HOW TO DRAIN YOUR HEATING SYSTEM – Pressurised – PLUMBING TIPS


– Plumberparts.co.uk. Honest reviews and advice. (Claps) Hold tight! As they say, in the land of plumbing. Welcome to today’s
Plumberparts.co.uk video. Today, we’re gonna look at
pressurised heating systems. Now, we’ve looked at them before, in the way of how they work, how they deal with their expansion and everything. But this video is actually a request from one of our followers on YouTube who said, “Look, I don’t
know how to drain down” “my pressurised system.” “I’ve got a little job that I need doin’,” “and it’d be great if you
could show me how to do it.” Now, as we say, don’t
do this sort of thing if you don’t know what you’re doing. You do need to have a
basic knowledge of plumbing if you’re gonna try and do this, but I’ll give you a step-by-step guide on how to isolate and
drain down the system, and then, you know, do
whatever work you’re gonna do. Have a cuppa tea, scrub your cat’s belly, I might even put a couple
of questions in here. So, anyway, let’s have a
look at how we actually isolate and drain down a
pressurised heating system, and then do whatever you like, and then I’ll show you
how you fill it up again, and then get it all back and working. Hold tight throughout the night! Blud! (In New York accent) Y’know,
my father always told me, the first thing you should do is isolate electrically
the heating system. That’s what we gonna do now. This switch here turns– (resumes usual accent) This switch here turns it off, alright? That’s the heating system off. We don’t want it coming
on or anything like that while we’re draining down. The last thing we want is
the boiler lighting up, or the pump coming on. It could burn the pump out, it could overheat the boiler
and crack the sections. So the first thing you do is make sure that the heating system is switched off. (honks) “Ah, but James,” I hear you
ask in your stupid voice. “How does that pressurised
heating system work?” “Well, y’know, I need a
basic knowledge of them to know how to drain one down.” Well, usually, you’ve got your boiler, your pump, any valves:
you could either have a three-port valve there
or a couple of two-ports. In this system, we’ve
got two two-port valves. Then you’re gonna have your coil going into your cylinder,
if you’ve got one; if not, a combi system. Then also you’re gonna
have your radiators, blah, back to the boiler, blah, back to the boiler. Cor, what a diagram. Beautiful. Now, some heating systems use
a gravity feed in the loft to actually push water down, via gravity, from a tank up there
with a ball valve in it down into the system. But nah, we don’t have that
on a pressurised system. ‘Cos we ledges, aren’t we? Yeah. Basically we have a
cold water main come in, comes in, goes through a filling loop into what we call the manifold that’s often at the bottom
of the expansion vessel, So we’ve a big expansion vessel like that. If you wanna know the principle about how pressurised heating systems work then watch our video on
pressurised heating systems. I’ll leave a link to that… here. So you got that, filling
loop, braided hose. You have a non-return
valve there, a valve there. This braided hose is
removable, so the system doesn’t automatically or accidentally fill up off the cold water main, which could pressurise it, which could bulge radiators, which could cause your whole world to come falling down. So yeah, there we go. That’s the basic gist of how they work. The water heats up, expands
into this expansion vessel. Like I said already, go to our
video on pressurised systems. Then you’d know. Ugh! So, let’s have a look at this system here. So here’s the loft that we’re looking at and the particular part we’re
gonna be taking notice of is that bit there. So here we are on the
lines down of possibly, possibly the worst pressurised
heating system install I’ve ever seen. Right, so, we’ve got our
feed from the cold main here. That’s this valve here, this Voss valve, we’ve got our braided hose here, that’s also got a little valve
in it that you can’t see, but it’s just a little
black-handled valve. Let’s get round here
and have a little look. Can you see that? There it is. Little black valve there, lovely. Now that braided hose comes up here and through this, which is
a non-return valve, okay? That means the heating
water can’t push back down the mains if there’s
any problems like that. Next, we have our little manifold, okay? All this is, is just a series of ports that allow water in and out of this particular part of the system. Now, we’ve got our pressure gauge here, which is currently
