Extractor fan advice - do humidistat fans work well?

[JohnD]

They may not use a lot of electricity if run when needed. But running them 24/7 is a different matter altogether. Say a 10w fan on 24/7 will cost around £15 to £20 a year

Do you remember the days when people used to have 100 watt lightbulbs?

And would sometimes use them for more than 2.4 hours a day?

 

[Harry Bloomfield]

Likely to cost MORE than hundreds of pounds.

I had this discussion with John a few weeks ago, due to air dilution in a bathroom (warm with colder air), they do not extract as much warm air as you might assume.

 

[Harry Bloomfield]

Do you remember the days when people used to have 100 watt lightbulbs?

And would sometimes use them for more than 2.4 hours a day?

Gasp!

 

[JohnW2]

I had this discussion with John a few weeks ago, due to air dilution in a bathroom (warm with colder air), they do not extract as much warm air as you might assume.

We did have that discussion, but I never agreed with you.

I really don't think that one can get away from the fact that if an extractor fan is 'extracting' (to outside of the house) X litres/minute of (at least partially heated) air, then X litres/minute of (cold) outside air must be entering the house somewhere in order to replace it..

Kind Regards, John

 

[JohnD]

We did have that discussion, but I never agreed with you.

I really don't think that one can get away from the fact that if an extractor fan is 'extracting' (to outside of the house) X litres/minute of (at least partially heated) air, then X litres/minute of (cold) outside air must be entering the house somewhere in order to replace it..

Kind Regards, John

It's quite normal for houses to be ventilated.

 

[JohnD]

Likely to cost MORE than hundreds of pounds.


Edit
The MHVR system I mean, of course.

 

[elsmandino]

Thanks ever so much for everyone's input - really appreciate it.

A lot to digest but I am certainly glad I did as it seems that just buying an extractor fan is less straightforward than I anticipated.

Having read everything, I think that I would like a humidistat as we leave wet towels in the bathroom and it would be nice to have the extractor automatically kick in, throughout the day, whenever they have dried enough to warrant it.

However - really interesting point about the damage (from a shower) already being done before the humidistat kicks in.

I think, therefore, that I would like an override switch, with a timer, that you turn on before you have a shower.

Going back to my original post, therefore, I think I shall indeed need an extractor fan with both a humidistat and a pull cord.

The Silent Tornado ones were the ones I was originally looking at as they seem to have very good reviews:

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Does that mean I need to look for something else or is there a way (electrically) that I might be able to force the humidistat version to run when I want it to?

 

[JohnD]

Of the ones that retailer offers, I think the Envirovent are the best quality.

But, do you have access above the ceiling, in a loft or something? A ducted inline fan can be much better than a little wall fan and very quiet.

BTW, for a manual override switch, just drive it from the light switch. No need for an extra one.

I suppose you could mount a separate humidity detector on the ceiling if you really want one. I don't think much of humidstats.

 

[elsmandino]

Thanks for that - Envirovent seem to do exactly what I want, here:

Envirovent SIL100HTP12V Silent Extractor Fan with Humidistat & Pull Cord | Extractor Fan World

Buy Envirovent SIL100HTP12V Silent Extractor Fan with Humidistat & Pull Cord at Extractor Fan World. Free UK mainland delivery when you spend £100 and over.

www.extractorfanworld.co.uk

Unfortunately, our bathroom is a bungalow extension with a flat roof so I have to disregard the inline fan option.

 

[Harry Bloomfield]

We did have that discussion, but I never agreed with you.

I really don't think that one can get away from the fact that if an extractor fan is 'extracting' (to outside of the house) X litres/minute of (at least partially heated) air, then X litres/minute of (cold) outside air must be entering the house somewhere in order to replace it..

I didn't say we did, rather I think we had to agree to disagree.

The only way your theory would work, would be if the house were an entirely sealed tunnel, only openable at the ends, with the fan the diameter of the tunnel. Then has much fresh cold air would be drawn in at the far end, as is extracted warm air. Other than that very limited scenario, dilution of cold air with warm air becomes a major factor, so not as great a heat loss as you suggest.

 

[Mottie]

Does that mean I need to look for something else or is there a way (electrically) that I might be able to force the humidistat version to run when I want it to?

With ours, it is wired to a permanent live as it should be. When it senses humidity, it comes on and stays on until the humidity has decreased. I have a separate pull switch for the switched live (that normally would come from the light) for a manual override - I just turn it on then off again and it runs for as long as the timer is set.

I did not have it connected to the light as I did not want it coming on and running on the timer whenever anyone turned the bathroom light on in the middle of the night for a wee or if anyone turned the light on in the evening for a wee and it blows all the warm air in the bathroom out the vent.

 

[elsmandino]

Thanks for that, Mottie - exactly the situation I am in. May I ask what extractor fan you have, please?

Not wishing to get to overcomplicated but:

Say you have an override timer for 5 minutes, which you pull.

If the humidity goes over the threshold, during that time, will the fan continue until the humidity has been reduced below the threshold - i.e. is their an overlap between the two methods?

 

[JohnD]

Thanks for that - Envirovent seem to do exactly what I want, here:

Envirovent SIL100HTP12V Silent Extractor Fan with Humidistat & Pull Cord | Extractor Fan World

Buy Envirovent SIL100HTP12V Silent Extractor Fan with Humidistat & Pull Cord at Extractor Fan World. Free UK mainland delivery when you spend £100 and over.

www.extractorfanworld.co.uk

Unfortunately, our bathroom is a bungalow extension with a flat roof so I have to disregard the inline fan option.

That's a pity

They also do a 150mm (six inch) version that is more powerful (also branded as Soler & Palau, same company)

You don't need the 12v version.

Timer is more use than a humidstat

I have the 100mm, starts with the light switch so runs a lot, very quiet and fine with baths, but steamy showers need a lot more extraction. Usually more power, otherwise you will need a lot more time.

There are many more models on the TLC Direct page (branded Soler)

Missing Cookie

 

[Harry Bloomfield]

Does that mean I need to look for something else or is there a way (electrically) that I might be able to force the humidistat version to run when I want it to?

Most/all bathroom design of bathroom fans which include a humidistat include a separate way to trigger them, and a timer function- apart from humidity trigger. Usually that will involve connecting to a permanent live and a switched live. The separate way to trigger them can be one of connecting to the room lights switched live, an actual switch, or even an external PIR to sense when the room is occupied. The switch, if there is a built in run timer, need only be an instantaneous one, one which makes only when a pull cord is tugged.

As said, it's worth having a PIR built in, then the fan will always run as soon as someone walks in, irrespective of whether they need to turn the light on, or remember to trigger the fan.

 

[Mottie]

Thanks for that, Mottie - exactly the situation I am in. May I ask what extractor fan you have, please?

Not wishing to get to overcomplicated but:

Say you have an override timer for 5 minutes, which you pull.

If the humidity goes over the threshold, during that time, will the fan continue until the humidity has been reduced below the threshold - i.e. is their an overlap between the two methods?

It is this make but the model may have changed slightly - we bought it about 15-20 years ago. I don’t think ours has the 12v ecowatt. The longest overrun will prevail. I.e. it won’t switch off on the timer if there is still humidity present above what it has been set to. You can adjust both the timer and the humidity settings.

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Silent 100 CHZ Design 12VDC + CT-12/6 ECOWATT This is the DC motor extra efficiency version, 5W only. The ECOWATT series are especially recommended

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I have the pull switch in reach of the toilet!