speed control causing noisy fans

[sliderule]

I have two bathroom ceiling fans (Delta BreezSlim)and two 4" inline fans (Solar & Palau TD Mixvent) , all around 1 FLA or less (120V). I installed KB Electronics speed controls (KBWC15K). It doesn't matter what speed I adjust to, all fans make a loud medium pitch screeching sound, sort of like a bearing has gone. Fans are fine without the controls connected. The speed control uses a triac and maybe this is the problem? Is there some other type of speed control that will fit in a 1-gang box?

Thanks

 

[GoldDigger]

Does the pitch change with speed?

 

[sliderule]

No change in pitch and maybe a slight change in intensity, if at all. I forgot to mention that I phoned KB Electronics and they had no idea. I am going to contact the fan manufacturers tomorrow. About 8 years ago I installed the same KB Electronics speed control on an inline fan in our house and it has been fine the entire time. It is a different manufacturer but I imagine the motor is similar.

 

[PetrosA]

Many of the newer motors will not work with speed controls. I had this situation a few years back with a replacement motor for a Dayton (Grainger) hood where the OEM replacement motor would not work with the original speed control. Customer was not happy, but a call to Grainger and a consult with one of their engineers confirmed that the new motor would require a simple on/off switch.

 

[sliderule]

I was worried this might be the case. The bathroom has two fans in it due to a large beam interrupting air flow so there is waay more air being sucked out of the room than needed. If I can't reduce the fan speed, I don't know what the solution will be.

I think I remember reading that one of the fans has a DC motor so maybe what they use to convert to DC isn't compatible with a triac's waveform?

I am just waiting for a reply from Delta on their fan.

I talked to Solar & Palau on their fans and they have a speed control that they sell - SC15. But... physically it looks identical to the KB Electronics one. The tech. I spoke to said it should work with their fans. I bought another brand speed control made/sold by Canarm. It also causes the same noise.

Many of the newer motors will not work with speed controls. I had this situation a few years back with a replacement motor for a Dayton (Grainger) hood where the OEM replacement motor would not work with the original speed control. Customer was not happy, but a call to Grainger and a consult with one of their engineers confirmed that the new motor would require a simple on/off switch.

 

[mopowr steve]

All fully variable speed controls I've dealt with cause fan humming that's why I use "quiet fan controls" that have pre selected speeds via split capacitance instead of the triac used in fully variable controls.

 

[PetrosA]

Let us know if you find a solution.

 

[sliderule]

Delta told me that rotary speed controls are simply not compatible with their fans. They did not elaborate but I assume it's because the motor is a DC. I have another bathroom fan, Panasonic I think (will have to look), and it runs perfectly fine on a speed control. So my options are maybe see if I can change out the guts of the Delta fan and try and get a Panasonic fan assembly in there (probably a very bad idea for code reasons). Second is tearing out the complete fans, but this is a lot of work, but do-able. Third is to install an inline fan in the attic space. The attic space is tight and awkward, but do-able and possibly easier than a re&re of the existing fans.

Solar & Palau said that you can use a rotary speed dimmer on their inline fans. They said that noise is a common with a speed control and there is nothing that can be done. Interestingly, the rotary speed control they sell (#SC-15) is a KB Electronics that I installed, but is re-branded for S&P. The options here are to live with the noise (no) or install a silencer in the downstream duct after the fan. I thought Fantech would be an option as they state right on their website that their fans are "100% speed controllable" but I phoned them and they also said noise from the controller is typical. A manufactured silencer is expensive but they are simple to make so that's what's going to happen.



Thanks!

 

[meternerd]

Have you tried a 3 or 4 position control for a ceiling fan? My fan is dead silent at all speeds.

 

[Dennis Alwon]

All fully variable speed controls I've dealt with cause fan humming that's why I use "quiet fan controls" that have pre selected speeds via split capacitance instead of the triac used in fully variable controls.

I totally agree with this. Use a speed selector 3 or 4 speed switch rather than a variable speed control

 

[sliderule]

Any brand or model nos?

Thanks!

 

[Dennis Alwon]

Any brand or model nos?

Thanks!

I use the Luton speed controls