Chiller Temp Question

[Gieser]

I just installed a 1/2 hp Tradewinds chiller on our 310. I want to keep my temp as close to 77 as possible. There is a controller for the chiller, so I do not have it hooked up to my AC3. I set the temp on the chiller at 77. The temp in the tank may rise to 79, and within 1.5 hours be down to 76.2. Then it will rise to around 79, and then very quickly within 1-2 hours, be down to around 76.5. There was a setting on the chiller that needed to be be set at "2" meaning a 1.1 degree difference for the chiller to operate. Is this temperature change okay, or is there something I need to or can do to keep it more consistently at 77?

[DarG]

Absolutely fantastic chillers. I personally would have gone larger for the size tank you have but that temperature change should be fine. I have a 1/3 on a 90 gallon. It only runs once or twice on the hottest summer days but I have it set exactly the same. 77 degrees, with 2 degree differential. I dont use another thermometer besides what the Ranco controller reads.
My Tradewinds kicks on at 79 and off at 77 according to the Ranco controller. That is the 2 degree differential used by Ranco ... kicks on at 2 degrees over the set point temp and off at the set point temp. Again, according to the Ranco controller. I have used a seperate thermometer in the past and it seems that the temp swing shown by both the Ranco as well as the Medusa controllers is smaller than what is actually measured by a thermometer. Your 3 degree swing as measured by a seperate thermometer seems about right if my memory serves.

Anyway ... to the point of your question. The same swing in my 90 gallon occurs in 40 minutes or so. No problems at all and I have been running chillers for 20 years. So that swing occuring in the course of over an hour to two hours in your tank should cause no problems at all. The issue with the Ranco controllers is that apparently a 1 degree differential is actually only a 1/10th of a degree as seen by the controller. This will probably short cycle the chiller which is not good for it. So stay with the 2 degree setting that you have now, it will be fine.

I have tried the 1 degree differential with the Ranco. It is strange. The controller will sometimes turn the chiller on for 5 minutes and sometimes 20 minutes. But it cycles on and off too frequently. You can try it with your much larger water volume and see what happens. But again, you dont want the chiller turning on and off for very short cycles. The Medusa controller I had in the past with a different chiller I had set to 1 degree. It was a true 1 degree, not a .1 degree. I believe the actual swing was close to a full 2 degrees with that controller set to 1 degree differential.

A little verbose but I hope I answered your question.