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If you can’t identify it or don’t know what it’s called, just ask our Parts Guru. This highly sophisticated tool taps into more than two centuries’ worth of Duff knowledge and expertise. The Parts Guru can save you time and money by helping you identify a part, determine the right replacement or find out how to fix it.

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To contact the Parts Guru, scroll to the bottom. There you can also attach any pictures that may assist the Parts Guru in addressing your inquiry. Here are some examples of questions, problems or issues the Parts Guru has answered, solved or resolved:


I can't find this faucet stem. Can you help me identify it?
If you know the manufacturer of the faucet, we can probably help you. If not, take a picture on your phone of either the faucet or the stem and send that to us. That will do the trick!
What is the right flush valve for my facility, given the demand for water and energy savings?
It depends. There are many flush valves, also referred to as flushometers (traditionally, a “flush valve” referred to the flushing mechanism in a tank-type toilet), on the market right now that help you save water. The first item we’d need to know is what flushometers and plumbing are currently installed. The major manufacturers have invested significantly in dual-flush technologies, low-water-use flushometers and even waterless urinals (literally, there’s no flush, and they therefore use no water). Give us a call or email and we can talk you through the options.
Can my facility use pex pipe in our heating systems?
The answer is “NO”–but “YES”. Pex pipe is a plastic material named for its component material: cross-linked polyethylene. It is often less expensive than alternatives like copper tubing, is flexible, won’t corrode and is easy to install. Pex pipe may be connected with push-on fittings, like SharkBite or other compression fittings, or stab-in pex fittings made of either a plastic or brass material. The reason the answer to the question is “NO” is because regular pex pipe may corrode from oxygen in the water in the line. However, most manufacturers make an “oxygen barrier” pex, which prevents diffusion of oxygen molecules into the water through walls of the pipe. As long as you use oxygen barrier pex for the heating system, the answer to the question is “YES”.
I am the plumbing supervisor at a hospital. I have always soldered. Why should I instead use copper press fittings?
Copper press fittings are made of copper–just like copper sweat fittings–but include a gasket that creates a water-tight seal around the copper tubing. With the use of a press tool, the joint is created. Some people don’t like press fittings because they require a new tool (and thus additional cost). Press fittings may also be more expensive than copper solder fittings. However, after the investment in the press tool and proper jaws (you may need separate jaws for the tool to join different sizes of fittings), you won’t have to pay for solder, flux, brushes, etc. Another reason many institutions switch to pressing is because using a press tool does not require a burn permit, in contrast to when soldering. Moreover, unlike when sweating, the line need not be completely dry to press a joint. Finally, press fittings are becoming increasingly popular, and not just for copper; black steel pipe and stainless steel pipe may also be pressed with the correct fittings and tools. More and more valves are hitting the market all the time–from press ball valves to backflow preventers to regulators. Call or email us if you have any questions about pressing.
I'm in charge of maintenance at a nursing home. We have had some geriatric patients injured falling off and breaking toilets. Are there any geriatric toilet accessories that will prevent this problem?
Indeed, you have a few options. A handful of manufacturers make supports that go beneath the bowl to stabilize a wall-hung toilet and can support up to 1,000 pounds. We also offer toilet seats that provide a larger area for your patients, as well as stabilizing rubber bumpers to grip the porcelain bowl. These special seats come with durable stainless steel hinges (or other materials, if requested) that won’t break where typical seats fail. You may also consider stainless steel toilets or specialized toilet carriers. Let us know about the setup of your bathrooms and we can discuss what’s best for your facility.
What spare parts are available for the backflow preventer in our mechanical room? Does it make sense to repair it or replace it?
Backflow preventers are used to protect a potable water supply from contamination (such as from any substances that may be in a heating loop or a storage tank). Because backflow preventers use moving parts, they are often required to be inspected or tested regularly. One type of backflow prevention device, a reduced pressure zone assembly, consists of two independent check valves, with a pressure-monitored chamber in between. The chamber is maintained at a pressure lower than the water supply pressure, but high enough to be useful downstream. The reduced pressure is guaranteed by a differential pressure relief valve, which automatically relieves excess pressure in the chamber by discharging to a drain. Two valves, often gate valves, are on opposite sides of the assembly to allow for testing and repair. Common repair parts for these devices are kits to replace the first check valve, the second check valve and the relief valve. Depending on the size and model of the device, you may be able to separately purchase just springs, rubbers, and/or gaskets for just one component of the device. Call us before you replace that backflow prevention device–it might make more sense to try to fix it first.
The commercial office building for which I'm the building engineer uses theremodynamic steam traps, among other kinds. Can I change out just the disc in these traps where they are failing?
Thermodynamic steam traps are commonly installed because of their compact size and versatility. They can be installed vertically or horizontally. In disc-type traps like these, the flow of condensate is controlled by a valve disc opening and closing against the valve seat. The valve disc is disconnected from all other parts of the trap, and rests on top of the valve seat. Because the valve seat, which is comprised of two concentric seat rings, is manufactured to fit just right with the disc, the manufacturers generally advise against replacing the disc. Rather, it probably makes more sense to install a new replacement trap.
I'm the plumber at a local university stumped on which side of the water heater I should install the expansion tank.
On a water heater intended to heat water for potable consumption, the expansion tank should be installed on the cold water line. This is because the process of heating the water causes thermal expansion. An expansion tank essentially absorbs the excess water volume that’s created. As the temperature and pressure reach their maximum, the diaphragm in the expansion tank flexes against an air cushion to allow for that increased water expansion. When the system is opened again or the water cools, the water leaves the expansion tank and returns to the system.
I need a new circulator pump. Is there a way to quickly swap out what I have for the replacement?
Heating circulator pumps are used to force hot water from the heating source (often a boiler) through radiaing devices such as hot water baseboard or radiators. Depending on the model, the pump is switched on as needed or wired to continuously run. The main pump types are three-piece circulators, which require oil lubrication and have more replaceable parts, and cartridge-style cartridge circulators, which are water-lubricated and have few replaceable parts. The most common replacement part for a cartridge circulators is a new cartridge. In any event, before we can tell you how easily you can swap out the old pump, we’d need to know whether the installed pump is cast iron (for closed-loop systems) or bronze or stainless steel (the latter two materials for open-loop systems, to avoid corrosion in a steady flow of oxygenated water). From there we can select the correct replacement pump.


