The plumber stated it was code to have one. but their was no catch drain or anything to prevent the thing from flooding the home. Technically the newer dip tubes should negate the need for a separate vacuum breaker, however here in NH, most inspectors will fail the job if they don't see one. If you are installing a 500,000 BTU heater, it can generate up to 5 gallons per hour! This allows air to enter at the vacuum relief valve and the heater/tank will not be drained down. These neutralizer assemblies can be for individual or multiple appliances and usually have a PVC housing or inline fitting. How is condensate neutralized prior to entering a drain? An Automatic Fill Valve will open when pressure drops below the set pressure. Once the vacuum reaches the hole, it will draw air through the hole and the tank will not drain down. We have been putting them in for years here and I have never seen one fail like you are talking about. Combustion condensate is very acidic and should be neutralized before entering a cast iron drainage system or storm drain system. I am new to this concept I have never heard of or seen one on a heater. When incoming water refills the system (higher pressure injects water into the closed loop), the Fill Valve will close once the pressure setting is reached. Some of these items are for Plumbing (open loop) and others are common to Hydronic Heating (closed loop). If the tank collapse from vacuum just from draining the line there is a much bigger problem. Make sure you have provided for proper drainage of this combustion by-product. Can you please explain a Combination Pressure Reducing/Automatic Fill Valve for a closed loop system? It is toxic and should not be discharged directly on to the earth either. A closed loop heating system is typically operated at a system pressure that ranges from 20 30 PSI. Never heard of an implosion , they are used here to keep the water from siphoning out of an overhead electric water head and burning up elements. This can cause scaling and corrosion of components. Some manufacturers provide Pressure-only valves and others ship their heaters with T&P valves. We will answer some questions about basic components in a hot water system. It seems to me if the tank is imploding due to a vacuum/siphon the manufacturer should be making the tank stronger period. Since incoming cold water supplies will have 40 PSI or greater, a pressure reducing valve must be used to regulate down to approximately 25 PSI. The Rheem marathon w/h have to have them. Is condensate that is generated by a gas-fired appliance safe to dispose of down any drain? Why are Vacuum Relief Valves not used much on top-feed water heaters? A Vacuum Relief Valve is a simple device that prevents back-siphonage of a water heater or storage tank. They either use limestone chips or a block of calcium carbonate to offset the low pH, acidic condensate. An atmospheric vacuum breaker. Welcome back to another article! A closed loop system will experience certain issues if too much fresh water is entered into the system. Not vacuumed in the tank. This hole will only allow water to back-siphon until the vacuum reaches the hole. What is a Vacuum Relief Valve and how is it used with a water heater? This should be a non-issue in my opinion. If the buildings water line were shut down, the system can back-siphon the cold water line. Boilers operate at lower pressures and can generate temperatures over 210F so they employ a Pressure-only Relief Valve. A Combination Valve will have all of these features built in. A top-connect water heater is subject to a back-siphon vacuum but this is easily prevented by having a siphon hole located near the top of the dip tube. If the tank starts to siphon out the inlet, the hole in the top of the dip tube will break the siphon because air will come in. How much condensate can a high efficiency water heater or boiler actually produce? Again excuse my ignorance, can someone clear this up for me?? In contrast, a Pressure Vacuum Breaker is designed to relieve a backflow of contaminated water and also function as an anti-siphon device. Most fill valves have a manual lever for quick-filling the system. Vacuum Relief Valves are also used on radiators to prevent losing water within the radiators if the system loses pressure or has been drained down. I've never seen one blow out. I am wondering if anyone has ever heard of a water heater imploding because it did not have a vaccuum relief valve installed on it?? Most manufacturers offer a version of a condensate neutralizer. How does a Pressure Vacuum Breaker differ from a Vacuum Relief Valve? Why would this VB have failed unless someone had shut the water down after the new heater and VB had been installed , who shut the water off and didn't check everything out once they turned it back on or did it fail while the water was on ? Water heaters that have top connections will use a Dip-Tube that forces cold water to the bottom of the tank. I just gamble that it won't leak. It also has a temperature probe that will lift the seat at approximately 210F (just before boiling). The plastic tanks will expand due to pressure without problems. The only place I have ever installed vacuum breakers for protection of the tank was on steam