Gil & Greg: I'll give this another try at Posting a reply. The temps were measured over several days time, with the heaters being both turned off between temp measuring events. The water temps were measured, one heater at a time being turned on, the other one off, with at least a day in between each event to allow the water in the heaters to cool off. The point of measurement for each heater was the outflow from the PT relief valve, which can be manually opened, and which is routed in my coach via a silicone hose about 2' to 3' long, thru a hole in the bottom of the compartment. Water coming out of those hoses was about 150 degrees for each heater/hose, demonstrating that each heater was working properly/the same.
The drain valves in this case were not an accurate source of temp measurement because of the way they are routed, so were not used for measurements.
Hope that clears up an confusion.