[KevinK]

I have 3 – 300W heaters, one about 1 year old, one about 8 months and one about 2 months, all connected to one and the same controller and because of that all have their heater set at max, as the controller handles the temp the 3 heaters are all different brands.

watching the heaters, and a external amp. meter the heater go on and off all the time while in heating mode, not all at once but as followed, as i had timed it (2 heaters)

heater a:

2:16:40 off
2:17:45 on
2:20:25 off
2:21:.35 on
2:23:53 off
2:25:55 on

that is 192 seconds off from the 555 sec. / close to 35% off

heater B different times within the same 2:16:44 to 2:25:55 as heater A

26 sec. off
15 sec. off
28 sec. off
28 sec. off
26 sec. off
27 sec. off
27 sec. off

that is 177 sec. off from the 555 sec, / close to 32% off

so independently from another thy go off and on (and my third heater as well)

would thy have a internal thermostat that allows them to get only a X temp in the glass tube before thy go off

the main breaker popped from our heat pump in the house, and thus it became colder in the house overnight, and found that the heaters did not keep up, hmmmm. 32 to 35% of the time thy are off