Posted by in Plumber Talk, on October 2, 2017

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This video briefly guides you through the steps involved when changing an immersion heater. If you have the right tools you can do it yourself. From turning off the water to switching back on and feeling nice warm water.

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Today we’re gonna change an immersion heater. It’s gonna be amazing. So, if you follow my steps, you’ll be fine. And you won’t have any trouble at all, so let’s go.
Alright, so the immersion heater we are changing today is an Economy 7 tank, which means it has two immersion heaters. The top one being the boost, and the bottom one being the night setback. Unfortunately, today we’re going to be taking off the night setback one, which means we’re gonna have to drain this whole tank down, before we can do any work. Firstly, turn off the water supply. Now we isolate the electrical supply. So what you do is find where the immersion heater switches off, turn it off, take the cap off the immersion heater, and using a pair of electrical testers, make sure that the power supply’s turned off and it is dead. Make sure one side you’re testing is to earth, and you test every other terminal on the immersion. And that is completely dead now.
Now that we know the immersion is turned off, we can drain it down. If you see this here, this is the drain-off. We’re gonna put our hose on that, take the hose outside, open up this valve, go and have a cup of tea, while this is all draining down. Cause it’s gonna take a good 10 or 15 minutes. Don’t be surprised if the drainoff leaks, they often do when they’re really old. So, we’ve got our towel under there anyway. Here’s our new immersion heater. We just quickly remove the packaging. Small set of instructions, put these to one side they’ll tell you how to connect it electrically, later on. And a small fabric seal that seals up this flat here with the flat on the tank. Often what I’ll do at this point is I’ll pop a bit of PTFE tape round the thread itself, and also you should find jointing compound, or even better copper slip. After I’ve put a little bit of PTFE on the thread, I’m gonna put some jointing compound on this fabric washer here. Just get it all over it, completely smear it. And that will help you get a really good seal. Now pop that on the immersion heater and push it right down. Do this carefully cause you can rip these fabric washers in half. Do the same again and get loads of compound on here. Now, this is an extra precaution, you can do this if you like. Just get some PTFE tape and get that wrapped around on the thread itself.
Now we’ve got this prepared, all we need to do is wait for the tank to drain down and the we can set about removing the old immersion heater. This bit will be difficult, but persevere. And if you go nice and slowly, you’ll be great. The next small tip I have, is now you’ve got this prepared, while the tank’s still draining down, go back to the immersion heater, remove the wires, and just loosen it off while there’s still some water in the tank. Because, the water in the tank will help to stabilise the copper wall of the tank itself. If there’s no water in there, you could end up rippin’ the whole flange out of the tank and getting yourself a whole new tank. And you don’t want that to happen. There’s a constant risk while trying to remove these. So if you loosen off while there’s water in the tank, it will still be nice and stable, and with any luck, you won’t rip the flange off. Let’s have a go at that. First you remove these wire clamps. Free up the wire, remove the neutral. Remove the live. And using your small adjustable remove the earth wire. For this part, you are gonna need some specialist tools made specifically for removing immersion heaters. This is an immersion heater spanner. This is just one type, I’ve got another type here. And if I really need it, I’ve also got a nice big pair of grips that can grab it as well. So let’s get this old immersion heater loosened off. And then once the hose stops, we can actually fully remove it. So, we put a towel along the bottom here, just down here to get any water that might come out. Pop our immersion spanner on, make sure it’s fully home. Then get my large pair of grips and turn that anti-clockwise to just loosen it off a little bit. I mean, that was tough. That pretty much took all my strength just to loosen it off. So, apply yourself properly, prepare properly and you will be able to loosen it off. Just be really careful. If you feel that it’s starting to buckle just stop, re-jig up the whole job and then try again okay. Just take it easy, apply yourself and it’ll be okay. So now we’ve loosened it off, we just need to wait for the tank to fully drain down and then we can properly rip it out and pop the new one in and connect it up.

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