Reducing the noise from condensing boiler fans

[boblothrope.livejournal.com]

Now that it's getting colder, I've started noticing something which bugged me last winter: noisy vent fans from condensing boilers.

These boilers are great -- they're super-efficient. But since they remove so much heat from the exhaust gas, it isn't hot enough to make it up a chimney. So it has to be vented out the side of the building, with the help of an exhaust fan.

These fans are very noisy -- they sound like a loud hair dryer. And since they're on the side of the building, the noise is audible inside nearby buildings.

Does anyone know of a way to muffle or reduce the noise, so I can suggest it to my neighbors?

Comments

[thetathx1138.livejournal.com]

It might be possible to make a baffle that forces the air down and line it with soundproof material, but I'm not an engineer or a physicist.