Blue light flashing three times

possible heating element shorted

May need to call a service to check.

The following gives a variety of brand names.

http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#honeywell

The gurgling sound sounds like you have gotten air into the system. Try purging the air out at the bleeder valves. Also check and make sure that your water inlet is working.

http://www.rheem.com/products/tank_water_heaters/contact_support/

Don't let them push a service call on you though. They don't publish any info

http://www.worcester-bosch.co.uk/homeowner/literature/gas-boiler-literature/greenstar-15ri-literature. Hope this helps :)

Copy following links for Richmond/Rheem FV to identify gas control valve and options for replacimg TRD glass vial:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/How-to-repair-Rheem-FVIR.html
http://www.thetankatwaterheaterrescue.com/forums/forum3/
Add comment as needed
Gene

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

Make and model?

http://www.digelair.net/pdfs/TECHLIT/BOSCH/MANUALS/Bosch-ProTankless_AM.pdf
http://www.bosch-climate.us/files/201009031238250.GWH715ES_English_12.2008.pdf

Above are the manuals required to diagnose and service your error code.

EA: No flame ionization detected with water flow.
Verify that all manual gas shut off valves are open. Check gas type. Reset error code and open a water tap to cycle the heater in an effort to purge air on new installations. Cycling hot water tap on and off multiple times may be necessary. If heater still faults with EA error code, have a licensed gas technician properly purge air out of the gas line leading to the water heater. Check three wire connections to ignition group on the lower front of the heat exchanger are secure. Check gas pressure. Check venting specifications are met. Improper venting may cause premature failure of the flame sensor rod. Check that the minimum power fan speed has been adjusted to the proper value. Observe inside the viewing window of the heat exchanger when a hot water tap is opened. Sparking should be followed by a steady blue flame. If flame is unstable or yellow with proper gas pressure.

Is it flashing 2-3? Try this: You can reset the control by unplugging the blower during start up, leave unplugged for at least 5 seconds, plug back in and within 30 seconds cycle temp control from hot to low 6 times.