Posted by in Plumber Talk, on June 10, 2017




This video will give you the basic system information needed to understand a vented hot water system. How they work, what the plumbing connections are and where to buy them online

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Holler, and welcome to this week’s video. Today we’re gonna look at indirect vented hot water cylinders so, enough of me looking cool and amazing, let’s have a look at this. So first up what we’re gonna do here is remove an old indirect vented hot water cylinder and put this new one in here. There’s a few connexions on these that you need to know about and basically how they work. Firstly, we have this part here, this is where our immersion heater goes in that will screw into there, seal out on this thread or on this flange and that is basically the electrical backup heater to heat up any water should there be a problem with the coil. If you actually look inside you will see there is a coil just inside down there that has hot water coming from the boiler that transfers heat into the main hot water cylinder and into the water. That coil is fed by a flow and a return on the side of the tank just down here. The flow always goes into the top, hot at the top and it comes out at the bottom slightly cooler. So that’s your flow and your return for the boiler.
So you’ve got a cold feed down here on the opposite side to the heating flow and return and a lot of people actually tee in their drain off just here or if it’s on the opposite side of the door you’ll run a 15 mil part round to the front so someone can get to it. Right, so lets have a look at the old tank. We’ve got very, very tight installation here, this is gonna be a nightmare. Down at the bottom here we’ve got the drain off, as you can see the old engineer that fitted this put a little 15 mil part round so you can get to it. So that’s nice and considerate. We’ve got the thermostat that controls the two port valve or the three port valve depending on what type of heating system it is. We’ve got our heating flow and our heating return going into the coil that I showed you on the other tank earlier. And at the top already removed, we’ve got the outlet, this is the hot water outlet that goes off to all your taps and as you can see down the back there we’ve got the cold water feed. And as you can see at the top as well we’ve got a immersion heater, generally when I’m changing these just put a new immersion heater in, it’s worth doing. So at the moment we’re draining down the actual hot water tank itself. Now, we’ve valved off the cold feed just up there and we are now draining it all down. So once we’ve done that we are then gonna have to drain down the heating system, so make sure that’s all turned off there so you can drain that down and then you’ll be able to remove these unions here.
So while we’re waiting for that tank to drain down what I usually do is get all the bits and bobs prepared on the new tank to go in. Now, looking at this new inlet here for the immersion heater, what I always find is a good thing to do is because the immersion heater needs to seal on this flat face that’s been covered up by this foam, the first thing I’d do is get out a knife of some sort and just try and cut the foam back a bit. So I cut round here and remove that foam. Once you’ve got most of the foam taken off just get some emery cloth in there pop it round and give this a good clean. If you want to know how to install an immersion heater into an indirect or a direct cylinder or a vented and unvented cylinder, just go back to our channel, type in change immersion heater and you’ll find our video there. Once your sure you’ve drained the actual tank water itself and there’s no water coming out of the taps or out of the hose at the bottom you can cut the pipe that feeds to the tank. Generally I’d always recommend you cut that pipe high up, especially in a situation like this where the feed tank goes down the back of the cupboard. If you cut it higher up, then when you make your second connexion, when you put the new tank in, it will be high up and easy for you to get at. You do not want to be leaning down behind a tank in a cupboard trying to do your connexions down there. You want to do that outside or in the room itself, it makes life a lot easier. So once you’ve cut that pipe then you can move to the flow and return, always slacking off the top one first, okay, you only do this when you know you’ve drained the heating system down and everything. Make sure there’s no water coming out of there.

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