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Setting up a hot wire anemometer

Setting up a hot wire anemometer

Setting up a hot wire anemometer

(OP)
I am measuring airflow in a circular duct with a hot wire anemometer. Is there a rule of thumb for how long the upstream and downstream sections need to be?

RE: Setting up a hot wire anemometer

At least 6 and preferably 10 diamaters upstream to any "things".  It's good to have the same downstream too.

This is generally impossible in most real systems.

RE: Setting up a hot wire anemometer

Is that going to be a stationary anemometer or are you going to traverse the duct with it?

rmw

RE: Setting up a hot wire anemometer

(OP)
It will be stationary.

RE: Setting up a hot wire anemometer

if you have a questionable straight section, use the 80/20 rule.

Put the probe 80% down the length.

Example there is an 8 foot run between two elbows, install it 8x0.8 = 6.4 feet down stream of first elbow.

Try traversing it there first, see what you get. Use that to scale up/down what the stationary reading gives you.

 

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

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