Heating System Care
Magnetic Filters and Inhibitor: What They Do for Your Heating
For London households, a magnetic filter captures circulating magnetic debris in the heating circuit, while central heating inhibitor slows internal corrosion; neither replaces cleaning when deposits need removing. If you smell gas, leave and call the National Gas Emergency Service on 0800 111 999 from a safe place.
This guide explains their complementary roles and the maintenance records to check. For the distinction between ongoing protection and removing contamination, read Powerflush explained: signs, process and whether you need one.
Call with your postcode, the boiler make and any fault code showing.
- Gas Safe registered: 648977
- Phone line open 24/7
- Same-day appointments available
Before You Check: Keep the Heating Circuit Closed
You can read accessible labels and maintenance records while keeping the heating circuit closed.
- Observe from a safe position without touching hot components.
- Do not open the filter or drain a radiator to inspect the water.
- Never open the boiler casing or work on gas.
Heating water can be hot and pressurised, and treatment chemicals need careful handling. Competent wet-heating work is distinct from gas appliance work, which requires appropriate Gas Safe registration.
Smell gas: avoid flames and electrical switches. Ventilate and turn off gas only if safe, leave, then call 0800 111 999.
Suspected carbon monoxide: get into fresh air and seek medical help through NHS 111, or 999 for serious symptoms. Medical help must not wait; then contact the gas emergency service. Treat a sounding CO alarm as real. CO has no smell.
Magnetic Filter, Inhibitor and Cleaning: Three Different Jobs
A magnetic filter collects circulating magnetic debris, inhibitor limits further corrosion, and cleaning removes contamination that needs clearing from the system.
The filter acts at one point in the circuit; inhibitor circulates with the heating water. Neither measure alone demonstrates the condition of the whole system.
Magnetic filter
captures susceptible particles carried through it. It cannot establish that radiators are clean or remove every contaminant. Ask for recorded inspection findings and details of collected debris.
Inhibitor
provides chemical protection at the specified concentration. Its presence does not establish that settled deposits have been removed. Ask for the product identity, concentration test and result.
Cleaning
addresses contamination using a method selected for the system. It does not provide lasting protection without appropriate subsequent treatment and maintenance. Ask what checks supported the recommendation and what was recorded afterwards.
What Does Central Heating Inhibitor Do Inside Radiators?
Central heating inhibitor is a treatment in the circulating heating water that slows corrosion inside radiators and other system components.
“Radiator inhibitor” normally means treatment of the connected heating circuit. This water is separate from drinking water and the domestic hot-water supply. Inhibitor is also different from cleaner: adding protection does not clear an existing blockage.
Product compatibility, the system’s water volume and existing treatment determine what is appropriate. Ask an engineer to check the records before recommending treatment:
- Which inhibitor is already present?
- Is it suitable for the system’s metals and materials?
- Has its concentration been checked using the appropriate method?
What Does a Magnetic Filter Capture Around the Boiler?
A magnetic filter attracts magnetic corrosion particles carried by water around the boiler’s heating circuit.
What Do 22mm and 28mm Magnetic Filter Sizes Mean?
The 22mm or 28mm label identifies the pipe connection size, rather than establishing overall suitability. An engineer also checks:
- Connection arrangement and isolation valves.
- Permitted operating conditions.
- Flow requirements.
- Space for maintenance.
- Permitted installation orientation.
A search for a 35mm filter likewise needs an exact model and suitable domestic application confirmed. Radiator count alone is insufficient for choosing a filter.
MagnaClean Professional and Fernox Filters: Identify the Exact Model
MagnaClean Professional and Fernox filters need an exact model match before fitting or maintenance instructions can be applied. Professional, Professional2, Professional2XP, DualXP and individual TF1 models should not be treated as interchangeable.
Copy accessible information into this identification record without moving or opening the filter:
- Manufacturer:
- Full model name:
- Connection details, if documented:
- Manual reference and revision:
These names identify equipment; they do not establish which product your system needs.
These can include magnetite, a magnetic iron-oxide corrosion product. Collected material needs removing according to the filter’s instructions. Some models also separate non-magnetic particles through another mechanism, but not every filter captures every contaminant.
Magnetic capture does not treat dissolved hardness or establish whether deposits exist in a combi boiler’s separate domestic hot-water path. A fitted filter does not prove:
- The radiators are clean.
- The inhibitor concentration is adequate.
- There is no other heating fault.
Ask for a Water-Treatment Record, Not Just a Clean-Looking Filter
A useful water-treatment record identifies the product, checks and findings; a clean-looking filter alone cannot establish adequate protection.
