rheostat splitting?

[big d]

so until my flexwatt arrives, I've been using heat pads for my balls.
a heat pad I bought today is a little hotter than I'd like so obviously I want to plug it in to my rheostat.
the stat already has 2 pads (only 2 inputs) plugged into it ,

so instead of trying, I thought i'd ask first and avoid damaging anything;

is it possible to plug a splitter or powerbar into a rheostat and run multiple heat pad from it?

[SlitherinSisters]

I wouldn't do it, only because I'm not entirely sure that it's safe to do so.

What you can do is go to Lowes, or any home improvement store, and get a lamp dimmer. As long as your room doesn't fluctuate in temps too much you it will be fine. Plus you said it's just a short term solution. A dimmer is $10 a Lowes.

[big d]

true. thats not a bad idea.

[Kaorte]

Rheostats really aren't a good permanent heating control. If there is any spike in the room temperature, your heating element spikes with it.

It would be more worth while to get a ranco or johnson controls thermostat from reptile basics. Then you won't have to worry about temp fluctuation and you can plug up to 6 identical heat sources into it.

[MarkS]

I used rheostats almost exclusively for about 10 years before slowly changing over to thermostats. If I remember correctly, my rheostats were rated for a maximum of 600 Watts. How much wattage it can handle should be printed somewhere on the rheostat. Just make sure you don't go over that and you should be fine.

[Skiploder]

Rheostats really aren't a good permanent heating control. If there is any spike in the room temperature, your heating element spikes with it.

It would be more worth while to get a ranco or johnson controls thermostat from reptile basics. Then you won't have to worry about temp fluctuation and you can plug up to 6 identical heat sources into it.

Please explain how a rheostat will spike with the room temperature.

Like MarkS, I used rheostats for many, many years before switching to proportional thermostats and never - I repeat, never had an issue with spiking when the ambient rose.

Never. A rheostat works completely independently of the ambient temperature. The ambient has absolutely nothing to do with how your proportional or regular thermostat operates, since those devices utilize a probe that measures the specific temperature of a heating device - not the ambient.

I still use a rheostat on two heating elements on my juvenile pseustes set up - one for the small RHP and one on the bottom ultratherm. Regardless of the ambient temp in the snake room, they maintain steady, even heat. Neither an UTH or a RHP will raise the ambient very much an enclosure. If you're worried about spiking ambient temps you need to regulate the ambient temp in the room which has more to do with the ambient temp in an enclosure than anything else.

As to splitting a rheo - I've never done it and would recommend spending $10 on a second one.

[kitedemon]

Skiploader, I am sure that you have had constancy with your rheostats for years I am 100 percent sure of that. You have also stated the crux of the rheostat issue. Constant ambient temps, they are unable to do more than deliver X (say 30%) power that will raise x (say 10 degrees) over ambient. That is great I am also confident in saying you have multiple rack systems and a dedicated room to you collection. That space has fully regulated ambient heating. You don't have the issues that exist if you have a small collection, no rack system (that creates a micro climate) in a living space. My house and the area I live has rapid and large temperature changes outside (26ºC 46.8ºF change in 24 hours) The interior temperature also changes with it. Where my snakes are I have ambient temperature variations from 84-70ºF. A rheostat cannot work under these conditions. My herpstat keeps the hot side 91º constant and my cool side from thermo-spill shifts a few degrees up and down from a base line of 80.9. When I was testing a set up with a rheostat I was getting hot side variations of ten degrees up and down and 15 on the cool side. That is unacceptable. I actualy and switching soon (next full cleaning day) to twin heating systems controlled by a herpstat pro One for the cool side one for the hot side. so I can have a comfortable work room again!

