Robert11 wrote:
Hello:

Never had the opportunity to look inside one, but as we just had a new wter
heater installed, I became curious. It's the typical upright cylindrical
kind, gas fired.

Was wondering:

Is the unit designed to keep a certain water level always in the tank, or is
it designed to trap an air bubble at the top ? There isn't any float
regulator inside, to the best of my knowledge.
How does this work ?

The tank is completely filled with water at service pressure and there
is no air cushion.

If it truly fills totally with water, isn't the internal water pressure,
with no elastiucity, a problem ?


Yes, that is why an expansion means is specified and usually required
for most homes.


How do they maintain such a good (hopefully) seal at the top of the tank ?
I imagine that the tank is fabricated from rolled steel, with a top and
bottom fastened on somehow. How is this done and sealed ?

Any pix on the web showing internal construction ?
Couldn't find any.

Thanks,
Bob