"New" Enclosure

Putting this here rather than DIY since the actual question is about the heating, not the enclosure itself. Mods feel free to move if required.

So, Our "Snakey", who we've had about a year, and would be about 18 months old, is growing nicel. I've been mostly lurking about here leeching tips as required. Thanks for the help, even if you didn't know you were giving it ;-) But he's hit a little over 60cm now and so is getting somewhat large for his 30x30x30 terrarium that we received with him.



So I picked up a second hand "Reptile Enclosure". It's a converted cabinet, and a pretty rough conversion. But the price was right, and I can do the few fixups needed to get it usable.



It's 95cm L x 45 D x 70 H. I need to move the heat lamp socket forward a little, it's too close to the back. Put in a vent on the cool side (I'll use the existing hole where the lamp is for the warm side vent), seal the base with pond sealer, clean the glass, buy a sliding door lock and put in a strip of timber to hold the substrate in. All pretty easy stuff.

The lamp in there is a 50w. It's nowhere near enough. With a 21 degree ambient temp, it was barely able to crack 27 degrees inside the enclosure, directly under the lamp, after running for a few hours. The thermostat that came with it is a simple on-off EcoTech, so I'd much rather switch to Ceramic lamps (The socket is ceramic already) and use my Microclimate PWM thermostat that's currently running his little 5W heat mat.

So, my main question is regarding the new lamp. How big? I've googled, used the search function here, there really doesn't seem to be any math to do to calculate this. Should I just go the 150W and be done with, let the thermostat do its job? Or will 100W be hot enough? Is there any calculations to work it out, or is it really just suck it and see?

Thanks

Put a basking rock under the heat, and try a 100w CHE. Let it heat up, and measure the temp on the rock. That's how we have always tested out new enclosures. Change the wattage as/if required.

If possible I would avoid relying on the thermostat too much. They are great to help control the heat source, but you should always be prepared for it to fail. If your heat source is too powerful and your thermostat blows, 'Snakey' will cook.
For that size enclosure I think 50 - 75 watts would suffice. If you find you need to increase the temperature of the basking area, consider installing a shelf or similar below the lamp, so the snake can get closer to the heat source and increase it's body temp. It's important that it can still escape the heat when it wants to.