Glossary

BER (Building Energy Rating) · Better Energy Homes Scheme · Boiler scrappage grant · Chemical flush · Combi boiler · Completion certificate · Condensing boiler · Flue · Gravity-fed system · Heat pump · Heating controls grant · HLI (Heat Loss Indicator) · Hot water cylinder · Inhibitor · Magnetic filter · MPRN · OFTEC · One Stop Shop · Output (kW) · Post-works BER · Power flush · Regular (heat-only) boiler · Renewable heat bonus · RGI (Registered Gas Installer) · System boiler · Technical assessment · U-value

BER (Building Energy Rating)

A rating of a home's energy performance from A1 to G, given by an SEAI-registered BER assessor.

Better Energy Homes Scheme

SEAI's scheme of individual home energy grants. It doesn't cover replacing a gas or oil boiler with a new gas or oil boiler.

Boiler scrappage grant

€2,000 when a fossil fuel heating system, oil or gas, is scrapped and replaced with a heat pump. Available since 6 October 2026. It doesn't pay towards a new gas boiler.

Chemical flush

Cleaning the heating system with a chemical cleaner before a new boiler goes on.

Combi boiler

A boiler that heats water for the taps as you use it. No hot water cylinder and no attic tank for the hot taps.

Completion certificate

The certificate the RGI gives you for the gas work when a new boiler is fitted. Keep it with the warranty papers.

Condensing boiler

A boiler that recovers heat from its flue gases, so less heat goes up the flue than with an old non-condensing boiler.

Flue

The pipe that carries the boiler's exhaust gases outside. A new flue route adds cost.

Gravity-fed system

A heating and hot water system fed by a cold water tank in the attic, with a cylinder in the hot press.

Heat pump

An electric heating system that takes heat from the air, ground or water outside. It works with a hot water cylinder.

Heating controls grant

An SEAI grant of €700 to upgrade the controls on an existing heating system. Homes built and occupied before 2011. Not available with a heat pump grant.

HLI (Heat Loss Indicator)

A figure on the BER that shows how fast the home loses heat. For the heat pump grant, a valid BER with an HLI of 2.3 or less means no technical assessment is needed.

Hot water cylinder

The insulated tank, usually in the hot press, that stores hot water. System and regular boilers use one. So do heat pumps.

Inhibitor

A treatment added to the heating water to slow corrosion and sludge.

Magnetic filter

A filter on the heating pipework that catches iron sludge before it reaches the boiler. Many makers want one for their longer warranties.

MPRN

Meter Point Reference Number: the 11-digit number on your electricity bill. SEAI uses it to identify the home.

OFTEC

The registration body for oil heating technicians. Oil boiler work is done by an OFTEC-registered technician, not an RGI.

One Stop Shop

An SEAI-registered company that manages a home energy upgrade and the grant application, and takes the grant off your price up front.

Output (kW)

The boiler's heat output. Bigger houses and more bathrooms need more. Published prices are usually for the smallest output in a range.

Post-works BER

The BER done after grant-funded work, before SEAI pays the grant.

Power flush

A deeper clean of a badly sludged system with a pump. Usually priced as an extra.

Regular (heat-only) boiler

A boiler that works with a hot water cylinder and a cold water tank in the attic. Common in older houses.

Renewable heat bonus

An extra €4,000 on top of the heat pump grant, listed by Citizens Information.

RGI (Registered Gas Installer)

A gas installer registered with the Register of Gas Installers of Ireland. By law, gas work in Ireland must be done by an RGI. Check anyone on rgi.ie.

System boiler

A boiler that heats a hot water cylinder, with the pump and expansion vessel built in. Suits houses with several bathrooms.

Technical assessment

A heat loss check needed before a heat pump grant for homes built before 2007, unless a valid BER shows an HLI of 2.3 or less. SEAI gives a €200 grant towards it.

U-value

How fast heat passes through a wall, roof or window, in W/m²K. The lower the number, the less heat escapes.