1
Most nights, it does nothing.
The flapper stays closed and your furnace breathes outdoor air, as designed.
For cool & cold climate homes in the U.S. and Canada
EfficiencyMax Furnace Backup Intake Damper
A spare tire for your furnace.
Save Money. Save Heat. Prevent Service Calls.
2 AM. Below zero. Snow drifts over the white pipe outside.
If your furnace has two white plastic pipes running outside, one of them is how it breathes. A blocked intake pipe is a very common “no-heat” service call, and most people never think about it until it happens to them.
When debris or snow or ice blocks that pipe, the furnace shuts itself off. EfficiencyMax opens a backup air path from inside your home that you or your HVAC technician easily install, so the heat stays on. A $44.95 part against a $300–$1,200 emergency call (typical emergency furnace repair range, Angi 2026).
- Patented in the U.S. & Canada
- Made in Eau Claire, Wisconsin
- Works on vertical or horizontal intake runs
- U.S.: $44.95, free shipping
- Formerly sold as FlameMeister
Installs inside your home, on the intake pipe near your furnace.
How it works
Three steps. Most nights, you never notice it.
2
When the intake blocks, it opens.
Snow, ice, or frost chokes the outside pipe. The suction pulls the flapper open and the furnace draws room air instead.
3
The heat stays on.
No pressure-switch lockout and no 2 AM wake-up. Clear the snow when it’s light out, and the flapper closes again.
This is the product
This is the product
Fail-safe: if the intake is ever blocked, the damper opens automatically. It’s like a spare tire for your furnace’s air supply. It’s a backup, not a replacement.
What’s in the package
The damper ships alone. The 2 other common parts come from your hardware store.
Why: a PVC tee & cement/primer cost less at Menards, Lowe’s, Home Depot, or your local hardware store than it would cost us to ship them to you.
Sold separately
PVC tee & Cement/Primer
Buy these locally for about $15: cement/primer combo pack & 2" PVC tee (or if you have a 3" pipe, a 3"×3"×2" reducing tee for 3" intakes).
Open the “What you’ll need” parts list — the same page the box QR code will open, with store links.
Included
EfficiencyMax Furnace Backup Intake Damper
P/N FM 2010. This is the patented flapper you get in the package. Formerly sold as FlameMeister.
One damper fits 2-inch or 3-inch intakes. Glue it to a 2" tee, or to a 3"×3"×2" reducing tee.
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
10-second fit check
Who it’s for
-
A 90%+ high-efficiency gas furnace or boiler (How to tell: check on or near your furnace for a sticker showing an AFUE of 90 or higher, a drain line for water, or two white PVC pipes running outside the house.)
- Two white PVC pipes running outside, one for intake air and one for exhaust
- 2-inch PVC intake (glues to a 2" tee) or 3-inch (glues to a 3"×3"×2" reducing tee)
- The furnace sits in an open basement or utility area, not a small closed-off room (see Safety)
All boxes checked? It fits.
Only one pipe, a metal flue, or an older 80% furnace? This isn’t for you.
Not just snow country
Snow isn’t the only thing that blocks an intake.
Your furnace’s outdoor air pipe sits open to the weather all year. Anything that plugs it can shut your heat off.
Leaves, nests, and critters
Blowing leaves, a bird or wasp nest, or a curious mouse can choke an intake in any climate. The damper opens and keeps the furnace running until you clear it.
Frost and freezing rain
You don’t need a blizzard. One night of freezing rain or heavy frost can ice over a pipe opening in Tennessee as easily as in Wisconsin.