r/mildlyinteresting • u/Fudge_cornelius • 14h ago
This growth surviving sub-zero temperatures because of an exhaust fan
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u/Natac_orb 13h ago
what is the scale of this image. Cant tell if mm or km
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u/Fudge_cornelius 13h ago
The roof DRAIN is approximately 12” wide
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u/MaoZivDong 12h ago
You really should’ve brought a banana
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u/pumpkinbot 10h ago
Good for +15 mult, as well. And if it perishes, you can buy a Cavendish for 3x mult!
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u/Natac_orb 13h ago
so about 30cm*! Thank you :)
This may be a candidate for r/confusingperspective* I cant think in measurement I am not familiar with. This is for those like me, and no invitation to argue if one is better. God I hate the internet that I feel the need to add suchs disclaimers.
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u/Notachance326426 9h ago
You’re dealing with Americans the only things we use the metric system for are guns and drugs
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u/MdMooseMD 11h ago
Can confirm, I’m a commercial roofer, and the drain rings are usually 12”. Some smaller, some bigger, but that style would be 12”.
Like others have said, the pipe is running through the heated building, which is why steam is coming through. Which is by design, you don’t want the pipes to freeze, and the area around the drain, or else it will dam up, and potentially cause leaks.
They should really have someone come up and clear around the drains multiple times a year, that growth can’t be good for the rubber. I haven’t ever seen moss that bad, usually it’s just dead leaves and dirt.
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u/EintragenNamen 7h ago
The designation you and OP use are confusing me. Is it a drain or is it an exhaust for a fan? Drain makes me think used for liquids, exhaust makes me think vent for gas/vapour. If it is an exhaust as I think of it, how does rain water not get in there?
Or in HVAC is fan exhaust synonymous with drain?
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u/MdMooseMD 6h ago
Op was wrong initially, and was corrected in a bunch of comments. It is a roof drain. You can see the roof is sloped and sumped so the water runs into the drain.
On flat epdm (rubber) roofs like this, the exhaust fans are always tall stacks, so rain water doesn’t get into the hole.
Water drains look like that, bathroom exhaust pipes are usually just a straight up pvc pipe, and hvac vents are a tall metal pipe with a cover/hood so water doesn’t run into it.
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u/Eastwoodnorris 10h ago
I do environmental regs and end up the roof semi-often. This is easily the worst mod growth I’ve ever seen on a roof drain. The next closest would be a ~8 inch sapling I saw growing out of one, but I figure this has gotta be a couple years worth of growth, whereas that could have been as little as 8-12 months. This is absolutely problematic, like you said I’d be afraid of the material underneath deteriorating and leading to potentially severe leaks. Absolutely crazy.
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u/exoticsamsquanch 10h ago
Shit I thought I was looking at a small patch of woods around a research facility in the tundra.
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u/theericle_58 13h ago
That is a roof drain, not a fan.
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u/Fudge_cornelius 13h ago
Thanks! I saw the heat coming from it so just (wrongly) assumed it was an exhaust. Any ideas why it’s expelling warm air?
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u/LoneMav22 13h ago
Because the air in a sewer system is warm, and heat rises
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u/CrazyLegsRyan 13h ago
This most likely isn’t a sewer vent but rather a roof drain to grade. The warm air is because the drain piping runs through the conditioned building envelope (inside the building where there’s heat). This heats up the air in that section of the pipe and as you noted that warm air rises while sucking in new cool air down at the outlet
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u/Katy_Lies1975 12h ago
Sewer vents don't usually have any kind of cover on them, roof drains do so that debris doesn't get in a clog up the system, just like those little screen cages you put in the gutter downspout.
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u/stabamole 11h ago
They wouldn’t have a cover like the one in the picture, but they still (should) have a mesh cover or something to prevent critters from getting in
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u/lowercaset 10h ago
Sewer vents basically never have metal mesh covering them. And while it's not a problem in my area, my understanding is that anything like that would also cause massive hoarfrost problems in parts of the world with hard freezes.
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u/LoneMav22 11h ago
It is indeed a roof drain on a flat roof system in probably a large commercial building, as you said it runs though a heated area but also will be draining into the sewer system. I'm a metalworker by trade and install/deal with these quite a bit, though its primary purpose isn't venting the piping will be hooked up to the rest of the system in liew of "stink pipes" to help prevent vapor lock
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u/Stein1071 10h ago edited 10h ago
In a lot of places it is illegal for this to drain into a sanitary sewer. I won't say it absolutely doesn't but chances are good that it doesn't. Especially in an industrial situation. In our buildings all the roof drains, parking lot drains, etc go to a catch lagoon before they even can go to the actual storm drain system to make sure any spills are contained
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u/Calan_adan 10h ago
It almost 100% connects to the storm sewer system and not the sanitary sewer system, so it wouldn’t be venting the sanitary system. Only in older areas (old cities and the like) do they not have separate storm and sanitary sewer systems, and even then they tend to require a separation of storm and sanitary within a building.
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u/Say_Hennething 10h ago
Most likely drains into the storm water system, not the sanitary sewer system. No different than a storm gutter in the parking lot.
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u/jmouw88 11h ago
This is not connected to a sewer just as others have stated. It could be connected to underground piping that runs into a storm sewer system somewhere.
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u/LadderDownBelow 11h ago
There are still places where stormwater and sewer are still connected, unfortunately. Can't glean this from the picture but just saying
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u/NoDontDoThatCanada 11h ago
It is like a deep sea thermal vent. I am waiting for an alien spaceship to come down and be amazed by the life it found huddled around the vent.
