Variability #1

It is recommended to not set the temperature of your home hot water heater above 60C.  Doing so may not affect adults, however children's skin is much more susceptible to burning.  This variability is therefore unacceptable because a child could be injured unsuspectingly.  Aside from the safety concerns, a variation of this magnitude might for some people be uncomfortable.  This variability in unacceptable.

 

Variability #2

A two degree variation will maintain the hot water within reasonable limits, and the magnitude of the variation is not significant.  This variation is realistic and acceptable.