Bathroom extractor

[Jupiter01]

With the multi speed fans, my concerns are as follows:
- we will forget to rev them up if this needs to be done by pressing button #2
- if it is being run at speed 1 throughout the day, is that inefficient as during the week no one is in at day times

I wonder if I should just go for one speed and presumably use my existing isolation switch and have it working with the light and set an appropriate timer delay?

Also sound is very unlikely to be a issue with these as they are tucked away in the loft. Am I missing something?

 

[JohnD]

I wonder if I should just go for one speed and presumably use my existing isolation switch and have it working with the light and set an appropriate timer delay?

That's what I would do.

 

[winston1]

- if it is being run at speed 1 throughout the day, is that inefficient as during the week no one is in at day times

Efficiency is energy out divided by energy in times 100%. It does not vary with length of use.

However running it all day is wasteful and environmentally unfriendly.

 

[Jupiter01]

Is this the one to go with then?
https://www.tlc-direct.co.uk/Products/ADAV100T.html

Also, I assume that these aren’t very high in energy consumption and therefore is it helpful to have a longer timer delay? My old one only ran for around 2 mins

 

[JohnW2]

Efficiency is energy out divided by energy in times 100%.

That's a very narrow-minded view. 'Energy efficiency' (which is what you have defined) is just one, technical, meaning of 'efficiency', but there are countless other ways in which the concept of efficiency is utilised.

It would not be efficient to travel from Oxford to London via Birmingham, and nor would it be efficient to have each and every one of the (many) sockets in an average house wired as dedicated radials from the CU, etc. etc. etc. - but none of that has got anything to do with 'energy out' or 'energy in'.

Much closer to context, it would be very inefficient to leave an extractor fan running 24/7 if it actually only needed to run for 1 hour per day - and, again, that has got absolutely nothing to do with 'energy efficiency'.

Kind Regards, John

 

[Jupiter01]

On the 2 speeds, is it up to me whether I have the automated timer invoking speed 1 or 2? Or do I need the special switch to benefit from speed 2?
Also, is there any advice or best practice on how long the timer delay should be set to in a window-less ensuite?

 

[JohnD]

check the instructions for your chosen fan. Often it can be installed with the wiring connected to a particular set of terminals for one speed, and differently for the other speed. This can only be changed by clambering up a ladder with your screwdriver, but is handy if you are not yet decided which speed suits you best as you have the option to change it.

If the fan can be operated with a speed-change switch, you need to get one from the same maker that is warranted compatible. A different make or model might not work.

If you have steamy showers, I expect you will need the high-speed and long run-on. There will be water in the tray, on the walls, the floor mat, and towels, as well as the condensation and steam.

I suppose you could try it at low for a week or two while you decide if it is adequate.

The fan in your link is rated at 28Watts, meaning it will run for almost 40 hours on 15p worth of electricity.

A kettle, fan heater or immersion heater could use that much in 20 minutes.

I consider the running costs of fans to be negligible.

 

[Jupiter01]

I hadn't realised that the costs were so negligible. my current fan only ran for around 2 mins. This wasn't long enough.
Very helpful @JohnD

P.S. Love the profile pic!

 

[JohnD]

 

[Jupiter01]

Flop loft insulation over the duct to keep it warm and minimise condensation.

My fan has arrived and I am gearing up to fit it today
Can I check that the above means that I can throw the fibre loft insulation over this unit?

 

[JohnD]

over the duct. Not over the fan.

I wouldn't "throw" it. Wrap it tenderly in a snug blanket, like tucking your dog up for the night.

 

[Jupiter01]

My ducting is above 3 layers of insulation. Is there much benefit in wrapping insulation around the duct in this situation?

I assumed you meant around the motor to suppress its sound

 

[JohnD]

the loft is well insulated, so the loft will be very cold in winter.

Blowing warm, steamy ar through a duct that is chilled by the cold loft will cause condensation to form inside it.

Insulating the duct prevents this.

Flexible hose is very prone to condensation because it collects in the grooves and doesn't run out.

 

[EFLImpudence]

Insulating the duct prevents this.

Does it really?

Will it not assume the temperature of the surroundings anyway. It has no inherent heat to contain.

It would be different if it were under all the insulation.

 

[JohnD]

blowing warm air into a plastic duct that is wrapped in insulation will warm the duct.