Camco 10493 Water Heater T&P Relief Valve, 3/4in NPT

Your water heater is a sealed tank full of water that gets hot, and hot water expands. On an RV or a boat, that tank lives through vibration, temperature swings, and years of hard use. The temperature and pressure relief valve is the one part standing between normal operation and a tank that builds pressure with nowhere to go. The Camco 10493 is that valve. It's a straightforward brass safety device that threads into the relief port on most RV and marine water heaters and opens automatically the moment temperature or pressure crosses a safe limit.

Here's how it works. The valve carries a 150 PSI pressure rating and a temperature probe that reaches 4 inches into the tank. If the water pressure climbs past the valve's set point, or the water temperature spikes, the internal stainless steel spring gives way and the valve vents. That relieves the tank before pressure can build to the point of damage. When conditions drop back to normal, the valve reseats and holds. It's a simple mechanism, and simple is exactly what you want in a safety part.

The body is brass, which is the right material for a fitting that sees hot water year after year. Brass handles heat and resists corrosion far better than plated steel, and it won't get brittle the way cheaper materials do. The probe is epoxy-coated, so the part that sits down in the tank water stays protected against scale and corrosion. And the spring is stainless steel, not plain wire that rusts and loses tension. Those three material choices are why a valve like this outlasts the bargain replacements.

Fitment comes down to three numbers. The valve size is 3/4-inch NPT, which is the standard relief port thread on the vast majority of RV and marine water heaters. The shank is 2-1/2 inches, an extended length that reaches through thicker tank walls and insulation so the threads seat properly. And the probe is 4 inches, sized to sit in the water where it can actually sense tank temperature. Before you buy, check your old valve against those three dimensions. If your existing relief valve is a 3/4-inch NPT with a similar shank and probe, this drops right in.

When should you replace a T&P valve? A few clear signs. If it weeps or drips constantly, the seat is worn and it's not sealing. If it's crusted with mineral scale or shows corrosion around the body, it's past its service life. If you lift the test lever and no water comes out, the valve is stuck and it isn't protecting you at all, which is the most dangerous failure of the bunch. Most techs will tell you a relief valve is a wear part. Replacing it during a water heater service or at the start of a season is cheap insurance.

Installation is within reach for most owners. Shut off the water heater and the water supply, let the tank cool, and relieve the pressure before you touch anything. Drain enough water to get below the valve port. Back out the old valve, clean the threads, wrap the new valve's threads with PTFE tape or pipe dope, and thread the 10493 in until it's snug and the discharge outlet points where you want it. Reconnect any discharge tube, refill the tank, and check for leaks before you fire the heater back up. If you're not comfortable working around a pressurized hot water system, hand it to a tech. There's no shame in that.

One note on what this is and isn't. This is a replacement safety valve, not a tank, an element, or a thermostat. It doesn't heat water and it doesn't regulate normal operating temperature. Its whole job is to open when something goes wrong. That's it. The English and French packaging makes it easy to source on both sides of the border, which is handy if you cruise or travel into Canada. Match the thread, the shank, and the probe against your old valve, and you've got a proven Camco safety part ready to go back to work.