Howdo,

Just a quick question about fans!

I've been plagued with condensation problems from my bathroom mainly
due to vapour from the batch condensing on the windows and outside
facing wall.

I'm trying to work out what volume extraction rate fan I should install
in the bathroom. I know that you should calculate the volume of the
room and then multiply this by the number of air changes per hour to
get a throughput rate.

My main problem is that some sites say 3 per hour whilst others e.g
http://www.thediyworld.co.uk/the_bathroom.html talk about 20 per hour!!
This obviously has a sevenfold impact on how many cubic metres per hour
is required and hence the fan.

What do you guys/gals out there recommend

TIA Graham

In article . com,
writes
My main problem is that some sites say 3 per hour whilst others e.g
http://www.thediyworld.co.uk/the_bathroom.html talk about 20 per hour!!
This obviously has a sevenfold impact on how many cubic metres per hour
is required and hence the fan.

Scottish regs say:
Bathroom or shower-room (with or without a WC):
mechanical extraction capable of 15 litres/sec (intermittent)

English:
Mechanical extract ventilation capable of extracting at a rate not less than
15 l/sec which may be operated intermittently or PSV. Rapid ventilation by
opening window.

With no mention of air changes.

My own is crap (replacement awaits bathroom refurb) but I do have it on a
one hour delay which is adequate.

Does that help?
--
fred

Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!

In article .com,
wrote:
Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!

Can you fit a switched supply to the fan so that
it can be overridden at night..?

wrote in message
oups.com...
Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!


I use a vent-axia 4" fan with a humidistat built in (great as kids used to
forget to put fan on if having a shower plus did not want coming on in
middle of night with lights), plus a pull switch (momentery) on the ceiling
for those scary Sunday morning moments after a curry!

In article , G.W. Walker
writes
In article .com,
wrote:
Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!

Can you fit a switched supply to the fan so that
it can be overridden at night..?

That should work, better still a timed supply to the fan, off at midnight, on
at 7?
--
fred

On this great day..4 May 2005 08:55:15 -0700, wrote:

Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!


I have a wall switch situated about 8-9ft from the bathroom floor where
I can switch off the darn thing.

It is normaly operated by the light switch with a 15minute overun

Mike

Pullout "stop" to reply by email

fred wrote:
My own is crap (replacement awaits bathroom refurb) but I do have it on a
one hour delay which is adequate.

On first reading of that I thought you were referring to your own
personal criteria for assessing the required power of fan for your
bathroom...

David

wrote:
.... snipped
The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!


I've used 2 pull cords: one operates the room downlighters, the other
operates the fan and the shower light.
It's quite pleasant to have just the shower light on when having a
shower; the main lights are on a dimmer outside (above) the door so it
can be turned down before turning on the lights in the middle of the
night; the separate pull switches avoid the annoying "fan in the night"
syndrome. It also means you don't need all the lights on for a shower
during daylight.

Dave S

In message .com,
wrote:

Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!

Install a fan with a humidity sensor and ignore the "switched live"
input. Set the sensor correctly and it'll come on a few minutes after
you start to run a bath and go off when the room is sufficiently
aired. It will not come on in the middle of the night when someone goes
to the loo. As for noise, some manufactures are better than others and I
believe the group's opinion is that duct-mounted fans are better in this
respect than the hole-in-the-wall type.

They're a fraction more expensive than simple timed models and need to
be mounted as high up as possible. They can also be a problem when there
is very high humidity generally, such as you might get before a Summer
thunderstorm, but they are usually easily adjustable. So long as there's
a good seal around the fan and the duct and there is no air "short
circuit" you should be ok.

Having had both sorts I'd never now fit anything else in a bathroom. The
question that then needs asking is whether the ventilation is required
simply for use of the loo. My understanding was that it was required
to control humidity and for no other reason.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... It's not so much how we stand as the direction we're moving.

Martin Angove wrote:

Install a fan with a humidity sensor and ignore the "switched live"
input. Set the sensor correctly and it'll come on a few minutes after
you start to run a bath and go off when the room is sufficiently
aired.