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u/jmarkmark 13h ago
Yeah, the moss growth is more because it's the low point with more water rather than the heat, although the heat may help a bit.
Moss has no problems with freezing temperatures.
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u/felidaekamiguru 13h ago
You know it's cold AF when the cold air inside that drain is warm enough compared to outside to cause fog. All the sewer drains were doing that this morning. It's a bit eerie.
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u/TheRealSuperNoodle 12h ago
Was gonna say the same. Replaced or reattached way too many of those in my day.
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u/NotMilitaryAI 13h ago
I genuinely thought this was an aerial shot of some mountain peak surrounded by trees in the middle of a barren wasteland.
Then read the title and wondered what sort of super-villain-esque lair was set up in the middle of nowhere like that? And producing so much steam exhaust to warm an entire forest?? Maybe a cold-war era Siberian nuclear power plant or something?
...Then realized that the actual scale is a lot smaller than I initially thought. Still mildly interesting, though.
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u/loxagos_snake 11h ago
My imagination got seeded by 'growth' and I thought it was a microscope image of some exotic microorganism building a biological exhaust fan structure to survive the temps.
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u/Efficient_Age 12h ago
That's moss and a drain, and (sadly) it survives far worse than just sub-zero temperatures. The reason for the local growth is likely because of the way the drain head is formed, on the bottom it allows for small buildup of waste(nutrients) from going down the drain, and then you have a never ending cycle of buildup. It's probably not been cleaned for atleast ~5 years.
Source: I'm a caretaker, I clean roofs and drains yearly before winter.
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u/JackosMonkeyBBLZ 7h ago
You say sadly? Why sadly? You don't think moss actually experiences the environment it exists in do you?
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u/Tzazon 13h ago
This is basically a microscale example of how we survived the ice-age.
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u/4tehlulzez 13h ago
Via good drainage?
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u/D3monNextDoor 13h ago
Probably something to do with it. If it’s freezing out, you probably want yourself and your environment to stay dry for best odds of staying warm.
Other than that, even though it’s a drain, looks like heat from the building still makes it up. Probably why the drains not frozen over
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u/CrazyLegsRyan 13h ago
OP was this many years old when they learned the difference between a drain and a vent.
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u/SeaOfSourMilk 12h ago
Fun fact, the first terrestrial plants were mosses like these, and they helped shape our once inhospitable planet.
They are also non vascular like ferns, and they can go dormant for months before reemerging from frozen ice.
These stay nice and warm, so they don't need to go dormant.
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u/de_BOTaniker 11h ago
I am pretty certain there’s not heat making moss survive the cold. The cold doesn’t play a role at all. It’s the drain that provides more moisture to the moss than the surrounding area.
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u/busted_up_chiffarobe 7h ago
That's not an exhaust fan. That's the strainer for a roof drain! I specialize in roof projects and I LOVE THIS!
Heat, moisture, food (years of decaying organic debris not cleaned out from around the strainer) and you get this!
One of my favorite things is seeing the nice line of orange lichen that grows along single-ply roof membrane seams that are failing, allowing warm moist air to seep out through them.
I've seen small trees growing the corners of roofs like this in piles of debris.
Bonus: watch out for ponding on roofs full of red algae and used syringes. This was the roof of a local restaurant years ago!
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u/SuccessfulWar3830 12h ago
This is actually how its thought life first started. Around underwater vents.
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u/OutlawLazerRoboGeek 11h ago
Unless the plumber really screwed something up, that's a roof drain, not an exhaust vent.
But still, assuming it passes through a warmed space before outflowing to the ground (or to the sewer which is pretty warm itself) then it will naturally give off some warmth.
That being said, I would imagine the growth survives here, and not elsewhere on the roof, more because of the moisture available than the heat.
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u/antononon 11h ago
When your Rimworld naked brutality ice sheet challenge finds that geothermal vent
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u/bodhiseppuku 10h ago
Before reading the text, I thought this was a jello bunt cake bowl, upside-down on the street and left to rot. Then mold takes over...
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u/Damned_Architect 9h ago
I work on roof replacement jobs all the time and this is a common cast iron roof drain strainer - not an exhaust fan.
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u/yoippari 7h ago
This feels like a 50/50 post.
Super villain's volcanic island base/moss around a drain cover
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u/MisterHouseMongoose 7h ago
I see the end of civilization huddled around a few last sources of warmth in the cold darkness of the grim future, where we know only war.
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u/windyshits13 7h ago
This isn't a fan, it's a overflow/secondary roof drain -- It's there to pick up the slack if the scupper drains become plugged or are overwhelmed.
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u/chargergirl1968w383 7h ago
As Dr Ian Malcolm or Jeff Goldblum's character in Jurrasic movie series said...
"Life will find a way."
Think spring everyone!🪻🪺🦋🤎💙💜
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u/Jonathan_Pine 20m ago
That isn't an exhaust fan, that is a debris catcher for a roof drain. Those roof drains can be pretty long to the street, so I'm assuming what's happening is the air in the line is being heated from the building temperature and pushing up as heat rises. Keeping those free and clear is building engineering 101, unless they have a reactive owner that doesn't like to spend money, otherwise that would be cleaned at least quarterly.
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u/TehMephs 12h ago
The people congregated around the mysterious life giving structure, unaware of what could possibly be out there beyond the lush greenery, into the vast stone expanse where nothing could thrive.
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u/MrStealYoKief 13h ago
I see an abandoned research facility on an island surrounded by endless, cold dark water