Wireless HVAC Fan controller

[ericnlyvone]

I have a room in my house that needs a "boost" from the HVAC system. I want to install a fan in the flexible ducts that service the room. However, these ducts are in the attic and the main air handler is in the basement. I'd like to come up with a wireless system that will turn the duct fan on and off when the air handler comes on and off. Any ideas?

[jwax]

I've seen air flow switches made from a flat sheet aluminum panel that, when hit with airflow, activates a microswitch. That would be automatic. Or do you want manual remote on/off control?

[ericnlyvone]

I've already used that approach with the previous and weaker fan. The problem is that when the new fan turns on it produces enough air flow to keep the microswitch engaged after the main airhandler turns off. I've tried adjusting the size of the "sail" on the switch to no avail. I may try adding a speed controller to the fan to slow it down a bit; it provides more air flow than neccessary.

Also, the use of the sail switch seems a bit cluggy to me. The idea of a wireless links seems pretty cool but might not be practical.

[jwax]

Ah yes, the "self-latching" problem of fan-activated switches to control the fan!
Have you considered using a remote control common on ceiling fans?

[CeaSaR]

How about adding a timer to the "sailswitch" so that the extra fan shuts down after a
predetermined amount of time. A bit of hysteresis and problem solved.

CeaSaR

[ericnlyvone]

Jwax,

I have a speedcontroller chosen that is made specifically for the fan. Cost's about $30.00. I'm told that the controllers for ceiling fans don't work very well for this sort of fan.

CeaSar,

I hadn't considered a timer approach. I'll have to give it some thought, that just might work!

Thanks,

[CeaSaR]

Thanks for the enthusiasm ericnlyvone. Here's a site,
http://www.delabs-circuits.com/cirdir/t ... 00019.html,
that lets you simulate a 555 on-line. Might give you some ideas.

You could even use a 556 to make a timer / PWM controller, just add some
power transistors to the second output, throw in some Pots and it's variable.
And probably do it for less than $30.

I am not an engineer, just a part time hobbiest. I think that is an advantage
sometimes as I think of different ways to do things. Although, I must admit
to admiration for engineers and the professionals. Thay can take an idea and
make it reality.

Good luck in your solution,
CeaSaR

[Lenp]

How about using a thermostat to sense the air ahead of the fan? I did a job last year in a factory with 20 ceiling fans that were interlocked with the HVAC system through a thermostat. When the discharge temp got to about 90, the ceiling fans came on. Need it in both summer and winter, just use two thermostats (or reset the same one) with a switch to change from summer to winter! The fan may still run after the HVAC shuts down but it will stop after the supply duct is purged.

Len