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How might I alter a greenhouse paraffin heater to burn more CO2 and less heat, please? Answered

I've built a few things since coming across this site, one of which is a basic hydroponic table for salad greens. I have a paraffin-based greenhouse heater, but I want it to burn with less heat. Do you know if this is possible, please? Alternative suggestions are welcome, with the aim of burning natural fuels to produce CO2. The heat is not needed during these warm days (although it is turning a little colder outside the greenhouse!) I have had a look at 'professional'solutions and they run to about US$500 which is far too much cash. I also checked to see what they did different to a normal burner but other than saying they burn lean they are not helping any further. I'm guessing they burn lean by allowing less oxygen into the fuel/air mix? Thanks for stopping by.


What about just using beer gas ? Is your sysem fairly gas tight ? Steve

One thing with using gas is that you can switch it off at night, when the plants use Oxygen and on again when they switch back to CO2. I'd try and find a CO2 sensor to monitor all this stuff.

Hi Steveastrouk,

Yes, I'd be keeping this simple and venting the gas before beddy-byes so the plants have oxygen for the night.

I couldn't afford a CO2 monitor anyways...

btw how do you do a subscript text here?

Dunno about subscripting. CO2 sensors aren't that dear are they ? I can buy the raw sensor for 10 quid or thereabouts... Steve

I have only seen them at the £400 mark.. would you kindly pm me the link, please?

About 40 quid for a complete board with a 0-10V output. Steve

??? eh???!!!! (sorry for slow reply -just getting over an operation ;-)

Little card, power in one side (15V I think), and a signal from the other which represents 0..20% CO2 - plug a cheap meter into it. Steve

AFAIK carbon-based fuel burning yields the best pennies/CO2 production, which is why I'm going for carbon-based CO2 production. Yes, my greenhouse is gas-tight; all the joins are silicone-sealed with the exception of the door frame (which has a plastic barrier as extra) and the vent - but as CO2 is heavier than air I'm quite confident that my CO2 will be used appropriately. Thanks for the prompt and the suggestion!

Just remember, CO2 doesn't just displace oxygen; it's actually toxic when the partial pressure is high enough that your lungs start having trouble getting rid of the stuff. Be careful when doing this -- put up appropriate signage to warn folks (eg firemen or police, if that ever becomes necessary), and make sure you air it out before walking in.

Yes, thanks, Ork; I very much appreciate your heads-up there ;-) The research I have done tells me that 2000 ppm CO2 is the baseline for toxicity: apparently at that level the first things people start to experience are headaches. For flowers the level is much, much lower at less than 1000 ppm. For those interested everyday ppm CO2 is around 350ppm just above suffocation level for most plants and at night its around 500ppm. I don't expect that I will be going OTT with the gas; just as much as any glasshouse gardener would do with a heater: all I wanted to do was to achieve as much the same effect but with less heat for the warmer days while the sun is shining down. Besides which I shall be leaving the door wide-open before I enter and while I'm watering the plants/veggies. Thanks for your time to post: it's a very worthwhile post and much appreciated. Any further thoughts on my main aim would also be appreciated. Thanks for stopping by! ;-)

High-carbon fuel give more heat per gram, so if you were to replace the heater with e.g. charcoal you'd get more CO2 per g but more heat also. Switch to natural gas, less heat less CO2 per g.
Burning lean uses more air, to ensure minimal CO & hydrocarbon output (in those systems anyway)
Beer-gas sounds like the best bet for cold CO2 it can't be that expensive?


I'm going to re-investigate beer-gas, thanks steve and lemonie.