Tell Us How Often Start Service and Relax The answer is...it depends. Read this and get to the right answer. We offer over 60 standard filter sizes.  We also offer custom air filters in the unlikely event that one of our standard sizes doesn't fit your system.  Picking the right size requires a little deductive reasoning and sometimes a measuring tape.  Follow these steps and you'll get to the right answer: 1.  Is your filter for a standard HVAC system or for a whole-house air cleaner?  If the air filter simply slides into a slot in the air duct as it enters the air handler or at a return, you probably just need a standard HVAC system air filter.  However, if you have an air cleaner installed in the system, a standard HVAC system air filter will probably not work.  An air cleaner is a separate unit installed in front of the HVAC system air handler.  It is designed to "scrub" the air using a variety of technologies, including ultraviolet light and high efficiency air filters. 

Air cleaners are made by a number of manufacturers such as Lennox, Air Bear, Honeywell, Carrier and many others.  The manufacturer of your air cleaner should be pretty obvious...look for a logo, company name, trademark or something similar. 2a.  Assuming you do not have an air cleaner, you have three ways to determine the correct filter size: i)  Look at the filter you are using now.  The size is usually printed on the filter frame and will be something like 16 x 25 x 1 or 14 x 14 x 1.  These dimensions refer to the nominal size of the filter.  Nominal dimensions are not the actual dimensions of the filter.  More on that below. ii)  If you can't find the dimensions printed on the frame, you can use a measuring tape to measure the outside dimensions of the filter.  This is a simple process...just measure each dimension to the nearest 1/8". iii)  Some filters are just too flimsy to measure accurately.  If this is the case, you need to measure the slot into which the filter is inserted.

2b.  Assuming you have an air cleaner installed in your system, you can determine the correct filter size in three ways: i)  Every air cleaner manufacturer uses model numbers on their units.  You can find the model number of your printed on the unit itself or stamped on a label.  window ac unit problemsYou may have to search a bit but it's there.  cost of a new home ac unitLook up the manufacturer name and model number on our handy air cleaner reference page.  room air conditioners portable ratingsWe list many manufacturers and the appropriate filter size for each model. ii)  Can't find the model number?  Pull out the filter that you are currently using and look for the manufacturer's name and part number.  You can use the air cleaner reference page to verify the air cleaner manufacturer name and replacement air filter size.

iii)  If you're still having no luck, you'll need to measure the filter dimensions to determine the correct size. 3.  Once you know the size of your HVAC system air filter, or in the case of an air cleaner, the manufacturer name, unit model number and/or filter part number, go to Step 1 of our filter selection wizard and see if you can find your size in the drop down menu.  Don't see your size?  Contact us about ordering custom-sized filters. Nominal Dimensions Versus Actual Dimensions To make things really interesting and fun, the air filter industry labels filters with "nominal" dimensions.  Nominal dimensions are different than the actual dimensions of the filter.  In fact, nominal dimensions are almost always slight larger than the actual filter dimensions.  This is done to alow for a little wiggle room inside the filter slot.  This is fine for HVAC systems since air pressure inside the system presses the air filter frame a against the frame of the filter slot which creates as a seal. 

In this way air won;t leak around the edges.  All you have to do is make sure that the filter size fits into the slot and is big enough to touch all four sides of the slit frame.  The slot fram is usually fairly wide (half an inch or so) so that the filter size does not have to be exact.  Again, this is fine for standard HVAC system air filters.  The wiggle room created by using nominal dimensions makes sure that the filter will slide into the slot (i.e., won't be too big or too tight) while also properly seating against the filter slot fram (i.e, not too small). Air cleaner filters are a different story.  Air cleaners are designed to use filters that fit the unit exactly.  While manufacturers often provide nominal sizes for air cleaner filters, you need to be very aware of the actual filter dimensions.  For this reason, we highly recommend using a filter specifically designed to fit the air cleaner unit you have.  In other words, don't just assume that a filter with nominal dimensions that match those listed by your unit's manufacturer will actually fit. 

Use the model number or filter replacement part number instead. Still not sure you know the correct size?  We'll do our best to help you get this right! Start your service todayMany machine shops, on occasion, have a need for welding. It may be for maintenance purposes, repair or to fill the odd contract. This story is a welding process primer for those shops whose main business isn't welding but need to know some basics. Considering the variety of welding processes available, selecting the right one for your shop could be a confusing and difficult decision. In any manufacturing operation, matching the best process to the application can be the difference between profit and loss on a job. Likewise, welding has many variables in terms of matching methods and materials. By properly selecting a welding process, many hours may be saved in production, repairs, polishing and grinding, or rejected welds. The object of welding, whether it's done on a production basis or occasionally, is the same: to produce a quality weld in the least amount of time.

Welding quality is determined by the success one has in creating a weld that penetrates sufficiently, without pores, pockets or gaps. Good surface finish is also a factor. In this article, we're going to look at the four most common welding processes. We'll briefly discuss what each brings to the job in terms of performance characteristics so you can better determine which welding process best fits your application. Unfortunately, there is no single welding process suitable for all welding situations. For this reason, it is necessary to weigh the advantages and disadvantages of each welding process. The most common welding processes used for fabricating metals are gas metal arc welding (MIG), flux cored welding, gas tungsten arc welding (TIG) and shielded metal arc welding (stick electrode). To make an evaluation of the welding process most appropriate for the job at hand, the following factors should be considered: Gas Metal Arc Welding (MIG) This process consists of feeding a bare metal filler wire_made of the same material being welded--in conjunction with a shielding gas through a hand held torch unit.

