Reptile & Amphibian Forums

I dont think im fully understanding Thermostats/Rheostats/ Proportional vs On off.

I was looking at Jeffs therms. And he stated that he runs 24 tanks off just 1 thermostat. And after looking at the picture of his.. i just dont see how this works. The thermostat it self only has 1 temperature probe.. so how can you use this for multiple tanks? Do you just monitor the temperature in 1 tank (the coldest) and base your overall setup on that 1 tank?

Im looking at the picture again and know your plugin your heating elements into his power strip.. but you would still need to run additional powerstrips on that one to get even near 24 tanks?

here is the link to the photos on Jeffs page that im speaking off
http://www.boaphileplastics.com/thermostat.html

Those are Ranco thermostats - ON/OFF type controllers. ON/OFF means that there is a differential around the setpoint. Say your desired temp is 82 deg (setpoint).. when the sensor near the heater reads 82 deg, the output is OFF. If the differential is 3 deg, then the output to the heater won't go ON until the sensor reads 79 deg. Get it?

Proportional sends pulses of power to the heater to maintain the setpoint. There is no differential persay - the heater always maintains the setpoint temp.

Those Ranco thermostats have a rating of around 1650 Watts or so. So, if each cage uses say 40 watts of heater, you could run power to alot of cages from one thermostat. Yes, you would need to daisy-chain power strips.

There is only one sensor per each thermostat, so that sensor had better be on a cage that the heater is always plugged in and always working. Otherwise, if the sensor senses low temp in the cage (due to that heater being unplugged), the output to the other cages will be ON, and there is the potential for overheating those other cages. That is why you run TWO thermostats wired in series if you have lots of cages. The odds that two sensors in different cages will be in cages with unplugged heaters is way less than with only one.
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Mark

Ok thanks.. that did help. It did understand the on/off therms.. but thought that I had seen some other therms (helix?) that their temp probe was a long piece and not a "probe" on the end of a wire.

I do understand that you will have to piggy back other heating devices off the power strip.. but again thanks for making it clear lol. The whole multiple tanks and just 1 heat probe kept confusing me -

Againthanks for clearing it up