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

 

[Guest125]

popcorn!

 

[GB.Kayak]

Just how much indepth explanation would you think is plausible here?? Over simplification it maybe but is totally relevant to the situation. The expanding foam insulation in this case isn't going to make the internal wall as cold (or anywhere near) as the external wall....

So what are you saying, that insulation material doesn't insulate between hot and cold and visa versa??

Insulation reduces the rate of heat loss ... it doesn't prevent it! At what point does over simplification = dumbing down? At what point does someone regurgitate ... I heard the engineer say ... at which point professionalism may be called into question. The correct description does not have to be complicated. I am saying what I have said which is basic physics and anything that says that heat and cold can be conducted or insulated is in my opinion misleading and can lead to unnecessary confusion in the future.

I do however recognise that in order to explain complicated concepts simplification is often necessary. We have not all studied degree level thermodynamics. Most of which I have long since forgotten!

 

[Anthony S]

There as been cases where cold spots have been found to appear on the inner leaf after the full injection of insulation in hard to fill cavities. So is that some sort of cold bridging ? who knows and who really cares.

 

[Engineer54]

God, we could nit pick to the enth degree on every single Thread/Post on that basis....


OK just for you,let's just say that insulation between two surfaces reduces the transfer between hot and cold to a point it is Extremely unlikely that one side of the insulation will have any great effect on the other side... Is that better for you??

 

[GB.Kayak]

There as been cases where cold spots have been found to appear on the inner leaf after the full injection of insulation in hard to fill cavities. So is that some sort of cold bridging ? who knows and who really cares.

God, we could nit pick to the enth degree on every single Thread/Post on that basis....

OK just for you,let's just say that insulation between two surfaces reduces the transfer between hot and cold to a point it is Extremely unlikely that one side of the insulation will have any great effect on the other side... Is that better for you??

Are these rhetorical questions ... to which answers are unwanted or unwelcome ... or would a sensible answer be welcomed?

 

[telectrix]

if air was a better insulator than fibreglass/kingspan/etc., then they wouldn't stuff the crap in studded walls and ceiling voids.

 

[Anthony S]

if air was a better insulator than fibreglass/kingspan/etc., then they wouldn't stuff the crap in studded walls and ceiling voids.

Behave yourself, they do it just for a p*ss take lol

 

[telectrix]

hah. went to do a quote last year. 320 LED downlights to 2nd fix in ceilings with 4" celotex wedged in. no cut-outs, just cables coming through 1" ( rough) holes in board. quoted double what i thought, just to make sure i didn't get the job.

 

[tex431]

No cavity wall- Victorian house.

 

[HandySparks]

if air was a better insulator than fibreglass/kingspan/etc., then they wouldn't stuff the crap in studded walls and ceiling voids.

Air is a better insulator than glass, which is why most of the volume of fibreglass insulation is air. The point being that the fibres prevent convection (and to some extent, radiation), which is largely how an unfilled cavity wall transmits thermal energy.

 

[GB.Kayak]

if air was a better insulator than fibreglass/kingspan/etc., then they wouldn't stuff the crap in studded walls and ceiling voids.

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!

 

[Leesparkykent]

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!

F**k about,I read the first three lines and got bored haha

 

[Tidy Max]

Hogwash!! So what about the cavity wall insulation balls, that gets pumped into cavities or the expanding foam type insulation sprayed into cavities??

Insulation material does not conduct either heat or cold, that's why it's called ''insulation''

What is the purpose of leaving the required breathable gap either side of foam insulation when plasterboarding a ceiling? i thought it was to stop the cold transferring though the insulation and causing condensation/damp onto the plasterboard?

That was my logic behind the suggestion anyway.

 

[ruston]

F**k about,I read the first three lines and got bored haha

Don't mess about there Lee, just say what you feel.

 

[Geordie Spark]

Don't mess about there Lee, just say what you feel.

I think we should make Lee an Honorary Geordie for that