Replies

1. 
   G.LaLonde | Jan 15, 1999 10:46pm | #1

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   Jon, Maybe I'm misreading you but...Do you have just a two wire 220 volt line supplying your air handler? If this is what you've got, I don't see where you are going to come up with a 110 volt power supply for your booster fans, without having a neutral wire running back to the panel.

   If you do have 110 volts available or want to run a new line into the unit, you can simply install another low-voltage relay that is triggered by the same control that starts your main blower fan and use that relay to power your booster fans.

2. 
   Guest_ | Jan 16, 1999 03:00am | #2

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   Jon: It seems like you could run one leg of the 220-volt circuit and a neutral and have 120 volts for your booster fan. But I once had a control panel in which I couldn't find a 120-volt option that tracked the 240-volt heater element, no matter how I tried to skin it. (I wanted to track hours with a 120-volt run timer). Ended up installing two in series although a high-wattage resistor of the proper value in series would have worked as well. Could you run your two 120-volt booster fans in series off of 220 volts? I don't know. Don't try it without an authority's recommendation or lots of replacements available.

   Yes, a transformer would work just fine. Just get one of the proper size (wattage or "kva" = kilowattage) or larger. Transformers with taps for 2:1 voltage reductions are readily available. Good Luck, David

1. 
   Guest_ | Jan 16, 1999 07:44am | #3

   *There are simple air-flow / pressure sensors used with in-line clothes dryer booster fans. When the sensor "feels" the dryer trying to exhaust the sensor kicks on the booster fan. Of course I have no clue where to get one seperately from the fan.Fantec makes booster fans w/ the sensor built in.

3. 
   arty_smyth | Jan 16, 1999 09:07am | #4

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   Jon, I just had an Aprilaire Humidifier installed on my furnace. It uses a current sensor attached to the blower common wire to switch it on and off when the blower is on and off. I think a current sensing switch could help. As for the speed control changing from low with heat and fast for cool maybe you could mount a remote switch near the air filter and flip the switch when you change the filters.

1. 
   arty_smyth | Jan 16, 1999 09:13am | #5

   *jon, arty again. Get your power from wherever you can and use the current sensor to switch it on and off. For my humidifer we took the 110 from the source that powers the furnace unit. You tap into it, power your blower and it only gets juice when the current sensing switch says the blower is on.

1. 
   G.LaLonde | Jan 16, 1999 10:22pm | #6

   *Hi David, How are things up in the frozen north??Are you suggesting he run another wire ( to use as a neutral) back to the panel? If he does that or already has another wire available in his feed to the air handler.....What does he need a transformer for??

4. 
   Jon | Jan 16, 1999 10:22pm | #7

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   I need to speed up two of the ducts on my HVAC system. I bought specialized booster fans for the purpose, along with a control that senses airflow in the duct. Unfortunately, that control has to be switched from heat to cool, and also requires threshold adjustments. That's too much of a pain, as I just want the booster fans to come on whenever the air handler is on. X-10 controls and other similar automation solutions also seem excessive, because I don't want to have to think about whether the booster fans are on or off.

   Is there any reason NOT to use a step-down transformer and run these 100V fans from the 220V line that supplies the main air handler fan? That strikes me as the most direct and most logical solution, as I can't find any 110V power in the circuit panel that's live when the fan is on.

   Thanks for any and all input.