I have a Richmond model 8MV50-2B. I'm having issues draining the tank to check the electrodes. Normally, on a water heater there is a shutoff down near where you attach the garden hose to drain the tank. I can turn the plastic fitting that the garden hose attaches too and take it off, but then there's no way to control the drain when you open the pressure relief valve at the top. What am I missing on this particular unit?

Spark is shorting out . clean spark electrode , check connection on spark electrode . change spark electrode

I'm not sure what you mean by "gurgles when refilling." If you mean that it is making noise when heating the water, that is usually a sign that sediment has built up in the bottom of the tank. This results in the surface of the tank bottom to overheat and the sound you hear is the water flashing to steam. This usually results in tank failure as the glass lining will crack an the tank will rust out. If it's not too late you could drain and flush the tank to try to remove the sediment but if has hardened to a solid mass it won't come out.

Some hot water means upper element is good, reset button is pushed in and not tripped, overheating is not issue, wires connected at top of tank are probably good, and unit getting power, but not necessarily full power. Otherwise we have not ruled out anything else.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#new

Check for crossover.
http://waterheatertimer.org/Crossover.html

Check for leaks: turn off all taps and put ear against pipe.

Gene
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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Tom W must have been 'recommended answer' from past answers, and not live answer.
What did Tom's answer say?
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Copy following link for general steps for Rheem, Ruud, Richmond, GE tank-type gas water heaters:
http://waterheatertimer.org/How-to-repair-Rheem-TRD.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Which type Richmond water heater?
Is this a tankless water heater or tank-type?

Tankless are notorious for 'cold water sandwich' under exact conditions you describe. You might need tankless with larger BTU burner.
Don't install a tankless.
http://waterheatertimer.org/Troubleshoot-Rheem-Tankless-water-heater.html

If you have tank-type water heater, then I suspect a clog in the hot water line, or single-handle faucet cartridge in show is going bad.
Same problems can contribute to tankless problems.
http://waterheatertimer.org/Low-hot-water-pressure.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Question posted under tank-type water heaters.
Open following links for instructions:
Replace drain valve:
http://waterheatertimer.org/How-to-replace-water-heater-drain-valve.html
Replace TP valve:
http://waterheatertimer.org/How-to-replace-TP-valve.html

Maybe I should look at your unit but, I'm not familiar with an exhaust vent on an electric water heater. That being said, I can't find your system, I did look, if your have 5 gallons of water inside the metal outer tank, I hope it tripped the breaker. If it didn't, you had better turn it off. The only thing you can do really is, pull the inspection panels off, if there is a small piece of insulation covering the thermostats, pull them out. You're going to have to let it drain, air dry. Only the lord knows how long that will take. There is insulation between the fiberglass inner tank and the metal outer tank so, I would have to guess it's pretty saturated with five gallons of water in it. Is this actually a gas heater?

the valve at the t-stat is no good, ist behind the cover at bottom of tank. drain tank to remove, make sure you shut of gas and power first.

First shut off power then remove acess cover and carefully move insulation out of the way so you can see around elements.Check to see if leak is coming from around element.If it is determine what type of element you have. Either screw in or bolted in. Both have thick rubber gaskets that can be replaced by draing water heater and removing element then install new gasket and reinstall element.
To drain heater shut off valve on incoming cold water supply line ,make sure electric power is off. Connect drain hose to drain valve and put other end to floor drain or sump basin.You can open faucet on hot side near by to prevent vacumn and drain. If you have screw in type disconnect wires,marking them for reattachment,then use large open end wrench or pipe wrench on hex section of element and turn to left to remove. If you have bolt in element spray bolts with wd-40 or similar and carefully loosen bolts then disconnect wires and remove element.install new gasket and reverse to reinstall. I would recommend that you replace elements at this time if you are sure this was the source of the leak.
If you don't think it's leaking around elements then check fitting on both water lines to water heater to be sure they are not leaking and seeping down thru insulation and leaking out of the bottom of heater. Next check around drain valve for leak and if it's leaking you can try tightening it a little or replace it with 3/4 x2 brass nipple and 3/4 inch female iron pipe boiler drain. Use teflon tape or pipe joint compound on all threaded connections.
After you have eliminated all other sources for leak then it is probably the tank itself. If it is less then six years old the tank should still be covered under warrenty. Most warrenties will give you a new heater but installation will not be covered unless you have extended service coverage.
I hope this helps you some. Thank you