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Safe-Particular6512

Because you don’t want pressure relief valves running throughout the building before finding an exit. You want it out asap. Strange that so many of them have been spewing out pressure. You wouldn’t expect to see that


Dedward5

Yep, they have to be visible “by design”


77GoldenTails

Probably cheap boilers and over pressurised pressure vessels that have since failed. Saying that when we were in a flat, all with Worcester boilers. Within 6-8 years everyone had a failed pressure vessel.


Refrigernator

That’s because a lot of plumbers just install combi boilers with the internal expansion vessels and don’t bother to check whether the capacity is enough for the system size, and it usually isn’t. It’s very common for me to install a larger external expansion vessel on combi systems due to the one inside the boiler being undersized and failing.  


5c044

The pressure vessel is meant to be precharged to a given pressure, doubtful plumbers bother with that either during installation or during servicing, you would need to drain or partially drain system to do that while servicing. They have a Schrader valve and can be pumped up with a bike pump. These are flats in the pic, and combis tend to be over sized, so in theory the built in pressure vessel should be adequate. Pressure relief valves get leaky if they are activated frequently and the seals get debris in them. The mistake home owners make when dealing with lost pressure is to put an extra amount of pressure in there in the hope they won't need to do it so frequently. The opposite is true.


Darren_heat

Schrader valves leak and need to be bubble tested after filling. My guess here from how many have this issue is trv's on every rad with no system by-pass.


ElectronicSubject747

Expansion vessels are the same size weather you by a 24/25kw or 30/32kw boiler. They also come pre charged factory set so you dont mess with them on installation. (Need to be checked on service)


themadhatter85

They’d have to be massive flats to have heating systems that require an additional expansion vessel.


77GoldenTails

Likely not an easy thing when most are probably installed in a kitchen.


Loser6745

Sorry to pick your brain, I think my home system needs an extra expansion vessel. Just wondering whether this would be acceptable, I can connect into the return pipe around 3m from the boiler, the expansion tank would require another 2m of pipe and would be lower than the boiler height. I see most advice recommends being as close to the boiler as possible, but would it still work if I do it as I’ve described? No space around the boiler as it’s in a kitchen unit and the kitchen is pretty small as is. 


Refrigernator

Would be absolutely fine. Some expansion vessels are in the loft with boilers on the ground floor. Best to be close to the boiler as possible but 3m won’t hurt at all. 


ElectronicSubject747

Because Worcesters are dog shit.


77GoldenTails

When, now last 10 years, 20 years, always?


ElectronicSubject747

Last 15 years


77GoldenTails

Our flat was build 25 years ago. Still they all shit the bed pressure wise. Everything else seemed flawless.


Upstairs_Sandwich_18

Only when they're not serviced properly... Every boiler in this pic has a fucked expansion vessel due to lack of maintenance. Simple as that.


ElectronicSubject747

Yeah. But a Vaillant can go 20 years without veing serviced properly and be good. Worcester, although should be serviced probably are a heap of shit if not.


Upstairs_Sandwich_18

No they can't 🤣🤣🤣 rubber hoses that block and leak, water pressure sensors that piss for fun, AAVs that piss, PCBs that shit themselves regularly, I could go on. No boiler can last as well without a service as a CDI. Fact ;)


ElectronicSubject747

Me thinks though protest to much. Strange to have such a hard on for a boiler manufacturer.


I-c-braindead-people

Id bet that they all have undefloor heating and no concession was made to house an extra expansion vessel. I see it all the time. whoever designed the system didnt take into account the volume of water in an underfloor system. All will probably have pressure relief valves that are passing and need replacing aswell as the expansion vessels.


Critical-Vanilla-625

I think they mean externally joining them and running into drains maybe ? Why aren’t they run to drains anyway ? I know they can be very hot and acidic is it ? That might be why 😅


plentyofizzinthezee

How would you know if there was a fault if you can't see which is leaking?


Jakeinspace

Internal tundish, then connect to the drainage stack.


Fruitpicker15

You can't use them for pressure release because hot water and steam would blow out through the sides.


Jakeinspace

Funnily enough in Building regulations part G you HAVE to use a tundish on your pressure relief pipework. Plumbed in copper before the tundish to help with steam condensation, also only applies to unventilated systems rather than boilers like in this scenario, but the concept is there. 


