can MagnaClean collect large debris rattling in return pipe?

Hello everyone,

A few weeks back I had my old backboiler ripped out and new Valliant combi boiler installed.

4 weeks on I've developed a problem!

It sounds like there are a few bits of gravel rattling in the return pipe running up the wall and back into the boiler from the floor.

The particles rattling in the pipe are noisy enough to be heard throughout the flat. The boiler itself is silent, but the rattling of this debris in the pipe running back up into the boiler is really audible and annoying.

I was worried the plumber might have scooped up some rubble when laying the new piping - the combi was installed in the kitchen which required some extra piping to be laid under the floor. But he thinks it might be some 1) rust from the radiators; or 2) solder that has broken off from the new piping.

He wants to install a MagnaClean (at my expense) which has a magnet to collect metal debris, BUT ......

I don't think solder would be picked up by a magnet as its not magnetic? What about copper filings from the install, or general rubble?

We have tried draining the system and then leaving the boiler re-pressurising tap open for an hour to flush the system, but this didn't help.

I've attached a diagram of how I think the flow works to help explain. I *think* the issue might be


1) that the debris is sitting in the pipe just below the boiler, but the draining plug is a few meters before this point, so not enough pressure in the last section of piping between the drainage point and the boiler itself to push what seems to be largish debris up the wall and then all the way around. (Although when the heating system is on and system pressurised the flow is obviously enough to move the debris up this wall pipe & rattle continuously without going anywhere)

2) or there is a filter on the return into boiler, and this large debris cant ever flow freely all the way around and out the drainage.

Is a magnaclean the best approach? I'm just worried I'm spending money £100+ on something that won't be able to catch non-magentic particles like rubble, or solder (non magnatised), or even copper filings or small stones/rubble.

Many thanks for any suggestions anyone can provide, I really appreciate it.

You are quite right, a magnaclean will collect only ferrous materials, such as black iron oxide which forms the destructive sludge in your heating system. See here for how it works and what it does.

Regardless of that, I personally think they are a good investment anyway, particularly when installing a new boiler on an existing system. If you have one you will see how effective it is when you come to clean it.

If there are very small particles that are being circulated around the system they may fall out of suspension in a radiator as the speed of the water slows as it goes from a small diameter pipe into the much larger radiator. If the particles are too large to circulate around the system and they remain in one location, then a filter of any sort won't trap them anyway if they don't reach it.

Most likely a piece of solder which a magnaclean would not trap anyway. Also as it seems to be trapped in the vert pipe it is not circulating to be trapped by the magnaclean.

Looks like you need to cut out bend/elbow below boiler to remove debris and then remake. To prevent any reoccurance you could replace bend with a tee with a short length of pipe downwards with a full bore valve at the end. When pump is off any debris would fall down into this dead end where it would stay until the valve was opened to flush it out.

Irrespective of this problem most posters on here would recommend a magnaclean on CH systems.

thanks Stem and jobloggs.

The plumber wants to install the MagnaClean directly onto the vertical return pipe feeding back into the boiler, which is where the debris becomes audible with all its rattling.

The other thing I've noticed is that the water pressure in the boiler seems to fluctuate slightly. In the evenings it can be 0.4 bars lower than at midday.

Is this any reason for concern?

Thanks again for all your help with this.

why not close the isolation valve on the flow, put a hose on the drain off and open it and turn the filling loop full on and see if you can push it through?

Sounds like the system could do with either a power flush or a mains flush.
Are you sure he cleaned the system thoroughly before he stuck the new boiler in?

Pressure will rise and fall slightly with temperature it's nothing to worry about.

I'd avoid a magnaclean, it's cheap plastic rubbish. It's designed to last the life of a boiler - 10 years - but boilers last longer than that, 10 years is the life of a crap boiler, yours will easily last 15yrs +. I've yet to see a magnaclean go past 3 years without having seals, valves, canister/lid, bleed point problems. I've seen a lot of water damage problems caused by magnacleans, british gas even cancelled a contract with them due to the amount of problems due to it being a poor quality product.

Go for a spirotech, it's GUARANTEED for 20 years.

I'm not a diyer, I'm in the trade so am going by personal experience and the experience of other people I know in the trade.