Condensation on a bathroom extractor fan

[tex431]

Hi got a customer who has a icon 45 bathroom extractor fan, fitted by myself and it develops water droplets on the front grill and drips on the floor. It is flush mounted in the wall through a 40mm polystyrene backed plaster board. I have put some expanding foam between the wall and the back of the plasterboard. Due to the nature of the wall I put a duct through the wall 150mm long, sloping out with a back draft flapper on the wall no water runs in the duct, it only forms on front grill. Any suggestion? Probably going to swop fan to a different brand. Never had this problem with this particular fan before

 

[ruston]

I think we should make Lee an Honorary Geordie for that

Aye, as blunt as a ceramic filleting knife.

 

[Leesparkykent]

I think we should make Lee an Honorary Geordie for that

I'll drop kent off the end of my forum name and no one will be any the wiser ;-)

 

[Engineer54]

As with all things, a little knowledge is a dangerous thing ... and you can prove anything with statistics, badly designed experiments, poorly chosen comparators or blatant withholding of the truth!

So is too much knowledge by the sound of it!!

 

[mache]

Oh dear, oh dear, oh dear ... the thermal conductivity, insulation value, of:


- Dry air @ 275 deg K ~ 2 deg C is 0.024 W / m K, @ 300 deg K ~ 27 deg C is 0.026
Dry Air Properties


- Polyisocyanurate foam, 'Kingspan' is 0.023 W / m K or 0.022 W / m K or 0.019 to 0.023 W / m K
Polyisocyanurate - Wikipedia, the free encyclopedia or
Celotex GA4000 Insulation Board for Floors, Walls and Roofs or
Kingspan Insulation - Kooltherm Rigid Insulation for Roof Wall & Floor Applications | Thermal Insulation - Kingspan UK


- Glassfibre 1.2 to 1.35 W / m K
Properties: E-Glass Fibre


What the manufacturers' brochures do not tell you ... the thermal properties of polyisocyanurate foam are dependent upon the gas used to 'blow' the foam. This gas can 'leak' and reduce the thermal properties of your insulation, it becomes a ~ 17 % better conductor in the first 6 months; a less effective insulator than dry air. In some other manufacturers' foams, I do not know about all, less than environmentally friendly gasses have been used as the insulating medium. The products of combustion of the foam are amongst the primary killers in house fires.


Glass fibre relies on its air content to do its insulating job ...


Air ... its problem is if heated it changes density and being a gas will rise being replaced by cooler, denser air. Its problem is heat movement by convection not conduction ... though its insulating properties are negatively affected by its moisture content.


As with all things, a little knowledge is a dangerous thing ... and you can prove anything with statistics, badly designed experiments, poorly chosen comparators or blatant withholding of the truth!


Furthermore, don't believe anything a marketing specialist tells you about the product that they are selling until you have used it and proven its capability and your need for it before buying!

So basically in all that you are agreeing that in a domestic situation, where air won't be dry and where it won't be still you are better off with an expanded foam insulation or glass fibre because it is those parts that prevent the air from moving around, hence providing the insulation factor and is why we wear clothes because they prevent direct enviromental air from cooling down our body because the clothes slow down the air movement changes. Our do you walk around in winter in just your budgie smugglers in the hope that theroetical properties of air at ideal conditions will stop you getting pneumonia....

 

[GB.Kayak]

So basically in all that you are agreeing that in a domestic situation, where air won't be dry and where it won't be still you are better off with an expanded foam insulation or glass fibre because it is those parts that prevent the air from moving around, hence providing the insulation factor and is why we wear clothes because they prevent direct enviromental air from cooling down our body because the clothes slow down the air movement changes. Our do you walk around in winter in just your budgie smugglers in the hope that theroetical properties of air at ideal conditions will stop you getting pneumonia....

I wouldn't wear glass fibre, I find that it itches too much ... I find that polyisocyanurate foam doesn't drape well and shrinks leaving gaps! ;-))

 

[ruston]

I wouldn't wear glass fibre, I find that it itches too much ... I find that polyisocyanurate foam doesn't drape well and shrinks leaving gaps! ;-))

The space foil can be manipulated easily and is quite trendy.:beatnik2: