this post was submitted on 21 Sep 2026
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Why does no one seem to use peltier elements to heat small greenhouses? (feddit.org)
submitted 1 week ago* (last edited 1 week ago) by viertesauge@feddit.org to c/gardening@lemmy.world
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Genuine question. When I look up options for heating greenhouses its either propane, kerosene or electricity. So if you dont want to use fossil energy for any reason, why not use peltier elements which would boil down to resistive heating and moving heat from the outside to the inside?

Is it because they dont last in the weather? Or because they require a DC source? (couldnt you simply move the PSU inside the greenhouse and use any conversion losses as additional heating?) Or maybe its because you would have to possibly cut a hole in your greenhouse walls so that the peltiers cold side is actually on the outside?

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[–] Blue_Morpho@lemmy.world 2 points 1 week ago (1 children)

A mini fridge is like $120 and would give ~300 watts of heating on 100 watts of energy.

A peltier would be like $80 (including power supply and fan. It would use 100 watts of energy and give 150watts of heating.

[–] viertesauge@feddit.org 1 points 1 week ago (1 children)

thats true but the frigde pobably isnt designed for being in the cold and weather all the time (although you might be able to modify it so that it could). plus the compressor would run all the time since its constantly trying to cool the outside (previously inside of the fridge). at that point you are better off installing a regular compressor heatpump. what is appealing about peltiers to me is that they have no moving parts and no nasty refrigerants that could leak. I wasnt really asking about compressor heatpumps vs peltiers anyways but about resistive heaters vs peltiers.

[–] Onomatopoeia@lemmy.cafe -3 points 1 week ago (1 children)

The math holds the same.

And what do you think a heat pump is? It's the exact same thing as a fridge, with a compressor, evaporator and condenser.

[–] viertesauge@feddit.org 1 points 1 week ago

when did i say that a compressor fridge isnt a compressor heatpump,lol

maybe try understanding a comment before you go on a downvoting spree. thanks for adding nothing to the discussion.