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AJ Soprano
12-19-2005, 10:11 AM
Not sure if this is the right place to ask this, but here goes. I have a natural gas pipe feed into the house which in feeds the furnace, gas fireplace, and hot water heater in that order. There are no leaks in the system. All 3 units have pilot lights that are continuously burning. When the hot water heater and the gas fireplace are running concurrently (i.e. the pilots have ignited the main burners), there is a resonating, medium-pitched hum that vibrates back through the gas line from the point where the feed splits off between the two appliances. I have read that this could be due to a change in gas velocity. Has anyone heard this or can anyone suggest how this hum may be prevented? I tend to think this may be the cause because shutting either burner down or igniting the furnace burner stops the hum.

jadnashua
12-19-2005, 12:11 PM
While this is happening, go outside and listen to the gas meter. The pressure regulator normally associated with the meter could be doing it. Also note, depending on the size of the piping, when multiple items are demanding gas, you may be trying to draw more than your regulator can supply. My unprofessional opinion.

hj
12-19-2005, 06:12 PM
What kind of gas pipes do you have? That sound is typically caused by using the corrugated stainless steel gas pipe, and making too sharp of a bend at a corner.

AJ Soprano
12-20-2005, 09:34 AM
I have cast iron pipe coming into the house and the first tee goes to the furnace (all tees and nipples to the furnace are cast iron). Beyond this first feed, it is still cast iron to the next feed which consists of a cast iron tee connected to a 3 inch nipple connected to a shutoff connected to another nipple which is connected to a flexible steel, yellow gas hose which feeds the fireplace in another room. The hose is probably 20 to 30 feet long and the only non cast iron component. The other branch of the gas fireplace tee continues on about 4 feet and feeds the gas water heater. This is the end of the line. As I said before, I only get the hum when the fireplace and water heater are fired up simultaneously. Any other combination of the 3 appliances, including all 3 on simultaneously, is quiet.

I can believe that the hum could be caused by a precise combination of pressure change and the corrugated pipe. The question becomes how can one disrupt the magic formula. I was thinking of maybe restricting some gas flow by not fully opening the shutoff valves or something like that, because it seems to me that too much gas pressure rather than not enough is causing the hum based on the fact that it goes away when all 3 appliances are burning. Does this make sense or does anyone have any other ideas?

Thanks.

hj
12-20-2005, 08:33 PM
The proper way, if you can get to it, would be to reshape the yellow flexible pipe's turn where it makes a corner and "straighten" it out a little.

aaronthedrumbeater
08-28-2011, 04:09 AM
I realise this is a very ols post, but did you sort out your problem? I'm in australia and have just moved into a new house. When I light the gas heater, the meter box or regulator (both are connected) start to hum. I have gas ccoktop and gas instant hot water heater as well, but issue only seems to occur with the heater running. Did you end up having to replace the converter, or was there some other issue?

hj
08-28-2011, 08:31 AM
It is the same issue. The installer bent the yellow corrugated pipe to sharply and it has to be straightened out with a smoother turn to eliminate the sound. There is NO other way to cure it.