Complete Steps for Building a Solar Thermal Soda/Beer Can Heater for a Greenhouse

I needed a way to add free heat to my greenhouse. I am growing cool weather vegetables like lettuce, spinach, cabbage and kale. They can take a light frost. My goal is to keep the greenhouse producing through January. Yes... freezing days and nights in my gardening  zone, zone 7.

This videos shows you every step of the build from supplies and cost, all they way to sealing the plexi-glass to the frame. Here is what you will see:

1. All the parts and costs
2. How to drill, seal and stack the cans
3. How to build the box
4. How to paint and arrange the cans
5. How to seal the glass

The  video will teach everything you need to know to build one yourself. You can make them as large as you wish. If you build a large scale design you will need to use wood for the frame backing.

Link to my blog entry with videos that show output heat tests of over 140 degrees.

The principle is pretty simple. Cool air comes in from the bottom. It is heated nicely as it travels up the cans. It is released back into the greenhouse from the top of the unit. Nature creates a natural current. Heat rises and moves upward creating a current that draws in cool air. This is a small scale model for my needs. Some solar heaters use over 200 cans in columns of 25+. They are used for heating rooms. This design is just for a small greenhouse.

Comments

[CuriosityCat_1]

I see that in 4 yrs, the creator of the video hasn't posted a response to how you create heat inside the greenhouse at night when it's freezing cold outside. Hopefully he will come back here & respond or maybe he answered it in his youtube videos or comments there? But I'd like to know the answer as I have wanted to do this for other heating options, during the night. thanks

[CuriosityCat_1]

I see no answer in how to make heat of a night in the winter when it's cold out.

[Happygirlten]

Nice! It worked fine through the can seemed to look like they are falling off.

[diy_bloke]

i have been doing this too and at a certain moment i wondered if the beer cans were really necessary... if maybe just a black box would do the same. after all the surface gets a set amount of energy from the sun. beercans are not going to increase that amount, so i really wonder

[GatisC]

How about air as insulator

[diy_bloke]

I am not really sure what you mean by that, but if you have just a black box the amount of air stays the same whether you put cans in it or not.
Again, I am not saying one can lose the cans: I just dont know

[knutknackebröd]

i was thinking the same, maybe its so there is more surface area to absorb the radiation (sunlight) and more surface area would also provide more convection(hot air)?

[diy_bloke]

Maybe, I am really not sure

[3967]

how is it possible if its cold outisde to get 135 degrees hot air from sunheated beercans? what is the physical principle here, could you explain this? greetings

[hamkat]

I'm thinking about trying black posterboard rolled into tubes.