rheostat splitting?

[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.