2 small fuses on the top of Tempra water heater blow out almost every time I use hot water. Please advise what to do

SOURCE: Low amount of hot water

You say a very new water heater. You won't get 40 gallons of hot water from a 40 gallon water heater because the continuing influx of cold water will cool your hot water down. However, it appears that your bottom water heater element needs replacing. If the top element is bad, you'll get no hot water. If your bottom element is bad, you'll get "some" hot water. Try replacing the bottom element. DON'T FORGET to turn off the electricity AND water first (closeby towels are also handy)!

SOURCE: What causes Water to leak at top of Rheem 21V40S-2

the tank is broke and the water is under pressure , the insulation around it is forcing the water to come out of the nearest opening,, need to replace the water heater asap,,, it could blow at any time then you will have a flood

SOURCE: I am a homeowner and

Hi,
The reset button is kicking out because the themostat is not....The reset is a safety switch so to speak. It is there to turn off the element incase the thermostat does not. I nrare situations the reset can go bad and kick at too low of a temperature, but usually not.To check out what is actually happening you will need to replace the t-sta and see what happens or sit there with an electric meter and monitor what happens in what order, very time consuming...
My recommendation would be to just change the t-stat and rest bot at once and you will be good again.

heatman101

SOURCE: Reliance 40 gal hot water heater. Model 54020RS960

Hello Bill The temp stat is a square box clipped in under the elements .Can be replaced in 5 minutes.Need a large flat screwdriver.

SOURCE: Specifications sheet for Stiebel Eltron Tempra 24

hope this is what you need.
http://www.stiebel-eltron-usa.com/techdata_tempranew.html

http://www.stiebel-eltron-usa.com/pdf/install_tempra_tempraplus.pdf