I recently changed all the heaters and thermostats in my house with brand new heaters and programmable thermostats. All heaters are wired to 15 amps double pole breakers with the appropriate size wire(14 is it? It was inspected so it is the right size). In my living room, I changed the 2000 heater for a 2500 watts. There is also a 750 watts on the circuit. Correct me if Im wrong, but the load on a breaker should not be higher than 80% of the total load the breaker can take. So 80% of (15amps x 240 volts) gives me 2880 watts. So technically I am good, but I somehow worry if I should have kept the original size for the heater. All is fine, no breakers are popping and both heaters work good. Am I just worrying for nothing?

Thanks

The 80% rule is a safety factor for the circuit breaker, no overcurrent protection device shall exceed 80% of it's rating, unless the OCPD is rated to be loaded at 100%, which most are not, and certainly your is not..

Then, a branch circuit conductor shall be rated 125% of the load. So 2500 w + 750 w=3250 watts x 125%=4062.5 watts /240volts = 16.93. The wire must be #10 wire on a 30 amp circuit breaker. You are really pushing the 15 amp circuit with #14 wire.

Electric heat is considered as a continuous load, and these safety factors are universal for any load, and are very typical.

Sorry but I see no other choice but to reduce load on the circuit. You can check with your inspector to double check me, but he should see it the same way.