reading about half a bar, which is borderline okay. This system’s colder than mine, so when it heats up, I imagine it’ll come up to about one to one and a half bar. At the top, we’ve got our
high-pressure relief valve. Now this has a small spring in it, so if the pressure gets above 3.5 bar, which is all the way around here on there, that spring’s gonna
lift up, and it’s gonna let water out of this pipe here, and that’ll go outside,
where it’s terminated at a safe place. The next thing we have to
look at is this part here. This is the expansion vessel. Water can expand down into this and be happy. And this side here is
heating system pipe, okay? This feeds the heating system. Alright? So. Now, and now only, can we drain the heating system down. One thing I wanna stress
about what we’ve done: those two valves should be off anyway. You’ve just got to make
sure they’re off, okay? Don’t turn them on again,
or anything like that. Make sure they’re both off. They should not be left on. Ever. Alright? “But now,” I hear you say, “What about draining the system out?” Well, most heating systems– okay, let’s say we’ve got
a two-bed house, okay? Look at this. A little– well, a
two-floored house, right? We got a radiator down
here, radiator down here, radiator down here, and
a radiator down here. Say the boiler’s in an outhouse
or something like that. Usually, what we’ve got here, we’ll have an airing cupboard up there. Your boiler flow will go up
into the airing cupboard. And then, it will get
distributed around these rads. Off through each radiator, it’ll come down like that, oh, lovely, and they’ll join up at the bottom and then go back to the boiler. Now what you do is,
you’ll be looking for is, you go downstairs, and you try
and find a little drain-off where you can put your hose
outside and let water gush all over next door’s primroses,
or something like that. Now, that’s great, you know. Sometimes, that’s brilliant. But, and I’m gonna show you in a minute, sometimes the systems
are actually laid out in a completely stupid way. Ugh! Which means, say we’ve got a system like this, it’s brilliant. But there’s a radiator in the hall that has two pipes that go down to it: a flow and a return, okay, and they go to that
radiator and pipe that up. You could drain all this lot out here, but that radiator there’s
gonna stay full of water, because there’s gonna be its
own little drain-off on it. And that’s gotta go out there. So keep an eye out for that, alright? We’ll show you one of them in a minute, ‘cos we do have those in this house. Let’s go and find a drain-off
now, pop a hose on it, and shove it outside, and actually start draining the system down. One other thing I’d say is, before you drain down the system, go round and turn all the
radiator TRVs on fully, okay? So they’ll all drain out nicely. In the words of Biff
of Back To The Future, “Well, looky what we have here!” This is a drain-off, this bit here, okay? Now, drain-offs do have a bit of a knack of having a bit of a leak sometimes. Nothing mental. All you have to do is
just pop a towel down, make sure that it’s okay. Now you get your hose, which has been in the van all night,
and it’s freezing cold, We gonna pop that on here. (grunts) That’s a nice tight sort of
fit on that spigot there, which means I won’t have
to put a jubilee clip or anything round that. What I’m gonna do now is take the hose (playfully) outside, ain’t I? Go. Go. Be free! Be free. Now we’ve got that outside,
all we need to do is get a grip and undo this, and you should start to hear water coming out. If you don’t hear any water coming out, then go on our video
on how drain-offs work. I’ll leave a link to that
on this video as well. Right, you should now go back upstairs to where your airing cupboard is. So the system pressure
now is reading… nothing. Hardly a thing. No bars whatsoever. So the system pressure
there’s not reading a lot. Come down here and have a look. Right, so, first thing I do is, remember we’ve got the heating
system power switched off? So, go down to your two-port valve, and latch that in the open position, and do the same on all two-port valves. Any motorized valves you find, latch them in the open position, okay? They’re not gonna come alive ‘cos the heating system is switched off. Go to the highest point. If you find anything like
an air vent, like this, you can go and just open
that up now, as well. And that’ll allow air into the system, so it doesn’t put a vacuum,
and that’ll go down. Right, and now, we go to
