I had a very stressful day dealing with the gas company on Friday because they didn’t properly check all of their equipment when I reported a failure.
The technician entered my house and proved he had pressure inside my house by simply cracking the line connection at the water heater briefly. He stated that ..BOTH.. my water heater (nearly new) and furnace had failed at the same time, and he showed me how to replace the 'broken' part of my water heater. Then he left.
I thought this was a bit mathematically interesting (probability-wise) to have two failures of equipment at the same time that use the same fuel source.
So after a couple hours of pondering & safely experimenting, I came to the conclusion that it was a flow restriction problem in their equipment, and that the long line across my backyard acted as a reservoir between the house and the gas meter in the alley.
After waiting a short while, the water heater, the smaller gas consumer of the two, would light and then run just fine. It ran for 20 minutes and made hot water as expected ..BUT.. just as soon as I tried to light the furnace, the water heater would immediately go out and wouldn't light ..AND.. if I didn’t wait long enough for the pressure to build back up, the water heater would light just fine, ..BUT.. then it’s flames were not very tall and it might go out altogether. So it appeared to be a dynamic problem.
When the same gas tech was sent back after I carefully explained my discoveries to the technical support person by phone conversation, the gas tech was a bit snippy ..BUT.. he had already changed their equipment in my alley before he approached me. I tried to tell him what I did, my diagnostic thought process, but he kept trying to talk over me. So then we walked into the house, and sure enough, both the furnace and water heater lit up and ran normally. The tech was surprised, as he had never seen this happen before. (?) At least he had the failed equipment to take back to investigate. My guess is that a piece of debris had partially blocked the flow inside their regulator or meter. ..BUT.. if I had followed his original advice and blindly got plumbers and HVAC people involved, it could have cost me a lot of money in service calls and/or equipment replaced that didn’t need to be.