My question is not found in these FAQ’s, where do I look next?
Check out the Hubbell Product Center at Here for a complete listing of all technical documentation available by model. Get easy access to Installation, Operation & Maintenance manuals, Sales Brochures, Service Bulletins, Wiring Schematics, Parts Breakdowns and various other technical documents related to the full line of Hubbell water heaters. Or, if you prefer, please call us at 800-647-3165 and ask to speak to a Sales Engineer.
Where can I purchase replacement parts?
Parts are available for your Hubbell water heater direct from the factory. Please call 800-647-3165 and ask for our parts department. Please have your model and serial number handy.
What is thermal expansion and how does it affect me?
Thermal expansion is created when water in a hot water system expands due to increasing temperature. When there are no faucets/fixtures open to release the excessive pressure caused by the water being heated up, and if there is no expansion tank in the system to absorb the expanded water, then it is likely that the water heater T&P (temperature and pressure) relief valve will open slightly and begin to drip to release the excessive pressure. This is not a condition that the T&P relief valve is intended, it is a safety device not an operational device. Thermal expansion can be evident immediately upon a new installation when a cold system is first undergoing heat up, or even occur years in the future due to seemingly unrelated changes to the plumbing system but enough so that thermal expansion becomes a problem. If Thermal expansion is present a properly sized expansion tank should be installed to resolve this problem.
My T&P relief valve is dripping water, what does this mean?
A temperature and pressure (T&P) relief valve is a safety device intended to relieve excessive pressure (typically >150psi) or excessive temperature (210°F/99°C). Typically, a dripping T&P is most likely the result of excessive pressure build up in the water heater. When a T&P opens due to excessive temperature, you will most likely see a significant amount of steam in the air as the water flashes into steam as it discharges from the T&P. A relief valve discharging due to excessive pressure is by far the most common reason for relief valve discharge. It is also worth noting that a T&P relief valve will begin to open when pressure is within 5% of its set pressure rating, as an example a 150psi relief valve will begin to open and “weep” at 142psi. See FAQ relating to thermal expansion for a more detailed discussion of this problem.
Where can I purchase a Hubbell water heater?
There are numerous ways to purchase a Hubbell water heater, mainly depending upon the model you desire and your geographic location. The easiest way is to contact Hubbell directly at 800-647-3165 and ask for the sales department where you will be directed to either our local representative, local wholesaler or dealer, internet or our own order entry department for quick and easy ordering.
Do I need a thermal expansion tank?
Yes, it is recommended that a thermal expansion tank be installed with your water heater, and in many instances this is required by code. When water is heated it expands. If your system is “open” then water can backflow into the water main and this “extra” expanded water simply flows back out your system. Increasingly, plumbing systems are being closed off and backflow prevention valves are being placed between homes and the water main. This is done for a variety of reasons. For example, increasingly valves are placed between homes and water mains to protect plumbing systems from inlet water pressure. Water pressure is increasing in many cases in order to meet the demands of more densely populated areas. If your system is “closed”, then this means when you heat your water and it expands, this increased volume has nowhere to go. As water is not a very compressible material, this causes sudden increases in water pressure which can damage your water heater and your other appliances. A thermal expansion tank is a pressurized tank typically located in line immediately before the water heater. The tank contains a pressurized bladder. As your water expands, it pushes against this bladder giving the increased volume a place to go preventing rapid pressure increases due to thermal expansion. If your system is closed, installing an expansion tank may lengthen the life of your water heater by preventing excessive pressure cycling. In addition, if your home has a history of leaky faucets or other appliances that wear out prematurely, an expansion tank may fix your problem.
Is the bronze body T&P relief valve OK for my application?
