How to regulate the speed of my new fan? - Page 1
Forum section: electronics / beginners

author: Charkel
author_rank: Contributor
timestamp: February 13, 2017, 09:54:58 pm
content: I have bought a heater with a fan but the fan is soo frikkin loud! I'd LOVE to be able to regulate it if possible.I took the top of and here are images of it without it's hat:I have worked with electronics all my life but I'm still bad at it and still haven't learned to solder.But please, explain how it could be possible and I'd be forever thankful!

author: DavidDLC
author_rank: Frequent Contributor
timestamp: February 14, 2017, 12:20:14 am
content: If it is AC, one possibility is to use a general light dimmer, but you need to check the power ratings. I have used a light dimmer to control a small fan like:https://www.amazon.com/Honeywell-HT-900-TurboForce-Circulator-Black/dp/B001R1RXUG/ref=sr_1_2/164-2738313-1261245?ie=UTF8&qid=1487031594&sr=8-2&keywords=honeywell+desk+fansIf it is low voltage DC you need something like a PWM controller.David DLC

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2017, 12:44:52 am
content: It's almost certainly a small shaded pole motor. A triac speed controller does work on those, but be careful not to slow it down too far as they can overheat, shouldn't be a problem within a useful range though.Standard light dimmers usually don't like driving inductive loads, it tends to let the magic smoke out. Motor speed controls use a very similar circuit with a few additions.

author: ez24
author_rank: Super Contributor
timestamp: February 14, 2017, 12:51:15 am
content: Whatever you do be sure to have a fire extinguisher, If you reduce sound by reducing air flow, the heat will increase inside the heater thus the heater may burn up. Also check your will and life insurance.If you do not like the heater, disconnect the fan, place in the middle of a driveway, turn on and see if it burns up. I have an old heater like this and I do not think it would burn up. I think new heaters would.

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2017, 01:17:49 am
content: Most of the heaters I've seen have a thermostat on the element that cycles as needed to maintain temperature. Some have a thermal protection thermostat that will shut it down if it overheats and the really cheap ones have a single use thermal fuse. It won't catch fire, but it may kill the heater if you don't know what you're doing.

author: Charkel
author_rank: Contributor
timestamp: February 14, 2017, 06:19:54 pm
content: I wouldn't run the heater over 1200W if I manage to slow down the fan. Isn't there just something I could install on the fan cable to control how much power goes to the fan? Like I do on my computer

author: james_s
author_rank: Super Contributor
timestamp: February 14, 2017, 06:38:41 pm
content: Yes, you can use a motor speed controller, it's similar to a light dimmer. The thing you will have to watch out for though is that slowing down the fan reduces the airflow and will increase the temperature of the heating coils if there is nothing to regulate them.You could put a controller rated for sufficient power in line to the whole heater which will reduce power to the elements as well as the motor.

author: David Hess
author_rank: Super Contributor
timestamp: February 16, 2017, 04:39:53 am
content: If it is a shaded pole motor which is likely, then there are a couple of options:1. A phase control dimmer will work but they are electrically noisy.2. An autotransformer like a variac will work but they are large.3. A small power transformer can be used as a buck transformer.4. My favorite is to place a high voltage plastic film capacitor in series with the motor. Measure the motor's AC current first to get an idea of what value to use. 2.2uF to 10uF is probably a good place to start.

author: JS
author_rank: Frequent Contributor
timestamp: February 16, 2017, 04:58:22 am
content: If you are getting a commercial dimmer be sure it can handle inductive loads, there are cheaper ones only capable of resistive loads.Same thing if you are building one, just adding a few caps gives the capability to manage inductive loads with no problems. Check the schem you have is for that.JS

author: neil t
author_rank: Regular Contributor
timestamp: February 16, 2017, 05:04:12 am
content: Type AC motor speed controller into ebay search there are heaps of different types/power ratings for under 20 Au dollars.