each radiator in the house. Now, pretty much go around the house. Always try to find if they’ve got a valve, a radiator that’s high up, like this one. Start on the top floor, the very highest radiator on the system, get yourself your radiator
key, and open that up, and that’ll allow… That’s sucking water into
the system now, okay? Now as the water level in this
rad is slowly dropping down, and when it gets to about
here, it’ll be the height of this little radiator here. Then I’ll be able to
open this up and do that. Right, remember what I told you
about sometimes having legs? We’ve got a radiator here,
as you can see, behind this. Now, there’s two pipes
there, you can see them, two pipes down there, and they run up behind this television, then upstairs. That means that this radiator, once we’ve opened up all
the rads upstairs and that, isn’t gonna drain down,
‘cos it’s on it’s own leg. So, we should find that somewhere, the guy who fitted this
has put in a drain-off. Now, there isn’t one there, and I can’t see one down there– ah-hah! There’s one, just there. Which means you’re gonna have the joy of pulling out this whole television and then getting your hose on there, and then trying to
drain that radiator out. Only really do that if
this is the radiator you actually want to work on. I mean, we’ve got another
radiator here, okay: you might not wanna work on this one. This has got another leg on it. There’s a drain-off here. If you don’t wanna work on this radiator, don’t bother draining it out, okay? It’ll just stay full of
water up to here, alright? So then, the system now
is fully drained down. You’ve gone outside and
y’looked at your hose, and the hose isn’t running,
the legs you’ve worked on you’ve drained down, and
everything’s absolutely hunky-dory. Now you can change that TRV, whip that radiator out
and put another one on, or do whatever pipework you need to do on this pressurised heating system. So you’ve done all that, okay. What do you do when you’ve
finished doing all the work? How you gonna fill this lot back up again? Now I’m gonna ask you a little multiple-choice question now, hm? It’s gonna be like, eh, Blue Peter, but without the drugs. And what this is gonna be is
this: what do you do next? Do you: a) close the drain-off and close the radiator bleeds? Do you: b) turn on the electricity to the heating system to get it running? Or do you: c) go on Twitter
and check your Twitter feed? Teachers, you can now
pause it if you like. Get these kids to have
a little think about it. The answer’s A. Go downstairs, go back to where you were. Turn off your drain-off, okay, turn that off and take the
hose off and take it outside, And then go round the house and shut all your bleeds
on your radiators, okay? This is so important. If you don’t do it, when you come to refill the system again, you’re gonna have all these lovely little leaks everywhere that is just gonna annoy you and maybe a customer if
you’re working in their house. So let’s go downstairs now
and turn the drain-off off and then let’s shut
all the bleeds as well. (sings) I gotta turn this bleed off. (sings) I don’t want no water coming out (sings) when I refill the system… (sings) Yeah. (resumes normal speech)
Not the phone again. “Can you please send me a
quote for my bathroom, please?” (thunking) In a minute, son, we’re filming! Right, we go back round all our radiators. I think this is the one
I showed you earlier. Turn that off, turn that off, make sure that’s not
doing anything anymore, go round to all the rads and do that, don’t forget any radiators. Right, so now you’ve
closed your drain-offs, and you shut all your air vents
and everything on the rads, and you’re ready to fill up. The best thing you can do is top it up so it goes to one bar,
go and vent a radiator. When no more water comes
out, come back here, have a look at that gauge,
put that back up to one bar, and then do it and so forth and so forth until you’ve done all the radiators. When the system’s then full
up, we’ll re-pressurise it. I’m gonna put this back to half a bar, ‘cos this system’s work really well at that pressure when it’s cold. But most of you are gonna put your system back up to one bar, which
is the cold working pressure for most heating systems. I’ll shut down our bleed here, ‘cos we don’t want water
coming out of there. And then I’m gonna open my valve here, and I’m also gonna open my valve there, and I’m gonna pressurise
the system to one bar. While this is happening, alright, is the time that you wanna go and check the work you’ve done, alright? Because you never know, I mean, this has never happened to
