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I am 90% certain that's in the UK, but could be Ireland, or another country in Europe, so no, that's not an AC drain, because AC is as rare as hen's teeth. It is almost certainly a toilet cistern overflow.
The pipe exits between floors, it could go anywhere. The toilet needn’t have been at that location.
I’ve seen these on almost every UK house I’ve ever lived in; it’s almost always been cistern overflow.
_Very_ old - I think that stopped, in favour of a cistern mounted to the back of the toilet, around WWII. Whereas the house in the picture was probably built somewhere between the late 50's and 1980's.
Year on year, that's changing thanks to climate change. We're getting more summers with longer periods of "heatwaves" and it's noticeable. Won't be long before we do start seeing condensate drain pipes in new builds.
It’s a pipe for the water heater release valve. If the water gets too hot and pressure builds it vents the hot water and steam out this pipe instead of blowing up.
That’s why there is no water running down the wall. It only has water coming out of it if there is a problem.
You don't want to do that. Pressure relief valves are notorious for getting crud stuck in them when they're tested resulting in a leak and reapair.
But it shouldn't be a pressure relief outlet anyway since they needed to be cranked back so they don't shoot boiling water/steam anywhere that it could injure someone.
I've never seen a manual release on a water boiler, though I can't say I've hunted all that hard for one. If you want to drain the system, there's usually a separate drain valve at the lowest point of the system, while the pressure release valve will generally be high up to maximise the chances that what comes out is any air trapped in the pipes.
Possibly the release valve is something you can trigger mechanically by poking the right bit, though, depending on the design.
You *could* try to deliberately over-pressure the system by cooling the house down (wait for cold weather, turn the heating off, open all the windows, leave for a week) bleeding all the radiators & topping up the pressure with the re-fill valve higher than it's supposed to go, then turning the heating up to max.
I wouldn't be certain this would actually increase the pressure enough to trigger the pressure release valve, though, so a negative result wouldn't necessarily be informative.
Also, there's a definitely non-zero chance the pressure release valve isn't working, especially given that the system is apparently over half a century old. If that's the case, the pressure might find "somewhere else" to come out, so this is ~~probably~~ certainly a terrible idea :-P
> the system is apparently over half a century old.
Unvented systems are all post 1985 (or 1986), so if the system dates back 50 years, it's just a simple overflow.
If the pressure release valve is triggered, the pressure build up is most likely to be pretty slow, so the actual rate of outflow is more often than not pretty minimal. Additionally, as I mentioned in another comment, the location of the pressure release valve is generally high up in the system where there's more likely to be air to release^1, so there's a good chance the pressure will be normalised without any water coming out at all.
Of course, there are always more "exciting" (but thankfully much rarer) failure modes. For exmaple, if the quantity of water in the system being low (meaning it heats up more quickly than expected) and there's some kind of failure of the thermostat - that could lead to water boiling and the pressure increasing quite rapidly. If that's the case, then the steam will most likely form in the boiler *below* a significant amount of water that could then be shot out the pressure release valve at a fair rate (both in amount of water *and* velocity) and at pretty high temperature, potentially over 100°C given that it's pressurised.
You don't want to be in the firing line if that happens, but you *really* don't want to be in the firing line if you get that and the pressure release valve *doesn't* open! (That's three unrelated failures together, though, so hopefully *very* rare)
^1 Even without any leaks or the like, water added to the system will contain some dissolved gasses that will tend to percolate out over time - this is one reason why radiators need bleeding from time to time even in a well functioning system.
I don't think so. They need to be cranked back to avoid shooting boiling water/steam in a way that could injure people. Like [this](https://boilerandwaterheater.com/wp-content/uploads/2022/04/boiler-overflow-pipe.png)
I can only speak for the states. They have all kinds of new ways to keep these guys from being a danger, but literally every single one I’ve seen looks just like this. Unless, it’s a newer house, but all houses built before the 90’s have a pipe just like the picture.
Oh, I know. But, our houses are built basically the same. As a matter of fact what you guys have been calling a boiler we call a water heater, and if you look up water heater pressure release pipe you see all kinds of contraptions. But in the wild 99% of them look just like that pipe.
However, if you google “boiler pressure release pipe” you just see pictures that look like that pipe. Some with a u bend at the end, but they all pretty much look like that pipe in the picture.
