BioGas Powered Hot Water Heater

I'm in the US, Los Angeles, and have been searching for a biogas compatible instant hot water heater.  I've been looking at the EcoTemp but the manufacturer tells me they won't support advice on using biogas.  Anyway, I'm hoping to find a solution quickly.  I'm volunteering my time to pull together elements for a portable and off-grid homeless shelter concept (  Biodigestion plays huge in the equation... I can be reached/texted at +1.323.420.6196.  Open to your thoughts.


Hey Allan,
have you checked Puxin?

You will need a gas pump as well as the heater needs constant preasure. - websites & marketing

Thank you Nick! What 12v gas pump do you recommend?

No idea about 12v pumps... sorry. All I know use 220V... - websites & marketing

Hi Allan

I can also recommend to you the PUXIN gas heater as mentioned by Nick. I'm using it for more than one year for water heating. According to my long experiance I can recommend you the following for a sucsessfull gas waterheater operation:

  1. The gas jets for most of the gas heaters are not designed for biogas (Methane) operation. That's the reasion why manufacturers don't support it. To make it working, first of all you have to widen the diameter of the jets to 1-1.5mm.

  2. The inlet gas pressure should be between 10-50mbar. I do not use a gas pump, unless the gas pipe between fermenter and heater is more than 5m long.

  3. Please note that the "biogas" leaving the fermenter consists mainly of methane (50-75%), carbon dioxide (25-45%). Approx. 100-2000 ppm will be hydrogen sulfide. The remining are negligible.

  4. Your gas heater will NOT ignite the biogas if the methane concentration is below 50%. This can happen in the beginning of the fermenter operation or if the feed composition is to poor.

  5. Hydrogen sulfide is very agressive and should be reduced to <100 ppm before entering the gas heater. Otherwise the internal heater parts will corrode wihtin short time. Easy methods can be provided if there is interest.

Best regard Markus


Thank you Markus:-)

Hey there Markus,

I've built and installed a couple DIY digesters and I never push the pressure inside the digester tank above 5mbar.

Therefore, for such a hot water heater, I'd need to compress the gas, but I'm curious... What's your trick, how do you get the gas to 10-50 mbar ?

I'll use fridge compressors but if you have anything easier, I'm all ears ;)



I am amazed at the pressure that a simple digester can produce on its own. Of course, the seals have to be sufficient. In my digester, the digestate exits through the top, just like the solar cities IBC version. To get the digestate pushed upward, of course pressure is needed. In my case, I have a floating barrel storage but the same could be accomplished using a bag with a heavy blanket on it (try sewing two layers, quilting it like your grandmother used to, and filling the resulting pockets with whatever). The math is too much for me, but in German we say "Trial beats science" (rough translation of "Probieren über Studieren"). I attached a manometer (u-shaped clear plastic tube) and added weight. It's amazing how much weight is required to get 10mbar (depends on surface area of the storage, etc. like I said, the math is incredible), but it is doable. So... my system can now produce enough pressure on its own to push the digestate up, over the top of the barrel, through the insulating layer, to a "T" where it can easily flow out the side outlet. Leave the T open at the top! If you don't you may create a siphon and empty your digester. Even Thomas Culhane did that once...

Hello Markus... and many Happy New Years!

I realized you had mentioned you may be able to share some "Easy Methods" to reduce Hydrogen Sulfide below 100 ppm... I am very interested:-)