me, I never get any leaks, but you never know, you might have a leak. So keep an eye on all that sort of thing. So we’re gonna pressurise the system now and you should be able to see in a few minutes, the system pressure here should start to rise. Take special note here,
this beast is rising up. (pipes hissing) We’re gonna get that so
it comes up to one bar. First place I’m gonna vent is just here. Just gonna let that vent now. (pipe pinging) And I’m also gonna vent just here. (pipe hissing) While you’re venting down, you’ll notice that the pressure up
here is going to drop. Right, so let’s go in now. See, we’ve let some air, we’ve let some air out now, and that pressure’s just dropped slightly. Now what I’m gonna do, ‘cos we’ve just dropped a little bit of pressure, I’m gonna turn our water back on and re-pressurise that back up to one bar. (pipe hissing) Now you’ve actually
got the airing cupboard vented of air, the next place I’d go to vent the radiators
out would be downstairs. So the idea is, you fill
the heating system up from the bottom, and then you go upstairs and then you keep filling it up. Every time you do a radiator,
pop back to your gauge here and make sure that it’s still at one bar or at whatever pressure you
wanna pressurise it at cold. But never over one bar: never pressurise a system
over cold above one bar. So anyway, I’m just gonna
pop a bit more in here ‘cos I’ve just done a radiator, and now I’m gonna go round and vent all the radiators on this system. While I’m doing that,
I’m gonna leave you with a quick thing to think about, okay? You’ve got the system back on, we’ve unlatched both of our valves, or whatever three-port valve or whatever control
motorized valves we have, they’re now unlatched and back
into their normal positions. What should we do next, now that we’ve drained this system down, and we’ve got it all filled up again and we’re pretty much ready to turn it on? What is the next thing we should do, okay? We have tested for leaks as well, alright? So that’s done. So basically, you filled up, there’s no leaks, everything’s brilliant. What is the next thing we should do? Should we: a) turn the power
on, and get it all running? Should we: b) inhibit the
system with an inhibitor? Or should we: c) ask the
lady who we’re working for for a cup of tea? It’s a trick question,
this one, really, innit? (laughs) I’m gonna go vent these rads, you can have a little think about it. See you in a sec. Now we’ll go all round our radiators now, and vent each radiator out. (radiator hissing) (radiator spluttering) Right. So that one’s done. Right, I’m back now, it’s
all vented, still at one bar. I might try at one bar: we’ll see. So yeah, the thing you shoulda done, the right answer, was
inhibit the system, okay? I’d say that was B, weren’t it? But also, the answer’s C. Because, I mean, if she hasn’t
made you a cuppa tea yet, you’ve done all the work and that, then what’s wrong with her? Or him, okay? You know, I’m not gonna be sexist here, but there are just as many men than women who don’t make tea for you
when you go round their house. I’ve done that– am I
digging myself a hole here? Inhibit the system, okay? Now when you get everything
turned on and running again, you’re probably gonna get
quite a lot of air about, so you might have to do a
little bit more venting. But every time you’re doing your venting, just make sure you turn
the system off, okay? So hopefully, you now know how to drain down your
pressurised heating system, how to safely fill it up to a safe level, and how to vent it all. And also then, you also know
the things you need to do to actually fully reinstate the system, and by that I mean inhibiting it. If you need any more help, or
you need any more information, visit our website at plumberparts.co.uk . You can follow us on Twitter and Facebook, and also, you can subscribe to our videos. We do loads of stuff on Twitter: we’re always retweeting some of the dreadful plumbing disasters that you guys come up against, and girls, on a daily basis. So, you know, give us a shout, we love to hear from ya. And we’ll see you in our next video, which is gonna be an
Ask The Plumber video. So if you’ve got any questions for us, ask ’em in the comments below, or ask them in any of our videos; or better still, tweet or Facebook us, and we’ll try to cover those in our next Ask The Plumber video. Until then, have a lovely day, have a lovely week, and I hope thee have a lovely week-end as well. (hurks) I’ll see thee later. Hold tight! Plumberparts.co.uk. Honest reviews and advice.

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