Temp control in a very hot/cold room?

[apexkeeper]

So I decided I want to put a small tank in my office at work. Probably a 30 or 40 gallon but I have some concerns since my office temperature varies greatly. It's an office in a machine shop so not the classiest place in the world and I don't leave the AC on constantly so in the summer it can get into the 80's. In the winter if people are coming in and out it can drop down into the high 50's low 60's.

I have a chiller laying around and obviously a heater isn't a big deal but A. can the tanks water temp be safely maintained through the extreme fluctuations in room temp? B. If so what type of thermostat system would be ideal to run both the heater and chiller?

[shifty51008]

get a dual ranco temp controller, it will be able to turn on a heater if it's to cold and turn on a chiller or fan if it's to hot.

http://www.etcsupply.com/ranco-etc211000000-stage-prewired-temperature-controller-p-110.html

[salajander]

You will probably need to overprovision your heater wattage as well if you expect to have a 20 degree diff from room to water temp.

[julie180]

Multiple heaters would be better than 1 larger one.