Your intake pipe is the white PVC pipe at your furnace (inside the house) that brings outside air in. Check its size there.
Vertical or horizontal uses the same parts; only the tee orientation changes.
Buy a plain 2" PVC sanitary tee (or a 3"×3"×2" reducing tee for 3" intakes) plus PVC cement & purple primer.
Same list for vertical or horizontal pipe.
| Part | Qty | Role |
|---|---|---|
| EfficiencyMax damper, P/N FM 2010 | 1 | Comes in the package. Glue it onto the 2-inch branch of the tee. |
| 2" × 2" × 2" PVC DWV sanitary tee, hub × hub × hub, Schedule 40 | 1 | The fitting the damper glues to, and the fitting that goes into the intake. A 2" Schedule 40 pressure tee is an acceptable substitute. |
| PVC purple primer + PVC cement (4 oz handy pack is enough) | 1 pack | For the damper-to-tee joint and the tee-to-pipe joints. |
| 2" PVC DWV repair / no-stop / slide coupling | 1, optional | Only if the existing pipe cannot be spread enough to seat both ends of the tee. |
A hub × hub × hub DWV sanitary tee, such as a Charlotte Pipe fitting. Glue the damper to one 2-inch hub. A Schedule 40 pressure tee of the same size is an acceptable substitute if the DWV tee is out of stock.
Only if the existing pipe cannot be spread enough to seat both ends of the tee. Ask for a 2-inch PVC DWV repair, no-stop, or slide coupling.
Apollo 2 in. × 2 in. PVC slide repair coupling
Open at Home DepotCharlotte Pipe 2-in PVC DWV repair coupling
Open at Lowe’sCharlotte Pipe 2 in. PVC repair coupling
Open at Ace HardwareSame list for vertical or horizontal pipe. Glue the damper onto the 2-inch branch of the reducing tee.
| Part | Qty | Role |
|---|---|---|
| EfficiencyMax damper, P/N FM 2010 | 1 | Glue it onto the 2-inch branch of the reducing tee. |
| 3" × 3" × 2" PVC DWV sanitary reducing tee, hub × hub × hub, Schedule 40 | 1 | The 3-inch run goes in the intake; the 2-inch branch takes the damper. No separate reducer is required. |
| PVC purple primer + PVC cement (4 oz handy pack is enough) | 1 pack | Oatey’s 4 oz clear regular cement is rated for pipe up to 3 inches. |
| 3" PVC DWV repair / no-stop / slide coupling | 1, optional | Only if the existing 3-inch pipe cannot be spread enough to seat both ends of the tee. |
A hub × hub × hub DWV reducing sanitary tee, such as a Charlotte Pipe fitting. The 3-inch run goes in the intake; glue the damper to the 2-inch branch. No separate reducer is required. Do not buy a double sanitary tee or a tee with a side inlet — those are different fittings.
Only if the existing 3-inch pipe cannot be spread enough to seat both ends of the tee. Ask for a 3-inch PVC DWV repair, no-stop, or slide coupling.
Charlotte Pipe 3 in. PVC DWV repair coupling
Open at Home DepotCharlotte Pipe 3-in PVC DWV repair coupling
Open at Lowe’sCharlotte Pipe 3 in. PVC repair coupling
Open at Ace Hardware
A ratcheting PVC cutter works on 2-inch pipe. For 3-inch pipe, use a fine-tooth saw. You will also want a marker, a tape measure, a rag, and sandpaper or a knife to deburr the cut pipe.
Watch the video, then follow the steps below. Install only on the intake pipe, not the exhaust. How to tell.
Get the PVC tee & cement/primer first.
Not comfortable cutting and gluing PVC? Your HVAC tech can put it in at your next tune-up (compare to an emergency call charge). The manufacturer recommends installation by a qualified person. If that doesn’t describe you, have someone qualified install it. MUST FOLLOW INSTRUCTIONS
The damper goes on the intake only, not the exhaust. Both pipes can be white PVC, so color alone does not tell them apart.
This damper is for a 90%+ two-pipe gas furnace or boiler with a PVC intake. Measure the intake: 2-inch or 3-inch. Do not install it on the exhaust or on a one-pipe or metal-flue system.
Buy a 2-inch PVC DWV sanitary tee for 2-inch pipe, or a 3-inch by 3-inch by 2-inch reducing sanitary tee for 3-inch pipe, plus purple primer and PVC cement. Purchase Locally Here. A Schedule 40 pressure tee of the same size is an acceptable substitute if the DWV tee is out of stock. If the intake is black ABS, buy an ABS tee and ABS cement instead.
Glue the damper onto the 2-inch branch of the tee using PVC primer and cement. Put a small amount of PVC cleaner or primer and cement only on the back flange — the flat outer ring, also called the glue surface.
Use only 4 dots of cement, spaced evenly around the circle. Don’t get any cement on the moving damper flap, its slot, or its edges, or the damper won’t open.
The patent describes cutting the intake about 12 to 20 inches from the appliance, cutting out a short section, deburring, and inserting the pipe ends into the tee sockets. If the pipe cannot be spread enough to seat both ends, add a repair or no-stop slide coupling in the same diameter.
Arrows on the damper must point straight UP. A vertical tee in the intake is typical; a horizontal run is also OK.
In both layouts, the damper face stays vertical, with the adjustment screw at the bottom and the green stripe roughly horizontal. On a vertical run, airflow through the tee is down toward the furnace, and the branch and damper point to the side. On a horizontal run, the branch and damper also point to the side — not straight up.
After install, adjust the balancing screw so the damper stays closed during normal furnace operation with an unobstructed intake.
Arrows on the damper must point straight UP. A vertical tee is typical; a horizontal run is also OK.
In both layouts, the damper face stays vertical, with the adjustment screw at the bottom and the green stripe roughly horizontal.
The patent describes cutting the intake about 12–20 inches from the appliance, cutting out a short section, deburring, and inserting the two pipe ends into the tee sockets. Use primer and cement, not RTV silicone.
