Thank you for all of your help. I will try to find out the manufactory
and see whether I can get any help from them.
The house is using gas heater. I cannot hold my hand for even 10
seconds if I turn on the hot water of the faucet (the sink). But when I
took a shower, even if I turn it all up to the hottest level, the water
is still just warm. The problem seem to come and go: one day it may be
hot, the next day it may only be warm. HOwever, the outside temperate
is about the same and hot water from faucet is really hot... Lily