Anyone exhausting into a greenhouse?

Knocking up a, somewhat square, lean-to greenhouse on the side of the shed I grow in, I was considering running the exhausted heat from the HID’s into the greenhouse for autumn/winter tomatoes and other predominantly summer veg.

Just curious if there’s anyone doing this or have done in the past?

It’s nothing fancy, Just a few frame with plastic roof sheeting and expander foam where needed. The shed side will be sheeted with ply.

I apologies to all carpenters out there, I’m not one and all my mates have a giggle at my builds.

Looks good to me man!!

GreenestBasterd said:

Knocking up a, somewhat square, lean-to greenhouse on the side of the shed I grow in, I was considering running the exhausted heat from the HID’s into the greenhouse for autumn/winter tomatoes and other predominantly summer veg.

Just curious if there’s anyone doing this or have done in the past?

It’s nothing fancy, Just a few frame with plastic roof sheeting and expander foam where needed. The shed side will be sheeted with ply.

I apologies to all carpenters out there, I’m not one and all my mates have a giggle at my builds.


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Sounds like an awesome idea, I would just make sure to leave at least a passive exhaust on the greenhouse as well. May want to have an exhaust fan on a thermostat out there, depending on the day I'm guessing the HID exhaust could heat up that space pretty good.

Give yourself some credit man, those joints you cut in the roof joist to sit flat on that 2x4 is pretty slick. I built a similar type greenhouse this spring, lean to against the side of my barn, mostly with whati had laying around, fully functional and been great buti truly slapped it together. Wrapped in greenhouse plastic now, I'll be upgrading plastic roofing panels in the coming years. Your idea is great also, I was thinking about building another grow room right on the other side of the barn wall too.

oodawg said:

Give yourself some credit man, those joints you cut in the roof joist to sit flat on that 2x4 is pretty slick. I built a similar type greenhouse this spring, lean to against the side of my barn, mostly with whati had laying around, fully functional and been great buti truly slapped it together. Wrapped in greenhouse plastic now, I'll be upgrading plastic roofing panels in the coming years. Your idea is great also, I was thinking about building another grow room right on the other side of the barn wall too.

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Thanks mate, appreciate the kind words.
I would of built it the same way you did but decided I’d challenge myself and possibly learn a few new skills along the way.
It’s amazing how much DIY and other handy tricks you learn from initially just growing plants.
I’ve sheeted the greenhouse but yet to cut the duct hole out into the greenhouse, just need to work out the best way.

I have a shed with the poly plastic roof,I vented my grow into it.The next day it was raining inside my shed ,the humidity mixed with cooler outside temps caused it.Pending on time of year I guess but it didnt work for me.Some venting maybe would have helped but I dont grow in the warmer months.

Watching how this all turns out.

I have one of those Rubbermaid 7x7 that I store tools and crap in but wanted to use a corner or a side for a guerrilla style grow seeing as my wife won't let me in our new house.

I already know the issues I'll prob have to deal with. Light leaks/Temp/Humidity fluctuations and I suppose bugs/pests unless I fit a small tent in there, but I only have a 4x4 and 5x5 which will take up too much room. I may have a 2x4ft kicking around but I can't really remember lol.

Good luck. Time to join the shed grow club lol

myke said:

I have a shed with the poly plastic roof,I vented my grow into it.The next day it was raining inside my shed ,the humidity mixed with cooler outside temps caused it.Pending on time of year I guess but it didnt work for me.Some venting maybe would have helped but I dont grow in the warmer months.

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Did you run any sort of dehumidifier? You bring up a good point. That air would be really humid.

pahpah-cee said:

Did you run any sort of dehumidifier? You bring up a good point. That air would be really humid.

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No,exhaust air was about 50% RH and 75F. The outside air was much cooler so condensation was huge,literally dripping from my shed roof.

myke said:

No,exhaust air was about 50% RH and 75F. The outside air was much cooler so condensation was huge,literally dripping from my shed roof.

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Ah I see, It’s the temperature difference. That’s a tricky one.

If you exhaust your greenhouse outside is should help with the condensation no?

I need to convert this to grow

I'm an indoor guy... this is just... bonkers

Here she is so far.
We’re in winter at the moment and there’s sun beaming in past 4:00pm on a sunny day.

I’ve yet to cut the hole for exhaust, I may split the 10” duct with a Y join and a 6” duct running off it. I think I’ve got a 10”10”6” Y joint somewhere.

My shoddy measuring and brickwork means there’s plenty of air-flow, even after some expandafoam.

I couldn’t cut the corrugated sheets cleanly at all.
Might have to get one of those weird multi-tool things to finish it off, above the door I just covered it up with more blue timber haha

GreenestBasterd said:

I couldn’t cut the corrugated sheets cleanly at all.
Might have to get one of those weird multi-tool things to finish it off, above the door I just covered it up with more blue timber haha

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Clamp a straight edge and a new blade in a skill saw.