Okay. I finally have a small update on what I’ve done.
Firstly, thanks for your reply. I usually keep the area and vents under the water heater clean. It’s a small area and my washer / dryer and furnace are in the room. So I normally vacuum and dust monthly at least. I did it again after your message because it shut off while I showered yesterday. Cleaning didn’t help.
I also read in the manual that there is a place to adjust the flame but I’m still trying to figure out what it looks like and where it is. I did remove the controller cover and am thinking it looks more like a nut than a knob based on the generic image in the manual (of a ‘typical’ controller).
I’ve since needed not water, so I restarted it earlier today. I’ll wait until it shuts off again before attempting to adjust. I’m slow-going because get a little anxiety when investigating as well. ðŸ˜ž
Also, I did get on my roof to check the vent – FYI the furnace and water heater vent intersect and share the flew – and there is no blockage and I don’t have a fan.