After sourcing some lovely radiators and having a drained system, this meant I could make modifications to my heart’s content! I actually decided to add the magnetic filter on at the very end of my plumbing refurbishment. This would be once everything had been put together. When it came to filling the system I would need to add corrosion inhibitor. The reason for this is you don’t want tap water inside a mass of steel throughout the house. You would eventually end up corroding the insides of your radiators and causing trouble for the boiler.
There are systems where you can add fluids such as corrosion inhibitor through the radiator. I came across magnetic filters and saw the benefit of being able to isolate it from the rest of the central heating. This meant that you could have a pressurised system, isolate the filter and then drain the compartment. By draining the compartment you would then have a capsule of space to be able to add liquids before opening the valve back up. This is significantly easier than depressurizing the entire central heating and then having to top it off.
This would be a really easy way to top up any chemicals that would have to go in, and it doesn’t even cover the benefits of the magnet!
Benefits of the magnetic filter
I don’t know how old my previous radiators were but I wouldn’t be surprised if they were a similar age to me. I found stainless steel piping discarded alongside copper pipes which would suggest the previous owner managed to get the central heating redone after the great copper shortage of the 70s (I don’t think it would actually be called the great copper shortage!)
The point I’m making is that there would be a lot of crud that has developed over the years without a power flush / clean. I realised I felt a bit concerned about adding 4 new radiators and exposing them to decades worth of crud and reduce their lifetime and overall effectiveness.
So by me needing to add inhibitor and also clean my system meant that adding a magnetic filter was a no brainer!
How to add a magnetic filter
I went for an Adey Magnetic Filter as they seem to be the Volkswagen Golfs of the magnetic filter world! I over specced mine which can do something like 20 radiators in a house so you can most likely get away with the micro variant.
The instructions say the ideal installation point is best on the return pipe under the boiler. This would theoretically mean that any metal shards that dislodges from the radiators will make its way through to the filter and be picked up before it goes into the boiler. I used the boiler manual to identify which was the flow and return pipes to the boiler. If you don’t have the manual to hand you can turn the central heating on (if it’s not drained). Then feel which pipe heats up quicker than the other. The one that heats up first would be the flow so it would be best to install on the other pipe. At 22mm diameters under the boiler, this meant I had to get a new pipe cutter as the 15mm wasn’t going to work.
This picture isn’t great quality but the filter came with a sticker template. This was meant to go on the pipe so you knew were to cut at each end.
For the DIY plumber this is great as I wouldn’t want to make the wrong measurement and cut too much out for the magnetic filter to slot into.
The above shows the clean cut for the magnetic filter to go into. Of course I had to ensure good prep so you can see bare new copper. Prep is the most important step in plumbing and you can see the reasons here for it. This includes why using jointing compound for compression fittings.
What the magnetic filter picked up
Once I put it all back together I did a quick test to see any leaks. I actually found one not on the magnetic filter but on the compression joint at the top of the pipe where it joins the boiler. I had obviously moved the position slightly so the nut needed slight tightening.
Before putting inhibitor in which would stay long term. You can use chemicals such as this to clean the system out. The idea is after a week you would then drain the system before adding water and inhibitor. I’m glad I did as the picture below was 1 week of running the central heating with this cleaner!
