers. I bought a muffler for a small 2 stroke motor bike and a tiny conical air filter (25mm again) from ebay, total cost $25. For a fuel tank I used a 10 litre gerry can with the supplied pickup and a $2 one-way air valve (ebay again). Easy.

On another note though ...
I bought a 'no-name' diesel heater 2 years ago and it has been faultless. Except for one thing (that no one has mentioned here), they are voltage sensitive at startup. Let me explain ...

Inside the heater diesel is sprayed in a fine mist onto a nickle/chrome wire loop that is at ~600°C. Some of the heat from the burning diesel keeps the wire hot (and an insulated ceramic base helps), but how does it get heated up in the first place? Electricity ! Lots and lots and lots of electricity.
At startup it will need around 5 amps at MORE THAN 12 VOLTS for at least 1 minute to get the wire hot enough to get the fuel burning. The 5 amps for 1 minute is not usually a problem, but at 2am in the middle of winter the batteries (stored under your van) will most likely drop to 9 volts after 30 seconds of heavy use and NEVER HEAT THE NICHROME WIRE ENOUGH for a start. (The same is true for a 24V system, it will drop to ~18V under load in the cold).

If your batteries are fully charged when you go to sleep the heater will happily cycle on and off all night as required, but if you have parked in the shade all day, watched TV, run the water pump for a shower or just had some lights on for a few hours your 12 volt system MAY NOT be at its optimum level, particularly if the batteries are more then a few years old. If you need the heater to work on a cold winter's night make sure your batteries are fully charged (easy at a powered site) or you will be disappointed.

Some one (maybe an RV magazine tester?) should investigate how to get a reliable 12 volts from a battery bank. Maybe a 10 amp continuous DC-to-DC converter, maybe a small 6 volt 'helper' battery with an auto switching circuit that adds it in when needed, maybe some new technology that mere RV users don't know about yet? Not just for diesel heaters, but for all the other 12 volt demands in modern RVs.


bye.

The air inlet, exhaust outlet and exhaust tube are usually ~22mm so 'standard' 25mm (or 1") parts will fit around them. I bought a small air filter and a muffler for a small trail bike from ebay for less than $30. During normal running it is very quiet with only a little 'jet roar' during startup.

bye.

Although several people have mentioned that these diesel heaters draw 5 or more amps for a minute or two at startup, no one has said a thing about the voltage requirements. We bought a no-name heater 2 years ago and have found it excellant, except for one very cold night ... Let me explain -


Inside a diesel heater a thick piece of nickle/chrome wire is heated to over 600°C with lots and lots of electricity and as it heats its resistance increases. When (if) it gets to 600°C it will set fire to a thin spray of diesel. Once the diesel is burning the wire will stay hot (from the flame) and the power can be removed.


But it takes both amps and volts to get the nichrome hot enough. And there is a problem with cold lead/acid batteries, the chemical reaction that produces electricity slows and voltage drops rapidly. A battery at 20°C may supply 5 amps at 12.3 volts = 61.5 watts, but the same battery at 0°C may only manage 5 amps at 10 volts = 50 watts; that's 12% lower. And this power drop is happening at the same time as the nichrome's resistance is increasing, requiring even more power to achieve the ignition temperature of diesel.


What this means is that your 12 volt battery system needs to be sized to supply the power you need at 0°C (not the 20° or 25° shown in the specification sheet), and it must be fully charged in order to start and restart and restart and restart your heater all through a cold winter's night. [ask me how I know about voltage droop]




There are several ways to ensure adequate 12 volt power -
* Oversize your battery system x 2
* Plug in to mains overnight to keep the batteries 'topped up'
* Run a generator for a few hours each cold day to keep the batteries 'topped up'
* Use a voltage boosting system,
... either a DC-to-DC boost converter
..... or switch in an additional 6 volt battery to make up for the loss


Maybe one of the RV magazines could do a tech story on what is actually required to have a (2 year old) battery system be able to cope with the demands of a modern RV; - lighting, water pumping, fridge management, TV, phone charging and heater startup. And maybe they could do some testing to show which 'solutions' work best when 500km from nowhere.


bye.

