“The installation difference [for eac’s] is the wiring,” he explained. “The fittings are about the same. You need to send a tech with those wiring skills.”

Installation variations

As contractors who deal with these products know, almost no two add-on installations are alike — unless you know you are working in, say, a tract housing subdivision and you’ve installed air cleaners there before, said Bryan. So keep track of your builders.

“I’ve rarely had a situation where installing an air cleaner was not possible,” said Bryan. “About 99% of the time, it’s a feasible application. Sometimes you have to get creative because of space limitations, but we usually find a way to make it happen.”

According to Bryan, an air cleaner add-on in a new furnace application — the ideal situation — usually adds another half hour to the installation time. “The easiest time to install is in a new house or with a new furnace. You can plan everything out, so it fits perfect,” he said.

“To save time with new construction applications, we also have about 200 feet of 22-by-10 duct made up in advance, which ties into the main cold air trunk line.”

At the other end of the spectrum are those impossible situations. “If somebody’s finished off their basement, which is becoming more prevalent, there may be no room to install the air cleaner,” said Bryan. But if they really want or need that air cleaner, “Sometimes they’re willing to give up space for air purification.”

According to Bryan, a typical retrofit application usually takes a bit longer to install, but it averages about 3 hrs per job. In one of the more common “creative” add-on scenarios, “You might have to make an offset fitting from the existing return,” he said. “You might have to move it out six to ten inches away from that spot.” Techs installing these system accessories obviously need sheet metal skills, such as the ability to make an offset and adapt it to the cleaner. “They must be able to lay out and determine, when they make the offset, that they have sufficient air volume,” said Bryan. Of course, a reduction in air volume would affect the operation of the entire system, and the profits realized from the air cleaner sale could be gobbled up in callbacks. With a correct installation, callbacks are minimal.

Sidebar: Side- and bottom-mount installations

To install an actual side-mount application, said Bryan, attach the outer housing to the home’s furnace or air conditioner and seal the connection. Next, attach ductwork to the inlet side of the outer housing and seal the connection.

“We always caulk on the inside, so the seal is invisible,” he said. “Even though it’s a furnace and usually hidden away in the basement, it still makes for a more-attractive finished unit.”

The following installation details were supplied by Research Products:

1. Once the outer housing is attached, take the inner assembly and begin inserting the media.

2. Take the media and attach one cardboard edge over each end of the inner assembly and snap hinged flaps into place.

3. With media pleats evenly spaced, position the first pleat spacer to align with notches on the inner assembly. Use the first pleat spacer as a guide for inserting the remaining five pleat spacers and snap each into place.

4. Close the end panels by folding them up and snapping them into place.

5. Slide the inner assembly into outer housing and attach front door.

A bottom-mount installation is suitable for furnaces in closets or other tight spaces.

To install, attach the air cleaner to a platform and seal the connection. Next, mount the furnace or air conditioner on top of the outer housing and seal the connection.

“A typical highboy installation will fit exactly like a new construction application,” he said. “However, for a highboy with transition, you’ll need to expand the ductwork to the dimensions of the air cleaner, so air is flowing through the entire area of the air cleaner.” (See Figures 3 and 4.)

“We also see many lowboys in the Midwest, and that type of installation would place the air cleaner on top of the return duct, so it would be laying flat on its side.”