All water heaters require a combination temperature and pressure safety relief valve to relieve excessive water pressure or excessive temperature water in the event of a runaway overheating condition. These relief valves are manufactured with a bronze body with a thermo-bonded (non metallic) coated immersion sensor. After independent third party testing conducted by Analytical Services, Inc. it has been verified that the T&P relief valve has no appreciable effect on the purity and quality of high quality ultrapure DI/RO water. However, should the installation warrant that no yellow metals be present in the plumbing system, as an option Hubbell can supply a 316 stainless steel pressure only relief valve and a separate temperature relief valve can be installed by others.
What is the difference between threaded NPT and Sanitation flanges?
Sanitary fittings are widely used in the food, dairy, beverage, biotech, pharmaceutical and other sanitary process industries. Sanitary fittings offer a way to connect two parts by creating a seal which is accomplished by means of a round gasket in a groove on the face of the fitting, with the two parts coupled by a re-attachable clamp. Similar to a traditional ANSI flange connection, the sanitary design eliminates the need for a male and female, since the fitting mates to another identical fitting. National Pipe Thread Taper (NPT) is a US standard for tapered threads used on threaded pipes and fittings as a means to form a seal when connecting two pieces. The taper on NPT threads allows two connecting pieces to form a seal when torqued as the flanks of the threads compress against each other. The Hubbell HD model is supplied as standard with NPT cold water inlet, hot water outlet and T&P relief valve connections. A customer with a sanitary system will in most instances install adapters to mate the NPT connection from the Hubbell heater to their sanitary plumbing system. However, as an option Hubbell can provide the model HD water heater with welded sanitary connections, thereby avoiding the use of NPT to sanitary adapters. However, it should be noted that the immersion heating elements are only available in threaded (straight not NPT) style. For the most stringent applications, the Hubbell heater can be specified with the Clean In Place (CIP) option including all electropolished interior surface and removable flanged end for inspection and cleaning, please consult with your Hubbell Sales Engineer for details.
Can Hubbell integrate a pump or other accessory with my heater?
Yes. For applications where it is desired to integrate the Hubbell heater with other accessories for a fully integrated packaged system, please consult your Hubbell Sales Engineer.
Why is the ASME stamp important for my application?
The ASME Boiler and Pressure Vessel Code (BPVC) is an American Society of Mechanical Engineers (ASME) standard that provides the rules for the design, fabrication and inspection of boilers and pressure vessels. The Hubbell water heater carries the ASME stamp verifying that the pressure vessel has met the BPVC and inspected by a third party Authorized Inspector (AI). In most industrial facilities a pressure vessel must be ASME stamped to meet state and federal requirements, not to mention end user insurance requirements based upon liability concerns.
Can I install my heater in a wash down or wet area?
The standard Hubbell model HD is designed for essentially NEMA 1 use to provide a degree of protection to personnel against access to hazardous parts and to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt). For wet areas, or washdown areas, please select optional NEMA 4 or 4X construction and consult with your Hubbell Sales Engineer.
What is delivery on a standard Hubbell HD model?
The delivery time for a standard Hubbell model HD water heater is 2 days or less. However, if optional accessories are selected the delivery time maybe extended, please consult with your Hubbell Sales Engineer.
What is the standard interior finish?
The standard interior surfaces have a mill 2B finish less than or equal to Ra 80. No surface treatment of material or welds is performed. As an option, Hubbell can provide mechanical finishing services for material and welds to achieve a high quality finish. In these applications the end user must specify the surface finish required, typically expressed as Average Arithmetic Roughness (Ra). Ra is the measurement of surface roughness, is the average deviation from a mean surface and is measured in micro inches or microns.
What is passivation?
Passivation of stainless steel is a process performed to make a surface passive by creating a surface film that causes the surface to lose its chemical reactivity. Stainless steel passivation unipotentializes the stainless steel with the oxygen absorbed by the metal surface, creating a monomolecular oxide film which can result in improved corrosion resistance of the metal. The passivation of stainless steel is performed when free iron, oxide scale, rust, iron particles, metal chips or other nonvolatile deposits are removed from the surface layer. When these particles are present they may adversely affect the metallurgical or sanitary condition or stability of the surface, and are likely to lead to contamination of the process fluid. As an option and when required for a particular application, Hubbell can provide passivation for the HD model water heater.
