We have a small guest toilet (with sink) adjacent to spare room. The existing ceiling exhaust fan is a 200mm Airflow, wired in to wall light switch. Problem is it works TOO well! The noise of the fan is almost painful, and you get the feeling the door is going to get sucked off the hinges. The fan is actually supposed to be "quiet" (45dB), and really it probably is - IF the toilet was actually much bigger in volume. It's <5m3. Allowing the standard 15 room air changes per hour (for a bathroom fan), fan capacity required is ~70m3/hr. Our fan is working at 260m3/hr!! For the occupant, that means you experience the feeling of being in close proximity to a black hole…a bit distracting while you are attending to delicate personal matters on the loo. And the accompanying sound is like a chorus of demons. The fan is not ducted. It vents directly into the roof-space above.
For the life of me, I cannot find a low-flow, quiet replacement fan. Anything in Bunnings and a range of specialist suppliers is even higher capacity and/or louder.
Does anyone know of anything that might be available (at modest cost)? Alternatively, is there some way of bodging up a "fix" for the noise. I DID see on another forum someone suggested a rheostat to throttle the current to the fan thereby slowing it down…is this even allowable/technically feasible with a ceiling fan?? Also, a rheostat! Are they even still a thing anymore?! Any words of wisdom or direction greatly appreciated. Thanks.
Ceiling Exhaust Fan - QUIET!
Last edited 03/10/2021 - 16:22
Comments
I fitted something similar to these to the lower sections of doors.
https://www.bunnings.com.au/haron-450-x-90mm-white-plastic-c…
Take a look at an inline fan:
https://www.fansonline.com.au/fanco-tt-mixflow-inline-fan-10…
You can place the fan further away from the vent, and run some ducting to it. This will reduce the noise.
That particular model has a low setting which is 145m3/hr, which will be even lower the longer the duct run is
Other option is a 'squirrel-cage', or radial exhaust fan - I recently upgraded our ensuite heat lamp combo and the new fan is significantly quieter.
But if you can duct the fan away from the inlet vent above your head, that'll make the biggest difference to noise.
Inline fans are good. Not super cheap if you want one with good suction though.
That 200mm Airflow is definitely far too big for that area. I have used this style of ventilation fans in areas that are similar to the size you have and they work well..
https://www.ebay.com.au/itm/384332755456?_trkparms=amclksrc%…
The problem you have now is a 240mm hole where the existing one is… good luck finding a low volume fan that size.
I am also interested to know if there is any way of limiting the power to the fan via a rheostat??
200mm Noctua Fan
https://www.pccasegear.com/products/39604/noctua-nf-a20-200m…18.1dB @ 146m^3/h
10.7dB @ 100m^3/h200mm Vent
https://www.universalfans.com.au/online/plastic-flyscreen-ve…You would need stands offs and bolts with this vent. But with this mesh one, it should be reasonable to clean.
You will need an old 12V, >1A power supply. If you don't feel comfortable wiring this to the fan, this isn't a project for you.
You should already have a power socket in the roof to plug the fan into.
Unless the fan is design for speed control, it's not ideal to add a rheostat style (or any style) speed controller. The airflow fan is cheap, so if you want to give it a go and it dies, it's not the end of the world. Google "1 phase fan speed controller" or similar. There are ones that look like a light switch or there are ones you plug the fan into and adjust once.
The other option would be to use duct and an inline fan and move it away. If you want to get really crazy, there are systems that connect to the cistern and pull air from the bowl itself. Because you are exhausting the unpleasantness from the source, you can use a smaller and quieter fan
Apologies for being absent for a few days…work commitments.
You guys rock. I really appreciate the guidance and advice provided. I'm going to chase up some of the leads. I did fail to mention that the room is not connected to an exterior wall, alas. So that probably limits some of the wall-based options.
Anyway, thanks so much for your help.
What about a vent set into the door to allow air to move into the room more easily? Fan won't be "straining" as hard to extract. Might reduce noise, will definitely reduce feeling that the door is being 'sucked into the room".