Airflow thru 6 mesh, .035 gauge screen

[veithmoore]

Happy Holidays! I saw your posting on airflow thru mesh screen and went to Perry's looking for answers. I haven't found what I'm looking for yet and was wondering if you can help?

Our problem concerns bees coming down the chimney and how to stop them.
We installed a Lymance chimney damper with a sealing gasket but not sure if it will stop the bees come next spring.
Planning on using 6 mesh, .035 diameter wire screen placed on the spark arrestor to make sure.

We installed gas fire logs and have a question on how the 6 mesh screen will impact venting thru the chimney.
The best info I found was from a company the makes screens for hot water heater vents. They sell an 18 mesh screen that says it provides 70% airflow. Would that mean a 6 mesh screen would provide 90% airflow?

No one seems to want to answer the question of the impact of placing the 6 mesh screen on my chimney cap, regarding the safety of venting the gas log fireplace.
Any input would be appreciated! Thanks, Veith

 

[russ_watters]

I had to google this: that's 6 wires per inch, and 62% free area. Airflow reduction depends on free area and system pressure drop. In other words, the airflow reduction depends on how much of a restriction this is vs the rest of the system.

Anyway, my suspicion is that chimneys are probably vastly oversized and as long as you can see a positive draft and no spillage into the room its probably fine.

 

[veithmoore]

I had to google this: that's 6 wires per inch, and 62% free area. Airflow reduction depends on free area and system pressure drop. In other words, the airflow reduction depends on how much of a restriction this is vs the rest of the system.

Anyway, my suspicion is that chimneys are probably vastly oversized and as long as you can see a positive draft and no spillage into the room its probably fine.

Thanks, happy holidays!

 

[Baluncore]

Is it a couple of bees, or a swarm building a nest in the chimney that is the problem?

There is a mesh used in a hive called a "queen excluder" that allows workers and drones to pass, but stops the larger queen from passing up into the honey store. The gaps are 0.163 inches (4.1 mm). That will not prevent bees entering, but since the swarm follows the queen, it should prevent a swarm building a nest in the chimney.
https://en.wikipedia.org/wiki/Queen_excluder

More smoke will pass through a long slot than a square mesh of the same width.

 

[veithmoore]

Is it a couple of bees, or a swarm building a nest in the chimney that is the problem?

There is a mesh used in a hive called a "queen excluder" that allows workers and drones to pass, but stops the larger queen from passing up into the honey store. The gaps are 0.163 inches (4.1 mm). That will not prevent bees entering, but since the swarm follows the queen, it should prevent a swarm building a nest in the chimney.
https://en.wikipedia.org/wiki/Queen_excluder

More smoke will pass through a long slot than a square mesh of the same width.

We were out of town and came home to a hive inside the house. The bee keeper came and took the queen which caused the swarm to follow her outside. We cleaned up all the dead ones but the bee keeper said they would come back because our house had been marked. They did return the next spring but we had put window screen over the chimney opening on the roof, but couldn't use the fireplace.
We changed to a gas fire log setup and are concerned about venting with 6 mesh by .035 gauge screen over the spark arrestor on the roof. Thanks for the reply! Veith

 

[Baluncore]

We changed to a gas fire log setup and are concerned about venting with 6 mesh by .035 gauge screen over the spark arrestor on the roof.

There should be no problem with a gas fire venting through that screen.
The #6 mesh size, woven from 0.035" diameter wire, with 0.132" openings, is slightly smaller than the queen excluder 0.163", so it should keep queen bees out. It may also keep out the other members of the swarm.

European honey bees have a standard size. But there are many other types of bee, some are bigger, some smaller.

The odd robber bee may visit, following the scent of the earlier swarm, but if there is no honey or sugar to steal, it will not return with its colleagues. With time the scent will fade.

 

[veithmoore]

There should be no problem with a gas fire venting through that screen.
The #6 mesh size, woven from 0.035" diameter wire, with 0.132" openings, is slightly smaller than the queen excluder 0.163", so it should keep queen bees out. It may also keep out the other members of the swarm.

European honey bees have a standard size. But there are many other types of bee, some are bigger, some smaller.

The odd robber bee may visit, following the scent of the earlier swarm, but if there is no honey or sugar to steal, it will not return with its colleagues. With time the scent will fade.

Thanks for the reply, very helpful. Veith