[djones]

My DIY plumbing has been strictly PVC except for adding a valve and hookup for an outdoor natural gas grill. I have a plastic flex furnace supply line that whistles so loudly you can hear it outside, it's a real pain in the ear. I think it's because it has a sharp bend in it right where it connects to the supply, but has to with the current plumbing - the supply is pointing straight into the a/c drain line.

Long story short, I want to put an elbow in so the flex line can connect vertically to the supply instead of awkwardly between other parts of the HVAC and am hoping the whistling will go away. Without redoing a lot of the plumbing, I still have limited space, so I want to go from the brass valve to the flex line with one connection. All I could find was a 1/2 flare to 3/8 flare 90º. Can I use that flare fitting without any issues? I'm assuming I'll need to dope/tape the 1/2 side, but I thought I'd ask about potential problems since the flare on that side is just going to be sticking dumbly into the threaded pipe.

Alternatively if I'm off base on the whistling and there's a better solution, I'm all ears.

[AQualityPlumber]

Just a quick note, do not use thread tape on gas fittings. It can clog up the orphasus inside. Just cake on the dope on the threads and test for leaks when you are done.

[AQualityPlumber]

And am I reading this right that you used pvc for gas piping?

[djones]

Originally Posted by AQualityPlumber

Just a quick note, do not use thread tape on gas fittings. It can clog up the orphasus inside. Just cake on the dope on the threads and test for leaks when you are done.

Ok, thanks. Not even the yellow tape on the back of the threads? What's it made for then?

Originally Posted by AQualityPlumber

And am I reading this right that you used pvc for gas piping?

LOL no, sorry if that was confusing. I mean that my experience is mainly with PVC and *water*.

[AQualityPlumber]

Again, do not use any thread tape for gas fittings. I'm sure they make tape rated for gas, but it's not a good idea. You will almost always get a pin hole leak and risk clogging up the unit if a piece Flys off inside. Use either a soft set thread sealent rated for gas, or a non soft set rated for gas. Make sure on the can it says it's rated for gas and fuel.

[djones]

Perfect explanation, thank you.

[IFIXH20]

Originally Posted by djones

My DIY plumbing has been strictly PVC except for adding a valve and hookup for an outdoor natural gas grill. I have a plastic flex furnace supply line that whistles so loudly you can hear it outside, it's a real pain in the ear. I think it's because it has a sharp bend in it right where it connects to the supply, but has to with the current plumbing - the supply is pointing straight into the a/c drain line.

Long story short, I want to put an elbow in so the flex line can connect vertically to the supply instead of awkwardly between other parts of the HVAC and am hoping the whistling will go away. Without redoing a lot of the plumbing, I still have limited space, so I want to go from the brass valve to the flex line with one connection. All I could find was a 1/2 flare to 3/8 flare 90º. Can I use that flare fitting without any issues? I'm assuming I'll need to dope/tape the 1/2 side, but I thought I'd ask about potential problems since the flare on that side is just going to be sticking dumbly into the threaded pipe.

Alternatively if I'm off base on the whistling and there's a better solution, I'm all ears.

If the Furnace has a whistling sound when its running, it may be too much gas pressure , bad gas valve, flue issue ,cracked heat exchanger, burners need adjusted. I do not think Furnace repairs should be done my DIYERS due to the danger that can occur if the system is not running proper, thats just my opinion. ( HOPE YOU HAVE A CARBON MONOXIDE DETECTOR).

[IFIXH20]

Originally Posted by AQualityPlumber

Just a quick note, do not use thread tape on gas fittings. It can clog up the orphasus inside. Just cake on the dope on the threads and test for leaks when you are done.

Do not dope the first three threads on gas

[djones]

Originally Posted by IFIXH20

If the Furnace has a whistling sound when its running, it may be too much gas pressure , bad gas valve, flue issue ,cracked heat exchanger, burners need adjusted. I do not think Furnace repairs should be done my DIYERS due to the danger that can occur if the system is not running proper, thats just my opinion. ( HOPE YOU HAVE A CARBON MONOXIDE DETECTOR).

We do have CO detectors, and my nose is more sensitive than most to the additive. I've twice had gas company reps look at me like I'm looney when I say there's a leak and tell them which joint, until their detector starts beeping.

I appreciate the other points though - I truly don't know why it's whistling, and was relying on my ear for the source. So it sounds like even if I've identified the location of the whistle, that may not be locating the reason?

[IFIXH20]

Is the whistling constantly or when the furnace runs