Comparing an immersion chiller to simple ice bath

For my first few brews I used an ice bath to cool the wort after the boil but had read so many glowing reports on the internet and in books about how much faster it is using a chiller, I decided to give it a go. This page reports my measurements comparing the simple ice bath to an immersion chiller.

Experimental Procedure

Figure 1. I am using a conventional 50' x 3/8" stainless steel immersion chiller arranged in a double coil, shown here sitting in the brew kettle.

Reported here are three cooling tests with the chiller and three in an ice bath. Each consists of cooling an approximately 20 litre (∼5 US gal) batch of wort.

The chiller

Appalled at the idea of just running so much water down the drain I decided to use an ice bath as the water source and a pump to circulate the cold water through the chiller. In fact this is not purely a question of water economy. The amount of water concerned would completely flood our tiny California garden and there simply is not any sewer drain. (As it almost never rains there is no need for gutters, down-pipes and drains.) I do also note that though this method saves water, it consumes power in making the ice so the overall impact of this process compared to using tap water is not entirely obvious to me. The pump is possibly less powerful than would be ideal. I get about 4.5 l/min (1.2 USgal/min).

For the three chiller tests:

The ice bath

The comparison ice bath data are derived from simply sitting the brew kettle in an ice water bath and occasionally stirring or rocking the kettle. All the ice bath tests were performed in Colorado where the ice comes for free by simply shovelling snow from the garden.

It can also be seen in the plots that the boiling point for the ice bath tests was only about 95°C due to the altitude. In California we are at sea level so for the immersion chiller data the plots do start from 100°C.

Figure 2. Three cooling runs using the ice bath method. Dotted lines show the raw data which exhibit large swings whenever the kettle was stirred. To smooth the data and make it easier to judge the overall cooling rate I fit simple power-law cooling curves which are shown as solid lines. In the following plot I show only the smooth fit, but remember that is representing the uneven cooling shown here. Note how the cooling curves start from 95°C due to the altitude in Colorado where these data were collected.

Figure 3. Comparing the three immersion chiller runs to the smoothed cooling curve fits from the ice bath runs.


Thoughts on speed of cooling

Thoughts on stirring


It is nice to have and I expect to continue using the immersion chiller. I especially like the fact it produces my hot washing-up water for me outdoors without having to fire up the gas burner again. However in terms of rapidly cooling the wort I do not see much improvement over a simple ice bath. Of course if you do not like that conclusion there are many other variables that can be played with to get a different answer. Your own individual circumstances will have a considerable impact. For example your process is likely to be very different if living in an apartment vs. a house with a large garden or for those who live in a desert vs. among snow-clad peaks.

If you have comments or suggestions feel free to contact me: