How to Find the Air Filter for the HVAC System in Your Home I can’t find the air filter in the HVAC unit in the home we just bought. Do all central heating and cooling units have filters? All central heating and cooling systems should have an air filter, but the filter can be harder to locate on some HVAC units than others. The air filter is usually located in the return air duct or blower compartment before the return air reaches the air handler. This allows the filter to clean the air coming from your house before it enters the HVAC unit. Common locations for air filters in HVAC units include: On horizontal HVAC units with the return duct attached to the side of the air handler, the filter often fits in a slot on the return air (intake) side of the unit. On vertical air handlers with the return air duct entering on the top of the air handler, the filter often slides into a slot above the HVAC unit. On vertical air handlers with the return air duct entering below the air handler, the filter often fits in a slot located below the HVAC unit.

On other HVAC systems, the air filter may be located behind the return air grill on a wall in your home. On HVAC systems with a return in each room, there may be an air filter behind each of the return grills. Good luck with your project, How to Choose Air Filters to Reduce Indoor Air Pollution (article) Choosing Air Filters for Your Home (video) How to Fix a Sticky Door Lock Beam EasyReach Retractable Central Vacuum System Hose Getting Ready for ThanksgivingIn addition to the various types of coils, casings and housings, we can also design and manufacture complete, robust industrial air handling units and other custom components. Return and Make-up Air Units Face & Bypass Units High Pressure Skid Mounted 30% roughing filters to HEPA filters Access doors and panels Packaging these components together allows us to create a custom product that directly matches your specifications, lowers your packaging and installation costs while providing single source responsibility.

Return air plenums are the ducting units used as the central chamber for return air ducting. Furnaces and air handlers should have a return air plenum so that they can operate at their maximum efficiency. Return air plenums recycle the air in a structure back to the air handling unit and exhaust the air out of the home. Minimum Cost of Return Air Plenums: $50 Maximum Cost of Return Air Plenums: $60 The cost of return air plenums fluctuates based on the individual manufacturer. Because the product is a single unit device, it is easy to compare prices between brands. Generally, a return air plenum will cost approximately $50 to $60 per unit. The other costs to consider are those for the labor and materials needed to install the return air plenum. The installation takes an average of about five hours with the sum of labor costs between $290 and $370. Also, the supplies and tools necessary to complete the installation range between $25 and $35. In total, a consumer should expect to pay a cost ranging between $365 and $460 for the return air plenum unit, installation and supplies.

Advantages of Return Air Plenums There are a number of advantages to installing a return air plenum over a ducted return system. One major advantage to return air plenum systems is that they are cheaper to install from a mechanical basis because less ductwork is required; the need for all return air ductwork is completely eliminated. In addition, there are reduced relief system costs as relief fans and non-powered relief fans are cheaper than return fans.air handling unit features They also reduce the amount of energy used and are self-balancing, so they remove the need for balancing labor. air handling units operationReturn air plenums also normally lessen the necessary depth of ceiling space. fan motor for ac unitShafts can be smaller as the complete open section of the shaft and ceiling are accessible for the return airflow.

Disadvantages of Return Air Plenums Although this type of system can be beneficial for certain homeowners, there are some potential drawbacks. When installing a return air plenum system, it is absolutely essential that the system is constructed airtight without any leaks above the ceiling space; with return air plenums, there is less control over where the air actually travels. When installing return air plenums, all wiring such as telecommunication, electric and control wires must be plenum-rated. Return air plenums, if not properly designed within the ducting framework, can cause outdoor air to be drawn into the building. Therefore, if the building is located in a humid climate, condensation of moisture can occur from the outside air. This can eventually result in mildew and mold growth within the building structure if a dehumidifier isn't used. It is also a possibility that return air plenums could lead to health issues within a building due to the possible buildup of dust and debris on ceiling tiles and other areas.

There may be building codes that specifically prohibit return air plenums. Most codes only permit the use of return air plenums if the materials that are exposed to the plenum satisfy particular smoke generation and flame spread limits. Last updated on Sep 8, 2014 Top Articles on Return Air PlenumsEnsure proper humidification system operation with these humidifier installation guidelines: Humidifier noise levels vary by technology, but in general, install humidifiers away from quiet or occupied areas. Direct steam injection systems can be noisy at the control valve, where boiler steam passes through on its way to a dispersion assembly. Non-pressurized steam generators produce noise when filling and draining. Some electric steam humidifiers produce noise when con­tactors cycle on and off. For very quiet areas, con­sider an electric unit with quiet solid state relay (SSR) control rather than contactors. When not dispersing into a duct or air handling unit (AHU), locate dispersion fan units in quiet areas remote from the steam generator.

