Star-Kap by Field Controls

A Star-Kap is something that gives spellcheck a problem but trust me, it is spelled correctly.
Have you ever driven around and looked at flues? What is up with those smashed B-vent caps on them?

Have you ever watched a bird bend a B-vent cap so it could go in and build a nest? By the way, have you ever seen flues without caps?

The normal definition of a flue cap is a rain cap. Yes, it is very important to keep the rain out. Wet flues do not function properly.

Star Kap by Field Controls

But what about a flue cap that prevents the wind from blowing down the flue? What about a flue cap that the roofer or satellite guy leans on and doesn’t crush? How about a flue that birds and squirrels can’t bend and crawl into to build nests? In my opinion, the answer to all these questions is the Field Controls Star Kap.

The Star Kap is rated up to 1000 degrees temperature which means you can use it with any fuel-burning equipment: gas, oil, wood, coal, etc. It is the only flue cap that we are aware of that was tested by AGA (American Gas Association) Labs and found to prevent downdrafts from the wind. This attribute allows HVAC equipment to operate safely.

Although their wind test simulates a constant 10-minute downdraft, that isn’t normal weather conditions, except in hurricanes and tornadoes.

During those conditions, downdraft might be the least of your worries.

Star Kaps come in sizes from 4′ to 14′ and can be adapted to fit any flue or chimney. Their cost is slightly more than a B-vent cap, but they are two or three times more functional. If the wind is your problem, the Star Kap is definitely the answer!

To learn more, visit the Field Controls website at

– By Jim Davis, National Comfort Institute Senior Instructor