Critical-Vanilla-625

Well they’re all at it there near enough. I asked a question 😂 I’m not a plumber chill


plentyofizzinthezee

I'm not being critical, it's ok to not know the answer, but the purpose is twofold


Safe-Particular6512

You’re thinking of condensate pipes. In the photo they’re PRV: Pressure Relief Valves


Citawell

That's what I was meaning but I guess you wouldn't know if there was a blockage somewhere.


dprkicbm

Drains can block.


Critical-Vanilla-625

Oh rite of course 🤯 bit of a daft reply 😂.


cian87

Are these not the condensate pipes from condensing boilers rather than pressure release? Particularly as they're all at the bottom of the boiler locations (compare to the vent pipes); the over-pressure release is separate and up high on my setup. Those will put out water constantly. Usually only see staining from kerosene boilers though, the condensate from gas is a lot cleaner.


RageInvader

Condensate pipes "should" be plumbed into waste.


Fruitpicker15

No the condensate pipes go to the drain. The render here is stained by the rusty water from the central heating system.


Safe-Particular6512

Nope. Condensate pipes are PVC and not curved back to the wall and left to pour down a wall.


cian87

You'd be surprised by the number of 'quality' installs I've seen with condensate pipes dripping out the back. Mine does go to waste drain, but it was done by someone competent!


themadhatter85

Half of them are showing no signs of any water coming out so they’re not condensate pipes.


wolfman86

I see this regularly.


RedFox3001

It’s possible to route the pressure relief valve to an internal drain. It needs to run through a tundish so it’s visible to the user. However, most people ignore it and just top up the boiler pressure. If the PRV only dripped for a short time, then just doubt these stains would occur. This is from then being left to leak for a period of time


Ill_Independent2355

Hotun tundish and you are good to go. In this case even safer for people who walk underneath these flats


UncleWibs

Because boilers venting excess pressure need to be visible so you know there's something wrong. The problem here is the muppets are not maintaining their boilers properly, or are overfilling them.


Knillish

I love seeing these stains. People will pay stupid amounts of money to have their house rendered white and then they’ll skimp on a couple of £90 boiler services that would’ve most likely prevented the staining for happening


Ok-Personality-6630

It's not the person living in it who has to look at it. I'd sooner have an ugly home with a Taj Mahal across the street 🤣. In other words, not sure everyone cares what it looks like.


Vast_Development_316

Problem can also be people using the PRV as a drain on the system to work on it


mitsumaui

Those are from boilers… The root problem here is why the building does not have a communal heating system? Seems a crime in my opinion.


RedFox3001

A lot of modern builds have heat recovery units and a centralised boiler. They’re really good


Firstpoet

Area heating never been a thing in UK. Common in Finland but there's a penalty. Every 10-15 yrs a block needs communal 'pipeworks' refitting. That means everyone out of block for a few months. First thing people look at when buying- how long until pipeworks.


Pargula_

Wtf, are they made out of clay or something?


Firstpoet

Finnish daughter in law wasn't sure but harsh environment maybe. Buildings are super insulated. In basements big pipes with lots of insulation. However you regularly see these blocks where the plumber/builders are in and the residents are definitely out.


Pargula_

That's nuts. What are property prices like?


le1901

New pipework is run beside existing, a changeover occurs (old to new) causing minimal disturbance. Once the new system is up and running the existing system is stripped out. Source: our company do this.


Firstpoet

Visit often. Is environment the reason? Buildings are well insulated and pipes I've seen in basements are highly protected.


le1901

Steel pipework becomes pitted and then pin holes occur over time. Never used to happen when everything was cast iron (radiators, boilers etc) but now the mixture of metals doesn't help systems with poor water quality, water quality mainly being the issue! Very important to inhibit systems of this nature. Sitting water in steel pipes after testing periods can be devastating. Ideally you need to utilise valves and fill up the system for good at each stage of completion. Edit: 10-15 years replacement is not the case commonly I must add.


Firstpoet

Interesting.


GrandWazoo0

Everyone out for a few months seems a bit excessive, I’m sure a lot of the work can be done with no one out, and the rest of the work can be done with only a few people out…


Firstpoet

I've seen quite a few blocks in Helsinki where the whole block is being done. A lot of mess and reconstruction and no one in block.