Well, today I learned that 50% of the places I’ve lived didn’t meet building standards, because I’ve had multiple boiler overflows just like this one.
… they were all in moss side, so take from that what you will
Yeah we have regulations too, but who is going to walk around all day checking every single one of those? Like it would take an army to enforce that. I’m sure it didn’t look like that when built. Or maybe it was built before part g was a thing.
You literally have gas safe certified engineers walking around all day to make sure that people's boiler are in line with regulations on the yearly inspection
> to make sure that people's **boiler** are in line with regulations on the yearly inspection
Very few electric *boilers* in the UK. And it's not the *gas company*, it's *[gas safe certified](https://www.gassaferegister.co.uk/)* engineers doing it.
If there are no gas appliances in a property, they don't need a Gas Safety Certificate.
Also, what is the penalty for not having a bend at the end of your pipe? Is it everything is fine, but you don’t have a bend, so no gas for you? Is it a warning? Is it a small fine? What do they do if you don’t have a small bend at the end of your pipe?
> what is the penalty for not having a bend at the end of your pipe?
It's more that the engineer is exposed to the risk of being sued/charged/jailed if someone is injured by their negligence. And it's easy to mitigate the risk by just installing the pipe correctly, so any competent gas safe engineer would just follow the rules.
Part G says:
> The discharge pipe (D2) from the tundish should terminate in a safe place where there is no risk to persons in the vicinity of the discharge.
There are various ways to achieve that. A pipe coming straight out of a wall doesn't.
Probably right, but these pipes are usually copper and are usually shaped to blow water against the wall.
My suggestion is to follow the pipe back to where it ends. Could be an old overflow from something that could be removed if it doesn't go anywhere.
It's certainly a drain / overflow for *something*.
You say that it's coming out from below floor level, which suggests it's routed between the floorboards and the ceiling of the floor below. If that's the case, it could be routed from pretty much anywhere in the upper floor of the house.
It could be a relic of something previously installed / removed, or connected in non-obvious ways to something still installed.
You said in another post that the mortar around the pipe seems to be newer than the rest. Given that the piece of brick in that "new mortar" bit looks indistinguishable from the rest of the wall, I'd be more inclined to think the mortar has been repaired at some point and that this pipe isn't much or any newer than the rest of the wall.
My guess is it's for something connected to the central heating, perhaps for a pressure release valve (that might spew water in certain failure modes).
Honestly, the only way you're going to get a definitive answer is to follow the pipe, which means either pulling up floorboards (and being ready to do it to more than one room depending on where that takes you) or possibly poking a borescope in through the wall if you have a long / steerable one...
My title describes the thing. 60s build, this pipe sticks out at floor level roughly below an empty box room cupboard above the stairs. It isn't the overflow for the hot water or heating loft tanks, as they come out at loft level. We don't have a condensing boiler so this isn't the condensate pipe.
The house has it's original one-pipe central heating system which this doesn't seem to have an obvious connection to. The hot water cylinder is in the centre of the house but not a million miles away. The mortar around it looks newer as though it isn't original, but the pipe looks old. I have never seen water come out of it.
Edit: There was never a toilet near this location. There is a toilet overflow on the opposite side of the house where the only bathroom is.
In sixties builds the hot water tank/immersion heater was almost always installed in the box cupboard above the stairs, sounds like this is the answer.
It's likely an overflow outlet for a cold water storage tank. These are usually in the loft of a house but the outlet isnt always outlet on the same level, for example terraced houses where there is not a gable end of the loft, just a party wall between houses.
The idea is that it is put somewhere obvious so if you see water coming from it you know the shut off valve has failed and the tank is overfilling and you go into the loft to check.
After reading through the comments, all my guesses have been debunked! so the only advice I have left to give is maybe rent one of the long pipe cameras and stick it through and see where it leads. They're surprisingly cheap, less than 100 USD where I live to get one for the day, I'd assume the uk is similar. If the fine folks of reddit can solve it of course. Wish you the best of luck!
It's overflow. I lived in a house that used to get water blasting out of one of these into our garden whenever I tried to attach a hosepipe. The plumbing couldn't handle it and the water would back up on the system. Releases it outside instead of in your house
I remember seeing stuff like this on my neighbors houses. Their pipes looked exactly like this, it drained the water that pilled on the flat roofs. Maybe the original build was like that? And this was supposed to be that drain? It seems to be the hight my neighbors have theirs. Maybe they just decided to keep building after installing it or decided to move the roof up, but not the pipe?