I'm in the market for a bathroom extractor fan and wonder if its worth
paying a bit extra and getting a heat recovery unit. BES sell a baxi
ec25h @ =A3188.30(13687) that has a built in humidity sensor. A bit of
googling reveals there is another model EC25P which has a PIR to start
the fan.

Its probably one of those novelty factor devices that has an very long,
if ever payback period.

In message . com,
"Martyn Pollard" wrote:


Martin Angove wrote:

Install a fan with a humidity sensor and ignore the "switched live"
input. Set the sensor correctly and it'll come on a few minutes after
you start to run a bath and go off when the room is sufficiently
aired.

I'm in the market for a bathroom extractor fan and wonder if its worth
paying a bit extra and getting a heat recovery unit. BES sell a baxi
ec25h @ £188.30(13687) that has a built in humidity sensor. A bit of
googling reveals there is another model EC25P which has a PIR to start
the fan.

Its probably one of those novelty factor devices that has an very long,
if ever payback period.


It really depends on your heating strategy I suppose, it'll probably
only make a real difference if you have a highly insulated,
draght-proofed house. Having said that, don't forget that a mid-quality
4" humidity fan is going to be £30 or £40 anyway, so £190 doesn't seem
quite so bad (effectively £160).

I considered one not because of the cost-saving, but because I hate
draughts in the bathroom. The one thing such a device *should* do is
eliminate draughts, or at least make them less noticeable, because there
is no "through flow" of air from, for example, under the bathroom door
to the extractor. Instead the air enters and exits at the hole in the
wall and is warmed to boot.

Apart from the cost (we were seriously short of cash at the time) the
main thing that put me off was that the smallest units are 6" IIRC, and
I had enough trouble core-drilling 4"! I hired a Hilti and did four 4"
holes in one day, three of them through the original house walls of
brick-brick-concrete render. It was a mighty undertaking.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... I appreciate your not breathing while I smoke.

Graham

Did all this last year and would suggest:

Get Vent Axia fan calculator brochure. This alerts you to other important
considerations not just those to do with Vent Axia products.
E.g. the easiest way in the world to duct a fan is with crinkly hose, but,
check how much this de-rates the fan based on hose length, numbers of bends
etc. If you look at the cheapo shed packaged items (fan and hose, maybe
light as well) you will see that the fan is rated at a reasonable throughput
in free air, but drops to perhaps half this if the full length of supplied
hose is used! Rigid duct is therefore recommended - plastic or galvanised.

Decide on number of air changes - plenty of suggestions for this already I
see.

Consider best position for vapour outlet - near toilet/shower/bath and best
position for discharge to outside.

Look at duct route through ceiling and establish length of straight and
number of bends.

Check with Vent Axia brochure what effect this will have on fan performance
for a given fan/duct combination.

Adjust duct and fan size to give throughput acceptable to you.

I still think there is some mileage in paying premium for Xpelair or Vent
Axia stuff. Other users claimed decent life expectancy for these last year,
when I did mine. Would hate to go to all the trouble and have to replace
the fan unit after 1-2 years.

Consider mounting fan on absorbent pads to minimise hum and putting flexible
connections either side of fan.

Once happy with fan and duct arrangement, consider controls - timer,
humidistat, switching etc to suit.

HTH

Phil

Martin Angove wrote:

Having had both sorts I'd never now fit anything else in a bathroom. The
question that then needs asking is whether the ventilation is required
simply for use of the loo. My understanding was that it was required
to control humidity and for no other reason.

Sometimes it would be nice to have it come on after someone has used the
loo. The problem is how to control it. Any suggestions? (Hint: this is a
splendid opportunity for the wags in this group to make hilarious quips
about motion sensors :-)

Tim Morley wrote:


wrote in message
oups.com...
Just happen to have a copy of the approved plans for my extension to
hand and they specify :-

"Install mechanical ventilation to bathroom & wc to extract at a min
rate of 15l/s switched with light & with min 15 minutes overrun."

The latter is the bit I know I'm going to hate when someone uses the
loo in the middle of the night and a noisy fan kicks in for 15 minutes.
Anybody know whether there is such a thing as a silent fan ? Any
noise seems loud at 3am!


