OK, first question... are you SURE the heater isn't heating water? As in, did you go outside, remove the cover, pop the release valve, and only cold water came out? If not, try that first to confirm the heater is the culprit.
If you do feel hot water from that release valve... then first thing to check is your "external shower" (hose) in the wet bay compartment. Make sure both Hot & Cold valves are turned off (closed). If they are left open, the water will mix and you will not get hot water from your sink & shower faucets.
2013 VOLTAGE 3200 (EPIC I & II)
2014 Ford F-450 PLATINUM