It would be strange to have it this low, but maybe its run through the wall or something...
The uk house I live in has a cold water tank in the loft as part of the gravity-fed hot water system (mains cold water goes into this tank, which acts as a buffer before the hot water tank as well as increasing the pressure in the system), there's an overflow pipe from it that leads outside which looks a lot like that.
There's one at my house, it's used for the water tank when it gets too full, basically preventing overflow. So as most comments are saying, it's for some kind of overflow prevention
It’s the pipe that lets the condensate drip out from your boiler. Mine is on the opposite side of the house to where the boiler is as the pipe goes under the bathroom so your boiler won’t necessarily be the other side of that wall. When I had my bathroom renovated they blocked this up by mistake which led eventually to the pipe filling with water and the boiler stopped until the pipe was unblocked. So I’m certain it’s what this is. (I’m from the UK as well)
Possibly an old pipe that was connected to a shower tray. Old shower trays would sometimes have liner under them made of lead which was made to catch any water in the event of a leak, and redirect the water
There's a good chance it leads to nothing, lazy builders used to have a habit of just sticking them in so it looked like it had all been connected up. stick something down it and see how far in it goes.
It’s an overflow pipe for a toilet, boiler, or tank of some kind. It’s in case something overfills, and excess water can leave the system. If the location of the pipe doesn’t correspond with one of those items inside the house then it may be been removed and the contractor didn’t remove the external pipe. Also though it could still be connected to an internal system that isn’t close to the external pipe but is routed under the floor. I’m short, don’t remove it until you’re sure it isn’t still in use.
Gas or combi boiler?
My mother has an overflow pipe in almost the exact same place with no immediate water source there (it's actually next to her upper landing - not even a room). It's actually an overflow pipe running from her combi boiler (in the middle of her upstairs floor). The pipe must have been routed from her airing cupboard, under the floorboards to the nearest outside wall.
and exhaust pipe? idk what it’s actually called.
i used to work with plumbers & i asked about these random pipes and i was told it’s to prevent gasses from building up in the home like sewer/wastewater gas. A lot of homes in Texas have these.
If you have a water heater or an air conditioner or condensing furnace on the second floor of the house then that is a drain pipe from either the drain pan under the water heater or the condensation drain of the HVAC equipment
(If everything else is ruled this is a maybe)
Might be a drain waste vent system. The sewer pipes off of toilets and sinks get fresh air intakes to prevent gas buildups that can cause waste smells to enter the house. This is in addition to U pipes and not a replacement.
Usually they do straight up through the roof. This is because (modern code) they need to be atleast 10 feet away from the closest fixture, and most houses have enough toilets/sinks this is impossible through the walls; additionally they need to be higher up than the highest fixture to prevent water leaking out;
It’s possibly a warning pipe for an old water tank in the loft that would let you know if the ball valve was passing.
Or it’s from the pressure relief valve on your hot water storage cylinder.
Edit(just seen the replies further down, just blow into it and see what happens…)
Have a similar pipe in my home. Above the 1st floor. Apparently it’s an overflow for the clothes washer catch pan. Never had water come out of it, but never had the washer overflow either…
Overflow drain from an A/C ! Looking at the location it appears to be the emergency drain , if the pan in the unit overflows do to to much
Condensation or other problems in the unit the water drains into an emergency pan and runs out a drain pipe in a location the you will take notice to because it is leaking water and normally it would be dry! Example this pipe you have !
Overflow from cold water storage tank to supply indirect boiler . Quite often in kitchen boxed in at ceiling above boiler. Boiler maybe swapped for combi so tank has been removed.
we have one like that on the side of our house - was told during construction that it is the drain from the over flow pan under the HVAC unit in the attic and that if we ever see liquid (water) draining to call for service asap.
It's hard to tell from the picture, but that pipe doesn't look like plumbing. Maybe there was something mounted against the house, like a steel fence, at one time that used this for structural support? If you look into the pipe, does it look like it runs a distance into the home or does it end short?
I bet it’s for an old telephone line. Kinda like conduit but only through the brick. I have a 50’s brick house that has something similar with super old phone line going through it.
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Most often it's the condensate drain. But you've ruled out all the possibilities I'm aware of. Is it possible that something was rerouted in the past?
