Warning: converting a diesel heater to gasoline is NOT safe. First, the heater was not designed for it. Second, gasoline is much more volatile than diesel, so failures can have drastic consequences.
It also voids insurance. This post only describes my journey. It is not
a how-to, safety, or official guide. Do such a conversion at your own risk
Now that the beast successfully roars, it needs to be converted for high altitude operation, and gasoline coming from the Ford Transit's tank. The goal is to have a dependable heat source at up to 8000' (2400m) in -25°F (-31°C) weather.
A few people have done such a conversion, but with various degrees of success, it seems. The main issue is a heater that unpredictably stops working because of soot buildup at high altitude.
Cleaning up the soot requires fully disassembling
the heater, i.e. disconnecting all the pipes and wires, and crawling
under the camper van. Not something one wants to contemplate in the middle of
Winter 😅
The excessive soot is usually due to either too rich a mixture because of the less dense air, and / or too low an exhaust temp and airflow due to the heater throttling down to its low heat output setting once the desired ambient temp is reached. Our conversion will need to prevent both issues.
Since I could not find a definitive success story or a detailed conversion recipe, I shall succeed by stumbling till I reach the right mix of smarts, luck, stupidity and visits to Urgent Care. After all, it's just gasoline...
First, a programmable controller is necessary, as gasoline behaves differently than diesel. It combusts much faster, carries 15% less energy by volume and requires a different air / fuel ratio. So the fuel pump rate and fan settings must be modified.
Also, smoothing out the delivery of fuel to take care of the current not-a-good-sign 'woop woop' combustion sound will be needed. Hopefully, that can be done by replacing the fuel pulse pump with a smaller one, resulting in a higher pulse rate for a given fuel flow.
Controller
Unfortunately, since the controller that came with the heater does not allow changing the combustion settings, it had to go. Too bad, as it has a 'plateau mode' that slows down the fuel pump to adapt to the lower air density at high altitude.
Original controller:
Instead, a $40 programmable controller + main board kit was procured on eBay:
Although it was advertised for the 3KW and 5KW models, it should still be compatible with my 2KW heater. The design and parts (glow plug, pump, etc) between the models are usually the same, except for the bigger casing from 5KW up. Suppliers seem to be mostly playing games with the heat output spec by changing the pump rate and fan settings.
Main Board
The new controller came with a "Blue" main board that mounts inside the heater, as controllers & boards are not cross compatible between versions. So my "Green" board was replaced:
A couple of connections had to be adapted, though. The new board only has a 2 pin header for the heat exchanger's Temperature sensor. No big deal, the sensor's 3 pin plug still mounts to it. It just needs to be shifted appropriately such that the 2 wires mate with the 2 pins:
Also, since I did not replace the wire harness, the new controller's 3 pin triangular plug (3 pics above) did not fit the original 3-in-line-pins connector (4 pics above). But the wire colors and functions are still consistent, so I just cut away the plug and spliced the wires:
Fuel Pump
Right now, the current 'woop' sound emitted each time the fuel pump pulses means that a flameout event is just a throw of the dice away. And gasoline flameouts can lead to mini explosions on restart due to excessive fuel accumulation. Ask me how I know... 😅
To mitigate this, the original 22ml pulse pump was replaced by a 16ml pulse pump. Each pulse now injects ~27% less fuel.
So, to deliver the same fuel flow, the pulse rate of the pump needs to be increased. Ergo, matching a given diesel heat output value with gasoline should now theoretically require a 27 + 15 = 42% pump rate increase. Which should help smooth out the combustion bursts and result in a steadier combustion with a long woosssshhhhhh sound.
And with all that done, tada, we're now ready to fire up the dragon once again ! Onward to the tuning.
Let's just hope that this project will end less 'terminally' than how these heaters' marketing portrays them:
Car on fire ? What were they thinking ??? 😂
Posts in the Diesel-to-Gasoline heater series:
- Installing the Gasoline Heater
- Installing a Fuel Pickup Line in the Ford Transit's Tank
- Gasoline & High Altitude Heater Conversion - Success !!!
- Programmable Controller & Pump for Diesel Heater
- 'Chinese Diesel Heater' - is it Good out of the box ?
- High Altitude Gasoline Heater for Camper Vans ?
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