Dimming vs. Proportional Thermostat?

[AlexisFitzy]

Hey I made a previous thread about thermostats asking opinions on the VE-200 vs a Herpstat Basic/Into/Intro +. I want the best thermostat possible for my incubator and for my rack so now that I've gotten a lot of opinions on herpstats and VE's I'd like to know more about Dimming and Pulse proportional, which is better? I know I'm probably over killing this Majorly but I'm really curious and I want the best! Lol even though I know both of them are great thermostats. I've read a lot online the dimming thermostats are best used for controlling lights for obvious reasons and the pulse is better for mats and heat tape for some reasons that I'm not quite clear on. So hopefully you guys will be able to clear this up for me you guys are the best and always know how to answer all my silly, overbearing, and obsessive questions lol. Thanks so much!


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[Rickys_Reptiles]

Traditional On/Off (Non-Proportional) Thermostats
Before we talk about proportional thermostats, you need to have a basic understanding of how a regular thermostat works.
In a nutshell, a typical thermotat will monitor the temperature using a thermocouple or probe attached by a wire. When the probe tells the thermostat that the temperature has reached one degree (or whatever the case may be) above the desired temperature, the thermostat will cut power to the heating device, turning it off. When the temperature drops back down below the desired temperature, the thermostat will turn power back on to the heating device. It's a very simple idea - if the temperature needs to go up, power to the heating device is turned on. Once the desired temperature is met or exceeded, it is turned back off. That being the case, the heating device is either getting full power or no power at all. This type of thermostat is best suited for heating devices that work in a strictly on/off fashion.
Proportional Thermostats
Similar to a traditional thermostat, a proportional thermostat has a probe that tells it when heat needs to be applied or turned off. Unlike a traditional thermostat, a proportional thermostat works like a dimmer in that it can adjust the amount of voltage being applied to the heating device. But it's better than a dimmer because it can measure the temperature and it knows exactly how much power needs to be applied to the heating device to maintain the desired temperature.
As a general rule of thumb, if a heating device works in a strictly on-or-off fashion, it will not run without a set amount of voltage. As such, proportional thermostats cannot operate things like the furnace in your home, or even a space heater, because those devices need full power from the wall outlet in order to function. However, heating devices that we commonly use in the reptile hobby, like heat pads, heat panels, heat rope/cable, heat tape, ceramic heat emitters and even incandescent light bulbs, can be operated by a proportional thermostat. With these types of heating devices, a proportional thermostat may be your best option.
Pros...
Gentle Warmth
By applying just enough voltage to the heating device, you're providing a more uniform, gentle warmth. This is because the heating element (tape, pad, cable, etc.) is constantly running right at the desired temperature, rather than bouncing back and forth between full power and no power.
Longer Lived Heating Devices
With an on/off thermostat, the constant on/off action causes more wear and tear on devices meant to be run on dimmers like heat pads, heat tape, heat cables and especially light bulbs.

Cons...
Proportional thermostats will not run a furnace, space heater, etc.
The only downside to pr oportional thermostats is that because they work by applying varying amounts of electricity to the device they're controlling, they generally will not run certain types of heating devices.
*Remember, I said MOST...
Spyder Robotics makes an entire line of proportional thermostats that also have a "Non-Proportional" setting which allows them to be used as a standard "on/off" thermostat. These units are quickly becoming my thermostat of choice for python enclosures...industry leading technology and still competitively priced. Apples to apples, these things are a steal.

reference: http://www.acreptiles.com/

[patientz3ro]

On/off type thermostats work fine for just about everything other than WHITE lights. I have one connected to a terrarium canopy full of "lunar" heat lamps. It may cause bulbs to burn out quicker, but it hasn't been that bad for me. Many people will tell you that the temp fluctuations with an on/off can be pretty drastic, but I think that's an overreaction for the most part. If you're using a thin substrate like newspaper or paper towels, I can see how it could be an issue. If you've got a nice thick layer of substrate, it should retain heat well enough to keep that fluctuation to a minimum. It also depends on the thermostat. I have a VE 100 connected to my UTH, and the temperature only has to drop about 2 degrees to turn on. It shuts off as soon as it reaches the set temp. I have a second thermometer probe for redundancy, and they always match. Plus, I spot measure the substrate with an IR temp gun, and it rarely fluctuates more than 2 or 3 degrees.

I'd say that they both work fine with most applications. I'd base my choice on other features. Price, alarms, overheating shut off, night drop, etc. You could also look at the HerpKeeper system from Digital Aquatics. I haven't tried it, but it looks like it has potential.

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[hig]

Go for proportional for your incubator! You want steady temps and what better way then with the proportional. On/Off could cause too much temp fluctuation.

[AlexisFitzy]

Thanks for the replies so far guys so is dimming and on/off like the same thing? Because the VE-200 is a pulse proportional thermostat and has an on/off setting as well, but if I get the VE I'll have it on pulse proportional. With the Herpstat intro and the Herpstat intro + they are both Dimming proportional. And everything from the Herpstat basic 1 to the Herpstat 4 has advanced pulse proportional capabilities. So I'm really wondering if I should go with Dimming Proportional or Pulse Proportional (should've made this clearer in topic lol oops :p) but I've been comparing the thermostats a lot and right now this is the only feature holding me back from choosing one of these thermostats. The herpstats are great but have some extras that I don't really need for an incubator and hatchling rack all I really need it to do is measure temps to the T lol. They both have safely shut offs and measure to the same degree. Don't really need the night drop since I'll only be using this thermostat with eggs and hatchlings and I believe they don't need a night drop. But any who thanks so much for you answers! I've learned a ton with just the first 3 lol! So which is best Dimming Proportional or Pulse Proportional?


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[patientz3ro]

If I understand it correctly, dimming proportional applies just enough voltage to produce the required temp. On/off is just what it sounds like, and pulse proportional applies an on/off voltage to maintain temperature without the larger swings produced by an on/off.

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[AlexisFitzy]

If I understand it correctly, dimming proportional applies just enough voltage to produce the required temp. On/off is just what it sounds like, and pulse proportional applies an on/off voltage to maintain temperature without the larger swings produced by an on/off.

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Ok cool thanks for clearing that up so quickly.


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[EAC Reptiles]

Ok, dimming and pulse are both forms of proportional control. The difference is how it is done. A dimming thermostat will vary the actual voltage to get to the correct temperature. On a pulse control thermostat, the thermostat will turn the heating device on and off at a very fast rate to control the temp. The pulse will change the amount of time the heat is turned on to get the desired temp, but it does this on and off cycle many times a second which gives you an even and controlled temp.

I hope this somewhat makes sense. If not Google how a dimmer switch works, then Google pulse width modulation. Or another way of thinking about is a sine wave (dimming) vs a digital wave (pulse).

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[patientz3ro]

...I hope this somewhat makes sense. If not Google how a dimmer switch works, then Google pulse width modulation. Or another way of thinking about is a sine wave (dimming) vs a digital wave (pulse).

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Something tells me if she didn't understand the first part of your post, there's not much chance that last sentence is going to clarify things! Comedy gold right there!

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