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Shop 4 Classics Style Guide

Registers, Air Return Grilles, and Vent Cover Tips

Shop 4 Classics offers vent covers in many different prices, styles, and finishes. The variety can make it difficult to choose a vent cover. The following tips are provided as a service from Shop 4 Classics. We hope you will find this information helpful.

What is the difference between a vent cover, a register, and a grille?

Most homes are heated and cooled by central forced air systems that consist of a furnace, an air conditioning unit, and ductwork. Warmed air from the furnace (winter) or cooled air from the air conditioner (summer) is delivered to the rooms in your home through forced air ducts. To provide efficiency and a uniform temperature from room to room, air is circulated back to the furnace through cold air returns.

A vent is an opening that allows air to pass. In this case, a vent allows air to pass between the room and duct. A vent cover is a generic term used to describe the decorative cover on the vent (i.e., duct opening). Registers and grilles are specific types of vent covers. Registers are vent covers that are typically used on forced air ducts. They have a pre-attached damper or set of louvers to help control airflow. For example, the damper can be closed to avoid heating or cooling a room that isn’t used. Grilles are vent covers that are normally used on air return ducts. Grilles do not have a pre-attached damper. Louver assemblies can be used with grilles so that the grilles can be used on forced air ducts and still provide airflow control. Registers, grilles, and louver assemblies can be found in the Vent Covers section of our website.

How do I determine the correct size to order?

Grilles, registers, and louver assemblies are selected by the size of the opening that they fit. If necessary, remove the existing grille or register to expose the duct opening. Measure the opening in the floor, wall, or ceiling. The width and length of the opening should match the width and length of the inside measurements* of your replacement grille, register, or louver assembly. Please measure again to make certain you measured correctly. Outside measurements will be larger than the opening. Be careful not to rely on outside measurements to select your replacement vent cover. Inside measurements of the replacement vent cover should match the measurements of the opening to ensure a proper fit. If the vent cover will be near a wall, cabinet, or other obstruction, measure the area to make sure you will have enough room to accommodate the overall size (outside measurement) of the grille or register.

* The outside measurement is critical to flush mount and baseboard vent covers. The overall dimension of a flush mount vent cover is required to size the opening to accept the vent cover. Overall size is also important to selecting baseboard registers. The overall width of a baseboard register should match the opening between ends of the baseboards to allow it to fit flush against the wall.

Installing Vent Covers

Can I special order custom size grilles or registers?

Unfortunately custom manufacturing of grilles and registers is uneconomical. Engineering and machining costs for small lots or one run jobs are prohibitively expensive. Often, you can solve a size problem by resizing a hole or mounting two grilles end to end.

Why is an air return grille called a "cold air return grille"?

Air conditioning is a relatively new concept for homes. Traditionally, air return vent covers were called "cold air return covers" because only cold air was circulated back through them by a furnace in the winter time. With the invent of relatively inexpensive residential air conditioning systems, the same system of registers and air returns were used to circulate air in the summer time. In the summer, hot air is recycled through air returns. Although no longer completely accurate, the term "cold air return grille" has stuck and is still used frequently today.

Why is register called a "heat register"?

As described above, homes were heated before they were cooled with air conditioning. In the winter, air warmed by a furnace passes through registers to heat rooms. When homes began to be cooled with air conditioning, the same registers were used to control air flow in the summer. In the summer, air chilled by an air conditioner passes through registers to cool the home. Today, registers are still often called "heat registers" even though both heated air and cooled air passes through them depending on the season.

Can I use a register in place of an air return grille or an air return grille in place of a register?

A register can be used in place of air return grilles and vice versa. If a register is used on an air return, the dampers should remain open. Closing the dampers can cause your heating and cooling system to work harder to draw air back through the returns. In most cases, the louver assembly can be removed from registers if necessary. Conversely, air return grilles can be used in place of registers to cover supplies. Air return covers do not have adjustable louvers to moderate air flow but if the room is always occupied, they may not be necessary. If air flow control is desireable, louver assemblies that install independently in the duct behind the grille can be purchased separately.

Why do some vent covers have screw holes?

