I’ve got a perplexing issue I could use some feedback on. I installed a new A.O. Smith direct vent water heater and an Empire direct vent wall furnace recently. Pressure tested the lines (having isolated the gas valves) along with a soap test and there were no leaks. I had my propane provider out to turn on the gas and test for leaks and they gave it the OK - pilots lit, both appliances functioning, and no leak whatsoever. Problem is I can smell the slightest odor of propane at both gas valves. I turn the shutoffs off at the valves the odor goes away, and when I turn it back on I can smell it. I had the company come back and the technician said he didn’t measure any leak and that the gas valves can sometimes smell. I don’t understand that at all, since by my understanding the odorant is in the gas, so if you smell it you’re smelling a leak. These guys have been out twice and I’m not sure what’s going on. I’ve got the same Empire heater in my shop and there’s zero odor. Any thoughts? Thanks

Have you tried a bubble test of the valves?

Yes, the valves were both tested with leak solution. Nothing. I tested them and the technician did as well.

This may or may not be relevant: When the tankless propane water heater at our home snaps on, there is a slight smell of rotten eggs near the heater (it's outdoors). The smell dissipates rapidly and does not return no longer how long the burner keeps running. At first we thought it might be a leak, but testing shows none.

Are you using home-made dish soap and water to test? There are better liquids available, like Rectorseal Better Bubble. It last longer than plain soap & water. And there are electronic testers available that are very very sensitive.

If it was in my house, it would bug me and I'd just replace the valve & flex.