What in the world is this sound?

[Michael Keelan]

Video not available. Sorry.

This was captured by a camera I set up pointed at the water heater. It wakes people in my house at 6 AM or thereabouts nearly every day even though no one is using water or even up. It happens even if no heat/AC is on. The gas company and city (sewer) can find nothing wrong. The heat/AC are brand new and it made no difference.
I would love to get someone to fix it if they just knew what it was. Ideas?

 

[Jadnashua]

1. Does it sound more like an explosion or a hammering? Hard to tell from the recording.
2. Does it happen at the same time every day?
3. Does it repeat, or a one-time thing?
4. Do you have a hot water recirculation system?
5. Is your heating system utilizing a setback thermostat?
6. If a boiler, does it have a program that determines optimum time windows?

 

[Sponsor]

 

[Reach4]

It sounded to me as a single bang or thump.

I would add a clock into your picture to see if it is actually the same time each day.

I have half a theory, but not the other half. Some power companies switch in a bank of power factor correcting capacitors at a fixed time each day... until they change the time. Whether this would happen at a different time on weekends, I don't know. Anyway, that is something that could happen each morning. Some people have UPSs on their computer that will beep when that happens.

How that resulting power glitch would be turned into a thump/bang, I don't know. You could see if you could replicated the sound by turning off the power for a fraction of a second.

 

[Michael Keelan]

It's usually one single bang, always early morning (5:45-7:15). The boiler was installed two years ago by the landlord (before my time) but likely she went with the least expensive option. Certainly no "bells and whistles" like a recirculation system. One theory was a pressure problem (needing a PRV and overflow tank). Basic, you see:

 

[Jadnashua]

Is the bang after someone has taken a shower or used some hot water?

OFten, the water utility's pressure tends to go up at night when they are refilling water towers and the overall use rate is down. Then, once people start to wake up and the water use rate goes up, the pressure drops, so it would be interesting to see what the pressure is doing. Got something like a GoPro that you could set on time-lapse and focus it on a water pressure gauge? If not, know of someone who might loan you one?

 

[Master Plumber Mark]

Take the hood cover off the heater and then pull up on the baffle in the smoke stack and move it around some
then put it back into place and see if that does not end the problem.....