On 6/29/2016 4:47 AM, Doug Miller wrote:
"Jim Wilkins" wrote in :

"Doug Miller" wrote in message
. ..
"james g. keegan jr." wrote in
:

PVC is acceptable up to 140F,

True

which is the hottest setting a water
heater should be at.

Utter nonsense.

http://inspectapedia.com/plumbing/Ho...ature_Laws.php

Like I said... utter nonsense. Quoting from that source:

"Water temperatures exceeding 124 degrees Fahrenheit (°F) (51 degrees Celsius (°C)) are
necessary to prevent the rapid growth of Legionella, the causative agent of Legionella
pneumonia (traditionally known as Legionnaires’ disease) in hot water systems."

I fully understand the need for scald prevention -- but that simply means that the water
delivered from the tap must not exceed 120 degrees F, which is easily achievable with anti-
scald mixing valves. The idea that the *water heater* must be limited to that temperature is
complete nonsense.

Older houses don't have mixing valves (not that they couldn't be
retrofitted.) 140F at the heater is the temperature that will allow the
water at the tap to be 120F. Any hotter and there is a scalding risk at
the tap if there is no mixing valve.