Noise from adiabatic (unheated water) humidifiers varies by type. Residential bypass humidifiers generate minimal noise. Atomizing systems have water pumps and sometimes also air compressors that generate a fair amount of noise. With these systems it is usually possible to place the dispersion nozzles remotely from the pumping station, isolating noise to a mechanical room. Create access to installed humidification equipment to allow convenient visual inspection and maintenance. Boiler-steam humidifiers contain devices (such as a control valve, a steam trap, and a strainer) that require periodic maintenance. While these devices can operate for long periods of time without attention, they should be accessible for inspection. Non-pressurized steam humidifiers are either cleanable or have disposable cylinders. Location should allow for easy access with ample space for servicing. Adiabatic humidifiers can require adjacent water treatment, so allow enough space for all system components.

Locate residential bypass humidifiers where it's easy for homeowners to replace evaporative pads, and place controls so they are easily accessed by the homeowner. Protect from water damage Protect areas surrounding humidifiers from water damage. The potential for water damage is always pres­ent with any steam or water appliance, but a properly planned installation virtually eliminates this risk. Be aware of valuable equipment or stored materials that are either adjacent or on a lower level. Install drip pans under humidifiers to contain water leaks when necessary. Use rigid pipe for steam For runs over 10 ft, use stainless steel or copper tubing, or steel pipe to connect non-pressurized steam generators to dispersion assemblies, rather than using steam hose. Though initially more expensive, there are several advantages to using rigid interconnecting pipe, including: Design for proper condensate drainage Non-pressurized steam systems generate condensate in dispersion tubes and in the piping that connects the steam generator to the dispersion assembly.

This water must be drained to prevent it from being discharged into the duct. For reasons of energy econ­omy, whenever possible drain condensate back to the steam generator. There are two ways to return condensate to a non-pressurized steam generator. One method is to pitch the dispersion assembly and steam piping to return condensate to the generator. When this is done, condensate flows counter to steam flow. This method works satisfactorily only when steam piping is adequately sized for humidifier capacity and when a given minimum recommended pitch can be maintained. Otherwise, the velocity of the steam will carry condensate into the duct. Usually, humid­ifier manufacturers recommend a maximum steam flow rate and a minimum pitch. The other method, used with higher capacity sys­tems, involves returning condensate through a separate line. With this method, the dispersion assembly has a drain connected to a condensate return line, and both are pitched so that condensate returns to the humidifier.

This installation requires an air vent in the return line. When wasting condensate to an open drain, a P-trap is required to prevent steam from escaping into the room. The trap is usually constructed of metal tubing. Water column height in the P-trap must be sufficient to withstand the operating pressure inside the humidi­fier. Consult the manufacturer's recommenda­tions for P-trap heights. If required, cool discharged water Many non-pressurized steam humidifiers have periodic drain and flush cycles or automated skimming where a portion of water in the tank drains to remove precipitated minerals. This water is typically 212 °F (100 °C) which, according to many municipal codes, should not be discharged to a sani­tary system. In this situation, add a water tempering device to cool discharged water. Water tempering may be required for condensate sent to drain, as well. Install a duct high limit humidistat This device is a must for most humidifier installations and is mounted in the duct downstream of the dispersion assembly.

It is usually set at 90 percent relative humidity (RH). If duct RH rises above that setting, it will shut down the humidifier. Wetted media humidifiers cannot oversaturate airstreams and so a duct high-limit humidistat is not a requirement. To ensure proper operation, the high-limit sensor must be located far enough downstream of the disperser to allow for full absorption and for humidity to equalize in the airstream. Otherwise, short cycling of the humidifier can occur, resulting in an unsatisfied humidification demand. Most humidifiers can use an inexpensive on/off-type high-limit humidistat, except in variable air volume (VAV) systems. In this case, a modulating high-limit humidistat provides more satisfactory control. Install an airflow proving switch If duct air flow stops for any reason all humidifiers, except for wetted-media types, must be shut down immediately to prevent water damage. This can be accomplished by using a duct-mounted airflow prov­ing switch.

Use a switch that is activated by the move­ment of a shaft, which has a vane or sail attached to it (often called a sail switch). Another type is a diaphragm-operated switch, in which the static pressure inside the duct actuates the switch. The latter type isn't a good choice for VAV systems, because when the VAV box modulates the airflow, the duct static pressure remains high and allows the humidifier to continue to operate without suffi­cient volume of steam-absorbing airflow. A sail-switch is the best choice for VAV applications. Place primary humidity control sensor in room center or in return air duct Humidity sensor or transmitter loca­tion has a significant impact on humidifier perfor­mance. Placing a sensor in the center of a room or inside a return air duct will give the best all-around control. Do not place a sensor near a supply duct, on a perimeter wall, in sunlight or near a heat-producing object. The humidity sensor should be located where it can measure an average space temperature and humidity.