Slowing fan motor speed

[Caltow]

I recently installed an HRV in my house, and due to it being a previsiously finished house I had to duct it into my furnace and obviously my furnace fan has to run along with the hrv to get the air around the house.

I wired the fan for its lowest speed when the hrv is on and its on medium for heat. The low setting is not low enough for my liking though and I was wondering if its possible to slow the speed with a rheostat or potentiometer?? Anybody tried this, or am I just going to burn the motor out?

Thanks for any assistance.

Terry

[Caltow]

care to elaborate?