Why use an extractor fan?

[ericmark]

I am not being silly I hope but why suck out rather than blow in? If I have a duct leading to a heater and blow in air the air is then heated before it reaches me, so no cold drafts. Air goes out under the door not in under the door so although still the same number of air changes no drafts.

 

[EFLImpudence]

Are you talking about the bathroom?

Why not just heat the air that is already in the room. No wastage.

 

[ericmark]

Basic all around the house. When the tumble drier starts we get drafts. When it stops the draft stops. Clearly that has to pump air out or house would get damp, but if we had something pumping warm air into the house then we would not feel cold drafts. i.e. house is positive pressure so any leak is air going out. With the old houses with wooden ground floor floors they would put vents near the fire to let air in close to fire so the fire did not cause drafts. Ideal is a heat recovery unit, but failing that pumping air in behind the radiator would ensure all air is hot.

I was looking at my Myson and wondered if a duct from garage to Myson so some of the air it sucks in was from garage would stop drafts. Down side is could then not use garage as a garage or it would also blow in fumes.

The house was built and designed to have a central fire to heat whole house, not what we think of as central heating but it was central and it did heat. However there was no duct for it to draw in air from outside. So in theroy I should not have a bathroom extractor or non condensation tumble drier as it could suck flue gases into the house. That fire is now for emergency only but still bugs me no duct was installed.

 

[endecotp]

When the tumble drier starts we get drafts. When it stops the draft stops. Clearly that has to pump air out or house would get damp, but if we had something pumping warm air into the house then we would not feel cold drafts.

Are you aware of MVHR, "mechanical ventillation with heat recovery"? A heat exchanger warms the incoming air from the outgoing air. I think it works best (i.e. is worth the capital costs) in colder countries than the UK, though. I don't think I've ever heard of connecting a drier to a heat recovery system though (at least not domestically).

 

[empip]

NuAire people have been around since early 70's - survivors ??

A work colleague once had bad condensation problems in his bungalow kitchen, tried everything within reason, decent expelair extractor etc, then bought into this kit
http://www.nuaire.co.uk/our-products/Residential/products?pt=1685
probably from mid to late 70's - Without the air heating - Just gently pressurising from the loft space. He always maintained that the kit cured his condensation problems, was it cost effective ?? Who knows, but it saved him much ear and heartache !!
He did have a supplementary wood burner, with a chain saw and permission to take fallen timber from nearby woods. Perhaps he blazed the cool air from the loft - he wouldn't agree to that.

-0-

 

[JohnD]

I used to have a heat-recovery ventilation unit, it was made by Dimplex but not a commercial success and I believe they discontinued it. It was whisper-quiet and would probably have been suitable in a living room. I made the mistake of fitting it in the kitchen as an alternative to an extractor, and it was not a success as it did not create suction to prevent cooking odours drifting round the house. Additionally the incoming air mixed with and stirred up the air in the kitchen which
I think made diffusion worse.

I do not think it would have been suitable for a bathroom either, as you want to suck the steam out with an airflow from the rest of the house, to prevent it spreading.

I am now a firm believer in extraction as close as possible to the point where moisture or odours are created.

 

[Spark123]

Buy a condensing tumble dryer?

 

[PBC_1966]

I am not being silly I hope but why suck out rather than blow in? If I have a duct leading to a heater and blow in air the air is then heated before it reaches me, so no cold drafts. Air goes out under the door not in under the door so although still the same number of air changes no drafts.

But for a bathroom surely the whole purpose is to exhaust that moisture-laden air to the outside, not just distribute it to other parts of the house?

 

[ericmark]

I am not being silly I hope but why suck out rather than blow in? If I have a duct leading to a heater and blow in air the air is then heated before it reaches me, so no cold drafts. Air goes out under the door not in under the door so although still the same number of air changes no drafts.

But for a bathroom surely the whole purpose is to exhaust that moisture-laden air to the outside, not just distribute it to other parts of the house?

Opening a vent to outside will allow any steam to go out without having a fan if the house is at a positive pressure. It was not really my house I was looking at but a friend who have a timber framed house in the centre of 20 acres of woodland and uses a wood burner for heating. There is a whole list of problems.
1) If fire lit too late the air in the house is colder than the air outside and fire will not draw. Cure at moment is open all doors and windows to let cold air out and close them once running.
2) When the fire is lit then there are huge drafts from doors and windows specially where the tree fell and crushed the house now covered with a tarpaulin.
3) Keeping the fire burning at a rate which will maintain the flue at 150°C.
So before designing want to see what is already made. No point re-inventing the wheel. Any extractor is a non starter because of the dangers of drawing fumes into the house. But if I just blow in air likely the flue will get too hot so need some control. I am in favour of a hard piped inlet to the stove and not allowing it to draw air from inside. But I am meeting resistance to this idea. Also looking at pressure switches to compare outside and inside air. Of course any hole has to be rodent proof. With fire out we have actually had one come down the flue to get into the house. Open windows is not really an option the squirrel is really daft, if caught death is only option, they are USA things not the native red so they are trapped and shot.

 

[stillp]

they are USA things not the native red so they are trapped and shot

Waste not, want not: http://www.airgunbbs.com/showthread...recipe-for-Squirrel&highlight=squirrel+recipe

 

[ericmark]

they are USA things not the native red so they are trapped and shot

Waste not, want not: http://www.airgunbbs.com/showthread...recipe-for-Squirrel&highlight=squirrel+recipe

Can't view unless registered.

 

[Taylortwocities]

It doesn't matter. I have an easy recipe for squirrel crumble.

Method:
1. Get a very old squirrel
2. Wait

 

[Spark123]

I can't see a small extractor fan being an issue, if it is then he I'd be asking if he has enough ventilation for the log burner anyway.

 

[ericmark]

Without a manometer how would you know?

 

[ban-all-sheds]

There is a whole list of problems.
1) If fire lit too late the air in the house is colder than the air outside and fire will not draw. Cure at moment is open all doors and windows to let cold air out and close them once running.
2) When the fire is lit then there are huge drafts from doors and windows specially where the tree fell and crushed the house now covered with a tarpaulin.
3) Keeping the fire burning at a rate which will maintain the flue at 150°C.

I would have thought that dealing with #2 should be top of the list, and nothing lower down the list even looked at until that's done.