Diesel heater

It will be showing a fault code. Might be best to start with that.

It could be a lack of battery charge (they do draw a decent amount on start up), but it could be other things also . No need for lithium, we have run our heater for 8 years now on our lead acid batteries.

If you're in a fairly cold area, it could be fuel waxing. It effectively solidifies in the lines and prevents the heater from starting or running.

I run my heater on Jet-A (kero). That's good down to about -45 deg C. A 50:50 mix of kero and diesel will prevent waxing.

Good luck.

From the couple of heaters I have come across they have a set start up regime. Not sure if yours does. Mine does the following. Switch on and the fans starts blowing. Fan stops and then you hear the pump start to click. wait a minute then the fan starts up (I assume the glow plug is warming up to ignite the fuel). Then the fan starts working and heated air starts coming through. I had an issue with mine last trip. The air intake hose had been hit by so many stones it starved the unit and as a result failed to iginte. The unit tried 3 times the above regime then through a fault code that had nothing to do with air starvation. Just happened I was under the van and noticed the crushed hose. Fixed that and all good!

If the battery is low or the wiring not sufficient you will have starting problems for sure. No need for Lithium though, just a battery in good condition.

Which brand of diesel heater do you have? The solutions are completely different depending on brand.
What capacity is your diesel heater?
Do you get an error code?
Low voltage is a major issue with diesel heaters. If a Chinese heater the power supply cable supplied with them is undersize to start with, which doesn't help matters. You want a minimum 6mm auto cable twin sheathed which is 4.57mm2 to with 300mm of the diesel heater.

Lithium batteries are *magic* if you need battery replacement.

Hi to all who responded about our parking heater problem , sorry bit with response
Van in storage .. brought extra battery ,work well first night but on power ,second night free camp would not start ,will check wiring to see if that’s the issuer ,if that doesn’t work we will start wearing a Bennie . Thanks for all your information
Cheers. Bill