water heaters and coils in ahu,s. The more components the better, Plumbing Zone - Professional Plumbers Forum. A condensing appliance can generate approximately 1 gallon of condensate per 100,000 BTU per hour. Here any heater that us feed on the bottom must have a vb If the cold feed line is lower then then the heater you must 90 up above the heater set a tee with vb and drop back down to feed the heater, No. yes, there is a hole in the dip tube that prevents a water heater from siphonage, and the need for this device seems to be more of a "make work" thing to me.. also , I wonder who gets to pay for the damages if. just asking the questions for my own education, The Fora platform includes forum software by XenForo, https://www.youtube.com/watch?v=tQMO1eyMRuM, http://www.watts.com/pages/_products_details.asp?pid=815, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. or do you just gamble on it and hope it never floods someone out?? A Temperature & Pressure (T&P) Relief Valve is typically used on a water heater producing 180F or less. also has anyone actually seen an imploded water heater in their plumbing travels? Just like every other repair I do! The Vacuum Relief Valve is located above the water heater and will open to atmosphere when a back-siphon (vacuum) occurs. ?anyone got a picture of one. one fails and floods out the home..a few weeks down the road?? Fresh water dilutes the boiler chemical treatment and brings in more calcium and minerals with each fill. For a better experience, please enable JavaScript in your browser before proceeding. Come join the discussion about the industry, safety, finishing, tools, machinery, projects, styles, scales, reviews, accessories, classifieds, and more! If you remove the vacuum breaker and drain the tank it will crack it everyone. I don't think it has anything to do with preventing tanks from imploding. As the water begins to backflow, the Pressure Vacuum Breaker will open to create an anti-siphon point and discharge the backflow water from its relief port. so this makes me wonder how many areas of the USA is this vaccuum relief valve required on a water heater?? If you put a vacuum breaker on a water heater what kind do you use? So the vacuum breaker is just to prevent back siphon. It is typically used on water heaters with cold water connections located near the bottom of the tank. This anti-siphon feature is standard on top-fed water heaters and is typically located just a few inches from the top of the tank. A closed loop system that keeps refilling usually has a leak in the pressurized piping that must be addressed. It is either a single or dual valve assembly that will regulate system pressure and provide automatic water fill. The tank works off of a siphon if it fails under normal operation it should be on the manufacturer. It has a high pressure spring normally rated at 125 or 150 PSI. It is important to note that closed loop systems use treated water that is heated over and over. Maybe I'm missing something. Excuse my ignorance, but can someone please explain how a hole in the dip tube breaks the vacuum when it is completely submerged, I'm not understanding this concept. All vacuum Relief Valves are used for in water heater/tank applications to automatically allow air to enter into the piping system to prevent vacuum conditions that could siphon the water from the system and damage water heater/tank equipment. Yep. It is hard to immerse the probe of a T&P valve in piping so the Pressure-only relief valve is mainly used. It is not required in Indiana. apparently it is required in New England. A vacuum relief allows air to enter into the piping to prevent back-siphonage. That would make it easier for hacks. If the water heater is in a finished area I install a drain pan and floodmaster anyway. JavaScript is disabled. Tankless heaters use a Pressure-only valve (no probe) but they also would be proper to use a T&P valve. So When you install one on the heater do you try to figure out a way to run some sort of catch drain from it to a pan or drain ??? Or through a wall and directly dumped on the ground? The pressure relief valve will typically be rated at 30 PSI but they are offered in many different PSI settings. Trail-er Blazing: One-of-a-Kind Mobile Trailers Provide Temporary Heat on Demand at University of Virginia, Integrating Snowmelt with BAS is Easily Achievable. How does a Pressure Relief Valve and Temperature & Pressure (T&P) Relief Valve differ? A forum community dedicated to professional plumbers. I am just having a debate on another forum about this issue. A couple of areas where these relief valves can be used interchangeably are on Pool heaters and Storage Tanks. Someone installed one on the top of a new water heater and it tripped open and flooded out someones home to the tune of $60,000.. . Seriously though I have only ever seen very old vac breakers drip and corrode. You Got What It Takes to Own a Plumbing Business. This protects heaters from dry-firing the elements or burner. Sounds like this plumber needs to get the manufacturer of the VB involved and find out why the VB failed in the first place. Has anyone ever seen one fail and flood out a home?? The vac breaker is there to limit back siphoning of the water heater.