There's no getting around the fact that hydronic heating can be messier than forced air. While there are plenty of advantages to using water to heat your home, failures usually result in puddles on the floor or, in severe cases, extensive water damage. If you've been living with an older boiler for long, you've probably experienced a dripping pressure relief valve (PRV) at least once.
Relief valves serve a critical role in your hydronic heating system. When the pressure in the system gets too high, the valve allows some water or steam to escape. This action relieves internal pressure, protecting your HVAC components and property from damage. If you have an automatic feeding system, your heat may still work even as this valve drips a substantial quantity of water.
Why Is Your Valve Dripping?
Although they might be a common sight, dripping valves are never normal behavior. A PRV drips for one of two reasons: either your system pressure is too high, or the valve is faulty. While there may be numerous underlying causes for either situation, these are always the immediate sources of trouble. Both issues require attention.
A faulty valve might not seem like a pressing issue, but remember that your PRV is a critical safety component. A valve that's dripping with normal pressure may not be able to relieve a sufficient amount of water pressure in an actual emergency. While modern boilers are typically very safe, an over-pressure situation can still cause potentially costly damage.
The other possibility is that your PRV is working as intended. In this case, the dripping means that the pressure in your system is too high. The valve effectively keeps the water pressure in check, but that doesn't mean you can ignore the situation. In addition to wasting water, there may be another problem that will eventually cause your heating system to fail.
How Should You Diagnose a Leaky Valve?
You can check the valve yourself relatively easily. Most PRVs should have a pressure rating printed somewhere on their casing. Check your boiler's current pressure on the indicator against the rating on the PRV. If the valve is leaking even though the boiler's water pressure is lower than its rating, there's a good chance you have a faulty valve.
However, higher pressure likely means you're dealing with a real over-pressure situation. In these cases, you should contact an HVAC technician with experience in boiler repair to help you further evaluate the problem. High pressure in a residential hydronic system can have numerous causes, so it's best to leave the repair to a qualified professional.