How to Fill a Worcester Bosch boiler using an external filling hose

Welcome to Aquaheat. This is a quick video on how to fill up your central heating system with an external filling loop. So here’s one that we fitted today on a new boiler. So we’ve got the, this is an external filling loop from the boiler, we’ve got a flexi hose here. Now, this is generally how it’s supposed to be left when it’s not being connected. However, you may find, a lot of times, these are still left connected. I’m gonna just run through how to do it.

First of all, we’ve got to take these caps off. All of this stuff is hand-tight, so you don’t need any spanners. Undo this one. Put that on, hand-tight. Put that on, hand-tight. Now, what we do is, here, open this, this is our cold, this is our central heating going in there. Turn that, so it’s perpendicular to the pipe, it’s in line. We can see that now this has livened up, all the cold’s come to here. However, I’ve got this one closed. Once I open that… This is our pressure gauge here. Now, our pressure’s fine at the moment, it’s perfect, it’s on the heat test, it’s coming up to under 2. But if that was like low, it’d be below 1 at zero, so I would then open this black one in line with the valve, and then I would make sure the heating’s off at the same time, by the way. I’d watch that black needle, I’d hear water rushing in, going up to 1. When it gets to 1, I wanna start slowing it down, if it gets just above 1, then we just crack it off. Turn that one off, then we turn this one off, then that’s it, it’s filled up.

If you find it’s not filling up, then it’s either your valves here are old and jammed up, or you may have a seriously bad leak on the system, so… But if it does work, then that’s it and that’s topped up. Now what we do, we’ve got to take this hose off. Now, there’s gonna be a bit of water in here, little pressurised water, but it’s shut here and it’s shut here. So I’m gonna undo this one. This is the clever bit so you don’t get wet. Undo that. Little squirt. I put my finger over there, my thumb, and then I undo this one. That creates a vacuum, and allegedly holds the water in. And then we undo that one. I’ve got a nice little container here. There we go, it just all drips in there.

Now, put our caps back on. So… Make sure you put these caps back on ’cause these start leaking, and you are supposed to take this off, and the reason why is for… The Water Board doesn’t like you leaving that connected ’cause of contamination of their supply, potentially, if either of these valves start to leak. Pop that in there, pop that in there. We’re good. That’s how you fill up a filling loop. So, please watch that again if it was… I was going a bit too fast and there was something that you didn’t really catch, but it’s pretty straightforward and… Yeah, thank you.

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