CitiGas West London Gas Engineers

Gas Safe Registered Gas, Heating & Plumbing Engineers | Based in Ealing | Covering West London

Boiler and Appliance Breakdowns | Repairs | Certification | Plumbing Solutions

Pressure Relief Valves (PRV)

They are normally pre-set at 3bar to discharge (open) the system if the pressure exceeds 3bar and will then close when the pressure has reduced to below 3bar.  Like all components they can either fail or more than likely once triggered quite often simply don’t seal correctly back up. Often this is caused by a bit of system debris sticking on the valve seating preventing it resealing and consequently causing subsequent water loss from the system. This causes pressure drop and many diagnose this incorrectly as a leak on the heating system. The PRV discharge pipe must be positioned where it will not cause a hazard to persons or property and is normally situated outside – the water will often evaporate before it can be noticed on the ground but brown rust or lime-scale stains are a good indication that it has been leaking. If this is the case we would be delighted to hear from you so please contact us at