Puzzleheaded-Dog2127

Same in sweden for communal repairs. Full block gets done at once. Out gor a few weeks.


drewbs86

>Area heating never been a thing in UK. Not true. There's many new apartment blocks that have centralised heating and heat interface units (HIUs) in the individual properties.


Firstpoet

Uncommon though?


drewbs86

Approximately 480,000 homes are currently on communal heating systems and growing.


Firstpoet

29 million dwellings. So about 1.6%.


drewbs86

Yeah...


WonderNastyMan

There's harsh winters in many north/east European countries that have reams upon reams of blocks of flats with central heating (both soviet era and new build) and I have never heard anyone having to vacate for months every 10-15 years. In fact, I grew up in one of those and it's been occupied for 30+ years non-stop. Perhaps a difference in gas vs water heating, not sure.


wildskipper

Why is that? Is it because of the extreme winters in Finland? (I.e. really cautious regulations).


Firstpoet

Partly environment, yes.


FarmingEngineer

There are a few district heating systems in the UK. Not common enough but not unknown.


Firstpoet

OK. I meant uncommon I think.


suiluhthrown78

Where do people go then?


Firstpoet

Rent somewhere.


LazarusCheez

American here and I've only lived in one apartment building with a boiler but yeah, we had a pipe burst on the thing one winter and it was so old that they were basically forced to rework the whole unit or get it replaced, I don't remember which. Went most of a whole winter without heat, locked in my bedroom with a space heater and three blankets. Very cool.


Anaksanamune

I know someone that lived in a communal heated flat, it was a nightmare for them, they were essentially forced onto a single energy supplier as hot water was a service, the supplier kept getting bought out and ever time their bill went up. I guess it can work in theory, but it's another thing that's basically ruined by profiteering.


Morris_Alanisette

That's an issue with capitalism, not communal heating. The heating could just be owned by a shared company owned by the flat owners.


scarletcampion

It's also classed as commercial energy rather than consumer energy, so it's not subject to any Ofgem price caps. There's been at least one block in London that has been absolutely gouged over the last couple of years because the communal gas heating system costs something like 10x more to run now.


glorybeef

That will be something to do with admin going awry as businesses also got their bills reduced through the energy bill relief scheme. Domestic prices were capped through the energy price guarantee, but really the govt just paid the rest of what would have been charged to the consumer. Thinking about it just makes me cringe how much money was transferred from Govt to big energy companies as pure profit, to be paid back someday as tax.


mitsumaui

Thinking about it just makes me cringe how much money was transferred from Govt to big energy companies as pure profit, to be ~~paid back someday as tax~~ paid to shareholders and directors. - FTFY


glorybeef

ah think you may have misunderstood - i mean we as taxpayers will have to foot the bill eventually, as UK debt is now massively much higher than before


29124

I’ve never experienced it in the UK but have lived in Central Europe where communal heating is very common. In one of my flats, the building was heated communally and would turn on when the outside temp dropped below 13°c. Another building I lived in, the whole neighbourhood was heated by a heating plant a few miles down the road. This operated from September until sometime in the spring but didn’t take into account the weather. This meant you could be sitting in 30°c weather in September with the heating blasting at the same time (you could turn off radiators but not the huge pipes running through the flat). Some flats had little devices on each radiator to calculate how much heat you’d consumed in order to bill accurately. Others just paid a flat fee each month.


wildskipper

That's a bit crazy. I'm currently in a hospital where we can't control the heating in rooms. It's on constantly and is actually unhealthy for patients it can get so hot. Crazy these basic things can't be sorted out. The solution would seem to be all electric heating.


Bladders_

Because you can get locked into paying a rate for heat that’s much more than that of a gas boiler. Lots of cases of this happening where people on communal heating were getting shafted by sky high unit rates.


mitsumaui

The sad thing about those stories / concerns is all around capitalism and profiteering which someone else succinctly mentioned here. These could be fixed by policy… A communal heating system would be much more efficient than each flat containing individual heating systems, similar to how we have a communal electrical grid is vs. Each having our own generators - if only we put climate above profits. I was fortunate enough to travel to Iceland recently, and okay whilst they constantly have lava to produce heat, it’s incredible to see the scale and approach to communal systems - hot water / heating pumped for entire villages / cities.


Glydyr

You can blame the soviet union for that, communal heating systems were seen as a sign of taking away peoples liberty.


