If you can find it, ZOne VI made a Cold Light Stabilizer, which has a extra plug outlet for the heater and a sensor for the head, also has a dimmer so you can fine tune it. I've tuned mine so that most average negs from the main film I use processed my most used developer at the avg temp for the usual time gives a mostly correct print at 5.6 (sharpest F-stop on that enlarging lens) for 10 seconds at 8x10. I use a light meter on the base board at the 8x10 height and record the settings on a piece of tape on the stabilizer, so I'm able to recall the settings if they shift or drift, but the head output is remarkable steady. I have an Aristo V54 bulb.