Sources used here: Gas Networks Ireland — if you smell gas, emergency numbers, and CRU — RGI and Safe Electric. Checked 19 October 2026. Your boiler manual overrides any general note on this page.
What to look at
Wait until the heating and hot water are off and the radiators are cool. Read the gauge on the front of the boiler. The acceptable cold range is printed on that gauge, or in the manual for that model. Brands do not share one Irish standard figure, so do not borrow a number from a neighbour’s boiler.
If the needle is below the printed range, many manuals allow one top-up through the filling loop, then closing the loop again. If you do not know which valves are the filling loop, stop. Do not open the boiler case. Do not loosen a pipe to “see where it drips”.
When once is enough
Top up once. If the needle is back down after a few days of normal heating, water is leaving the system. Repeated topping up hides a leak, a radiator valve, or a failed expansion vessel. That is the point to call someone. On a gas boiler, the person who works on the gas side must be a Registered Gas Installer and should leave a Declaration of Conformance for gas work. Electrical controls, if they are part of the fault, need a Safe Electric contractor.
Stop and leave the house
If you smell gas, do not look for the leak and do not keep using the boiler. Gas Networks Ireland says: turn gas appliances off if you can do that safely, do not smoke or use a flame, do not switch electrical items on or off, open windows and doors, and if the smell stays, turn the gas off at the meter only if you can do that safely. Call 1800 20 50 50 from outside the area of the smell. If you cannot get through, call 999 or 112. From outside Ireland the published number is +353 1 920 5050. Do not use a phone in the room where you smell gas.
A frozen condensate pipe
In a cold snap a boiler can lock out because the condensate pipe outside has frozen. Thawing that plastic pipe with warm water is a common manufacturer step. Do not pour boiling water on it, and do not open the case to “reset something inside” if the manual does not tell you to. If it locks out again the same day, call an RGI.
Then call a heating business
Gas and wet heating sit under plumbing and heating. Town lists: plumbers in Dublin, plumbers in Cork, plumbers in Galway. Confirm the RGI number on the official register. Local Trades Ireland shows CRO and public contact, not a live competency feed. A town list is submitted for search only when that town has at least 10 businesses in the trade.