Kitchen Gas Appliances - Hissing Sounds

I'm new to natural gas; I've had a couple of propane-burning devices over the years, but with this house that my wife and I bought a couple of months ago and which stood empty for most of the two years prior; I'm getting my first experience with natural gas that actually comes through a meter on the side of the road.

First of all, it should be noted that the piping was pressure-tested up to the "appliances" before the city would turn-on the gas and no leaks were found...

What is concerning me somewhat is a Perfection Wall-Mounted Space Heater which was manufactured in 1980 according to the metal plate. .

I lit one of the heaters about a month ago and it sounded somewhat similar when it started, but the noise wasn't quite as pronounced and it ended altogether within a couple of hours of being lit. Now that it's getting closer and closer to the teens in my neck of the woods, I went ahead and lit the other heater this afternoon; I actually lit it a month ago, but we weren't using that room, there was a small leak at one of the couplings in the pilot tube and my even more inexperienced wife had a concern about a hairline crack which measured about three inches long, well above the unit's burner; But, since she could see the reflection of flames through it, I agreed to patch the crack before I relit the device and didn't get around to it until this afternoon.

Of course, it should also be noted that I "tightened" the coupling back when I was originally messing with it; I put "tightened" in quotations because all I really did was little more than touch it and the leak tested as being fixed. And for the record, I patched the crack with a swab of furnace cement, the remainder of which will probably sit in my workshop, forever...

What is "bothering" me is a hissing sound which is somehow related to the position of the knob, you turn from Off to On with pilot in the middle.

I can have the valve open to the unit and get no sound, but when I depress the control knob, I hear a hiss which sounds like it may be a leak; Though, everything inside tests as being leak-free and the noise continues with the control knob set to On.

There's plenty of flexible tubing in the unit; So much tubing that there's almost a 180 bend just north of the valve and fairly large bend, as the tube turns toward the unit's interface.

I suspect that the noise may be attributable to possible constriction in the tubing, but I really have no way of knowing if this is "normal" behavior and it is for that reason, I have turned to this forum.

The pilot burns a beautiful blue; Though, if I manuveur my spray bottle to try and test at the very base of the flame, or the extreme northern end of the pilot tube, I get some orange or possibly yellow edges; But my feeling is that my hand and spray bottle may simply be blocking the airflow. Nonetheless, this may have some bearing on the subject, so I'm posting that info and reiterating that otherwise, the pilot is a pretty shade of blue and the burner appears to be operating normally.

Everything tests as leak free. I smell no gas from below or above the unit and though at no point did I test for leaks using a match, I did light and relight the device several times on two different occasions and I never experienced anything abnormal when I was in the vicinity, holding a flame.

I just have this hissing sound that you can only hear when you kneel down in front of the unit and though my gut reaction is that it may be related to the restricted flow through the bends; I can't be certain that there might not be something else malfunctioning, or a possible minute leak from behind the control knob which might not show-up via a soap test because I haven't gotten my spray bottle in exactly the right position.

Finally, I should add that I've tested everything else quite thoroughly, including both sides of the valve and that I contacted the manufacturer and after about three weeks, I received a photocopied owner's manual which was for a similar heater, two generations newer than mine along with a note that this represented the oldest manual they had on file and because it was close, it was the best they could do in honoring my manual request.

Any help or suggestions would be appreciated...

Thanks in Advance;
R

PS) In anticipation of being told to do a search which I did before initially posting this message, but in the meantime, I did a more thorough search using every possible word combination; I feel that it may also be important to point out that the actual pilot flame on this unit burns more loudly than the pilot on the other heater; I get a beautiful blue flame and my carbon monoxide detector shows no problems; It appears that the flame is in the correct position in relation to the thermocoupler, but you can more easily hear the pilot flame burning in addition to the hiss which prompted this post.

Hello: magister

Thanks for a well detailed problem description and many explainations. So many that it becomes slightly confusing exactly when the hissing is heard.

When only the pilot flame is on or the burner flame is on? If th hissing sound is only when the pilot flame is on, a slight downsize of the pilot flame may solve the noise problem.

Flame size is the only means of controling a hissing pilot flame which is burning all blue and sounds like a blow torch.

If the hissing sounds happen when the burner is on only, then the burner flames may be to sharp. Sharp meaning getting too much air.

Closing the air shutter slightly may resolve this problem. Do not close the shutter or shutters tto much so as to cause yellowed flames or flame tips. Only enough to silence the hissing sounds.

Tubing bends etc will not cause the noise problem described. Attempting to reply to all your questions here in one reply since I have many other questions to attend to. Hope my reply answers all of your questions.

Regards & Good Luck, Forum Host & Moderator.
TCB4U2B2B Company Enterprises. Energy Conservation Consultants & Gas Appliance Diagnostics Technicians.

Tom, thanks for getting back to me...

I hear the hiss and it is slight, you have to get down on the floor and hold your ear up to the machine to hear it, when I depress the control knob to light the pilot and when the knob is in the "On" position.

Of course, the sound is constant when the pilot is lit and the knob is fixed "on"; And also, you have to be diligent to seperate the quieter hiss from the louder buzz of the pilot, which are two distinct sounds. When the burner is lit, the burner sound is so much larger that it is impossible to distinguish whether or not the minute hiss is still under there...

I'll do some experimentation with adjusting the pilot, though the hiss actually sounds lower than the flame.

Thanks for letting me know that it isn't the constriction of the tubing and giving me a couple of things with which to experiment.

Any other ideas would be appreciated...

Because this is a newly-lit heater in a newly-purchased home, I have no comparison that I can make concerning gas usage; Basically, we're using 4 units (gallons or pounds?) a day for two twenty-two year-old space heaters set on 70 and a 50 gallon hot water heater in a fifty year-old, uninsulated cinder-block, 1622 square-foot single story, supplemented by an electric heater at night, set on low in one bedroom nowhere near the thermastats.

At night, we're in the 20's and in the daytime, we hover between 40 and 60 depending on the day...

Thanks again and further thoughts are more than welcome

Hello: magister

The amount of gas useage for any home is totally based on personal usages and can not be compared to prior occupants.

All factors of variations taken into considerations where circumstants remain the same and can not be changed. Examples are insulation, building materials and outside temps, etc.

Comparing the two usages between occupants would be totally useless as a means of determining consumptions. Your requirements are not the same as the former occupants. Therefore, energy consumptions will vary.

The unit of gas used is based upon your personal needs. The amount of gas is measured in cubic feet and therms. The costs are related to the amounts used. Refer to your gas bill for additional information.

Regards. Gas Appliances Forum Moderator Moderator.
Web Site Host & Multiple Topics Moderator.
Tom_Bart......Company Enterprises.....TCB4U2B2B
Energy Conservation Consultant & Natural Gas Appliance Diagnostics Technician.