Is my extractor powerful enough ?

[Gary111]

Hi, Ive just fitted a backdraft cowl to my extractor fan, the flap only opens around 2cm, Im wondering if that means its not very powerful ?
It does have a few metres of ducting to go through.

 

[stem]

Depends what it is connected to. That would seem good to me for a bathroom or WC extractor. Infact often it's less than 2 cm, but it depends upon the fan it is connected to. Extractors have varying rates, a cooker hood may extract 300m3 to 400m3 per hour, but a fan in a WC or bathroom only 20m3 to 40m3.

If it's a cooker hood / chimney I would expect it to open to its full extent when on max.

A few metres of straight ducting should be ok, say 3 to 5, but bends are more of an issue. Centrifugal fans are better than axial fans in overcoming the resistance of the duct.

 

[JohnD]

I wonder what sort of fan you've got, and if it is ventilating a steamy bathroom.

a fan in a WC or bathroom only 20m3 to 40m3

that sounds terrbly low.

mine is

• Airflow: 95 m3/hr

 

[bernardgreen]

When sucking air out of room the has to be a way that replacement air can get into the room. Most often this is a by means of a gap under the door

Does the flap open a bit more when the door to the room is open than when the door is closed. ?

 

[Gary111]

Thanks, it has at least 3 bends and its rectangular ducting.

Depends what it is connected to. That would seem good to me for a bathroom or WC extractor. Infact often it's less than 2 cm, but it depends upon the fan it is connected to. Extractors have varying rates, a cooker hood may extract 300m3 to 400m3 per hour, but a fan in a WC or bathroom only 20m3 to 40m3.

If it's a cooker hood / chimney I would expect it to open to its full extent when on max.

A few metres of straight ducting should be ok, say 3 to 5, but bends are more of an issue. Centrifugal fans are better than axial fans in overcoming the resistance of the duct.

 

[JohnD]

I wonder what sort of fan you've got, and if it is ventilating a steamy bathroom.

still wondering.

 

[Gary111]

still wondering.

When im next at the property ill look what model fan it is, its from a bathroom.

 

[Gary111]

still wondering.

Hi, its a vent axia 100LT

 

[Gary111]

 

[JohnD]

Hi, its a vent axia 100LT

Thanks. It has the look of an older design, the casing is large, the electric usage and the noise are both greater than modern designs with ball-bearing motors. However, the air throughput (if running well) is good at around 100 cu.m/hr.

Does it sound like it is running well, and is the delay timer set to max?

If yes, and extraction is poor, probably due to the duct, you will need a more powerful one. Can you get at the duct? An inline fan can be around three times as powerful.

If the noise is a nuisance, we can easily find a quieter one

You need fresh air to enter, preferably through the gap under the bathroom door, since water vapour is lighter than air so will rise towards the ceiling.

If it is a steamy bathroom with a shower, you need a more powerful fan. The one you gave is fine for a WC, and adequate for a room with a bath if you run it consistently and long enough. Having the fan automatically start with the light switch defeats people who dislike ventilation.

A cold bathroom, with uninsulated walls, is very prone to condensation, so needs extra ventilation, and preferably improved insulation. Heating a cold room is expensive.

 

[Gary111]

Thanks John for taking the time to give me such detailed advice.

I only have access to the end of the duct unfortunately where it vents out.
I wonder of its possible to fit an extra fan there ?

 

[Gary111]

Ps I have a vectaire elx 1003 i was hoping to use somwhere, not sure if i can use it in the steamy shower where the other is fitted ?
I think its supposed to be low level constantly running