When We First Turn On Hot Water We Hear This Loud Noise Outside
by Cindy Solomon
(Franklin, Tennessee, USA)
We have an external Hot Noritz tankless water heater that was installed in May of 2008. In March 2016 we had to replace the ignition switch. Everything was good until recently. For the last several months, whenever you turn on the hot water after it's not been used for a while I hear this loud "whoop" kind of noise outside.
The unit is on the bedroom side of the house and I can sometimes hear it in our kitchen which is on the other side of our house. We had a local plumbing company come out and service/clean it the other day. He heard the noise when he first got there (I turned on the hot water hoping it would make the noise and it did). He felt that after cleaning the unit that would make it stop.
It did not. It's still doing it. I am worried about safety issues (is it gonna blow up or anything?) but I'm also sure my neighbors--whose bedroom is just across the yard from our water heater--are sick of hearing that "whoop" noise every morning at 5:30 when my husband gets up to take a shower.
Does anyone have any suggestions on what the problem might be?