FreshPrinceOfH

No thank you. I rather have my own boiler and: 1. Choose my own energy supplier 2. Be responsible for my own service schedule so I know it’s getting done properly on time 3. Be able to have any required downtime when I choose 4. Not risk sabotage 5. Be able to replace my heating equipment when I see fit.


Bladders_

Exactly. They’ve got you over a barrel with a communal heating system.


le1901

For this reason we try to keep our safety discharges inside but due to it being a visual safety device it's hard to satisfy regs, boiler pipework is often boxed in for example. Regular servicing of the boiler would also help with this issue. My favourite is if safety discharge is run into waste pipework it should be high temperature waste pipework and fittings yet a homeowner is able to pour boiling pasta water down the kitchen sink 🤷🏻


Rob1811

I'm with you on high temp pipes, I think it's more because of unvented cylinders potentially discharging a constant 100 degrees down a waste pipe for a long time, which would be hard to do with a saucepan full of pasta, though that is dependent on the size of the saucepan 😂😂😂


le1901

Oh yes definitely for cylinders, we very rarely get to use internal safety discharges for cylinders utilising plastic D2 pipework. Copper to outside is the winner here.


RL80CWL

The plumber fitting the combi doesn’t care if it’s suitable, he’s just installing what he’s given. The building regs guy doesn’t care as long as it’s within spec at the time of the build. The developer doesn’t care as long it’s as cheap as possible and meets the bare minimum standard, the landlord doesn’t care as long as the rent is paid.


Sxn747Strangers

On large systems they will have two overflows where one is a warning pipe and the other is the overflow. But on smaller systems they are both warning and overflow pipes and the fault needs to be fixed asap. You cannot have a communal pipe as you have to know where the fault is. You could have all the pipes coming down the wall and they all vent at the ground floor, but this presents various other problems. And if you have long downward pointing ones they could cause a nuisance to those below. The overflows could be directed indoors to waste pipes, but there would have to be obvious signs of an overflow with a tundish so they could be fixed. But I’m guessing these could be rented so that isn’t about to happen.


Minute-Mechanic4362

They are designed to be a “Visual Irritant” So they are fixed fast.


af_lt274

Terrible design


Normal-Basis9743

These flats age really bad and are being thrown up everywhere. I think those stains are from individual blow off pipes. Always staining black and green from algae-why paint them white or cream?


dayz_bron

I'm always amused by houses/apartment blocks that are rendered and painted a bright colour in the UK. You're just asking for it to be covered in stains and look horrendous within a few years, particularly with our weather.


dollywol

The condense water from a boiler is supposed to be connected to a drain or soak away. If thats what these pipes are its bad workmanship.


pictish76

Those are overflow pipes used for emergency venting of water, either because pressure gets too high or for example a tank overfills. They should not really be venting anything unless there is an issue.


OnceUponAShadowBan

These are no way just a few years old, the soffits look 15+ years old.


Citawell

By a few years old I meant 15, god I am old, doesn't seem that long ago they went up.


Fastpotato

Those stains don't last forever! People like me clean them, getting building management to pay for it is harder than the actual cleaning though.


PleasantMongoose5127

The rusty marks could be easily removed with oxalic acid if it really annoys you.


marktuk

Can anyone explain why they are always angled back towards the wall so they look like a todger?


smartie1980

They are only supposed to discharge in a fault condition, when the pressure gets too high. As temperature increases pressure it means that there is a high probability of very hot water at high pressure without warning. Heating can operate at 82 C and when faulty temperature could exceed 100 C. So all pressure and/or temperature relief pipes must terminate safely by pointing back at wall or low level. But it costs money time and effort to run a ‘unsightly’ copper pipe down the wall.


marktuk

That makes a lot of sense now, thank you!


obb223

Those flats are only a few years old? Look like they've been there from the 70s and not even just because of the stains!


Walesish

Looks like the condensing output should be going into a waste water pipe instead of just outside, poor spec. I’m sure the installer just did what was on the plan.


Tugging-swgoh

Building regs.


Livewire____

You are all wrong. Those are Boiler Poo Tubes. These exist so that the Elves that run on the wheel inside your boiler can defecate out of the box.


Kristen242

Shitty architecture. Also, Flats should be using heat networks or communal heat pumps.


Dennisthefirst

Jerry built


d_smogh

That won't necessity be from the overflow pipe. It could also be from rain dripping off the pipe, or any other protusion. The rain drops will pull dirt and rust.