I use a vent-axia 4" fan with a humidistat built in (great as kids used to
forget to put fan on if having a shower plus did not want coming on in
middle of night with lights), plus a pull switch (momentery) on the
ceiling for those scary Sunday morning moments after a curry!

Is that a momentary version of a 'standard' sort of ceiling-mounted bathroom
light pull switch? If so, where did you get it?

John Stumbles wrote:
Is that a momentary version of a 'standard' sort of ceiling-mounted bathroom
light pull switch? If so, where did you get it?

http://www.tlc-direct.co.uk/Products/MK3190.html

Owain

TheScullster wrote:
Graham

Did all this last year and would suggest:

Get Vent Axia fan calculator brochure. This alerts you to other
important
considerations not just those to do with Vent Axia products.
E.g. the easiest way in the world to duct a fan is with crinkly hose,
but,
check how much this de-rates the fan based on hose length, numbers of
bends
etc. If you look at the cheapo shed packaged items (fan and hose,
maybe
light as well) you will see that the fan is rated at a reasonable
throughput
in free air, but drops to perhaps half this if the full length of
supplied
hose is used! Rigid duct is therefore recommended - plastic or
galvanised.

Decide on number of air changes - plenty of suggestions for this
already I
see.

Consider best position for vapour outlet - near toilet/shower/bath
and best
position for discharge to outside.

Look at duct route through ceiling and establish length of straight
and
number of bends.

Check with Vent Axia brochure what effect this will have on fan
performance
for a given fan/duct combination.

Adjust duct and fan size to give throughput acceptable to you.

I still think there is some mileage in paying premium for Xpelair or
Vent
Axia stuff. Other users claimed decent life expectancy for these
last year,
when I did mine. Would hate to go to all the trouble and have to
replace
the fan unit after 1-2 years.

Consider mounting fan on absorbent pads to minimise hum and putting
flexible
connections either side of fan.

Once happy with fan and duct arrangement, consider controls - timer,
humidistat, switching etc to suit.

HTH

Phil


I hate bathroom fans. If you dont have a window and must have one,

1. pick a large low speed unit, 9" or 12" rather than 6". This will
reduce noise.
2. forget 4"ers, theyre just a waste of time.
3. Use rubber washers at every mounting point you can to reduce noise.

It seems silly to use noisy annoying energy consuming fans when nature
will do the airshifting for you.
1. if you have a window, use it! Fit a lock that allows you to lock it
securely a half inch open. Silent, zero energy.
2. If no window, fit 2 tubes not 1, have the outlet ends pointing
opposite directions. No fan needed. It is fair to say you either need
larger ducting, or else to have them open for longer since the flow
rate is lower.


A humidistatic dehumidifier will avoid you throwing all that heat out,
and dehumidifes the whole house. And enables you to dump the tumble
dryer too.


NT

In message ,
John Stumbles wrote:

Martin Angove wrote:

Having had both sorts I'd never now fit anything else in a bathroom. The
question that then needs asking is whether the ventilation is required
simply for use of the loo. My understanding was that it was required
to control humidity and for no other reason.

Sometimes it would be nice to have it come on after someone has used the
loo. The problem is how to control it. Any suggestions? (Hint: this is a
splendid opportunity for the wags in this group to make hilarious quips
about motion sensors :-)


A PIR wouldn't be difficult to wire up, but then you're back to the
problem of it coming on every time someone used the bathroom. A Methane
sensor would be fun, but probably impractical.

Try Owain's suggestion instead (somewhere else in this thread) of a
momentary action pull-switch in the bathroom, or if that doesn't suit, a
momentary action rocker switch or similar outside the bathroom.

The humidistat fans I've fitted all also have the switched-live input
and a timer so they can be used in this way with no modification.

Hwyl!

M.

--
Martin Angove: http://www.tridwr.demon.co.uk/
Two free issues: http://www.livtech.co.uk/ Living With Technology
.... Eventually land east of San Andres fault will fall into the Atlantic.