Clean Systems | Power Flush, Radiator Flush & Boiler Magnetic Filters

Quick guide summary

Why is a clean heating system important and how should I keep it clean?

A clean system will lower heating bills and reduce maintenance costs. Dirty radiators cannot circulate heat effectively and will make the boiler work harder to heat the home, costing more in energy bills. A dirty system will eventually damage components of the system beyond repair. We help you identify if you have a dirty system and explain the necessary steps to getting it cleaned and keeping it clean.

Overview of system cleaning

How important is an inhibitor?

A chemical added to heating systems that prevents corrosion (rust).

‘Sludge’ and ‘Grit’

what are they and how do they affect your system?

Power flush & Radiator Flush

we explain what a power flush is and when you need one.

Magnetic filters

what are they and how do they work?

How to use this Guide

How does your system get dirty

what are the signs/effects of rust?

Cleaning and prevention

We review magnetic filters

How does your system get dirty?

A lack of ‘Inhibitor’…

All water based heating systems must contain a percentage of a chemical called ‘inhibitor’. Inhibitor is a chemical mix that prevents corrosion and bacterial growth. The life span of inhibitor varies between products, but in any event if the system is drained for maintenance inhibitor must always be added back when the system is re-filled with water.

If at any point inhibitor has not been added to the system then, over time, the pipes and radiators will begin to corrode and a build-up of rust will occur.

What are the signs and effects of rust?

‘Sludge’ and ‘Grit’ in the system

‘Sludge’ is a common industry term for a build-up of rust in the system. Sludge builds up in open vented system. A harder form of debris forms in sealed systems, which we refer to as ‘grit’.

Signs of rust in the system

The effects of sludge and grit vary. Sludge tends to lead to cold spots at the bottom of radiators, as the rust settles at the bottom in little piles.

Grit tends to affect system components in the boiler and system, such as the heat exchanger (you will experience only warm water) or the pump (which will eventually seize).

Where the system is heavily affected by sludge or grit, the components, and sometimes the radiators, will need replacing and the system ‘powerflushed’.

Cleaning and prevention

When a system is heavily affected by sludge or grit, sometimes the only way to properly clean it is to ‘powerflush’ it. This is usually a day’s work and costs can range between £500 and £750. An alternative, perhaps where the system is less dirty, is a ‘chemical cleanse’.

What is a power flush?

A powerflush is a means of thoroughly cleaning the pipe and radiators in a heating system. A cleaning solution is pumped through the system and breaks down the rust build up. The rust particles are then captured by a magnetic filter attached to the machine.

Whilst flushing, all radiators are turned off and one opened at a time in order to focus that machine on that section. Each radiator is turned on one at a time until all the radiators are done.

After cleaning, the system is refilled with water and inhibitor is added.

My boiler cover provider has told me to have a power flush

If you have called out your boiler cover provider to a fault they have deemed to have been caused by rust, then they will replace the faulty parts but it will be conditional on you having a powerflush. They are likely to insist this is done before they fit new parts.

Radiator Flush with a Chemical Cleanse

A strong chemical is added to the system and left in for a period of hours or days, depending on the strength of the chemical. The chemical will break down the rust over that period. The system is then drained down, radiators flushed and refilled with clean water and inhibitor added. If the system is heavily rusted then this may not be sufficient and a powerflush will be required.

Boiler Magnetic Filters

Magnetic filters are a little device close to the boiler that keep your heating system clean long term. Heating water is always sent from the boiler around the radiators and back to the boiler again. The magnetic filter is fitted on pipe that returns water back to the boiler. As water passed through the device, a large magnet attracts any rust out of the water onto the magnet so that only clean water is passed back to the boiler. The filter will need to be cleaned out once a year or so.

They are very commonly installed as part of a new boiler installation and some manufacturers will extend their boiler warranty period when they are fitted at the same time. NB for a heavily rusted system a magnetic filter alone will not be enough to clean it.

We Review Magnetic Filters by Brand

We have reviewed 10 models of magnetic filter by price, size, warranty and function. All filters do broadly the same thing, which is to pull magnetic and non-magnetic dirt out of the system. Some have developed their filtration systems more than others however.

We have separated the filters into two groups by warranty period. The first group contains filters with a warranty of 8 years or more. The second group contains filters with a warranty of 2-5 years.

We have identified a ‘best buy’ in each group, which we think provides a great all round product in terms of technology, price and warranty period. Speak to your fitter about your preferred choice and why. NB check the height you have available to fit the filter.

Magnetic Filters with 8 + years warranty

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Make Magnaclean Magnaclean Sentinel Fernox Worcester
Model Micro 2 Professional 2 Vortex 300 Omega Filter Greenstar Filter
 
Price £83.50 £93.50 £90.00 £77.00 £127.00
Height 151mm 203mm 205mm 209mm 279mm
Technology Standard filter Standard filter Vortex (Screw) - slows down water to improve retention Standard filter Slows water down to improve retention of rust
Debris removed: Magnetic
Non magnetic
Magnetic
​Non magnetic
Magnetic
​Non magnetic
Magnetic
​Non magnetic
Magnetic
​Non magnetic
Warranty 10 years 10 years 10 years 25 years 8-10 years with new Worcester boiler

Magnetic Filters with a 2-5 year warranty

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Make Fernox Altecnic Grant Sentinal Fernox
Model TF1 Compact Dirtmag IQ Vortex Eliminator TF1
 
Price £72.00 £78.00 £95.00 £49.00 £78.00
Height 192mm 238mm 243mm 251mm 288mm
Technology Cyclone Water hits internal mesh and drops to bottom or attracts to magnetic if rust Standard filter Cyclone - 'spins down' particals to bottom of collection chamber Cyclone - 'spins down' particals to bottom of collection chamber
Debris removed: Magnetic
Non magnetic
Magnetic
​Non magnetic
Magnetic
​Non magnetic
Magnetic
​Non magnetic
Magnetic
​Non magnetic
Warranty 2 years 5 years 2 years 2 years 2 years

What would you like to do next?

Use our calculator to get an estimate of boiler installation cost

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Advice on Water Pressure and ‘flow rates’

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Book a survey with a local heating company

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