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Which in-line fan to pick? FKD 12XL or 10xl?

Posted by kurtzicus (My Page) on
Tue, Feb 7, 12 at 2:56

Which in-line fan to go with?

Going with 48" culinarian.

Have MUA installed in floor under range, with 8" supply for MUA (good enough -- 100 year old house, but some new construction addition).

Was planning on running 30 feet of 10" ductwork out to my roof. The ductwork has 3 90 degree turns in it (one is after the fan). A quiet kitchen fan is important, and we'll use a muffler.

Going with a modern aire infinitely variable speed 48" hood.

Question is go with the fantech FKD 12XL or 10XL?


Follow-Up Postings:

RE: Which in-line fan to pick? FKD 12XL or 10xl?

Great choice on Modern Aire hood. The 10Xl requires a 10" duct and the 12XL a 12" duct. Simplisticly you should match the potential performance of the stove to the blower - this is done as follows:

- maximum potential btu output/100=recomended cfm of the blower
- allied to this is a pretty technical area called "effective duct length - EDL" which takes into account static pressure issues for duct type, bends etc.

Typically unless the duct run is very complex we dont get into the static pressure issue and rely on btu/100 to estimate the required cfm.

Once you have determined this required cfm that will indicate the size of Fantech inline blower you should use and therefore the size of duct.

As a side point make sure you use the inline duct silencer - these are amazing and work on the same principle as a car exhaust muffler.

There is a link below with some useful information on ducting and size etc.

Here is a link that might be useful: Range Hood Duct technical information

RE: Which in-line fan to pick? FKD 12XL or 10xl?

Sorry I don't have time right now to look up their respective flow rates versus pressure drops, but it is worth noting that to make a 12-inch axial fan operate as well as it can with 10-inch ducting, smooth (and long) properly-contoured transitions would be needed. Even so, if the goal is for the 12XL to flow higher cfm, it will have to do so with some additional pressure drop due to the transitions. If the goal is to run at a lower tip speed for less noise, then the constant rpm fan curves would have to be consulted.


RE: Which in-line fan to pick? FKD 12XL or 10xl?

The fan curves show that the 10XL with no back pressure moves about 1200 CFM. Not enough for a 48" stove. The 12" fan used with a 10" duct isn't characterized in their curves. I think you need more muscle. They have a few 10" restaurant roof blowers that move more air. And 30' of duct, a muffler and some right angles will create some pressure.

I have a 24" BS range and 30" BS hood. I'm stuck with an 8" duct. The Fantech 8" axial fans can't move more than about 800 CFM. I got a BS roof squirrel cage that's supposed to move 1000CFM. I didn't have room for a muffler but it's pretty quiet. I hear a low pitched rumble under the hiss of the baffles at full speed. If I reduce it to about half speed the rumble is gone. I have about 12' of duct going straight up through the roof.

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