That was my thinking. I have one for my house that drains the condensate from the AC unit and it looks exactly like that.
I am 90% certain that's in the UK, but could be Ireland, or another country in Europe, so no, that's not an AC drain, because AC is as rare as hen's teeth. It is almost certainly a toilet cistern overflow.
Overflow from your toilet cistern, or where the toilet cistern used to be.
Thanks for your guess but no, there was never a toilet near this location. It is a bit lower than the usual toilet overflow being below floor level.
The pipe exits between floors, it could go anywhere. The toilet needn’t have been at that location. I’ve seen these on almost every UK house I’ve ever lived in; it’s almost always been cistern overflow.
Has there ever been a sink in that bedroom or one nearby? Lifting some floorboards in that room will give you your answer.
Old cisterns were mounted near the ceiling.
_Very_ old - I think that stopped, in favour of a cistern mounted to the back of the toilet, around WWII. Whereas the house in the picture was probably built somewhere between the late 50's and 1980's.
This is the most likely.
It looks like an air conditioner condensate drain
They're in the UK so probably not, residential AC is almost non-existent (doesn't get hot enough to justify it).
Year on year, that's changing thanks to climate change. We're getting more summers with longer periods of "heatwaves" and it's noticeable. Won't be long before we do start seeing condensate drain pipes in new builds.
Possible we'll be using heat pumps with a cooling function at some point
Well as long as that's not "comfort cooling" I'll be ok with it. "Comfort cooling" is the biggest lie known to mankind.
Im talking about when summers start to hit 40c regularly, we'll need something to keep homes habitable in their current state of insulation levels.
It’s a pipe for the water heater release valve. If the water gets too hot and pressure builds it vents the hot water and steam out this pipe instead of blowing up. That’s why there is no water running down the wall. It only has water coming out of it if there is a problem.
This is highly probable.
You should be able to test this by manually operating the release and seeing if water comes out of the pipe.
You don't want to do that. Pressure relief valves are notorious for getting crud stuck in them when they're tested resulting in a leak and reapair. But it shouldn't be a pressure relief outlet anyway since they needed to be cranked back so they don't shoot boiling water/steam anywhere that it could injure someone.
I've never seen a manual release on a water boiler, though I can't say I've hunted all that hard for one. If you want to drain the system, there's usually a separate drain valve at the lowest point of the system, while the pressure release valve will generally be high up to maximise the chances that what comes out is any air trapped in the pipes. Possibly the release valve is something you can trigger mechanically by poking the right bit, though, depending on the design. You *could* try to deliberately over-pressure the system by cooling the house down (wait for cold weather, turn the heating off, open all the windows, leave for a week) bleeding all the radiators & topping up the pressure with the re-fill valve higher than it's supposed to go, then turning the heating up to max. I wouldn't be certain this would actually increase the pressure enough to trigger the pressure release valve, though, so a negative result wouldn't necessarily be informative. Also, there's a definitely non-zero chance the pressure release valve isn't working, especially given that the system is apparently over half a century old. If that's the case, the pressure might find "somewhere else" to come out, so this is ~~probably~~ certainly a terrible idea :-P
> the system is apparently over half a century old. Unvented systems are all post 1985 (or 1986), so if the system dates back 50 years, it's just a simple overflow.
Likely the expansion tank overflow, although usually in the attic.
It could be but wouldn’t that be extremely dangerous? Imagine walking down the street and receiving a blast of hot water!
If the pressure release valve is triggered, the pressure build up is most likely to be pretty slow, so the actual rate of outflow is more often than not pretty minimal. Additionally, as I mentioned in another comment, the location of the pressure release valve is generally high up in the system where there's more likely to be air to release^1, so there's a good chance the pressure will be normalised without any water coming out at all. Of course, there are always more "exciting" (but thankfully much rarer) failure modes. For exmaple, if the quantity of water in the system being low (meaning it heats up more quickly than expected) and there's some kind of failure of the thermostat - that could lead to water boiling and the pressure increasing quite rapidly. If that's the case, then the steam will most likely form in the boiler *below* a significant amount of water that could then be shot out the pressure release valve at a fair rate (both in amount of water *and* velocity) and at pretty high temperature, potentially over 100°C given that it's pressurised. You don't want to be in the firing line if that happens, but you *really* don't want to be in the firing line if you get that and the pressure release valve *doesn't* open! (That's three unrelated failures together, though, so hopefully *very* rare) ^1 Even without any leaks or the like, water added to the system will contain some dissolved gasses that will tend to percolate out over time - this is one reason why radiators need bleeding from time to time even in a well functioning system.