Most of our grilles and registers are available with screw holes so that they can be wall or ceiling mounted. These vent covers have countersunk holes and matching screws to secure them in place.

Can I flush mount my vent cover?

With the exception of natural wood grilles, all of our vent covers are surface mounted. Most are also self-rimming (see illustration, right). Self-rimming vent covers have a base that is slightly smaller than the opening so that the base will recess into the opening but the rim will rest on the surface. To flush mount these vent covers, you can cut into the finished floor or a frame that is recessed the depth of the vent cover.

Installing Registers and Grilles

Lay the vent cover in the hole in the floor or frame. Draw a line around the outside of the vent cover. Set your router to the same thickness as the outside rim of the vent cover. Cut along the inside of the line being careful not to cut outside the line. Several passes of the router may be required. Chisel the rim until the vent cover sits flush into the floor or frame. In applications that require close tolerances or a great degree of precision, we recommend that the product itself be used to make actual measurements.

How do I install natural wood grilles?

All flush mounted wood grilles come complete with a frame designed for new installation of hardwood floors. To install, nail or glue the frame to the sub floor. The grille will drop into the frame for easy removal and ease of cleaning.

Flush Mounting Wood Grilles
Flush Mount

Surface mounted wood grilles are self-rimming. The grilles simply drop into the duct opening. Wall wood grilles can be installed with glue, screws, or double face tape to secure them to the wall.

Surface Mounting Wood Grilles
Surface Mount

Can I paint my grille to match my wall or ceiling?

Aluminum and cast iron grilles can be painted to match your decor. The cast iron grilles can be primed and painted with direct to metal primer and paint. The aluminum grilles have a powder-coat finish. You can paint directly over this coating with a paint suitable for metal. Oil-base or latex paint can be used with the aluminum grilles if the grille is cleaned with alcohol and then primed with Kills primer before painting. Speak with a local paint expert for help selecting direct to metal paint.

All unfinished wood grilles must be stained and sealed or painted to retard warping due to moisture. All surfaces (i.e., top, bottom, and edges) must be sealed. Wood vent covers are pre-sanded by the manufacturer. Additional sanding may be required.

What is a gravity baseboard register?

A baseboard register is a heat register that is installed on the wall with its bottom edge resting on the floor. It is called a baseboard register because a section of the baseboard is cut away to allow for the register. The ends of the baseboard butt against the sides of the register.

A gravity register is an old style register that was used with gravity-based heating systems. Prior to conventional forced-air heating and air conditioning, many homes relied on a heating system based on the principles of gravity. These old homes would have a furnace (typically wood or coal) in the basement. The furnace would be vented throughout the house. Because it is lighter than cold air, the hot air from the furnace would rise from the basement and vent through gravity registers. The rising hot air would warm the house.

Gravity systems weren't particularly efficient and provided no cooling in the summertime. Eventually, most gravity furnaces were replaced with modern forced-air furnaces and air conditioners. The modern system utilizes the existing vents because replacing the ductwork in an old house requires a major remodel. So...although the gravity furnace has been replaced, the gravity baseboard registers remain functional and in place.

Gravity Baseboard Register

What is a high-velocity outlet and why does Shop 4 Classics offer them?

High-velocity outlets are the equivalent of registers for high-velocity heating and cooling systems. As opposed to the rigid ducts of conventional central air systems, a high-velocity heating and cooling system forces air through 2" diameter flexible tubes. The tubes deliver high pressure cooled or heated (depending on the season) air throughout a home or building. At the end of each tube is a high-velocity outlet.

The small diameter flexible tubes of high-velocity systems can be more easily threaded through existing walls, floors, and ceilings. This makes a high-velocity heating and cooling systems a popular choice for retrofitting an old home. Most systems include plastic outlet covers but Shop 4 Classics offers quality-crafted wood, brass, and aluminum outlets more fitting a vintage home.

Which finish is best for me?

Shop 4 Classics offers many choices of finishes. For tips on selecting the right finish for your vent cover, see our finish tips.

Wood Grille Species

Do I have a warranty?

All items are warranted by the manufacturer. For more information, see Warranties. Also each product detail page includes a Manufacturer Information box which links to additional information about that manufacturer's warranty and return policies.

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