This should help you with terminology related to boiler insurance. It includes the terms we use in our Terms and Conditions. The intention of the glossary is to help you understand some of the technical terms used on the website. That is, it is a ‘layman’s guide’ to the terms. It does not constitute a legal or policy definition of any word term or phrase. If you want a more detailed technical or definitive explanation of any term, please contact us and we will do our best to help you.

Bleeding the radiators

If air gets in the heating system, it can prevent the water circulating properly, a radiator that is warm at the bottom and cold at the top needs to be bled. By turning the radiator bleed valve (with a radiator key), the air will rush out until water spurts out of the bleed valve. This should be done when the heating system is turned off and the system is cold; otherwise, more air can enter the system. This is not covered by the insurance as it is a maintenance matter.

Boiler insurance

The term used generically to describe the parts replacement insurance for boilers and central heating systems. The parts inside the boiler (and other specified parts) are what is covered by the insurance. The heating appliance as a unit is not covered for replacement as all boilers wear out so the need to replace a boiler is an eventual certainty and therefore not an insured risk.


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British Thermal Unit – a unit of energy for measuring heat output. Domestic boilers typically range from 30,000 to 90,000 BTUs.

Casing (of boiler)

A boiler will have an outer casing (the part of it you see), the condition of which is not essential to the working of the boiler. In other words, if it is dented, the boiler will still work and the insurance will not pay to fix the dent.

Claim limit

The upper limit per claim that the insurance will pay. It does not mean every claim will automatically pay this amount. The insurance pays for repairing or replacing a faulty component/s up to the claim limit.

Combination boiler

A boiler that is turned on when a domestic hot water tap is turned on or when the heating system is timed to go on. New combination boilers must now be condensing boilers, which re-use the condensation from the flue gases.


When a boiler is beyond economical repair: usually an engineer will make this decision. The insurance will no longer pay for repairs after a boiler has been condemned.

Condensing boiler

Condensation from a boiler contains heat; this creates water vapour, which is discharged through the boiler flue. In recent years, boilers have been re-designed to capture some of the latent heat produced by condensing the flue gases making them more efficient. Legislation now requires that all new natural gas, LPG and oil-fired boilers are condensing; these boilers may have two heat exchangers.

Condensing boilers will need a drainpipe installed to allow for the safe disposal of the excess condensation. This condensation is slightly acidic and is corrosive, all pipework associated with condensation must be formed of plastic construction. Because condensing boilers are more complex than conventional heat only appliances they are generally more expensive to buy and insure.

Consequential loss

A term used in insurance policies to state that the insurance would not pay for losses suffered by the insured because of the failure or breakdown of the items that are insured. For example, in boiler insurance, the insurance will pay for the boiler to be repaired but not for the ten new kettles, which the customers bought to supply themselves with hot water while the boiler was not working. In boilerplus, the term consequential loss means losses or damage not directly covered in the term consequential loss means losses or damage not directly covered in the Terms and Conditions.

Conventional boiler

A boiler that heats hot water which is then stored in a hot water cylinder, as well as heating the water in the radiators. New conventional boilers must now be condensing boilers, which re-use the condensation from the flue gases.


A radiator, standard in most homes through which hot water circulates allowing the heat to disperse to the surrounding area, (space heating). Radiators are fed by two pipes, which each have an isolation valve attached for maintenance purposes and to control the temperature of the radiator.

Cooling-off period

When you take out the insurance, this is the period of time you have to change your mind and ask for a full refund. You can ask for this refund in writing, over the telephone or by email. If you make a claim during the cooling off period, you cannot receive a refund as you will have received the benefit of the insurance and will therefore be liable for the premium.


Damage caused by corrosion is long-term; it is not the result of a sudden and unexpected breakdown of a component. Where corrosion damages parts in a heating system, the insurance will not cover the cost. Corrosion can be avoided by having appropriate corrosion inhibitors and filters added to the system.

Draining down (springing the system)

When the water in the central heating system is drained away (by opening the drain off valve).

Faulty component

A component which is insured (see under Equipment Covered below) and which is destroyed or damaged by wear and tear or any accident or misfortune not excluded under any part of these Terms and Conditions.

Heat exchanger

A key component inside the boiler, which holds circulating water while the heat from the burner is transferred to the water. The design of the heat exchanger is a crucial part of making boilers more fuel-efficient because the more heat that is transferred from the burner to the water, the less heat is wasted directly out the flue. Due to this, heat exchangers are frequently re-designed and upgraded; therefore, the one in your boiler may no longer be manufactured even if your boiler is relatively new. Boilerplus protects you against the heat exchanger becoming obsolete with an age-related payment. So if your heat exchanger fails and cannot be replaced due to it being obsolete you will receive a payment that you can put towards a replacement boiler.

Heating appliance

The boiler

Insured person

The person(s) or company whose name appears on the Certificate of Insurance.


This policy is underwritten by Inter Partner Assistance S.A. UK Branch, with a registered office at 106-118 Station Road, Redhill, RH1 1PR. Inter Partner Assistance S.A. UK Branch is a Branch of Inter Partner Assistance S.A. (Financial Conduct Authority registration number 202664), which is a Belgian firm authorised by the National Bank of Belgium under number 0487. Deemed authorised by the Prudential Regulation Authority. Subject to regulation by the Financial Conduct Authority and limited regulation by the Prudential Regulation Authority. Details of the Temporary Permissions Regime, which allows EEA-based firms to operate in the UK for a limited period while seeking full authorisation, are available on the Financial Conduct Authority’s website.

Isolating valves

These are valves, which allow the water supply to be cut off to parts of the heating system. For example, the circulating pump should have isolating valves on either side of it allowing an engineer to isolate the water to the pump allowing him to replace it without draining down the entire system. Without isolating valves there may be extra time and expense incurred because the system will need to be drained down.

Normal working hours

9am to 5pm from Monday to Friday only (not including bank holidays) or the hours which your chosen engineer charges standard daily rates, whichever is longer. Engineers typically charge extra outside these hours and the insurance will not pay the increased rate.


The pipes that contain the water associated to the boiler and the central heating system.

Policy excess

The amount deducted from each claim, which the policyholder has to pay. This is typically used in insurance to prevent frivolous claims which are costly to process and which drive up premiums.

Power flushing

This process is carried out when the water in the heating system becomes contaminated and affects its performance. The process involves circulating fresh water around the system using external pumps at high pressure in an effort to disturb and remove contamination and blockages. Sludge and scale will impair the flow of water through the system, which will reduce the efficiency of the heating and can cause parts to fail. Power flushing the system can restore a system to good working order but the high pressure may expose weak points in the heating system necessitating repairs, power flushing is not covered by the insurance.


Putting water back in the heating system.


The fixing of a broken component, which would otherwise need to be replaced. Excludes cleaning of or adjustments to components. A good way to know whether the work carried out on a part counts as a repair is if there are bits and pieces left over from the repair.


Damage caused by the build-up of lime scale in hard water areas, which affects the performance of the central heating appliance and central heating system. Scale will damage components throughout a heating system and the insurance cannot cover this cost as it is not an unexpected cost due to breakdown but a certainty caused by untreated water in the system. Scale can be avoided by the installation of scale filters and by treating the system water with appropriate chemicals.

Service organisation

The industry-qualified firm that carries out the regular service and breakdown repairs.

System cover

Conventional radiators (including valves), thermostats, expansion tank and plastic oil tanks on oil fired systems (not contents). Conventional radiators (including valves), thermostatic radiator valves, and above ground pipework on gas fired systems (not pipework under floorboards or in an attic or loft or steel pipework).

Water jacket

Another name for heat exchanger or heat engine.