Herms Coil

[Afterlife Spirits85]

Just wondering to people that have built their own Herms system, does ur coil sit in the heating element in ur hlt or is there a gap between them

 

[user 44743]

Usually a HERMS coil is heated by the water. The element can be on and off and its temperature can rise quite high at times, as necessary to maintain the water temperature. So the water is a more consistent and usually gentler method of heating the coil.

 

[mr_wibble]

I have a separate Heat eXchange vessel that houses the heating element and coil.
It has a much lower water volume than my HLT, so can change temperature far quicker.

The HX heating element is at the bottom of this pot, and there's about a 1-2cm gap between it and the bottom of the element.

I used a heating coil like this one: http://www.ebay.com.au/itm/AC220V-2000W-Stainless-Steel-Electric-Water-Heating-Element-Tubular-Heater-/331639754995 (except 2500 watt on a 20A circuit). Along with a HERM-IT coil. It's a pretty easy build.

I don't think you'd want the HX coil touching the element, that's the whole point of the water - evens out the temperature, prevents hot-spots.
Otherwise, you would just go RIMS.


EDIT: Posting at my link

 

[Afterlife Spirits85]

Im just trying to work out if i had a copper coil sitting on heating element would that create a hot spot and ruin either element or coil

 

[user 44743]

It could create a hot spot at times when the element was on; how bad that would be depends on things like how fast the wort is flowing. As already mentioned, it would also cause variability in the heating of the recirculated wort - because the element usually varies much more than the water it heats.

It 'probably' wouldn't ruin the element or coil, the heat shouldn't be that intense unless the water boils off. Though its not entirely ideal on the element if the contact between element and coil was a good one, as the heat stresses would be less uniform.

That said, I doubt a casual/slight contact would be a huge problem in most cases, but even a minimal gap would be best all round.

 

[Afterlife Spirits85]

Ok. Im more talking bout in my hlt where the temp would probs get to a max of 80 degrees

 

[jyo]

The only problem with using your HLT as your herms heat source is that you are using a huge body of water to regulate temps. If you overshoot mash temps, then your system will take a long time to balance between the temp being read in the mash, and the temp of the water in your HLT. Also your ramp times will be a lot longer. Think smaller. My herms used a small copper coil in a kmart kettle.

 

[user 44743]

Ok. Im more talking bout in my hlt where the temp would probs get to a max of 80 degrees

The water in the HLT may only get to 80c, but the element itself gets hotter - if there is direct contact then so can the coil. Probably not 'much' hotter because the wort is flowing through and there will still be lots of water around to help even it out, but it would introduce 'a' hot spot and reduce consistency as the element goes on or off. Unless you can quantify how much, then having at least a small gap would be more certain.

A big volume of water can be helpful if you're regulating its temperature manually, as volume aids temperature stability. Using the HLT also requires less extra equipment and complication. But big volumes can't be adjusted quickly (e.g. to compensate for recirculation rate slowing) so where good automatic control/regulation is available then smaller containers (or RIMS) are popular.