size fan for shower room/bathroom ?

Andy From Sligo

Hello have a large shower room of 12ftx10ft thats got a toilet in there as well and got smell and condensation. - i do open window but it bangs internal door when windy and rather not have blast of cold air coming in when i want to keep house warm. Been looking at 4" fan from likes of topline/Homebase.


it says on box it extracts 100m/h - do you reckon it will cut it with this size room or do you think i should be looking at a 6" fan?

Thanks for your help -

http://www.topline.ie/plumbing-and-heating/cooling-and-heating/air-conditioners-and-fans/fans/airstream-pull-cord-bathroom-ventilation-fan-100mm

MightyMunster

Shower rooms should have an air change rate of 15 to 20 per hour.

Your room is approximately 25 cubic metres (assuming 8ft ceiling height) 3.6 x 3 x 2.4.

100 per hour from that fan is only a quarter of the recommended air change rate.

You should be looking for 15 x 25= 375m per hour.

Andy From Sligo

MightyMunster wrote: »

Shower rooms should have an air change rate of 15 to 20 per hour.

Your room is approximately 25 cubic metres (assuming 8ft ceiling height) 3.6 x 3 x 2.4.

100 per hour from that fan is only a quarter of the recommended air change rate.

You should be looking for 15 x 25= 375m per hour.

thanks for the reply - so even if i put 2 x 4" in the room it still wouldnt be enough and it even sounds like a 6" fan wouldnt be sufficient then?

Dardania

Andy From Sligo wrote: »

thanks for the reply - so even if i put 2 x 4" in the room it still wouldnt be enough and it even sounds like a 6" fan wouldnt be sufficient then?

This reg suggests that that fan may be sufficient if considered in terms of volume flow :

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1647,en.pdf

15l/s is 54m3/hr - where's the 15 to 20 arch coming from?

sydthebeat

Dardania wrote: »

This reg suggests that that fan may be sufficient if considered in terms of volume flow :

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1647,en.pdf

15l/s is 54m3/hr - where's the 15 to 20 arch coming from?

agreed, its more than sufficient

Dardania

OP don't forget that the air has to come from somewhere - usually people do this via an undercut of the door, or grillage in the door, and from there it is expected to come via vents in other rooms. And a polite suggestion about airflow - don't just consider the shower as a reason to get air out of the bathroom (so if you can get a nice airflow path that crosses the shower and the WC, great...)

Also, to reduce condensation build up, heat input to the space is necessary, to keep the surfaces above a dewpoint temp...so are you heating the house while showering?

The controls on that fan look good - both timed and humidity controlled (presuming you fit the permanent supply, as recommend by the building and ETCI regs). Be aware it may be noisy at night...so if you can prevent reverb / vibration of the fan it iwll help...

MightyMunster

A quick search shows 15-20 air changes is recommended for bathrooms with showers e.g. vent axial, tlc direct.

The building regs are much lower but having an undersized fan can result in mould on ceilings etc in my limited experience.

Dardania

MightyMunster wrote: »

A quick search shows 15-20 air changes is recommended for bathrooms with showers e.g. vent axial, tlc direct.

The building regs are much lower but having an undersized fan can result in mould on ceilings etc in my limited experience.

Could you link to these e.g. from CIBSE? Not being antagonistic - I'm just concerned about high air change rates requiring massive heat input in order to replace lost heat...

sydthebeat

MightyMunster wrote: »

A quick search shows 15-20 air changes is recommended for bathrooms with showers e.g. vent axial, tlc direct.

The building regs are much lower but having an undersized fan can result in mould on ceilings etc in my limited experience.

but air changes per hour is not a proper metric measurement.

how can a 100mm dia fan running at 30 litres / second be measured in air changes per hour?
that measurement is completely dependent on the volume of the room.

any vent axia extracts that ive just checked are measured in m3/hr or litres/sec

also tlc direct also work in litres/sec and m3/hr
https://www.tlc-direct.co.uk/Technical/Ventilation/VentRegsCalc.html

Andy From Sligo

tanks all - still confused .. so is this 4" fan suitable enough for the size room to minimize condensation and smells or not then. Thats all I really need to know (i cannot understand all this regulation figures, good job im not a builder I would be rubbish lol) just so i know what size fan to buy, because obviously if I buy 4" and its insufficient or not large enough then i wont be able to take it back or use it any where else and will be waste of money. Thanks.

Andy From Sligo

sydthebeat wrote: »

agreed, its more than sufficient

sorry, are you saying this 4" fan will be more than sufficient?

Andy From Sligo

Dardania wrote: »

OP don't forget that the air has to come from somewhere - usually people do this via an undercut of the door, or grillage in the door, and from there it is expected to come via vents in other rooms. And a polite suggestion about airflow - don't just consider the shower as a reason to get air out of the bathroom (so if you can get a nice airflow path that crosses the shower and the WC, great...)

Also, to reduce condensation build up, heat input to the space is necessary, to keep the surfaces above a dewpoint temp...so are you heating the house while showering?

The controls on that fan look good - both timed and humidity controlled (presuming you fit the permanent supply, as recommend by the building and ETCI regs). Be aware it may be noisy at night...so if you can prevent reverb / vibration of the fan it iwll help...

Thanks for the advice- I would most probably get the pullcord version and just turn it off at night, I want it to run continuously in the day to remove smells from the drains from the shower room and toilet rather than just run it on the humidistat

sydthebeat

Andy From Sligo wrote: »

sorry, are you saying this 4" fan will be more than sufficient?

yes it is, especially as it has an over-run facility (which i would set @ 15 mins)
That fan has a capacity of almost double the required regulation.

I would most probably get the pullcord version and just turn it off at night, I want it to run continuously in the day to remove smells from the drains from the shower room and toilet rather than just run it on the humidistat

i wouldnt do that.
Wire it up to the bathroom light and set the over run.

if youve smells coming from drains the fan is not a solution, you need to deal with why there is smells. maybe theres no u bends or are drying out due to no usage etc. or just need a good clean.