[Skiploder]

Skiploader, I am sure that you have had constancy with your rheostats for years I am 100 percent sure of that. You have also stated the crux of the rheostat issue. Constant ambient temps, they are unable to do more than deliver X (say 30%) power that will raise x (say 10 degrees) over ambient. That is great I am also confident in saying you have multiple rack systems and a dedicated room to you collection. That space has fully regulated ambient heating. You don't have the issues that exist if you have a small collection, no rack system (that creates a micro climate) in a living space. My house and the area I live has rapid and large temperature changes outside (26ºC 46.8ºF change in 24 hours) The interior temperature also changes with it. Where my snakes are I have ambient temperature variations from 84-70ºF. A rheostat cannot work under these conditions. My herpstat keeps the hot side 91º constant and my cool side from thermo-spill shifts a few degrees up and down from a base line of 80.9. When I was testing a set up with a rheostat I was getting hot side variations of ten degrees up and down and 15 on the cool side. That is unacceptable. I actualy and switching soon (next full cleaning day) to twin heating systems controlled by a herpstat pro One for the cool side one for the hot side. so I can have a comfortable work room again!

I have mainly 4 and 6 foot cages - I'm down to one 4 drawer rack. If you are using a heat pad, as the OP stated he is, a rheostat (once set to the basking site temp) will NOT heat ambient in the enclosure.

In fact, my one rack is run off of a Herpstat. The Herpstat is consistently running between 40 and 50% to maintain a 91 degree basking spot. Isn't that what a rheostat does?

The RHP in my pseustes grow out cage is set so that the at it's surface, the temp of the panel is 127 degrees. That works out to a constant 90 to 92 degree basking site on an arboreal branch.

In my ackie enclosure, one of the halogen lamps is set on a rheostat and it maintains a 160 degree basking spot. Since the cage is 6' long, the cool end of the cage only varies a degree or two despite this consistent output.

In a small enclosure like a small cage or tank, and using a heating lamp or a CHE, you could consistently raise the ambient temp with a rheostat.

The problem with not controlling ambient temps in the room is that regardless of what heating element you are using, you will also have wild ambient swings in either direction. None of my thermostats, be it on an RHP, flexwatt, bulb or UTH could make up for the 14 degree ambient variance you listed. Only proper control of room ambient temps can achieve that.

People come on here all the time asking it they can use a rack in a room that is a 68 degree ambient. This brings up a valid issue - ambient room temperatures are just as important as ambient cage and hot spot temperatures. A thermostat or a rheostat is one of two temperature control issues a keeper should be concerned with.

Let me repeat, in the OP's case, a rheostat hooked to a heat pad is not going to affect the ambient temp if properly set.

[Kaorte]

If your room temperature is not constant you will see temperature fluctuations with a rheostat. They can't measure the temperature of the heating element so it can't adjust when it gets too hot or too cold, you have to manually adjust it.

Skiploder, would you recommend a rheostat over a thermostat?

[kitedemon]

I agree, they do not change the ambient but a proportional thermostat will compensate for ambient variations that a rheostat cannot it just set a specific output percentage nothing more. If you have the constant ambient temps the rheostat works perfectly that is ideal.

Also there is two ambient temps that we have to be concerned with the ambient room and ambient enclosure. A enclosure heat source will effect the ambient enclosure temps mine does as the enclosures ambient temp (taken from about 2 inches off the bottom on the centre line middle and front not an IR but a probe style for ambient temps) is higher than the ambient room temps. This is from the thermal gain of the primary enclosure heating.

"None of my thermostats, be it on an RHP, flexwatt, bulb or UTH could make up for the 14 degree ambient variance you listed."

Mine does! The cool side is currently at 81.1 the room ambient is 77.3 and my hot side is at 91.1 running at 10% power (13.8º) I had to run tests and have a higher than normal wattage for my enclosures to compensate and over come the variations. I can handle a drop of another 7-10 degrees in a pinch. I had to increase the efficiency of the enclosure to handle that however.


I have no experience with rack systems but quite a lot with temperature regulated control systems. I am sure a rack could be designed that would work perfectly in a 68º room. It just requires lots more money. Now I think about it I am kinda surprised that they are not available, too small a market to mass produce enough to make it cost effective I guess.

OP Skiploader is correct a rheostat hooked to a heat pad is not going to affect the ambient temp if properly set. If you are using heat pads you must limit the voltage with a rheostat, for this to work correctly you must also have a room temp set to the cool side temperature of 80º. The alternative to this is more complex and expensive.

Skiploader I think we are actually saying the same thing in a differing way. I am sorry for a bit of a side track everybody it is a personal project of mine, I love technical problems.
Alex