Campervan Ventilation & Heating

We make a custom ventilation fan for the van's pop-out side windows, and we test an hcalory HC-A01 portable diesel heater for the campervan.

Camper van ventilation is critical to keep mold and mildew from ruining your day, especially in these cold and rainy Pacific Northwest winters.

In addition to camping with doors and windows open, enabled by the bug nets, I wanted an active fan to force air out of the vehicle, and some source of dry heated air to give me a fighting chance in the winter.

Ventilation Fan for Pop-Out Van Window

Not wanting to cut a hole in my van, I was forced to work with those pesky pop-out side windows for active fan ventilation.

So I designed a ventilation duct to exhaust air out through the narrow 1 inch window opening, laser cut it from plastic sheet, epoxied it all together and integrated two USB blower fans.

The main structure of the duct was made from ¼ inch acrylic sheet, while the portions that passed through the window opening were made from thin 2mm acrylic sheet to keep the plastic from taking up much of the narrow window opening.

If you are interested in a copy of this CAD model, you can download them here (.zip 764kB)

A local public library has a maker space equipped with a laser cutter/engraver, making it easy to precisely cut the acrylic sheets from my CAD model.

I used two AC Infinity blower fans because they were the right size, quiet, powered by USB and can be daisy-chained together so that the pair only uses one USB power port.

Ventilation fans basically result in outside air being brought into the van to displace inside air.  Thus, they will cause the inside air temperature and humidity to approach the outside air temperature and humidity.

The value of this comes into play when the inside humidity is higher than outside humidity, such as when:

• Moisture is brought into the van on wet clothing or equipment.

• Cooking inside the van.

• Breathing and perspiration from people and pets inside the van.

• Using a propane heater inside the van.

But a ventilation fan cannot bring inside humidity lower than outside ambient humidity.  This is where an externally vented heater or air conditioner comes in to play.

Portable Diesel Heater

Small portable heaters are now readily available in a variety of packages, some burning propane or diesel.  However, these heaters actually produce quite a bit of water vapor as part of their combustion byproducts:

Propane Combustion:    C3H8 + 5O2 → 3CO2 + 4H2O + Heat

Diesel Combustion:        2CnH2n + 3nO2 → 2nCO2 + 2nH20 + Heat

I chose to go with a diesel heater available from hcalory in a portable “toolbox” configuration, and will be running it outside the van, only plumbing the heated air into the van through the front window.

Here is my thinking:

• I’m sticking with a portable heater, versus permanently installing it in the van, so that I have the option to leave it behind when not needed, such as during the summer.  My van is small, so keeping all my systems small, modular and portable gives me options to leave things behind when not needed.

• Running the heater outside the van keeps all of its diesel fuel vapors, combustion exhaust vapors (including water vapor), pump noise and fan noise outside the van.

• Routing the hot air into the van through the front window, combined with my ventilation fan at the back window, makes sure that the warm dry air generated by the heater circulates throughout the van.

• With the heater located outside the van, it will be heating outside air to feed into the van.  This is not as efficient as having the heater inside the van, where previously heated air can then be further heated, but my van is small and I anticipate never running the heater on more than its lowest setting, so there is no real loss by locating the heater outside.  I may be singing a different tune if the outside temps drop below 0°F … so we’ll see.  It’s not so much the heat that I want from the heater (I sleep better in the cold).  It’s really the dry air that I want from the heater to manage moisture in the van.

So I purchased the HC-A01 heater, with 5 liter diesel fuel tank.  Similar heaters are also available through Amazon, including other models from hcalory.

The hcalory HC-A01 diesel heater has two operating modes:  an "always on" mode where you select a heat power setting from 1 to 10, and a "thermostat" mode where you select a target temperature.  I have only run my heater in this first "always on" mode.

Operation is very simple.  Simply attach the heater to a 12V power supply and press the power button.  The heater will say "start heating" and go through a fully automatic start-up process, including warming its glow plugs and pumping fuel to the combustion chamber.  This initial start-up process consumes up to 115 Watts of electrical power and can take a few minutes. The first time that it is fired up will take extra long while it pumps fuel all the way from the fuel tank, through the fuel filter, through the pump and to the combustion chamber for the first time.

Once the heater is running, simply rotate the dial on the control panel to select a heating power level ranging from 1 to 10.

Here are steady state results from a winter trip to a temperate rainforest in Olympic National Park:

• Heater located outside van, with heated air output run into van through front window.

• Heater running full-time on lowest heat setting.

• Exhaust fan running in back window to exhaust air out of van at approximately 40 CFM.

Heater & Ventilation Performance

Parameter	Outside Van	Inside Van	Difference
Temperature	38 degF	59 degF	+21 degF (warmer)
Relative Humidity	84%	56%	-28% (drier)

Most import to me, there was no condensation on the windows the next morning!

Also, here are the approximate fuel and electrical consumption rates:

Diesel Heater Fuel & Electrical Consumption Rates

Heater Setting	Fuel Burn Rate	Time to Burn 5L Tank	Electrical Power
Minimum (1)	0.08 L / hour	64 hours / tank	12 Watts
Maximum (10)	0.34 L / hour	14 hours / tank	45 Watts

More on Delica Campervan Conversion

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