How to spot a leak in your boiler pressure valve

The boiler pressure relief valve is responsible for allowing a pressure to leave the internal system safely. It’s a boiler part that serves an essential safety function by preventing dangerous levels of temperature and pressure build up. Excessive pressure can lead to internal damage, loss of heating capability and even risk of explosion. Due to this, any leaking identified to be coming from the pressure relief valve should be addressed as soon as possible.  

That’s why we’ve compiled all the information needed for spotting a leak in your pressure relief valve and fixing it in this blog. 

How to spot a leaking boiler pressure relief valve 

A leaking boiler pressure relief valve is often evidence that the valve is defective or damaged. As a result, it’s no longer performing the function it should be. Due the high temperature of any water leaving the boiler in the leak, it might not be noticeable as liquid dripping on the ground. Instead, you might notice limescale staining around the edges of the heating unit or other damage to the water lines. It should also be possible to feel the pressure leaking from the boiler when you get close to it. 

The potential causes of a leaking boiler pressure relief valve include: 

• Blockages 
• Limescale build up 
• An ineffective valve seal 
• Electrical signalling problems 

Fixing a pressure relief valve 

Firstly, only a gas safe engineer should attempt to fix a defective pressure relief valve. They have the expertise and knowledge necessary. 

Step 1 

Switch off all power to the boiler. This will often be a specially designated breaker, but it could affect other areas of the property. The fill valve should also be shut off to make sure no more water is introduced to the boiler. 

Step 2 

After waiting a few hours for the water in the boiler to cool, it can be drained. Open the drainage valve and drain the water into a suitable area until the pressure reading drops to zero. At this point the drainage valve can be closed. 

Step 3 

The valve can now be carefully removed from the boiler using the pipe wrench. Here, care should be taken to ensure the drain pipe isn’t still connected if one’s present. 

Step 4 

Assuming you’ve already sourced a quality spare pressure relief valve, turn it into the boiler and tighten it using the pipe wrench. Ensure the part is straight and facing the same direction as the previous one. The boiler can now be turned back on. 

New and refurbished boiler parts UK 

National Boiler Spares provide a responsive service for fixing boiler parts, with our spanning a massive range of components from top brands. Contact us to arrange next day delivery when vital boiler parts such as pressure relief valves stop working.