Some camper trailer manufacturers offer diesel heaters/hot water as an option. The ones I've seen have the unit outside the main tent and on the drawer bar for ventilation, with the warm air ducted inside.
Diesel is safer than petrol. Many 4WDs are already carrying diesel in 20 litre drums, so it removes the need to carry petrol or gas for heating. I assume a diesel heater would use less power than a 12 volt heater.
We recently bought a portable gas hot water heater for use with an outside spa. I assume we could also take it camping, but haven't thought about piping the warm air inside the camper for heating. I guess it's possible.
Personally I just wear socks and long pyjamas to bed and cuddle the wife!

Originally Posted by Homestar

Doesn't look like it has a muffler, but if it needs one, I'll sort that later. It won't be used while we're asleep or anything so that's not an issue but no idea how loud the exhaust is to be honest.

Linky here - 12V 5KW Diesel Air Heater Tank 2 x Vent, Duct, Thermostat Caravan Motorhome RV | eBay

Use Promo code 'Awesome' and it knocks $32 off.

Sorry but i didn`t see the tank listed in the included extra`s
Let us know if you do get a tank

Originally Posted by bgennette

Although several people have mentioned that these diesel heaters draw 5 or more amps for a minute or two at startup, no one has said a thing about the voltage requirements. We bought a no-name heater 2 years ago and have found it excellant, except for one very cold night ... Let me explain -


Inside a diesel heater a thick piece of nickle/chrome wire is heated to over 600°C with lots and lots of electricity and as it heats its resistance increases. When (if) it gets to 600°C it will set fire to a thin spray of diesel. Once the diesel is burning the wire will stay hot (from the flame) and the power can be removed.


But it takes both amps and volts to get the nichrome hot enough. And there is a problem with cold lead/acid batteries, the chemical reaction that produces electricity slows and voltage drops rapidly. A battery at 20°C may supply 5 amps at 12.3 volts = 61.5 watts, but the same battery at 0°C may only manage 5 amps at 10 volts = 50 watts; that's 12% lower. And this power drop is happening at the same time as the nichrome's resistance is increasing, requiring even more power to achieve the ignition temperature of diesel.


What this means is that your 12 volt battery system needs to be sized to supply the power you need at 0°C (not the 20° or 25° shown in the specification sheet), and it must be fully charged in order to start and restart and restart and restart your heater all through a cold winter's night. [ask me how I know about voltage droop]




There are several ways to ensure adequate 12 volt power -
* Oversize your battery system x 2
* Plug in to mains overnight to keep the batteries 'topped up'
* Run a generator for a few hours each cold day to keep the batteries 'topped up'
* Use a voltage boosting system,
... either a DC-to-DC boost converter
..... or switch in an additional 6 volt battery to make up for the loss


Maybe one of the RV magazines could do a tech story on what is actually required to have a (2 year old) battery system be able to cope with the demands of a modern RV; - lighting, water pumping, fridge management, TV, phone charging and heater startup. And maybe they could do some testing to show which 'solutions' work best when 500km from nowhere.


bye.

Some good points there. My system will have 400Ah of batteries which is overkilled to the max, but I see your point. Other thing is I wouldn't run it overnight, I've camped under canvas at minus 7 and didn't need it, so doubtful I'd ever need to do that. Would like it to work the following morning before I get up though, so some testing come Winter will be in order. 😊

Fridge will be the biggest draw on power but thankfully the fridges demands will be the lowest when the heater will be used. If I start to run short of power, the heater would be the first thing axed from the system as well. I've lived without one while camping all my life so it's one of those little luxuries rather than something I actually need. 😁

Originally Posted by rangieman

Sorry but i didn`t see the tank listed in the included extra`s
Let us know if you do get a tank

Don't be sorry mate, now you've said that, I can't either... 😆

Will advise when it arrives...