diesel heater

2 Articles

Condensing Diesel Heater Hack Is Dripping With Efficiency

December 13, 2025 by 13 Comments

Not a huge percentage of our readers probably get their heat from diesel fuel, but it’s not uncommon in remote areas where other fuels are hard to come-by. If you’re in one of those areas, this latest hack from [Hangin with the Hursts] could save you some change, or keep you  ̶2̶0̶%̶ ̶c̶o̶o̶l̶e̶r̶  25% warmer on the same fuel burn.

It’s bog simple: he takes his off-the-shelf hydronic diesel heater, which is already 71% efficient according to a previous test, and hooks its exhaust to a heat exchanger. Now, you don’t want to restrict the exhaust on one of these units, as that can mess with the air fuel mix, but [Hurst] gets around that with a 3″ intercooler meant for automotive intake. Sure, it’s not made for exhaust gas, but this is a clean-burning heater, and it wouldn’t be a hack if some of the parts weren’t out of spec.

Since it’s a hydronic heater, he’s able to use the exhaust gas to pre-heat the water going into the burner. The intercooler does a very good job of that, sucking enough heat out of the exhaust to turn this into a condensing furnace. That’s great for efficiency — he calculates 95%, a number so good he doesn’t trust it — but not so good for the longevity of the system, since this intercooler isn’t made to deal with the slightly-acidic condensation. The efficiency numbers are combustion efficiency, to be clear. He’s only accounting for the energy in the diesel fuel, not the energy that heats the water in his test, for the record; the electrical power going into the blower is considered free. That’s fair, since that’s how the numbers are calculated in the heating industry in general — the natural gas furnace keeping this author from freezing to death, for example, is a condensing unit that is also 95% efficient.

Another thing you can do to get the most from your diesel heating fuel is add some brains to the operation. Since this is a hydronic system, the cheapest option, long-term, might be to add some solar energy to the water. Sunlight is free, and diesel sure isn’t getting any cheaper.

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Intelligent Control For That Cheap Diesel Heater

September 21, 2019 by 40 Comments

If you own a caravan or a boat, you’ll know that keeping it warm can present something of a struggle. Open-flame gas heaters carry a risk of carbon monoxide poisoning, while solid fuel stoves are heavy and require safe flues. The prospect of a diesel heater then is enticing, bringing as they use a safer fuel and allow for easy external exhaust. Unfortunately they’ve been something of an expensive option, but the arrival of cheap imported heaters in recent years has made them an attractive choice. [Ray Jones] has improved upon their sometimes basic control electronics with the Afterburner, an intelligent controller that packs both ESP32 and HC-05 modules to both enhance the feature set and the connectivity of the devices.

The full list of capabilities is somewhat exhaustive but has a few stand-outs such as the ability to connect 1-wire temperature sensors to the system. It’s not compatible with all the heaters on the market, but there is a comprehensive guide to those models with which it can work. Meanwhile, all the code and other resources are available on GitLab should you wish to try it for yourself.

Diesel is something of a dirty word in 2019, but maybe biodiesel will save devices like this one.

Thanks [Bob] for the tip!