TRV valves are a type of component used in water heaters. They regulate the flow of hot and cold water as well as pressure between the tank and the tap. These valves can become defective or worn out which will lead to an increase in your utility bills because they're not functioning properly. If you notice that your TRV valve is becoming faulty, it's important to have it replaced quickly before further damage occurs. TRV valve is a reverse-acting temperature and pressure relief device that opens automatically when the system reaches its setpoint. It's easy to test TRV valves with these steps. Steps: 1) Check for any visible damage 2) If there are no visible damages, then check if it can open by applying pressure 3) If it cannot open, then replace the TRV valve 4) If it does not have any visible damages or can open, then you should consider replacing your thermostat because the thermostat might be bad