The welding wire picks up electric current supplied by a standard power source. On contact, it creates an arc that does the welding. As wire is fed from the unit to the work, it functions as a continuous, consumable electrode, therefore requiring fewer starts and stops. For routine joining applications, a MIG welder probably offers more advantages than any other welding process. Here's some advantages of MIG welding: A power supply that gives direct current reverse polarity (DCRP) is recommended for use with the MIG welding process. Generally, welders use straight polarity current, which means the flow of electricity moves from the torch to the workpiece. In reverse polarity welding, current travels from the workpiece to the welding torch. For MIG welding, a DCRP current produces the best arc transfer and a smoother weld surface than other types of currents. Special consideration is required when welding outdoors or in drafty areas with a MIG welder because air or drafts can blow the shielding gas from the weld puddle and cause porosity.

The MIG welding process also requires more complex equipment, which is initially more costly. The following equipment and supplies are necessary for MIG welding: The same constant voltage equipment used for MIG welding also performs flux cored welding. The difference is the wire that is used as an electrode. Rather than running a solid wire coupled with a shielding gas, flux cored welding uses self shielded wire with flux inside (some flux cored wires require a shielding gas). Cored wires are generally used on thicker material (4 mm and up) than the solid wires used with the MIG process. Advantages of flux cored welding are: Porosity is a problem for welders. It often occurs in drafty areas when flux cored welding with a shielding gas. This difficulty can be overcome by using self shielded, flux cored wire. It performs similarly to a stick welder in such conditions so windy conditions are less impactful on the weld. Importantly, the material used to fill flux cored wires can be custom formulated to match the base metal, which helps produce a better weld.

This can also make flux cored welding less sensitive to rust and scale on the welded piece than other processes. Between its MIG and flux cored capabilities, a wire welder can perform most tasks a stick welder can do, and often more efficiently. While a good quality wire welder costs $450 to $2,000 (depending on its size), the costs for wire and gas are much less than that for stick welding rods. Coupled with the ability to weld aluminum and sheet metal, a wire welder can pay for itself very quickly. Gas Tungsten Welding (TIG) This process uses a nonconsumable tungsten electrode and shielding gas that protects the welding area from contamination. TIG welding can be done in all positions, including overhead. Its concentrated heat and precise control of the arc allows thin material (0.01 inch) to be welded. The advantages of TIG welding are: Power supply for TIG typically uses alternating current (AC) for aluminum and magnesium, or direct current straight polarity (DCSP) for steel, stainless steel and various other alloys.

AC/DC switchable power units are available to accommodate a variety of workpiece materials. Although TIG welding is a relatively slow process, compared with wire-fed MIG or flux cored, it provides high quality welds. However, it also requires greater operator skill level than the other processes. Because there is no spatter nor flux created from a TIG weld, it is an ideal option for applications where cosmetic appearance is important. The following equipment is necessary for TIG welding: TIG welding produces quality welds. Because of the variety of materials that it is capable of welding, it is considered one of the most widely used processes for precision and cosmetic work. Another factor to consider is that TIG machines also have stick welding capabilities (TIG/stick welders). While costing more than MIG or stick-only welders, a single TIG/stick machine gives the user great flexibility. Shielded Metal Arc Welding (Stick) This process uses a consumable, flux coated electrode containing mild steel, stainless steel, cast iron or various other alloys.

These electrodes are selected to match the base material being welded. Other than the power source, electrode holder and work clamp, no other equipment is required. The advantages of stick welding are: Some limits of stick welding are: If you plan to purchase a stick welder, an AC/DC welder power supply is best. For most applications, DC reverse polarity welding offers advantages over AC. These include easier starts; fewer arc outages and sticking; less spatter (better looking welds); simpler learning curve, and better welds on relatively thin materials. What's The Deal With Duty Cycle? One way of classifying the "size" of welding power sources is measuring how much amperage can be generated in a given "duty cycle." Duty cycle is the number of minutes, out of a 10-minute cycle, a welder can operate. For example, one of Miller's AC/DC units (Shopmaster 200) can deliver 200 amps of AC, constant current power, at a 40 percent duty cycle. That means it can weld continuously at 200 amps for four minutes.

It must cool down during the remaining six minutes to prevent overheating. Duty cycle and amperage, however, are inversely proportional. Reducing amperage increases duty cycle. Operating at 130 amps, the same power supply has a 100 percent duty cycle_it can weld continuously at this amperage level. At the other end of the power curve--operating at 300 amps--it has about a 20 percent duty cycle. This is effectively two minutes' welding out of 10. With duty cycle in mind, consider that thin metals require less amperage than thick metals. For example, to MIG-weld 18-gauge steel in a single pass takes roughly 70 amps. Welding 1/4-inch steel in a single pass requires roughly 180 amps. The phrase in a single pass is the key. Because a series of thin passes can be made to weld thicker material per pass, less amperage is required. However, multiple passes take more time. And, you may still exceed the machine's duty cycle, spending even more time waiting than welding. What Size Welder Should You Consider?