I am located in the United States and have a natural gas (not LP) range in my kitchen fed by a natural gas utility.
Sometimes when I turn on my range, the appliance makes a whining or humming noise. This only occurs when gas is actually flowing:
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If I adjust the burner on the stove top, the volume of the noise increases and decreases with the flow of natural gas. That is, on setting 2 it is quiet, on 6 it is very loud.
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If I am using the oven, the noise only occurs when the oven burner is actually lit.
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If I am using the broiler, the noise is constantly loud because the broiler burner is always on full blast.
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No other NG appliances (clothes dryer, water heater, furnace) make this this noise.
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At no time do I smell natural gas anywhere in my house. I have checked all flexible hose connections on each gas appliance and several black iron connections with soap and it appears there are no leaks.
This led me to believe it has something to do with the flow of gas specifically in the gas range. Google was helpful enough to point out a few useful links:
Based upon the problem description, the most likely cause is air and
fuel ratios. Either to much air or to much fuel into the top burners.
Which will create a hum, whistle or whining sound. Generically
referred to as "noise."Burner air ratio to fuel can be adjusted by slightly closing the air
shutters on the burner tubes. One at a time close each shutter
slightly and test. Flame must remain all blue. Listen to the burner
while doing this adjustment. Noise should stop when properly adjusted.
Based on your symptom and details the gas pressure regulator is most
likely causing the whining noise as the gas flow is being regulated.
Replacing the gas pressure regulator will likely resolve the whining
noise.
It appears my range has no user-serviceable components: I am not able to adjust "air shutters" or anything else on this model of range. This leads me to believe the most likely culprit is its gas regulator.
I do not want to replace or fix this range unless there is a reasonable risk that it will leak natural gas or some other issue that could cause damage to my house.
Given the evidence presented in this question, is there an elevated risk of my range malfunctioning in such a way that it will create a risk of fire, explosion, or anything else that might damage my house or its occupants?
Best Answer
My background is Industrial, Commercial, & Residential combustion & appliances. I often also consult to Commercial & Residential Cooking Equipment OEMs.
The noise you are most likely hearing is a high-pitched hum, caused by turbulent flow in some pipe fitting. Most frequently, the source is an undersized or too lengthy flexible pipe fitting. If you notice, black iron pipes have straight smooth sides. This does not guarantee laminar flow, but it does greatly reduce internal friction & turbulence (low pressure drops). This results in quiet & efficient flow.
Many plumbers enjoy the speed & efficiency of flexible tubing to make the final 18" or so easier to pipe to the appliance. Flex hoses are flexible by using overlapping corrugated sections. They cause VERY turbulent flow...but are acceptable under certain conditions...and very quiet when sized and used properly. There are very specific flow rates assigned to each individual flex line manufacturer's rating. Exceeding those rates will always cause excessive pressure drop (lower firing rates to you) and usually an improper air-fuel ratio (although not necessarily in atmospheric-type burners)...but they will ALWAYS cause a whine or loud hum.
Increase the flex line size (less than $30 in parts), or try to decrease the length...substituting pipe.
Warning, a burst regulator diaphragm can cause a noise, but the gas odor (caused by the chemical mercaptin) will be evident as it leaks through the regulator vent. Accumulations (natural gas floats in air) are explosive. You would easily smell the gas. LP gases have a 1.5sg (Air is 1 specific gravity) and will drop quickly in air...and also go down drains! A gas company can easily check for leakage (and should)...however, their meters check in parts per million (ppm). Gas is only combustible in very defined %. A room at 100% gas will not support combustion...but do not open the door and introduce oxygen! Accumulations build to %...and the danger...and exceed the flammibility limit and self-extinguish (not enough oxygen). Competent gas appliance installers use a method of a soapy water spray (or a specific leak detection soap) brushed onto every joint. They just look for the bubbles. It is very accurate to show problems (many OEMs use this approved method to detect leaks). Any joint can leak in ppm (some pipe dope will outgass and set detectors off), AND be safe AND in full compliance with all standards. No fitting is leak-tight.
Bottom line, change the flex. If it is not a code issue in your area...it is a 15-20 minute job by a normal plumber. Best Wishes.