An Affordable Diesel Heater to Warm Your Boat

This is a guest post from a Canadian cruiser who has spent many a chilly fall heading south. His first-hand experience with diesel heating on a boat is something we wanted to share.

A good diesel heater for your boat can run all night safely, use very little fuel, and cost under $200 installed. I know because I found one.

I’m a Canadian from northern Ontario, so cold weather and I have a long history. That experience has been useful while cruising south in the fall, when Old Man Winter occasionally catches up with me.

Starting with Propane

My first heating solution was a Mr. Heater Little Buddy — the same propane heater Carolyn covers in her article. It worked, but needing to store it when not in use got old quickly.

I upgraded to a propane ice hut heater, permanently mounted to a bulkhead. That one connected to a 10 or 20-pound propane bottle and worked well enough. I added a fan above it to move the heat around. Total cost: under $200, including the fan.

But propane heaters come with real drawbacks on a boat.

Safety: They use an open flame, which consumes oxygen. You need a unit with an oxygen depletion sensor that shuts it down before levels get dangerous. You also need a working CO detector aboard — no exceptions.

Fuel consumption: Propane burns fast when you’re heating a boat. You’ll run through a 20-pound tank in roughly two to three nights of eight-hour use. That is not practical for extended cruising.

Condensation: Propane is a wet fuel. In weather under 45°F, you will get significant condensation on your overhead and walls, which means constant wiping down on cold mornings.

Because of the overnight safety concerns, I never ran my propane heater while sleeping. Run it in the evening, shut it off, restart in the morning. It worked, but it wasn’t the answer.

Discovering Diesel Heaters

When my propane unit finally quit, I started researching replacements and found diesel heaters — sometimes called parking heaters or bunk heaters.

The well-known brands are Webasto (German) and Espar (American). Truckers use them for cab heating. They start around $1,000 and go up from there. Defender carries one model at $3,200.

The biggest advantage of diesel heaters is where you mount them. You do not have to put the heater inside your living space. You mount it in an outside locker and run ductwork into the cabin. The exhaust stays completely outside, which means no CO risk inside the boat. You can run it all night with the hatches closed and sleep warm and safely. That is something you simply cannot do with a propane heater.

You can also plumb the heater into your onboard diesel tank rather than rely on the small tank that comes with the unit.

Over $1,000 for a heater I might use a few weeks a year while heading south, though? That stung. Then I found Chinese diesel heaters.

Chinese-Made Diesel Heaters

These units are popular in the van conversion and RV world. They appear functionally identical to the Webasto and Espar units — same components, same design, a fraction of the price. Mine cost $120. Cruisers and van lifers alike widely use units like the Vevor diesel heater (Amazon).

The kit comes with everything you need: the heater unit, a control panel, a small diesel fuel tank, a fuel pump, an exhaust hose, a fuel hose, a short piece of ducting, and miscellaneous hardware.

Installing the Heater

Installation is straightforward and requires nothing more than a screwdriver and a wrench. Most boaters mount the unit in an outside locker and cut a hole through to the interior for the ductwork. Some run the ductwork behind panels for a cleaner look, with just a vent visible inside. Every boat will be different.

Connecting the fuel and wiring is essentially plug-and-play. A few things worth knowing before you start:

Make sure the exhaust outlet and the combustion air intake are on opposite sides of the boat.

Use properly sized wiring and fuse for the load. Undersized wiring means you won’t be able to start the heater — I discovered this the hard way. Our 12 Volt Wiring Size Chart takes the guesswork out of sizing wires correctly.

The ductwork gets hot. Be careful where you route it.

The exhaust pipe runs very hot and requires a stainless steel extension to exit safely. You may also need a longer exhaust pipe depending on where you locate the unit.

David and Dan on SV Whitetail put together this short video showing their install. It’s not the Vevor, but very similar and a great real-world look at how it comes together on an actual cruising boat:

Decoding the Manual

The manual that comes with Chinese diesel heaters is written in what I can only describe as incomprehensible English. It is, by a factor of 1,000, the most challenging document I have ever tried to interpret. One passage, in a section on temperature control, reads: “…which makes gears clearly shown and is very convenient for the part old hands.” There are no gears. I still have no idea what “part old hands” means.

The controls include an “up regulation” and “down regulation” button. Neither is labeled with an arrow. I got the heater running quickly, then spent considerable time unable to lower the output while sweating in 85-degree heat.

Eventually, I gave up and went to YouTube and several online groups dedicated to these heaters. Between those resources and some trial and error, I pieced together the basic operations. Budget some time for that learning curve.

How I Use It Day to Day

I was never able to figure out the timer function. As it turned out, it didn’t matter, as my unit came with a remote control fob.

Lying in bed at 40°F outside, knowing I have a fob under my pillow that will fire up the heater before my feet hit the cabin sole, is a very good feeling.

Because the heater sits in an outside locker with the exhaust vented outside, there is no carbon monoxide risk inside the cabin. I run it at its lowest speed through the night. At that setting, my 2.5-gallon tank lasts over 20 hours. Advertised fuel consumption is 0.1 to 0.24 liters per hour, which tracks reasonably well with my experience.

When it’s chilly at wake-up, I bump it to high for a few minutes. By the time coffee is ready, the boat is at 72°F.

What to Know Before You Buy

You can also get a self-contained unit with the fuel tank attached — similar in concept to the propane portable setup, but diesel and safe to run overnight.

A few more details worth knowing:

• These heaters are quiet. Installed in an outside locker, you won’t hear anything.
• They draw more power during startup than during normal operation, but only for a couple of minutes.
• Replacement parts are widely available, and at under $100 for a complete replacement unit, a failure is not a financial crisis.
• I’m now in year two with no issues.

The Vevor diesel heater on Amazon is a solid place to start if you’re shopping.

For a broader look at staying comfortable in cool weather aboard, Stay Warm When Cruising in Chilly Weather covers gear well beyond just heating.

Learn More

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