This Thursday, we at NACH.TV are shooting a master plumber inspecting two hot water tanks, one gas and one electric.
We need your input.
** What do you want to learn?** What do you want to see?
Tell us, and we’ll do it for you. Okay? 
Thanks.
How about something on the different sacrificial anode types and where they are used?
Maybe a simple explanation of the operation/function of the gas control valve
Ben,
This may help with inspection coverage
Texas SOP
(k) Water heaters. The inspector shall:
(1) report the energy source;
(2) inspect the unit and report as in need of repair fittings that leak or are corroded;
(3) report as in need of repair temperature and pressure relief valve piping that lacks gravity drainage, is improperly sized (no smaller than the outlet fittings), has deficiencies in material, or lacks a correct termination;
(4) report as in need of repair a temperature and pressure relief valve that does not operate when the valve is of an operable type and operation will not cause damage to persons or property as reasonably determined by the inspector (for example, it would be reasonable not to operate the valve if there is improper or undetermined termination of the drain pipe, a corroded or damaged valve, improper installation of valve or drain pipe, the drain pipe is of inappropriate material or there is no water supply cut-off valve at the unit);
(5) report as in need of repair any broken or missing parts, covers or controls;
(6) report as in need of repair deficiencies in the burner, flame and burner compartment, the operation of heating elements and the condition of wiring;
(7) report as in need of repair deficiencies in materials used for the gas branch line and the connection to the appliance, the absence of a gas shut-off valve, or a valve that is not properly located, is inaccessible, or leaks;
(8) if applicable, report as in need of repair deficiencies in the vent pipe, draft diverter, draft hood and their condition, draft, proximity to combustibles and vent termination point, observing for adequate combustion and draft air;
(9) report as in need of repair the lack of a safety pan and drain (including the termination of the drain line) when applicable;
(10) report as in need of repair an unsafe location or installation; and
(11) inspect garage units or units which are located in rooms or enclosures opening into a garage and report as in need of repair the following:
(A) a lack of protection for physical damage to the unit; and
(B) burners, burner ignition devices or heating elements, switches or thermostats that are not a minimum of 18 inches above the lowest garage floor elevation.
Oooooh…Yeah, Baby.\:D/
Where and how the different types can be installed; i.e. garages, interior rooms of the home, etc. Typical discrepancies from homeowner installations and repairs (or should I say attempts at repairs) i.e. TPR valves installed on top of the pipe extention so as the probe is not within the upper 6 inches of of the tank water, lack of using dilectric unions and what they look like (99% of the time we find standard old plumbing nipples in place of the unions). Proper flue installations, common discrepancies, proper inspection techniques, flame roll out on older units, common materials used for piping, do’s and don’ts, when to say the tank is shot all to hell and just needs to be replaced (I know when but some do not). Thermostat locations and precautions, etc.
How the expansion tank works and why it is on the cold side.
Drain pans.
Hopefully it will have more detail than the fireplace one which did not even delve past DIY.
How they are used for radient floor heat
tankless
Please do not waste time on gee 40 gallon models are popular 101.
That all sounds great !! I look forward to watching, and learning!
You guys Rock!!
Yea, to pick up what Robert says about the xtank, especially when there is a backflow preventer installed on the water service. See this too often, (no xtank) on retro-fits.
To whoever wants this is a pretty good explanation of expansion tank and why. From watts:
Cover when and where you would install an extrol tank.