On 22/01/2013 10:00 PM, Jim Wilkins wrote:
"Existential Angst" wrote in message
...
Awl --

Ahm semi-re-plumbing the lines to the HW heater, and I noticed what
appears to be some sort of vent/pressure relief ditty coming off the
*CW inlet to the HWH*. From the CW pipe to this gadget is copper,
from the gadget to the wall is 1/2 black pipe. The 1/2 pipe goes
thru an outside wall, altho I have yet to find anything outside!

I'd be hardpressed to imagine that this thing still works, whatever
it was. I'm sure it's 25++ years old.
It's not an anti-water hammering device, afaict. Is it safe to just
get rid of this thing? City water pressure is barely 60 psi, I have
gauges plumbed into a couple of lines, very little variation.
It would make my life a lot easier if I could ignore/get rid of this
thing.
--
EA

http://www.oconomowocplumbing.com/de...-relief-valve/

City water can be shut off, making the tank a closed system. Then
simply heating cold water can generate enough pressure to pop the
relief valve. I found that out by experience after closing the meter
valve to make a repair.
jsw




The relief valve on our HWS cracks every sunny day (solar system), old
gas system used to as well.

Check out the Mythbusters video on what a HWS explosion can do - quite
impressive & destructive even if it is enhanced by the Jamie's.