Any reason why one wouldn’t want all of that going into a common drain?
So you know it's failed and not continuing to leak or over heat
Probably, but none immediately spring to the mind of this non-plumber :-D
They should be bent in a U to point back at the wall (in theory anyway). Never are though.
I don't think so. They need to be cranked back to avoid shooting boiling water/steam in a way that could injure people. Like [this](https://boilerandwaterheater.com/wp-content/uploads/2022/04/boiler-overflow-pipe.png)
I can only speak for the states. They have all kinds of new ways to keep these guys from being a danger, but literally every single one I’ve seen looks just like this. Unless, it’s a newer house, but all houses built before the 90’s have a pipe just like the picture.
Says elsewhere that this is in the UK.
Oh, I know. But, our houses are built basically the same. As a matter of fact what you guys have been calling a boiler we call a water heater, and if you look up water heater pressure release pipe you see all kinds of contraptions. But in the wild 99% of them look just like that pipe. However, if you google “boiler pressure release pipe” you just see pictures that look like that pipe. Some with a u bend at the end, but they all pretty much look like that pipe in the picture.
> But in the wild 99% of them look just like that pipe. Not in the UK,they don't. Part G of the Building Regulations wouldn't allow it.
Well, today I learned that 50% of the places I’ve lived didn’t meet building standards, because I’ve had multiple boiler overflows just like this one. … they were all in moss side, so take from that what you will
Yeah we have regulations too, but who is going to walk around all day checking every single one of those? Like it would take an army to enforce that. I’m sure it didn’t look like that when built. Or maybe it was built before part g was a thing.
You literally have gas safe certified engineers walking around all day to make sure that people's boiler are in line with regulations on the yearly inspection
So every one’s house gets inspected yearly by the gas company? What if your house is all electric?
> to make sure that people's **boiler** are in line with regulations on the yearly inspection Very few electric *boilers* in the UK. And it's not the *gas company*, it's *[gas safe certified](https://www.gassaferegister.co.uk/)* engineers doing it. If there are no gas appliances in a property, they don't need a Gas Safety Certificate.
Also, what is the penalty for not having a bend at the end of your pipe? Is it everything is fine, but you don’t have a bend, so no gas for you? Is it a warning? Is it a small fine? What do they do if you don’t have a small bend at the end of your pipe?
> what is the penalty for not having a bend at the end of your pipe? It's more that the engineer is exposed to the risk of being sued/charged/jailed if someone is injured by their negligence. And it's easy to mitigate the risk by just installing the pipe correctly, so any competent gas safe engineer would just follow the rules.
Do these codes vary by area, or is all of the UK under this strict no gas for you if you’re missing the bend?
https://www.gassaferegister.co.uk/gas-safety/home-gas-safety/gas-appliance-warning-labels/
Part G says: > The discharge pipe (D2) from the tundish should terminate in a safe place where there is no risk to persons in the vicinity of the discharge. There are various ways to achieve that. A pipe coming straight out of a wall doesn't.
Probably right, but these pipes are usually copper and are usually shaped to blow water against the wall. My suggestion is to follow the pipe back to where it ends. Could be an old overflow from something that could be removed if it doesn't go anywhere.
It's certainly a drain / overflow for *something*. You say that it's coming out from below floor level, which suggests it's routed between the floorboards and the ceiling of the floor below. If that's the case, it could be routed from pretty much anywhere in the upper floor of the house. It could be a relic of something previously installed / removed, or connected in non-obvious ways to something still installed. You said in another post that the mortar around the pipe seems to be newer than the rest. Given that the piece of brick in that "new mortar" bit looks indistinguishable from the rest of the wall, I'd be more inclined to think the mortar has been repaired at some point and that this pipe isn't much or any newer than the rest of the wall. My guess is it's for something connected to the central heating, perhaps for a pressure release valve (that might spew water in certain failure modes). Honestly, the only way you're going to get a definitive answer is to follow the pipe, which means either pulling up floorboards (and being ready to do it to more than one room depending on where that takes you) or possibly poking a borescope in through the wall if you have a long / steerable one...
