I have installed two inline duct booster fans to increase the airflow for my furnace/ac in a new addition that I got built. The new run that I installed is an 8" flex duct that runs about 25 ft. then splits into two 6" flexible ducts running to the two registers that I installed for that addition.
I checked the new run from beginning to end and there are no obstructions or slack in it. Right now I have one booster fan in each of the 6" split runs and they are controlled by a Suncourt ducstat.
I have two issues that I am puzzled with:
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First, The fans are really not blowing a lot of air through the registers, although they are positioned about 3-4 feet away from the registers.
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Second, The fans turn on for a few seconds only and then turn off, then a few minutes later they come on briefly and then shut off (they don't stay on continuously for the entire furnace blower cycle) I have followed the Suncourt Ducstat instructions carefully and set it up correctly.
Any advice as to what the issues could be will be appreciated.
Before anybody asks the obvious, the fans are installed correctly with the correct airflow direction!!
Best Answer
Has your furnace/AC unit been sized for the addition?
Try unplugging the fans from the ducstat and plug them into a regular outlet and see if they continue to cut out.
Keep in mind that these fans will only help move the air that's available from the main blower, they won't increase the air available. Your run of 8" duct and then split into 2-6"ducts is going to have a lot of resistance to air flow. Those two fans will help accelerate the existing air to it's destination. The plenum and main blower will supply a certain amount of air for the entire house, the fans won't increase that amount. The strain on the fans due to the lack of air could be overloading them and causing them to kick out.
I've seen this a lot on this site and one of the good solutions is to add a mini split system for the addition because you're probably taxing your existing system.