I have a forced air HVAC system in my two story house and wish to balance the airflow for the summer and winter, which require different duct settings for each season due to the different levels of my house. I have done this without measurements of any kind for years but have not been satisfied enough with the results. There are a number of duct air flow meters for sale but the cheap ones seem to be garbage and the professional grade instruments are too expensive to consider for such brief use.
I made a simple rectangular funnel that fits over my air ducts. It tapers to a 4 inch round opening into which I want to put a fan, that is a small motor with a propeller or fan blade. Air flowing past it will cause the blade to turn, generating a small but readable voltage in the motor which I can measure with my multimeter. I can use the data as relative readings, which is better than having no readings at all. I have a number of computer fans but they are all brushless and they cog. Even a small cogging resistance prevents the fan from rotating in the low flow air coming from some of the ducts.
I need a small motor that has no cogging whatsoever and is relatively inexpensive to which I can attach a propeller. If the motor has low inertia (coreless), that would be better. I think it has to be brushed for me to get a voltage off it but I am not sure about that. My local RC hobby shops have not been helpful.
Thanks much, mike (mihiganmike711)