HOW NON RETURN VALVES WORK – Plumbing Tips
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This video covers how non return valves or check valves work. We tell you how to install them, where to install them and why. If you need any more help just ask!
Hold tight and welcome to today’s plumberparts.co.uk video. Today we are going to look at non-return valves. This is a non-return valve right here.
Now firstly you will see there’s an arrow. That tells you which way this valve should go. So, inside, it moves one way altogether. See that? If I blow with the arrow, it comes out. If I blow against it? Nothing comes out. Before we carry on with this video, I’d just like to apologise for my voice. I’ve been on a cricket tour, and I’ve come back, and I don’t have much of a throat at the moment. I have no idea why.
So, we are gonna go and have a look at where you can install one these. I’m gonna show you how to install one on a basin, and hopefully you’ll learn a little bit about where you can put them, why you install them, and how they work.
Right, first up we’ve got this sink here. Now, on one side of this sink, we’ve got mains cold water, and on the other side of the sink we’ve got a pretty poor flow on the hot water side. Now there’s no non-return valve on the hot water side yet. So, what happens is, say
you’ve got the hot water open. You open it up, there’s not much coming out. You open up the cold, and it flies out at much higher pressure, and it pushes cold water back down that hot pipe. So now when I open this up, the hot is now running cold, because all that cold water’s been pushed down that pipe, and wait a few minutes and it’ll come back hot again. To prevent this happening, we put a non-return valve in. It’ll go this way round on the hot side, and stop the cold water pushing back down that pipe and back down the system.
Now I’m going to show you how to install one of these. It’s as easy as 1, 2, 3 or ABC. Just two compression things, and then I’ll go to the drawing board and show you schematically where you’ll find one of these.
So, firstly let’s go under this sink and find out our hot and cold. Now I’ve been running the hot for a while, so that one there is nice and warm, so that’s the hot now. Just get your screwdriver or whatever, and turn that off. And it’s not a bad thing to turn the cold off as well just in case. Pop around here, turn that off too. Now just make sure they’re both off. Nothing. So, going back under here, we’ve got a small little bit of copper pipe just here. We’ve also got our flexi. Now my plan is to pop our non-return valve here, and then add it with the flexi at the top. Just loosen that off and take that away. You’re probably gonna get a little water out that’s been sitting in that hose. Here we go. What I do now, because we have like-new olive on here, is take this piece of pipe out. Now we can build our new section of pipe.
So firstly I’m just gonna cut a small length of the female. Pop that olive, then on that one. Next, cut another small piece of pipe, and pop that right down, as far as it will go and tighten that up. Right, gotta get that on, I’m just gonna cut this piece down, and also, it’s the end of the length of copper pipe, now this bit’s slightly wider, I’ll often find a pipe slice makes a beautiful taper for it to push into a compression fitting. You see the difference in there, nice little taper that end, hard horrible pooey in there. Right, so now we pop a nut and olive on this end, and a nut and olive on this end. Now it’s the time to make sure you’ve got the arrow pointing the right direction. Now we want the hot water to be coming up through, in line with this arrow. So our valve is gonna be on the bottom here, and our flexible hose is gonna be on the top here, so let’s install that now. So, let’s pop our, tighten this up, got that one there like that. Fortunately, I think this pipes got a bit of give in it, so we can just push right there, get our new nut and olive on and get our flexible on without it kinking. Now we will tighten up the nut and olive for our flexible. So our arrow’s in the right direction, as you can see. Now we should be able to turn the water on, test for leaks, make sure everything’s alright. Alright, so we’ve turned everything back on and tested for leaks, and there are none, I mean I’d expect nothing less from myself. I back myself not to get leaks on 15 mil copper pipe. So let’s firstly see whether the hot water’s got enough pressure to actually push the non-return valve open. Bear in mind that the pressure here wasn’t very good in the first place, so I’m not expecting a great deal here.