Hello robertoa

Information on heat traps in tanks is found (Here - Link 1) (http://www.waterheaterrescue.com/pages/WHRpages/English/Troubleshooting/Tanklets/water-heater-heat-trap-issues.html) and (Here - Link2) (http://www.r2000manitoba.com/hot_water_tanks.shtml).

I hope this explains everything !

:)

What is a heat trap at the top of the tank...
Credendovidis gave you a explanation. Here's what they look like. Regards, Tom