Red Bulbs for retics?!?

[dannybgoode]

I am an M0 radio amateur ( equivalent to an Extra class ham in your neck of the woods) so have a very sound knowledge of electronics.

A rheostat does not control the temperature in the same way a thermostat does as it does not take any account of changes in ambient room temperature-it will apply x watts to the heating device regardless of whether the ambient temp is 0c or 100c.

This can (and does) cause overheating whereas a proper thermostat will compensate accordingly.

Further a rheostat applies constant power to the device being heated whereas a pulse proportional stat sends on/off pulses to the device being heated (hence why they're not desirable on a light emitting bulb) and controls the temperature by varying the length of the on pulses. This is a far more efficient method of temperature control as no electricity is 'wasted' so to speak and is by far the best method of controlling a ceramic element (you are correct in that non pulse thermostats work in a similar manner to a rheostat-indeed they contain a rheostat-but as per my earlier point they compensate for changes to ambient temps).

All thermostats I have ever come across will only fail in the off position and as for hysteresis (I don't need to look it up but thanks for the offer) your rheostat set up taking into account my point about ambient air temps will over a 24 hour period create a far larger temperature than a proper thermostat so is a total non issue.

Yes, a rheostat is better than no temperature control but it is no substitute for a proper thermostat either and to suggest otherwise highlights your lack of knowledge not mine.

[bigsnakegirl785]

Originally Posted by Hank

It is best to not speak of what YOU are not familiar with. That Is EXACTLY how dimmers(electronic control) and rheostats(variable resistor) operate, by varying the voltage which results in a temperature/light change of the controlled device. I feel most confident relying on a dimmer, while a thermostat set-up will either fail in an ON OR OFF state, depending on the relay configuration, a dimer provides a constant voltage output WITHOUT the hysteresis swing(look it up), of a thermostat control. AND, to be smart, isn't it OUR responsibility to be 100% aware of our pets surroundings? ALL the time?? If you like to spend lots of $ to improve your "feel good quotient", then go for it.

Sure, they control the voltage, but they don't read the temperature and adjust the voltage accordingly. That is up to YOU. So, no, they don't control the temperature. YOU control the temperature.

Herpstats actually have a fail proof in them that will cause them to shut off should they fail, and the part responsible is replaceable and they sell the parts. So not entirely true.

That's what thermometers and temp guns are for. To double check that the thermostat is working correctly.

I'd really rather not go to work one day with the dimmer set for morning temps and then when it gets up into the upper 80's having the heat STILL running and find out my animals have overheated because the heat was still running in such a warm room and they had no way to escape because - the temperature was not being controlled. The heat sources would still put out heat, the heat gets trapped in the enclosures, and the temps continue to rise because - hey enclosures trap in heat! Even thought the dimmer is controlling the voltage the heating element will continue to put off heat no matter the ambient temps.

Sorry, but I'm not putting my animals' lives at risk like that.