My tenant’s gas water heater has a Honeywell control valve. He keeps it at maximum heat. the pilot went out a few times, and will now stay lit, but the burner won’t ignite. It did have a code flashing 4 times (excessive heat shutdown), and I have cleaned out the arrester, vacuumed the inside of the chamber, but that didn’t work. What could cause this?
Typically 4 flashes indicates high temperature shutdown which can be caused by improper venting. Check the top of the tank for signs of backdrafting.
If there isn’t a venting issue you may have to replace the gas valve and ask your tenant to keep the heater at a lower temperature.