Posted by in Plumber Talk, on September 7, 2017




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Hold tight, and welcome to today’s video. Oh my God. Anyway, today we’re going to be looking at feed and expansion tanks, and the systems that they feed and how they work. We’re going to go up into a loft and show you one in situ, and so you can have a look at that, and be marvelled by the positions people put them in. Just imagine that this is the loft bit, here, and this is the roof. This is the ceiling running across here, and there’s your loft area there. You’d put the tank here, wouldn’t ya? But no, loads of people just always put them right there. Miles away. And I’m not going to put any lights up in there, and then I’m going to cover it in rockwall. Cheers, buddy! Thanks for that! Anyway, so firstly, have a look at how they work. I don’t know where the whiteboard’s gone, it’s disappeared, so we’re going to use… A bit of wood. Don’t know that you’d be saying that I don’t help you guys out. I’m using wood.
Right then, so, you’ve got your boiler here, alright? You’ve got your flow, you’ve got a pump, let’s say this is the house plan, so you’ve got two motorised valves, okay? And then you’ve got your coil for your cylinder going back to your boiler, and also you’ve got a couple of radiators on the system, upstairs and downstairs. Let’s make it a nice little two pipe system as well, but as they say in the world of the fends, and a common return. Everything going around like that. Lovely. Now, we draw a line up here, above this line is the loft. A place where no man should venture unless they really have to, because it’s complete grief. No one ever has fun in lofts. So, up in the loft we have a tank. We’re going to shape this tank like that, it’s like that, okay, it’s that big. In the tank, we have, a cold water feed, call if CWF, with a ball valve. Ball valve.
So the water level is there. You have either a bottle that is a larger size bottle that allows the water and air to split slightly when it’s filling up, and gives the air a chance to go upwards. Off the top of that, this pipe here, which is the expansion pipe. Now, this is where people get a bit silly. You have the feed pipe, there’ll be a hole in the bottom of this tank here below water level, and that will go along and should really go down into here, okay? So your feeding water down into the system, okay? Not all the time, just when it needs it. So there’s a leak, you’ll sometimes see the ball valve’s dropped a little bit, and there’ll be a drip going on, then your nose starts to twitch. You’ll be like, hmm, there’s a leak. Better sort that out, hadn’t I? A lot of people, though, what they’ll do is they’ll be lazy and they’ll just put this into here okay? They’ll put this into the side of the expansion pipe. Because they’re all the same system. So, if we thought about it like this, the water level across the whole system is like that. Now, as we’ve said in our video about pressurised heating systems, when you heat cold water up the molecules and the particles in the water start to get more and more excited and active. Like Ministry of Sound, it’s going mental. So these particles start moving more and basically the water body expands. Now, as we said in a pressurised system, you have an expansion vessel in that that takes that expansion. But not here. That’s why we’ve got this thing here, the expansion pipe, right? So, the water level is just about here when it’s cold, now when this all comes on, and these radiators and everything heats up, the expansion is not enough to be able to push on this body of water here, but it will be able to push slightly up this pipe here a little bit. So you put the crook high enough so it can go up a little bit, but not so high that it goes into the system. But if you do have a problem and it’s over expanding, or anything like that, it’s going to run up here and safely go into your tank. If it gets really bad, the water level will come up, and you’ll have an overflowed pipe probably about here, that will run off outside and out of the house. Right, so if we wanted to drain one of these systems out, it’s really, really easy to do. There’s usually a valve on the cold water feed here, turn that off, go to the lowest point in the system, you’ll often have one on the boiler, and in front of the drain cock. Then you can undo the drain cock there, take the hose outside, and the water level will drop out of here, drop out of there drop down out of here, and drop down slowly out of the system as you drain it out. The next thing you have to do, is you have to open up any of the bleeds on the radiators, and also, obviously, make sure the system’s switched off.

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