Last night, while walking near my natural gas meter, I picked up the smell of (natural) gas again. I smelled gas before in the same area outside but it was brief and then it went away. This time I called my local gas company’s emergency number. The person on the phone took my information and gave me some basic safety information (i.e. basically stay away from the suspected area and keep any sources of ignition including a telephone away from it). A gas technician arrived within less then 30 min. Not bad for a long weekend evening.
The technician smelled around the gas meter and supply line and took measurements with a gas detector. He initially couldn’t find anything but continued to inspect the area. He then noticed my recently installed direct vent for the tankless water heater and told me that it is possible to smell gas coming out of the vent. I wasted no time and decided to test his theory: ”Ok. Let’s fire it up!”, I said. I noticed a brief look of concern on the technician face. So, I went inside and turned on the hot water while he turned on the gas detector outside.
When I returned ouside his detector was beeping loudly and the smell of natural gas was in the air. However, the smell and his detector reading would go down within minutes. We repeated turning on the hot water with the same affect.
So, we have proven that the technican was correct. A brief burst of unburnt natural gas can come out of the tankless water heater vent when the hot water is turned on. He assured me that this is perfectly normal and safe.
