This post is another installment in our ongoing series highlighting unsung but important components that are installed with hot water home heating products. Specifically, we’ll focus on pressure relief valves that are used on home central heating boiler systems, and pressure and temperature relief valves that are used on water heaters.

Pressure relief valves used on boiler systems are often factory-set at 30 psi, the commonly accepted operating pressure inside most hot water home heating systems (think boiler, baseboard heaters, radiant floor, radiators, etc.). The P&T valve used on tank-type water heaters carries two separate ratings, typically 150 psi as the pressure limit, and 210 degrees F for the top-end temperature. A couple of the more popular manufacturers that are used for these purposes are Watts Regulator and Cash-Acme.

Virtually all central heating boilers and domestic water heaters all include pressure relief safety valves either installed standard on the unit from the factory, provided with the equipment for the plumbing and heating contractor to install, or are specifically addressed in the manufacturer installation instructions provided with the heater.

Pressure relief valves are designed to automatically open when a preset pressure level for the valve is exceeded. Notice the pipe (often copper), open at the bottom, that routes from a brass valve on or close to the heater, hopefully terminating at the floor drain in your mechanical room. When a pressure relief valve ‘pops,’ the excessive pressure is typically relieved in the form of hot water draining thru that pipe to the floor drain. That’s often an indicator that something could be amiss, and giving your heating contractor a call asap would be a wise course of action.

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In the case of some of the fancier (ie. more costly) water heaters now available, the lines between boilers and water heaters start to blur a little – for our customers, but not for our team at Save Home Heat! Regardless, the application of pressure relief valves versus combination P&T valves should always closely follow specific manufacturer requirements and instructions.

In some cases, the pressure may simply be released and the relief valve close on its own; in others, possibly not. A steady drip or mini-flood could potentially ensue. Either way, this is not an occurrence to be ignored or dismissed, even if the circumstance rights itself. Make that call and be sure this occurrence isn’t a symptom of a potentially greater, more costly and messier issue.

Please reach out to our team today if you have any questions or concerns about pressure or temperature levels inside your water heater or boiler system. You can count on receiving the professional service and information that you need.

A Reduced Pressure Zone Device (RPZD, RPZ or RPZ valve) is a type of backflow prevention device used to protect water supplies from contamination. RPZDs may also be known as reduced pressure principle backflow prevention devices, or reduced pressure zone assemblies.An RPZD is considered suitable for high hazard applications, that is, where the consequence of backflow into the water supply would cause significant harm. They are considered suitable because they prevent both backflow and back-siphonage, because of a redundant design (even with two check valves broken the device still provides protection), and because they are testable to verify correct operation.

There are several types of home heating products that our team at SHH installs that use either pressure relief valves or their close relative, the P&T valve. These include:

While central heating boilers have separate, dedicated pressure relief valves, with independent over-temperature safety switches installed in the boiler, standard residential water heaters, on the other hand, combine those two functions in a single valve that’s known as a “pressure and temperature relief valve,” aka. a P&T valve. The difference is essentially that simple: in one case (whole-house boilers), the functions are performed by separate components, and in the other (standard water heater), the job is performed by a combination component. It’s interesting to note that boilers typically reside in a much higher price bracket than most (but not all) water heaters. Our readers are welcome to speculate.

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A pressure relief valve – not to be confused with a whole-house pressure reducing valve (known as a PRV) – is a safety component that helps protect closed and hot water-based systems against experiencing excessively high pressure inside the system. The job of these valves is to monitor water pressure inside the system and respond accordingly if overly high pressure is detected. Water pressure exceeding the design limits inside such systems can cause a variety of problems, from leaks, parts failures, equipment and system failure, to performance issues, as well as shortened lifespan of the equipment and key components.

Homeowners in the Boulder-Denver metro area trust our team at Save Home Heat for reliable, friendly, expert advice and high quality service and installation for all things hot water and home plumbing and heating – and lots more! Plumbing, all types of heating, cooling, hot water, complete electrical services, central indoor air quality (IAQ) products, and anything related can be found under our 40+ years-and-counting umbrella. Please reach out to our team today if we can be of service.

It’s always a good idea to take a quick look at the floor around your boiler and/or water heater when you find yourself nearby, to see if there’s any moisture, or evidence of recently dried water, on the floor or on the outside of the unit, itself. A regular quick inspection as part of your monthly routine would be even better.