How long should a Bathroom Fan timer run for + adequate ventilation, Air Change perHr

[DaleBlack]

I have a bathroom with toilet and shower and I am wanting to install a exhaust fan timer.

It either does not get turned on and leaves the whole room dripping in water or left on all day or worse.





m
feet





3.28084


m2
Lenght
3.4
11.2


8.16
Width
2.4
7.9



Heigh
2.4
7.9



Volume

19.6m3

691.6




I have a Fantech ECE152 fan installed. Its a Fan in flue design whereby the motor is pulling air not sitting on the ceiling pushing it, apparently this is both more powerful and obviously quieter. In fact very quiet which contributes to it being left on.
It is also ducted.

https://www.fantech.com.au/FanData.aspx?Pid=ECE152M
https://www.fantech.com.au/images/PDF/Catalogue/ece.pdf

537575
537576

The fan is 532 m3/h or 313 CFM and the bathroom is 19.6m3 (from above) so the Air Changes per Hour are = 532/19.6 = 27.17

I found this


According to the Home Ventilation Institute (https://www.hvi.org/resources/publications/bathroom-ventilation/) (HVI), for a bathroom to be adequately ventilated, it needs to undergo approximately 8 air changes per hour. The HVI recommends 2-3 air changes or running the fan for 20 minutes after showering to remove all the steam from the bathroom after a shower.

I have the option of a Timer with two models one with a 6 and 12 minute delay.

so at 12mins with a 532 m3/h fan in a 19.6m3 bathroom I will get 12/60*27.17 Air Changes or = 5.4 which is double the 2-3 air changes above.


this link (image attached of my results) seems to indicate its the right size as well

537578

https://universalfans.com.au/exhaust-fan-calculator/

What recomendations or comments do people have?

(PS I realise when ducting is added with bends and straight ducting vs flex, the capacity becomes worse)

[droog]

I suspect the answer will be related to how long it takes to remove damp air from your particular room.
If the air being drawn in does not circulate around the room very well then the fan will need to run longer regardless of the volume exchanged.

Any of the timed fans I have installed I have used adjustable timers and set it where it produced the results I required.

This is the type of controller I use
https://www.cabac.com.au/p/lighting/wiring-devices/timers

[DaleBlack]

Hi Droog

The sparky is the one who said 6 or 12 minutes so maybe he has chosen a limted option.

https://www.cabac.com.au/p/lighting/lighting-controls/timers/hns450tm

I see this one from your link can go 1-24 hours

[droog]

Hi Droog

The sparky is the one who said 6 or 12 minutes so maybe he has chosen a limted option.

https://www.cabac.com.au/p/lighting/lighting-controls/timers/hns450tm

I see this one from your link can go 1-24 hours

Yes but in hour increments
"Time delay from 1-24 hours, in hour increments"

I use this one for fan
https://www.cabac.com.au/p/lighting/lighting-controls/timers/hns440tm
"Time delay from 1-59 minutes, in minute increments"

Even if your sparky wants to stick with FanTech so it all matches for manufacturer support just fit an adjustable one
https://www.fantech.com.au/images/pdf/catalogue/runontimers.pdf

"VZ24C Up to 24 min*"
"* 1.5 min increments"

Assuming that is suited for your fan

[DaleBlack]

Yes but in hour increments
"Time delay from 1-24 hours, in hour increments"

I use this one for fan
https://www.cabac.com.au/p/lighting/lighting-controls/timers/hns440tm
"Time delay from 1-59 minutes, in minute increments"

Even if your sparky wants to stick with FanTech so it all matches for manufacturer support just fit an adjustable one
https://www.fantech.com.au/images/pdf/catalogue/runontimers.pdf

"VZ24C Up to 24 min*"
"* 1.5 min increments"

Assuming that is suited for your fan

I went with a 1 - 25 min timer in the end, the shower bathrooms are on 25min and the toilet-powder room 10min for now, I will see how I go.

What is your or anyones opinion of humidity detectors? someone told me I was wasting my time :> with momentary switches and having them come on with the lights, and should just go with one of those