"Harry Bloomfield" wrote in message
...
It happens that Mary Fisher formulated :

The PIR copes with that need.

As I said, the op asked about a bathrom, not a lavatory.

Mary

For a bathroom which does not include a lavatory then a humidity
controlled fan (no PIR) is fine.

Quite.

David Hansen explained on 23/04/2006 :
Moisture build up can be controlled with a suitable window. No need
to burn electricity and more reliable.

It can, however forced ventilation can do it better, more reliably and
less wastefully - draw the moist air out directly.

Windows are not often well placed to where the moist air is produced,
such as over a cooker. Windows are highly dependent upon which way the
wind is blowing, if it happens to be blowing at the window the moist
air can be blown through the rest of the house.

A well placed fan can draw the moist air straight out from source and
its small current draw is usually more than offset by the savings in
lost heat through an open window.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

ARWadsworth wrote:
"The Natural Philosopher" wrote in message
...
David Hansen wrote:
On Sat, 22 Apr 2006 21:48:18 +0100 someone who may be The Natural
Philosopher wrote this:-

Its no necessary for ventilation per se, but it IS necessary in
conjunction with modern insulation and draughtproofing standards..in
essence the theory is that you build what amounts to a hermetically
sealed polystyrene box, and then punch specific holes in it to control
moisture build up.
Moisture build up can be controlled with a suitable window. No need
to burn electricity and more reliable.


Well sure, it can, but windows let cold air (and thieves) in as well as
hot sticky air out.

The purpose of the extractor fan is to provide a secure way to exhaust
saturated air, and replace it with warm drier air from the rest of the
building..thats the theory anyway.

A theory that only works if there is a way for air to enter the room with a
fan. You need a gap under the bathroom door to let warm drier air in.


Part of the regs mate.

Adam

David Hansen wrote:
On Sun, 23 Apr 2006 12:52:59 +0100 someone who may be "Mary Fisher"
wrote this:-

Moisture build up can be controlled with a suitable window. No need
to burn electricity and more reliable.
Ah but David if you open a window you let in fresh air, which can sometimes
even be COLD!!!!!!!!!

Suitably designed natural ventilation will provide adequate
ventilation without excessive cold draughts. The only "problem" is
that it requires more thought than an extractor fan.


Actually, it almost certainly won't..

The requirements for fans are for RAPID dispersal of SHORT TERM extra
localised humidity without excessive heat loss.

In an ideal world you might do it with a convective heat exchanger -
hots sticky air rising up, and warming cold dry air on the way in...in
reality, a fan is cheaper...and its arguable as to how 'natural' sucjh a
system is anyway.

Fans are totally natural. Every bee comes with four. :-)

On Sun, 23 Apr 2006 22:18:42 +0100 someone who may be The Natural
Philosopher wrote this:-

Suitably designed natural ventilation will provide adequate
ventilation without excessive cold draughts. The only "problem" is
that it requires more thought than an extractor fan.

Actually, it almost certainly won't..

An assertion that is made from time to time, usually by those who do
not understand properly designed natural ventilation but are instead
wedded to old-fashioned energy-intensive concepts. The future is
with those that reduce energy intensity.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 23 Apr 2006 23:53:54 +0100, David Hansen
wrote:

On Sun, 23 Apr 2006 22:18:42 +0100 someone who may be The Natural
Philosopher wrote this:-

Suitably designed natural ventilation will provide adequate
ventilation without excessive cold draughts. The only "problem" is
that it requires more thought than an extractor fan.

Actually, it almost certainly won't..

An assertion that is made from time to time, usually by those who do
not understand properly designed natural ventilation but are instead
wedded to old-fashioned energy-intensive concepts. The future is
with those that reduce energy intensity.

A 30 watt fan for 15 minutes is hardly energy intensive compared to
what is consumed by everything else in the modern house. 1000 watt tvs
and 500 watt computers are not unusual.

What about the wasted heat energy with the permanent drafts you seem
to be proposing?

Fans at least make sure the damp air / bad smells are going in the
right direction and quickly. Leaving a window open will not stop damp
air coming into the rest of the house under the door.

On Mon, 24 Apr 2006 08:00:56 GMT someone who may be marvelous
wrote this:-

A 30 watt fan for 15 minutes is hardly energy intensive

It all adds up.

There are indeed more energy intensive bits of equipment, but
computers and televisions, the examples you gave, have reduced
electricity consumption due to the introduction of more modern
displays.

What about the wasted heat energy with the permanent drafts you seem
to be proposing?

You are the one proposing permanent drafts, not me.

Fans at least make sure the damp air / bad smells are going in the
right direction and quickly.

Only if it is designed, installed and operated correctly.

Leaving a window open will not stop damp
air coming into the rest of the house under the door.

Not if it is designed, installed and operated correctly.

The idea that every problem should be dealt with by mechanical means
is very 1970s. Our understanding has moved on since then.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

"David Hansen" wrote in message
news
snip

The idea that every problem should be dealt with by mechanical means
is very 1970s.

Indeed. I often remember the adverts for 'Mrs 1970's' oil heated house,
people wearing hardly anything indoors with snow outside - as though such a
life style were desirable. I thought it was wasteful and unsustainable even
then.

Our understanding has moved on since then.

The acceptance of that understanding hasn't moved as fast :-(

Mary


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

marvelous wrote:
On Sun, 23 Apr 2006 23:53:54 +0100, David Hansen
wrote:

On Sun, 23 Apr 2006 22:18:42 +0100 someone who may be The Natural
Philosopher wrote this:-

Suitably designed natural ventilation will provide adequate
ventilation without excessive cold draughts. The only "problem" is
that it requires more thought than an extractor fan.

Actually, it almost certainly won't..
An assertion that is made from time to time, usually by those who do
not understand properly designed natural ventilation but are instead
wedded to old-fashioned energy-intensive concepts. The future is
with those that reduce energy intensity.

A 30 watt fan for 15 minutes is hardly energy intensive compared to
what is consumed by everything else in the modern house. 1000 watt tvs
and 500 watt computers are not unusual.

What about the wasted heat energy with the permanent drafts you seem
to be proposing?

Fans at least make sure the damp air / bad smells are going in the
right direction and quickly. Leaving a window open will not stop damp
air coming into the rest of the house under the door.

He saw fit to omit the part of my post where I posited the actual cost
in energy and materials to MAKE a proper heat exchanged 'natural' air
ventilation system.

Essnetially what a house ventilation system should consist of is an
inion of rooms inside a dome,through which sticky hot air goes in flues,
and cool air is drawn from the outside

And indeed the most energy efficient SHAPE of a house is actually sphere..

Igloos rule OK!

David Hansen wrote:
On Mon, 24 Apr 2006 08:00:56 GMT someone who may be marvelous
wrote this:-

A 30 watt fan for 15 minutes is hardly energy intensive

It all adds up.

There are indeed more energy intensive bits of equipment, but
computers and televisions, the examples you gave, have reduced
electricity consumption due to the introduction of more modern
displays.

What about the wasted heat energy with the permanent drafts you seem
to be proposing?

You are the one proposing permanent drafts, not me.

Fans at least make sure the damp air / bad smells are going in the
right direction and quickly.

Only if it is designed, installed and operated correctly.

Leaving a window open will not stop damp
air coming into the rest of the house under the door.

Not if it is designed, installed and operated correctly.

The idea that every problem should be dealt with by mechanical means
is very 1970s. Our understanding has moved on since then.


But our ability to perform actual real cost benefit analysis has, it
seems, not..