Built in HERMS coil / Immersion Chiller

Hi Elco,

I would like to canvass your’s and the rest of the community’s opinion on a potential modification to my setup.

I currently have a two vessel system, 20 gal Blichmann kettles, one is the mash tun the other doubles as a BK and HLT. I have a 7.5m stainless steel herms coil mounted to a lid.

During the mash the wort is recirculated through the coil which sits in the HLT/BK, the water heated by the element which is controlled by a PID and temperature probe on the coil outlet.

The sparge is done by pumping the entire volume of water on top of the mash bed and then back into the HLT/BK for the boil. Obviously the lid with the coil is removed from the BK for the boil.
Cooling is done with a plate chiller.

This setup I find works well, returning 75-80%.
I would however like to simplify the system a little more and use a fixed HERMS/Immersion chiller in the BK and ditch the plate chiller.

My questions (finally) do you think your new High Flow HERMS Coil would be efficient enough to use as a chiller? Do you think the bulk in the kettle would negatively impact the boil?



I think you could use it as a chiller, but you definitely should add whirlpooling to increase efficiency.

The biggest contributor to inefficiency in an immersion chiller is that it cools the wort around it and if that wort isn’t replaced by hot wort, the efficiency drops. You want to be stirring or whirlpooling while you cool.

In our tests when using the coil for heating the mash, actively circulating the HLT made a big difference in efficiency.

One thing I would do if you use your coil for double duty is to flush it with clean water before you are going to boil. You’ll also want to make sure that any pressure buildup inside the coil can escape.

I don’t think it would affect the boil much.


I already have a whirlpool tube in the boiler and the tube would flushed with the sparge water prior to the boil so it should be clean.

Just need to part with some money.

Thanks for your input.


I’m thinking of buying wort myself. Which would you recommend from this list https://diligentchef.com/best-wort-chiller/