Some frequently-asked questions...


As rust is magnetic, all that needs to be done to keep a heating system clean is to install a strong magnet in the waterline. The magnet will filter out the particles and collect them. But when we looked at manufacturing such a device, we were astounded at the quality of some of those available. Often cheap plastic, with cheap valves. And then there’s the issue of whether they can actually do the job. We have seen ‘magnetic filters’ with extremely small magnets, and some of them not even neodymium magnets! We think that if the price is cheaper than our product...then that tells you everything!


So we set out to manufacture a magnetic filter that was big enough, and strong enough. It had to be metal construction, but it also had to have a magnet capable of performing. The BoilerGuard was the result...


The BoilerGuard uses a N42-grade, rare-earth, neodymium magnetic rod

...similar products do not!


The BoilerGuard truly is all-metal construction

...similar products can be cheap plastic!


The BoilerGuard is guaranteed for life - yours

...similar products might come with a 2-year guarantee!


BoilerGuard FAQs

Can the BoilerGuard be fitted on larger systems than typical?

Yes, but it makes much more sense to simply fit the BoilerGuard’s bigger brother, the MagnaMate. It’s standard in 28mm (with 22mm optional) and two units fitted in parallel will provide protection for 42mm systems. We provide two MagnaMates for just £329 (free postage).

Are isolating valves included?

No. We looked around for valves that could carry the same long guarantee as our BoilerGuard, but couldn’t find any. So we leave you the option for you to supply your own if you want to. You may only need one. How so? Because you may be installing the BoilerGuard immediately adjacent to the boiler, which probably already has an isolating valve on the return pipe.

Should I fit the BoilerGuard horizontal or vertical?

We always suggest vertical. However, it CAN be fitted horizontal (tails up) if required.

Is the BoilerGuard really ‘all-metal’?

Yes, totally. It will withstand extraordinary system temperatures and pressures...where others might fail.

Can I add chemicals to the system through the BoilerGuard?

Yes, and extremely easily. The BoilerGuard has a volume (with the magnetic rod in place) of 0.5 litres. So simply drain the BoilerGuard, take the magnetic rod out, pour the chemical in, replace the rod. Done! Or you can use the air vent or drain valve as an injection point.

Is it tamper-proof?

Yes, unlike similar products to ours, the BoilerGuard’s magnetic-rod cap can only be removed using a pair of pump pliers. There is nothing for some inquisitive child to press and cause a system leak!

How is it sealed?

The BoilerGuard uses a simple, everyday, pump valve union, and hence a pump valve washer. So NO special seals are required - nothing to leak!

Is the magnetic rod really N42-grade neodymium?

Yes, unlike many others we have seen, we manufacture a ‘magnetube’ (a 22mm, highly magnetised tube) of N42-class neodymium magnets (20% stronger than N35). We have seen magnetic filters using ferrite magnets in the water line. In our opinion, such magnetic filters are only suitable as a weight for sea-fishing.

Can it be fitted straight from the box?

Yes, you have to install valves, but the BoilerGuard comes ready assembled, ready to go.

What are the dimensions?

It is 150mm in length by 70mm in width.

Where should I install it?

Always on the return pipe if possible.

What’s this about an amazing guarantee?

Yes, it really is for life, as long as it may be. We guarantee the structural integrity of our products - meaning that no welded joint will leak, the body won’t crack or rust. It will stay together as the day it was hand-made. This is what sets our products apart from others. We are so sure of the quality of our products, that we are able to provide such an extraordinary guarantee. Rival manufacturers are evidently unsure of the integrity of their product(s), so give, what we would call, an inadequate and a rather pathetic guarantee. The guarantee comes in writing with every BoilerGuard.

Is the BoilerGuard a British product?

Yes, we're proud to say it is. It is a quality product hand-made in England, not China - like so many similar units. We even manufacture the core magnetic rods, by hand, not import them from China.

Why don’t you sell the BoilerGuard in plumbing merchants?

Because by the time they have added their mark-up charge, it would make it too expensive. You get it the cheapest possible by buying direct from us.

Does the BoilerGuard filter non-magnetic particles?

No, there is no need in the vast majority of cases. If you should require a non-magnetic filter for any reason in addition to the BoilerGuard then install a Y strainer, sized for your needs. But if you have non-magnetic particles in the system, you should be finding out why! The vast majority of ‘sludge’ in a system is magnetic sludge. There is usually very little ‘bio’ contaminants in modern, sealed systems, if any at all, so a magnetic filter is all you need.

So why is it square-ish?

When fluids flow in a pipe, the particles tend to flow in uniform. That’s great in a pipe. But inside a magnetic filter, this isn’t really what you want. A disturbed pattern in flow scatters the ferrous particles so that they are far more likely to wander close to the magnet - where they get picked up by the magnetic field. The square-ish BoilerGuard thus breaks up the uniform pattern of flow. Particles bumping into each other is called ‘Brownian Motion’ after the Scottish botanist, Robert Brown. It’s thus particles moving in a random way rather than flowing in uniform motion. It’s all clever stuff, you know?

How do I clean it?

Turn the valves off, place a small bowl under the bottle and open both the air vent and drain plug. Unscrew the top union nut and the magnet can be lifted out. Wipe the magnetic tube over a drain.

Can I get next working-day delivery?

Delivery is FREE, and we try and get your delivery to you the next working day, but PLEASE NOTE that next day delivery cannot be 100% guaranteed - we are at the mercy of couriers!

I want one, but with alterations, can you do that?

Yes, we can! We can build BoilerGuard/MagnaMate-based magnetic filters to your exact specification. Just email us. We can add high-temp magnets, or ports 180º faced, for example. Or maybe labelled with your company name/logo. Our MagnaMate is 275mm, but we can supply longer magnetic filters.


Technical specification:

Height: 150mm

Width & depth: 70mm

Standard port size: 3/4” BSP female (22mm fittings added)

Material: Grade 304 stainless steel

Magnetic rod cap size: 1.5” BSP male

Magnets: 5 x Neodymium N42-grade, bi-directional

Gauss: 13050 (1.305 Tesla)

Magnet strength: 11 kilograms (x5) 108 N

Max operating temp of magnets: 80ºc

Pipe fittings: Brass

Air vent: Brass

Drain valve: Brass

Fluid capacity: 0.5 litres

Weight: 1.1 kg






 THE magnetic filter - made great, in Britain