Central heating leak in Macclesfield
In short
If your boiler pressure keeps dropping, the system is losing water somewhere — heating circuits are sealed, so the water has to be going out. The usual suspects are radiator valve glands, the pressure relief discharge outside, a pinhole in buried pipework, or a failed expansion vessel making the gauge behave as though there is a leak.
Also called: boiler losing pressure leak · leaking radiator valve · heating pipe leak under floor · system keeps losing water
Signs you need this
- Boiler pressure dropping over days or weeks
- Needing to top up the filling loop regularly
- Rust-coloured or salty staining under radiator valves
- Damp patches on a floor near heating pipework
- Water dripping from the discharge pipe outside
- Radiators that need bleeding far more often than they used to
A sealed heating system holds a fixed volume of water. Nothing evaporates, nothing gets used, and nothing should need topping up. So a gauge that reads 1.2 bar in October and 0.4 bar in November is telling you something specific: roughly that much water has left the system. Repeated topping up is not maintenance, it is a symptom — and it does real harm, because every refill brings in fresh oxygenated water and accelerates corrosion inside the radiators.
Start with what can be seen. Radiator valves weep at the spindle gland as the packing hardens, and the giveaway is a small rust or salt-like deposit under the valve rather than a visible drip. Bleed valves left slightly open do the same. Joints on exposed pipework, particularly in airing cupboards and under boilers, show the same tell-tale staining.
Then check outside. Most boilers have a pressure relief discharge pipe terminating outside the property, usually a short copper pipe pointing at a wall. If that pipe is wet, dripping, or has left a lime-coloured stain on the brickwork, the safety valve has been passing — either because the system was over-pressurised, or because the valve seat has picked up debris, or because the expansion vessel has lost its charge and pressure is spiking every time the system heats.
That last one is worth understanding, because it is frequently misdiagnosed as a leak. The expansion vessel absorbs the expansion of heating water as it warms. When its internal air charge is lost, the pressure rises sharply on every heat-up, blows out through the relief valve, then reads low when cold. The gauge behaves exactly like a leak, but no water is escaping anywhere you can find. Testing and recharging the vessel — or replacing it — fixes it properly.
Buried pipework is the hardest case: heating pipes in screed or under a solid floor, which are common in extensions and post-war housing. Thermal imaging is genuinely effective here because the leaking pipe is hot, and the repair is often a matter of cutting one small section of screed rather than re-piping the room. Where a run has failed twice, re-routing overhead or around the perimeter can be cheaper than chasing the third failure.
What the job covers
- Pressure testing the sealed system to confirm and quantify the loss
- Inspection of valves, glands, joints and the pressure relief discharge
- Expansion vessel charge test and recharge or replacement
- Thermal imaging for buried pipework in screed or solid floors
- Repair, re-route or renewal of the failed section
- Refill with fresh inhibitor once the system is sound
What it costs
We don't publish a price for this yet, because a number pulled out of the air is worse than no number at all — your plumber has to honour it. You'll get a firm price for your actual job when they ring you back, before any work starts. The quote itself is free and there's no obligation either way.
Common questions
How often should I need to top up the boiler pressure?
Rarely — once a year at most, and many systems go for years untouched. If you are topping up monthly, there is a leak or a failed expansion vessel, and topping up is quietly corroding the system from the inside.
There is no water anywhere but the pressure still drops. What now?
That pattern usually points at the expansion vessel or the pressure relief valve rather than a leak in the pipework. Both are testable in a single visit, and both are far cheaper to sort than lifting floors.
Need this doing in Macclesfield?
Tell us the job and it goes straight to our local plumber — one call back, usually the same day. Free quote, no obligation.