What is electropolishing?
Electropolishing refers to a process where surface metal is removed and leveled by anodic dissolution in an electrolytic solution with an imposed current. Electropolishing passivates the surface creating a mirror finish without the use of mechanical polishing. In addition, electropolishing stainless steel improves corrosion resistance by reducing the exposed product surface area, removal of metallic and nonmetallic surface inclusions, obtaining a smooth releasable surface for improved cleanability and removing some or all of the cold worked/structurally modified abrasive finished surface to expose unmodified base metal. As an option and when required for a particular application, Hubbell can provide the HD model water heater with electropolished interior surfaces.
Is 277 volt 3 phase voltage available for a water heater?
For all water heaters 277V is only an available option in 1PH, not 3PH. The 277V 1PH voltage is a derivation of your existing 480V 3Ph power. Where 480V is the line to line voltage on a 3 phase system and 277V is the voltage from any one of these lines to neutral, thus making the 277V power available in 1PH only.
What is the R value of a Hubbell water heater?
Hubbell uses a blown-in polyurethane foam insulation for all cement lined water heaters and tanks up to 150 gallon capacity. This insulation has an R value of 7.2 per inch. Most Hubbell tanks have a minimum of 2 inches of insulation resulting in an R value of 14. Certain models are available either standard or as an option with 3 inch insulation and therefore have an R value of 21. Large storage water heater tanks over 150 gallon capacity and custom made stainless steel or alloy tanks have either 2" or 3" fiberglass insulation with an R value of 3.5 per inch.
Why Hubbell recommends 300 series versus duplex stainless steel?
While it is true that duplex stainless steel typically offers higher strength and resistance to Stress Corrosion Cracking (SCC) and chloride corrosion compared to austenitic (300 series) stainless steel, there are other factors that ultimately make it a less desirable choice compared to 300 series stainless steel. Duplex stainless steel makes up only 1% of the stainless steel market making it less readily available and higher cost especially in flanges, fittings and formed parts such as tank heads. While it is commonly stated that this added expense is offset by the ability to use material that is thinner due to the higher strength, this only applies to very large tanks where a reduction results in using a lower common plate thickness. As an example, a thickness reduction of 25% for a tank that is 3/16" thick in 300 series stainless steel still results in using the common 3/16" thick plate size in duplex stainless steel. The higher strength of duplex also has the negative result of decreased formability and machinability, adding cost to the fabrication and production process. In terms of welding, duplex stainless steel presents many problems in maintaining the proper two phase mixture which commonly leads to issues in the Heat Affected Zone (HAZ) such as loss of corrosion resistance, toughness, and post-weld cracking. This is true in all duplex stainless steel welding processes including TIG, MIG and Laser. By comparison the process of welding austenitic stainless steel is much more forgiving. The main weakness of austenitic stainless steel is its susceptibility to Stress Corrosion Cracking (SCC) and chloride corrosion. Three factors that all must all be present cause this type of corrosion: elevated heat, the presence of chlorides, and residual stresses. In water heaters elevated heat and the presence of chlorides cannot be controlled. However, post-weld heat treating in a vacuum furnace followed by cooling in an inert atmosphere relieves the residual stresses in austenitic stainless steel tanks and therefore eliminates the susceptibility to this corrosion. For this reason, this post-weld heat procedure is performed on all Hubbell stainless steel tanks. The heat treating process is highly controlled and verifiable, unlike the difficult to control process of welding duplex stainless steel. Therefore, Hubbell offers stainless steel tanks fabricated from the 300 series (typically Type 304L or 316L) only, as this is a far more proven and verifiable material and fabrication process which will result in longer tank life. Of course, an alternative option is to specify the Hubbell cement lined steel tank which also provides a considerably longer life and is a more economical solution compared to duplex stainless steel and 300 series stainless steel.