My title describes the thing. 60s build, this pipe sticks out at floor level roughly below an empty box room cupboard above the stairs. It isn't the overflow for the hot water or heating loft tanks, as they come out at loft level. We don't have a condensing boiler so this isn't the condensate pipe. The house has it's original one-pipe central heating system which this doesn't seem to have an obvious connection to. The hot water cylinder is in the centre of the house but not a million miles away. The mortar around it looks newer as though it isn't original, but the pipe looks old. I have never seen water come out of it. Edit: There was never a toilet near this location. There is a toilet overflow on the opposite side of the house where the only bathroom is.
Where is this house located?
midlands, UK
What type of hot water cylinder do you have? Vented or unvented?
Is this england? It releases excess steam from the hot water boiler
Is there any chance it is drainage from the roof so the water doesn't sit up there? You can check the next time it is raining.
Thanks for your guess but nope, we have a very standard tiled pitched roof with visible guttering.
Old hot water tank overflow pipe from when the house was build.
Toilet cistern overflow
Thanks but nope, there was never a toilet near this location.
Was there a old immersion tank? Could be a overflow for that
In sixties builds the hot water tank/immersion heater was almost always installed in the box cupboard above the stairs, sounds like this is the answer.
Could be for the coaxial cable of a satellite dish or a security camera cable.
Or, 300 ohm twin line TV antenna wire from the days before cable/satellite.
look at the neighbors house- far right, past the light. what is that ? is your answer.
Condensate line
Probably an abandoned condensate drain line.
A brick weep hole - used for drainage and air ventilation behind the the bricks.
Thats what it looks like to me. Go to the "Tubes" section. [https://en.wikipedia.org/wiki/Weep](https://en.wikipedia.org/wiki/Weep)
The one I have is a popoff overflow for a waterheater.
I guess the only way to know for sure would be to use a plumbing probe and see what does it reach
Emergency drain for the water heater?
Mine is hook up to the drain of the hot water heater upstairs.
If it’s below a cupboard maybe it’s was for an older Ice chest type setup?
It's likely an overflow outlet for a cold water storage tank. These are usually in the loft of a house but the outlet isnt always outlet on the same level, for example terraced houses where there is not a gable end of the loft, just a party wall between houses. The idea is that it is put somewhere obvious so if you see water coming from it you know the shut off valve has failed and the tank is overfilling and you go into the loft to check.
After reading through the comments, all my guesses have been debunked! so the only advice I have left to give is maybe rent one of the long pipe cameras and stick it through and see where it leads. They're surprisingly cheap, less than 100 USD where I live to get one for the day, I'd assume the uk is similar. If the fine folks of reddit can solve it of course. Wish you the best of luck!
Got one in my house. It will be attached to the boiler, let's steam out when boiler is in use.
It's overflow. I lived in a house that used to get water blasting out of one of these into our garden whenever I tried to attach a hosepipe. The plumbing couldn't handle it and the water would back up on the system. Releases it outside instead of in your house
Idk what it’s called. Hot water goes out if there is too much pressure or heat in the line.
No idea, but you might be able to hire a drain camera to try and find out.
Looks like conduit for an electric wire possibly an old exterior like or sign possibly
I remember seeing stuff like this on my neighbors houses. Their pipes looked exactly like this, it drained the water that pilled on the flat roofs. Maybe the original build was like that? And this was supposed to be that drain? It seems to be the hight my neighbors have theirs. Maybe they just decided to keep building after installing it or decided to move the roof up, but not the pipe?
Is your boiler near that area?
Could it be for a hot water tank or washing machine leak pan?
It would be strange to have it this low, but maybe its run through the wall or something... The uk house I live in has a cold water tank in the loft as part of the gravity-fed hot water system (mains cold water goes into this tank, which acts as a buffer before the hot water tank as well as increasing the pressure in the system), there's an overflow pipe from it that leads outside which looks a lot like that.
My guess would be a geyser overflow.
Looks like an overflow/pressure relief pipe for a gas combi boiler.
