Heating system losing pressure — causes and repair in Tbilisi

What the pressure should be

A flat boiler gauge usually shows 1–2 bar on a cold system and a little more when hot. The exact figure is in the boiler manual. If the manual describes topping up through the filling valve, top up the cold system as instructed and note how long it takes to drop again.

Possible causes

• a leak on a radiator, valve, pipe joint or a hidden pipe in a wall or floor;
• water inside or under the boiler — the heat exchanger, pump or joints;
• the expansion vessel has lost its air charge: pressure rises sharply when hot and drops when cool;
• the safety valve is releasing water — drops are often visible at its pipe or under the boiler;
• radiators were bled recently: topping up afterwards is normal.

What to tell the technician

• how quickly the pressure drops — hours, days or weeks;
• whether it rises a lot when the system heats up;
• whether there are damp patches or drips anywhere, including under the boiler and at the neighbours below;
• the boiler brand, model and error code (photo).

How the technician finds the cause

The technician starts with the boiler: the expansion vessel charge, the safety valve and the internal joints. If the boiler is fine, the system is pressure-tested section by section to find where the water goes. The fix depends on the cause: recharging or replacing the vessel, replacing a valve or joint, or repairing a pipe section.