Not happy with the way ours is working. Its high speed for a few seconds and slows way down and speed up again. Hearing it is driving us nuts. It like hitting you gas pedal to get up to 40 and letting off slowing down to 20 and hitting gas again to gas back to 40 on and on and on. Is this normal? Going to call company tomorrow. Our installer kind of showed some concern when he was testing system.