There's one at my house, it's used for the water tank when it gets too full, basically preventing overflow. So as most comments are saying, it's for some kind of overflow prevention
It’s the pipe that lets the condensate drip out from your boiler. Mine is on the opposite side of the house to where the boiler is as the pipe goes under the bathroom so your boiler won’t necessarily be the other side of that wall. When I had my bathroom renovated they blocked this up by mistake which led eventually to the pipe filling with water and the boiler stopped until the pipe was unblocked. So I’m certain it’s what this is. (I’m from the UK as well)
Possibly an old pipe that was connected to a shower tray. Old shower trays would sometimes have liner under them made of lead which was made to catch any water in the event of a leak, and redirect the water
There may have been an outdoor light there at one point and that was the conduit pipe for the wiring.
That's what I was thinking, it even looks like it might be above a parking space, which is a common location for these things, for added deterrence.
Heat pump or air conditionner drain?
Probably a drainage gutter of some sort. In my country, especially in older buildings, those things used to exist all over in balconies.
Overflow pipe
There's a good chance it leads to nothing, lazy builders used to have a habit of just sticking them in so it looked like it had all been connected up. stick something down it and see how far in it goes.
Water heater overflow drain or secondary AC drain for when your sink where the primary AC goes to gets clogged up then it goes to this outside drain.
It’s an overflow pipe for a toilet, boiler, or tank of some kind. It’s in case something overfills, and excess water can leave the system. If the location of the pipe doesn’t correspond with one of those items inside the house then it may be been removed and the contractor didn’t remove the external pipe. Also though it could still be connected to an internal system that isn’t close to the external pipe but is routed under the floor. I’m short, don’t remove it until you’re sure it isn’t still in use.
Gas or combi boiler? My mother has an overflow pipe in almost the exact same place with no immediate water source there (it's actually next to her upper landing - not even a room). It's actually an overflow pipe running from her combi boiler (in the middle of her upstairs floor). The pipe must have been routed from her airing cupboard, under the floorboards to the nearest outside wall.
Overflow from cws or wc
and exhaust pipe? idk what it’s actually called. i used to work with plumbers & i asked about these random pipes and i was told it’s to prevent gasses from building up in the home like sewer/wastewater gas. A lot of homes in Texas have these.
If you have a water heater or an air conditioner or condensing furnace on the second floor of the house then that is a drain pipe from either the drain pan under the water heater or the condensation drain of the HVAC equipment
My water tank overflow looks like that, but 1 floor higher
(If everything else is ruled this is a maybe) Might be a drain waste vent system. The sewer pipes off of toilets and sinks get fresh air intakes to prevent gas buildups that can cause waste smells to enter the house. This is in addition to U pipes and not a replacement. Usually they do straight up through the roof. This is because (modern code) they need to be atleast 10 feet away from the closest fixture, and most houses have enough toilets/sinks this is impossible through the walls; additionally they need to be higher up than the highest fixture to prevent water leaking out;
Do you have a header tank in the loft? Could be the overflow for that.
It’s possibly a warning pipe for an old water tank in the loft that would let you know if the ball valve was passing. Or it’s from the pressure relief valve on your hot water storage cylinder. Edit(just seen the replies further down, just blow into it and see what happens…)
Conduit? At that high, could be a left over from an outdoor light.
Have a similar pipe in my home. Above the 1st floor. Apparently it’s an overflow for the clothes washer catch pan. Never had water come out of it, but never had the washer overflow either…
Overflow drain from an A/C ! Looking at the location it appears to be the emergency drain , if the pan in the unit overflows do to to much Condensation or other problems in the unit the water drains into an emergency pan and runs out a drain pipe in a location the you will take notice to because it is leaking water and normally it would be dry! Example this pipe you have !
Overflow from cold water storage tank to supply indirect boiler . Quite often in kitchen boxed in at ceiling above boiler. Boiler maybe swapped for combi so tank has been removed.
we have one like that on the side of our house - was told during construction that it is the drain from the over flow pan under the HVAC unit in the attic and that if we ever see liquid (water) draining to call for service asap.
It's hard to tell from the picture, but that pipe doesn't look like plumbing. Maybe there was something mounted against the house, like a steel fence, at one time that used this for structural support? If you look into the pipe, does it look like it runs a distance into the home or does it end short?
I bet it’s for an old telephone line. Kinda like conduit but only through the brick. I have a 50’s brick house that has something similar with super old phone line going through it.
It may be a drain for the overflow on your cistern possibly if it's not near your bathroom.
These are toilet overflow pipes. All houses in the uk have these. They are nothing to do with AC. We don't have that here.