I was planning on installing a diesel heater so I needed to find out: what size diesel heater do I need? Do I need a 2kW or 5kW diesel heater?

So I did some research and this is what I found: If you have a small or medium sized caravan then a 2kW diesel heater is the best option. If you have a larger van, pop top or camper trailer with a lot of canvas then a 5kW diesel heater may be better. Don’t even worry about an 8kW diesel heater… they’re too big for a caravan or camper (and are often just 5kW units anyway).

What’s interesting though:

There’s heaps of people out there that chose differently and are still very happy…

…it’s all about weighing up what’s best for YOUR situation.

Here’s some of the pros and cons:

2kW Diesel Heater: Big enough for most caravans

A 2kW diesel heater does a great job if you’re in a small space that doesn’t experience a lot of heat loss:

Because of their lower output you can get your van up to temperature and then have it ticking over on Low or Medium

(and then you shouldn’t have to worry about constantly turning it off and on)

2kW Diesel Heater - Available off eBay

[The frequently recommended 2kW diesel heater here off eBay]

Pros:

  • Big heat for a little unit. Even though 2kW is the smallest diesel heater, they’re capable of producing a lot of warmth. Most (but not all) people who’ve installed them even in 21 ft caravans say they’re fine.
  • Can be turned down lower. A 2kW unit on Low produces way less heat than a 5kW unit on Low. This can be a good thing if you’ve got a small space that heats up and keeps the heat.
  • Smaller case size. You can fit a 2kW unit in slightly smaller spaces than a 5kW unit.

2kW vs 5kW Diesel Heater Size Comparison

Cons:

  • Faster equals louder. You need to run the unit at a higher setting to achieve the same heat output as the 5kW version. This means higher fan and fuel pump pulse rate (which means it’ll be louder if you’re in a larger van or you’re in a camper trailer with lots of canvas)
  • Takes longer to heat up. If you have a larger space they can take longer to get the room up to temperature.
  • Uses more fuel and power. To produce the same amount of heat as a 5kW diesel heater a 2kW will use more. 

Watch this quick summary:

Verdict: We started with a little 14 ft caravan…. if we’d installed a 5kW Diesel heater in it then we would’ve been cooking

(even if it was turned down to Low)

For a caravan this size a 2kW unit is perfect

2kW Diesel Heaters: This seller on here eBay is highly recommended and has 99.7% positive reviews

But in our 21 ft caravan when we did a lap of Australia?

A 2kW diesel heater would’ve been running on High just to keep the larger space up to temperature…

…which would’ve definitely annoyed the neighbours more!

[Read: 7 Tips To Quieten Your Diesel Heater Fuel Pump Noise]

5kW Diesel Heater: Great for larger vans or campers with lots of canvas

I’ve never come across anyone that’s said that a 5kW Diesel heater isn’t enough:

They work REALLY well

(the most common complaint is that they work TOO well)

Our 5KW Diesel Heater from eBay for Our Jayco Swan Camper Trailer

[The 5kW diesel heater we bought here off eBay]

Pros:

  • They’re VERY warm. If you need to warm a large area (or you have a caravan or camper with a lot of canvas that experiences a lot of heat loss) then these do the job really well.
  • Usually cheaper. For some reason there’s usually more 5kW diesel heaters for sale on eBay (so they’re at a cheaper price).
  • Quickly warms up your caravan or camper. If your caravan is cold and you want in warm quickly then these literally produce more than 2.5x the heat of a 2kW unit.
  • Quieter. You can achieve the same heating effect at a lower setting (so there isn’t as much fan or fuel pump noise).

Cons:

  • Needs to periodically run them on high. To stop diesel heaters getting a build up of carbon they need to be run on high. Because 5kW units are more efficient they’re typically run lower… so they need to be run on high for 15 mins or so every now and then.
  • Can be too warm. If you’ve got a small van then a 5kW unit can be too warm even when they’re on Low. This can mean needing to turn it off and on (or opening a window slightly… which can be good for condensation anyway).

Verdict: We sold our caravan and downsized to a Jayco Swan camper trailer…

Jayco Swan 5kW Diesel Heater Installation - Step By Step

…after I made my choice between a Gas vs Diesel Heater then we installed this 5kW that we bought here off eBay and couldn’t be happier

ReadJayco Swan Diesel Heater Installation [Step-By-Step With Pictures]

When we were purchasing I wasn’t sure what was more important:

  1. a. The small cabin size, OR
  2. b. The heat loss due to the canvas

John McK (the guy on YouTube who has hours of footage and benchtests piles of them) recommends that if you had to choose between the two, go the 5kW.

His view is that you can run it higher for a few minutes and burn off the carbon, whereas if you have a smaller 2kW unit and run it hard all the time it’s noisier AND more prone to wear and tear.

[when you watch his videos and see the logs that he has kept of testing hundreds of these things, he’s the person I’d believe]

Summary: Choosing between a 2kW or 5kW diesel heater for your caravan or camper

If you have a small caravan then a 2kW diesel heater (like this one from eBay) is the best option.

If you have a larger van, pop top or camper trailer with a lot of canvas (or you’re just not sure) then a 5kW diesel heater may be better:

It’s better to have too much heat than not enough

(you can open a window slightly which’ll help with condensation anyway… and you can turn down a 5kW but you can’t make a 2kW warmer)

Click here to see the 5kW Diesel heater we bought from eBay…

…or read our eBay Diesel Heater Review [Pros, Cons, FAQs]

PS: I haven’t gone into whether or not you should run your diesel heater on thermostat vs. manual Hz, the impact of a 0.02 mL fuel pump vs. a 0.016 mL pump for a 2kW diesel heater, etc… more to come on this!