You would use a time clock and some relays. Most of this stuff is controlled by some sort of building or energy management system these days.
A shareholder of a multi-family building in the penthouse was complaining about the noise of rooftop exhaust fans when they sleep. We are proposing on putting vibration isolation and also adjusting the speed of the fan during night time to further reduce noise. I think a VFD with 3-phase motor is a simpler solution than a multispeed fan.
You mean a VFD? it depends on the manufacturer and the model. The Powerflex ones we use can be controlled remotely by either binary switches on an operators panel, or they can be connected to a PLC.
Not VFD, but it doesn't matter, I will use a VFD for this and replace it with 3-phase motor.
bardac.com
Is PSC the same as capacitor start motors?There are some. The best known us Invertek, which is a UK company, but they are sold in the US by a company called Bardac.
E3 Series - Single Phase VFD | Bardac Drives
But they ONLY work on PSC (Permanent Split Capacitor) and Shaded Pole motors. Unless your motor is one of those, you cannot use a VFD on it. And sit down when you get the price… they are about 2x the cost of an equivalent 3phase VFD, probably because the sales volume is so much lower.
You're going to lose your ventilation pretty fast when you slow that kind of fan down a little bit. A three phase motor and a drive would be the easiest way to do it if that's what it takes to make the man upstairs happy.
I see... we're probably going to be doing this by trial and error incase vibration isolation isn't enough. I am not sure why the mechanical engineer doesn't want to first check if vibration isolation would be enough for preventing noise before installing both the VFD and vibration isolation.
One issue I saw is that the equipment is roof-mounted, correct? The roof is good at transmitting noise especially if your roof is made up of tins. How about relocating your roof vent equipment to a more rigid wall or column? Just install the piping to achieve the same ventilation requirements.
A better way is to use a timer relay, with no hassles compared to photocells that could inadvertently put the vent motor ON when leaves of trees cover the sensor.
Hello Tainted. I am Bardac's Mid Atlantic Area Sales Manager and I'd be happy to try to help you source a solution for your fan problem. Could you please reply with what your supply voltage and phasing is and a picture of the fan motor nameplate? Our prices are competitive and by working with me directly I can ensure you get exactly the solution you require.
@Tainted sorry for the bonus reply. I've never used this forum before and realized you might not see my reply if I didn't @ you. I hope I'm able to help.
I had a situation similar to that on a three story office building. The fan was actually above the ceiling on the first floor, and was very loud. They put sound insulation above the ceiling to quiet it down. They fired the hvac contractor, and the new one came in, and said it wasn’t even supposed to be running. It was a smoke evac fan! The fire alarm contractor programmed the panel wrong, and it was running all the time!
Or even using an even larger blower wheel or even blower type (I did not look at link to what unit this actually is or is similar to) but running at a slower speed, can more closely maintain CFM of flow yet have less noise from mechanical items.
I wonder if the whine will be noticeable from the apartment below, we will do trial and error with the carrier frequency
