I've bought an extractor fan for a downstairs utility room / WC. The
room is entirely internal with no external walls though I am able to
run the vent pipe through an adjacent false ceiling so that bits OK.
The fan has a standard run-on timer that would be connected via the
lighting circuit but I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?
TIA

aberdeen wrote:
I've bought an extractor fan for a downstairs utility room / WC. The
room is entirely internal with no external walls though I am able to
run the vent pipe through an adjacent false ceiling so that bits OK.
The fan has a standard run-on timer that would be connected via the
lighting circuit but I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?

Best and much easier solution IMHO would be to return the fan and buy a
replacement model with a built-in humidistat, that will deal with any
excess moisture as necessary as opposed to running continuously.

hth
David

"Lobster" wrote in message
...
aberdeen wrote:
I've bought an extractor fan for a downstairs utility room / WC. The
room is entirely internal with no external walls though I am able to
run the vent pipe through an adjacent false ceiling so that bits OK.
The fan has a standard run-on timer that would be connected via the
lighting circuit but I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?

Best and much easier solution IMHO would be to return the fan and buy a
replacement model with a built-in humidistat, that will deal with any
excess moisture as necessary as opposed to running continuously.


In theory you could use a current relay in conjunction with a delay off
switch/relay. I use this combination to turn our cooker hood on whenever
the electric hob is used.


--
Michael Chare

On Thu, 13 May 2010 13:42:59 -0700 (PDT) someone who may be aberdeen
wrote this:-

I've bought an extractor fan for a downstairs utility room / WC. [snip]

I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?

It is entirely feasible. The best thing to do is buy a fan with this
built in. It normally runs at low speed, high speed can be activated
by a pull cord or external signal from lights, humidistat or motion
detector.

Alternatively one just turned on by a humidistat may be a better
solution.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000...#pt3-pb3-l1g54

In message , David Hansen
writes
On Thu, 13 May 2010 13:42:59 -0700 (PDT) someone who may be aberdeen
wrote this:-

I've bought an extractor fan for a downstairs utility room / WC. [snip]

I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?

It is entirely feasible. The best thing to do is buy a fan with this
built in. It normally runs at low speed, high speed can be activated
by a pull cord or external signal from lights, humidistat or motion
detector.

Alternatively one just turned on by a humidistat may be a better
solution.

Has anyone any direct experience of using a *humidistat* in a domestic
environment?

I have fitted one in a bathroom to bring in a boost setting on a heat
recovery extract system and have yet to discover if it is effective.

The flat is currently unoccupied and hence unheated. The initial set up
appeared to show the trigger point as around 60% rh and the stat was set
up to 70% to avoid nuisance tripping. When I checked recently, the
trigger and hence the humidity level had moved down to around 50%.

Obviously weather/temperature changes hugely affect rh and I am worried
in case a situation can arise where the fan is trying to dry out the
whole of Hertfordshire and hence not switch off:-(

regards



--
Tim Lamb

"Tim Lamb" wrote in message
...
In message , David Hansen
writes
On Thu, 13 May 2010 13:42:59 -0700 (PDT) someone who may be aberdeen
wrote this:-

I've bought an extractor fan for a downstairs utility room / WC. [snip]

I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?

It is entirely feasible. The best thing to do is buy a fan with this
built in. It normally runs at low speed, high speed can be activated
by a pull cord or external signal from lights, humidistat or motion
detector.

Alternatively one just turned on by a humidistat may be a better
solution.

Has anyone any direct experience of using a *humidistat* in a domestic
environment?

I have fitted one in a bathroom to bring in a boost setting on a heat
recovery extract system and have yet to discover if it is effective.

The flat is currently unoccupied and hence unheated. The initial set up
appeared to show the trigger point as around 60% rh and the stat was set
up to 70% to avoid nuisance tripping. When I checked recently, the trigger
and hence the humidity level had moved down to around 50%.

Obviously weather/temperature changes hugely affect rh and I am worried in
case a situation can arise where the fan is trying to dry out the whole of
Hertfordshire and hence not switch off:-(


I have a humidistat in our new bathroom which controls a dehumidifier built
under a seat and drawing ducted air from a high level. It works very well
set to just under 75%. If the room gets steamy when the shower is in use
for a long time it turns the dehumidifier on, generally just about when I'm
getting out of the shower.

The one we have is basically a strip of material which stretches when damp
connected to a microswitch, very crude but effective although it has quite a
lot of hysteresis.

In message , Calvin Sambrook
writes

"Tim Lamb" wrote in message
.. .
In message , David Hansen
writes
On Thu, 13 May 2010 13:42:59 -0700 (PDT) someone who may be aberdeen
wrote this:-

I've bought an extractor fan for a downstairs utility room / WC. [snip]

I would also like to wire in a way to have the
fan on permanently on a low speed with a fan speed controller so that
when the tumble dyer is on (its a condensing model) any excess
moisture can be extracted by the fan running at a low speed. Question
is - is this feasible and if so how ?

It is entirely feasible. The best thing to do is buy a fan with this
built in. It normally runs at low speed, high speed can be activated
by a pull cord or external signal from lights, humidistat or motion
detector.

Alternatively one just turned on by a humidistat may be a better
solution.

Has anyone any direct experience of using a *humidistat* in a
domestic environment?

I have fitted one in a bathroom to bring in a boost setting on a heat
recovery extract system and have yet to discover if it is effective.

The flat is currently unoccupied and hence unheated. The initial set
up appeared to show the trigger point as around 60% rh and the stat
was set up to 70% to avoid nuisance tripping. When I checked
recently, the trigger and hence the humidity level had moved down to
around 50%.

Obviously weather/temperature changes hugely affect rh and I am
worried in case a situation can arise where the fan is trying to dry
out the whole of Hertfordshire and hence not switch off:-(


I have a humidistat in our new bathroom which controls a dehumidifier
built under a seat and drawing ducted air from a high level. It works
very well set to just under 75%. If the room gets steamy when the
shower is in use for a long time it turns the dehumidifier on,
generally just about when I'm getting out of the shower.

The one we have is basically a strip of material which stretches when
damp connected to a microswitch, very crude but effective although it
has quite a lot of hysteresis.

OK both.

I am relieved that I may get away with penny pinching and not buying the
temperature compensated version.

Follow up on the *baffle box* soon.

regards

--
Tim Lamb