We're scheduled to install a new well pump at a single family dwelling next week. What information do you need to know to help me size a well pump for this job?
Before diving in to pump sizing, we need to know the well’s depth to water (which tells us what type of pump you’ll need, for instance one designed for shallow or deep wells) and anticipated water usage (which may be determined by a water bill or a fixture count, which we can help guide you through). You should probably also review the Well Pumps section of our website to better understand the difference between constant pressure well pump systems versus conventional, single-speed pumps. From there, we’ll have adequate information to determine what pump is best for your application.
Can you help me find the seals for this old split-case pump?
Almost certainly, the answer is “YES”. This is one of our specialties. If you know the model number of the pump, that’s great. If you can get a picture of the nameplate on the pump, that’s even better. If you’re struggling to find the metal stamped nameplate, don’t worry; just give us a call, or email us a picture, and we can walk you through it.
I am in charge of maintenance at a factory. We have big machines that use a small pump to cool liquid. I have no idea what brand the pump is, nor do I know how to find out what kind of pump it is. What should I do?
Just give us a call or email us a picture of the pump. You probably have what is called an immersible pump — a vertical multistage pump in which the wet end of the pump is actually immersed in the fluid. These are designed to pump cooling lubricants for machine tools, condensate transfer and similar applications. They’re commonly found on large CNC-type machines; grinding machines; cooling units; and industrial washing systems; and YES, we can find you the correct replacement.

Water Treatment

I'm at a jobsite where the water softener isn't providing adequate flow. What should I do?
The short answer is to give us a call. The less abbreviated answer is to get gather information on the water source, the water treatment equipment and the water usage. There are many variables involved in properly treating water. Of course, the issue might also stem from the supply. Because of our expertise in both pumps and water treatment, if you gather information about the source of the water we may be able to help you isolate whether it’s a problem with the equipment, the setup or otherwise.

Will this water softener remove iron from the water?
Water softeners weren’t originally designed to remove iron or hydrogen sulfide. But they may incidentally remove iron from the water, depending on the type of iron that is the problem. “Ferrous iron” has not been exposed to oxygen (i.e., hasn’t been “oxidized”). This type of iron is dissolved in the water and can easily pass through standard filtration systems. Because a ferrous ion is a cation (i.e., positively charged), it can–theoretically–be removed from water with an ion exchange resin found in typical water softeners. “Ferric iron,” on the other hand, cannot be exchanged by a water softener, and must be physically “trapped” in a filter. Depending on how much ferric (oxidized) iron is in the water, we may recommend a whole variety of different treatment options. The short of it is: Please call us so we can discuss what’s best for this application. Possible options include cartridge-style filters, whole-house filters, air-injection, special resin or other media in the mineral tank, a special resin cleaner–or some combination of these.
I am a service tech at a plumbing service company. Can you please size the water softener for this house?
Yes, but we’d ideally like some more information to do so. First, we’d need to know the hardness. If you don’t have that information, just get a water sample and bring it to us; we’ll test it here. You can use any bottle or container to obtain the sample–just make sure to rinse it out a few times first. Preferably, you draw the sample from cold water, as the water heater may introduce new/different contaminants. We’d also like to know the level of iron or other contaminants about which the homeowner is complaining. If you’d like to remove chlorine or tastes/odors, please let us know that as well. Again, please provide us with a water sample if you have any doubts.

To properly size the system, ideally, you can provide us with the number of people residing at the house, how many children live there, whether there are any atypical uses of water (e.g., rain showers or special shower jets, irrigation needs, and so on) or another indication of typical water usage. A recent water bill would work.

From this, we can determine the size of the softener unit needed. To complete the system, we’d need to determine whether the system should be time clock- or meter-initiated, whether your customer desires continuous soft water, the size of the plumbing coming into the dwelling, and a few other considerations. Call our water treatment experts if you have any questions whatsoever.

I'm a well driller and would like to know your thoughts on the best way to disinfect a private well system please.
Water disinfection is just what it sounds like–ridding the system of whatever is infecting the water. A proper disinfection removes, deactivates or kills microorganisms, viruses, cysts and bacteria. Because well water doesn’t run through a municipal treatment plant, which typically disinfects the water supply, private well owners must somehow treat their wells. This can be done either chemically or physically:

“Chemical” disinfection often uses a substance such as chlorine, iodine, bromine or ozone; “physical” disinfection treats the water with ultraviolet (UV) light, ultrafiltration or distillation. UV systems expose water to light as just the right wavelength for killing microbes, and may also kill bacteria, viruses, fungi, protozoans and cysts. With UV lights, the light source must be kept clean and the lamp periodically replaced. UV light does not remove gases, heavy metals and particulates. Often a complete water treatment system should include additional filtration such as activated carbon, any of which filter must be maintained or replaced, as the case may be.

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