Re: [Phys-l] Copper and aluminum

[Bernard Cleyet <bernardcleyet@redshift.com>]

On 2010, Dec 13, , at 13:51, Josh Gates wrote:

> Hi everyone,
>
> My HS chemistry is rusty, and my application of replacement reactions is non-existent.  My goal is to insulate my hot water pipes in my cold basement.  I have a few options:
> - buy an expensive aluminum tape; the reflectivity helps with loss due to radiation, presumably.
> - use foam "noodles" to insulate them, which presumably helps with loss from conduction (I guess)
> - use Al foil around the pipe to help with radiation, and then foam around it, or
> - use foam with Al foil around it.


Forget the sticky Al foil;  it's for flu pipe.  The E amount of radiation at ~ 80C is minuscule compared to convection.**  When you're inclined, replace the iron pipe w/ PEX and use "noodles".  As suggested, tape the ends together and the ends.

http://www.pexinfo.com/


**Furthermore, noodle or anything else other then air or other transparent (to IR) material over the Al defeats its purpose.  Think about it.

On 2010, Dec 13, , at 16:14, brian whatcott wrote:

> The "unless" involves either a return flow pipe  or an 'instantaneous' 
> heater. The return pipe need only be narrow gauge, but still it wastes 
> energy if it flows hot water  to waste.It may be pumped back into the 
> hot water tank feed, which itself has an appreciable energy cost, but 
> still is a luxurious detail.  Embellishments might include a timer to 
> activate the pump for just a few minutes before the earliest time of use.


As I've posted, Costco sells (sold) a pump and relief valve so water will circulate w/o the need for a extra return pipe.  It includes a 24 hr. timer.


bc has a GE Radiation Calculator.