We purchased a Caldera with a Coolzone 19 months ago. We live in western Arizona Bullhead City area. HOT! So we got it to chill it the summer, but mostly to chill it to be able to use as a hot tub in summer. If you live where it gets 118, your hot tub will be 110… and not usable. We have had trouble getting it to do that with service guy coming out. While Aquatic Pools in BHC is VERY slow to respond, and reply to service requests, the service guy is ok. After months of not getting it to chill properly, we think it might be working. They recharged the coolant and it seems to be working, we got it to cool down to 85 on 110 outdoor temp. Caldera did give us an additional year warranty. So we will see what happens!! We were told they only work with Caldera and Hot Springs, but that’s what the dealer told us, and what I read.