Ask the engineer to complete or update:
- Date and filter model:
- Inspection and cleaning findings:
- Inhibitor product:
- Concentration test method and result:
- Relevant water-cleanliness checks:
- Recent draining, refilling or water loss:
- Action taken and next review:
Testing and dosing are different actions. Fernox Protector F1 guidance describes annual concentration checking; this does not mean automatically replacing or adding inhibitor annually.
Draining or refilling calls for reassessment against the applicable product instructions. Record what happened so the engineer can assess remaining protection. Heavy debris capture also needs context: it does not, by itself, measure the current corrosion rate.
When to Call an Engineer About Filters or System Water
Call an engineer when the next step involves opening or altering the system, or when leakage, recurring water loss or heating problems need investigation.
For a Missing, Leaking or Inaccessible Filter, Request a Fitting Assessment
A missing, leaking or inaccessible filter needs an assessment of the existing installation before fitting or replacement is recommended. An absent filter alone does not explain a breakdown.
Ask:
- Is the pipework suitable for the proposed filter?
- Can it be isolated and maintained with adequate access?
- What does the existing water condition indicate?
Report visible leakage without opening or tightening the canister. Request a fitting assessment that covers model selection, maintenance access and the proposed work.
For Suspected Sludge, Ask for Evidence Before Choosing a Flush
Suspected sludge needs investigation of system water and circulation before an engineer decides whether cleaning is needed.
Ask for the recommendation to consider:
- Filter contents and maintenance history.
- Water-test findings.
- Cold radiator patches and other symptoms.
- Pipework, including any microbore sections, and overall system condition.
Chemical cleaning and powerflushing are different options whose suitability depends on those findings. A permanent filter is not equivalent to a cleaning visit, and one cold radiator does not establish the need for a flush. Where the findings support it, arrange a.
Powerflush assessment for a contaminated heating system
Gather accessible labels, treatment records and a description of the symptoms. Wet-system work is not automatically gas work; gas appliance work requires the appropriate Gas Safe registration.
Boiler repair, servicing and gas work
Arrange a Heating-System Assessment in London
Contact All Service 4 U to discuss magnetic filter fitting or a heating-system assessment in London. Our Gas Safe registered engineers cover domestic gas boilers and central heating; our business registration is 648977.
Have your postcode, boiler model, accessible filter model, symptoms and recent treatment records ready.
Discuss My Heating System: 020 3740 6785. Call us 24 hours a day, 7 days a week, or contact us about your heating system.
020 3740 6785
Frequently Asked Questions
Is a Magnetic Boiler Filter Worth Having on an Older System?
A magnetic filter can provide useful ongoing debris capture on an older system, but suitability depends on its condition and maintenance needs. Age alone does not settle the decision. Existing contamination and other faults need assessment, and the filter needs continued maintenance. Ask what the proposed filter would address and whether separate cleaning is justified.
Does the Filter Need Emptying, and Is That Included in a Boiler Service?
Collected debris needs removing according to the filter’s instructions, but you should confirm whether that work is included in your booked boiler service. Maintenance needs and service inclusions are separate questions. Ask: “Does this appointment include filter cleaning and water testing, and will the work and findings be recorded?” Do not open the filter yourself to check.
Where Should a Magnetic Filter Be Fitted?
A magnetic filter is commonly fitted on the heating return before the boiler, with its exact position governed by product instructions and maintenance access. The engineer checks the filter and boiler instructions, permitted orientation and available space. A location that accommodates the connections may still be unsuitable if the filter cannot be serviced safely.
How Much Does It Cost to Install a Magnetic Filter on a Boiler?
The fitting price depends on the selected filter and the work required. Call 020 3740 6785 for a price for your job, and ask what the proposed work includes. The main factors are:
- Filter selection.
- Pipework alterations.
- Installation and maintenance access.
- Separately justified cleaning or water treatment.
Any additional cleaning recommendation should be supported by findings.
Can I Add Central Heating Inhibitor Myself?
Whether adding inhibitor is suitable for you depends on the system, product instructions and safe access; there is no universal dosing procedure. Identify the existing treatment and consult the applicable instructions and safety information. If the chemistry is unknown or access involves unfamiliar pressurised components, stop and ask an engineer. Never open the boiler casing or work on gas.
Is MagnaCleanse the Same as a Permanent Magnetic Filter or a Powerflush?
MagnaCleanse is equipment used during cleaning, while a permanent magnetic filter stays on the heating circuit; neither term alone describes a complete powerflush procedure. Powerflushing and chemical cleaning describe treatment approaches that need explaining in the proposed work. Sentinel X800 is a cleaner, not a substitute for lasting inhibitor protection. Ask which method, chemicals and checks are included.
Still have a question or need urgent assistance? Call 020 3740 6785, tell us what has happened and we will tell you what happens next.