Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit

Control for fractional HP motor needed

zepfanzepfan Posts: 280Member
Does anyone know of a control, or an Inexpensive VFD that could be used on a 115 volt 1/10 hp motor? The application is an an exhaust fan for a lab that is served by a VAV box. The board in the vav box would send a 0-10 volt signal to the exhaust fan’s control, the signal would increase as the damper in the box opens. A vfd may be the only way to go, but the fan is so small that this me be overkill. I did not know if anyone had a like experience, and what control they used for this. Thanks to all


  • Jamie HallJamie Hall Posts: 12,104Member
    Is this a standard AC squirrel cage motor? If it is, the speed it runs is fixed by the frequency of the power fed to it, so a variable frequency drive is going to be the only hope. If it is the type with brushes, you might be able to control the speed by varying the voltage applied (think Lionel electric model trains!).
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • EBEBRATT-EdEBEBRATT-Ed Posts: 6,509Member
    120 volt VFDs are available, mostly Chinese made.
  • zepfanzepfan Posts: 280Member
    Thanks for the responses. We have not received the motor yet and the submitalls do not state weather it is PSC, shaded pole, or ec. Normally we would use a wall mounted scr to very the speed of the fan, but that requires manual adjustment. We are looking for something that is automatic
  • Jolly BodgerJolly Bodger Posts: 206Member
    What type of lab? Sounds like you need to keep the room negative. Seems like a 1/10hp motor might be small for controlling space pressure. I have come across some of the newer ECM motors have a 0-10 input.
  • pecmsgpecmsg Posts: 1,107Member
    Not a very big exhaust fan. If a squirrel cage fan just control a damper.
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!