Moved in to a new, fancy building. When I take a shower, hot water comes out for 3 or 4 minutes then turns cold. Then hot again after 3 or 4 minutes. Also, the water pressure slows down when the water gets colder.
The heater fires up fine. Thermostat is set near the top.
Anyone have any ideas? I have had many of these instant heaters over the years in Korea and Malaysia but never had any issues so no clue.