Home » Blocked Main Heat Exchanger / Noisy Boiler / Failed Powerflush
Noisy banging boiler. My name’s Alan Hart, and today I’ve got a job where the customer’s complaint is the boiler is noisy and it’s banging and clanging. They have had a company go out and do a flush on the system and try and try and clean the system. So what we’re going to do, we’re going to go out, going to have a look what’s wrong with it, and possibly we’re going to do a flush on this system. We’ll have a look and see what’s been done before, but yeah, let’s go and have a look.

This is an alpha combi boiler and, it doesn’t look like the system’s been flushed really, but the customer has said that they’ve had somebody out to it who’s done a flush on it. We’ve just removed the filter and just had a look at the magnet inside. And as you can see on this magnet, it’s got a lot of magnetite on that magnet and the boiler is very, very noisy and it’s screaming. So what we’re going to do is we’re going to flush the system out.

Because the blockage is in the heat exchanger, we’re syphoning the chemicals, the cleaner, the F3 directly into the heat exchanger, and then we’re going to turn the flow off at the boiler and we’re going to ruin the hot tap. And what that will do, it will put the chemicals through the plate heat exchanger, and also through the main heat exchanger. So just to explain what we’re doing with this, this has got a cementer heat exchanger, which is a multi pass heat exchanger.

I’ll just do a little drawing and I’ll show you how that works shortly. And it’s the same heat exchanger, or very similar that’s in the ideal Vogue, the Baxi platinum, the Baxi 800, all the premium boilers, really. So it’s a really good quality heat exchanger, but because it’s multi pass and the system’s full of sludge, then what that means is, if you get sludge in the heat exchanger, it’s not one continuous coil. So like a Viessmann is one continuous coil. So if you flushed it, you would be going through the muck, but it’s not like that on a multi pass, so I’ll just explain to you what a multi pass bills.

So if you imagine, I’ll just draw it on here. So we’ve got flow in, and then you’ve got coils in the heat exchanger, we’ll just draw this on there. Me drawing is a bit shocking, I don’t know if you can see that, but if you imagine your flow there that goes into the heat exchanger then, and then it [inaudible 00:03:06] inside, and it goes around the coils in different sections. I’ll show you a heat exchanger, so you can see, and then it comes out on the other side here, as the return, whichever way around.

So that’s how it joins. So I’ll show you a picture of a heat exchanger that’s cut up, so you can see, but what it does is, if part of it blocks, then the rest of it can still be heating. But when it is on high, it can start to boil in the heat exchanger because part of it’s not getting enough flow around it. So what we’re trying to do with this, a lot of people say that if a cementer heat exchanger blocks up, you, you cannot clean them. I’ve done quite a few of them to be honest, and I’ve always managed to clean them. So touch wood, if we’ve got any, haven’t gotten any in here, but touch wood, touch wood, we’ll [inaudible 00:04:10] clear this one, but to be honest it is quite bad.

So just to recap what we’re doing here, we’re syphoning the chemicals into the heat exchanger at the top of the heat exchanger, on the top holes on the left hand side. And what that’s doing is, it’s putting chemicals directly into that heat exchanger. We then close in the isolation [inaudible 00:04:39] underneath the boiler. And then what that does is, when we run the hot water, it allows the cleaner just to circulate around the boiler.

So the chemicals are in the system now and their flushing round, and we’re going to leave that now. We’ll leave that for about an hour or so, until it starts to clear it. And then once we start to get flow through and we know it’s working, if we get it working, then what we’ll do, then we’ll connect the power flush machine onto it. And then we’ll fully power flush the system then as well. So the way I would do it, I would put a couple of bottles chemicals in, let it flush the heat exchanger first, then open your valves underneath, put the heating on, let it go around the system and let it run around the system for an hour or so. And that’s before we put the power flush machine on.

Open up radiators in all the house and let the chemicals circulate through all the system. We’ve then got [inaudible 00:05:47] so some of the muck will go in the filter, if there’s any mock in… You could also connect your MagnaCleanse onto that if you wanted to, but that’s what we’re going to do with this. Let’s go see if we can get this sorted.

Allen Hart

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