eHERMS, Chiller, & Sparge Water Heater

[JadeAug]

So I decided to try my hand at building one of these magical unicorn appliances I have read about people making. This all started because was an exclusive BIAB brewer for the past few year, and I was wanting a better way to control mash temps. I have recently upgraded to a cooler mash tun after a melted bag incident but I still desire more control.

Like many of you I am a mechanical engineer and a control freak who loves to tinker with their gear and have max control over their process. In fact I think I actually might enjoy designing and building my brew system more than actually brewing the beer. Since I am an apartment kitchen brewer I wanted to use my existing brewing infrastructure to save space so I figured the best way to do this would be to turn my counter flow chiller in to a multipurpose heat. The other heat exchangers I have seen posted on this forum try to make a HERMS CHiller by putting a coil in a water chamber but since I figure chilling is the most demanding use of the homebrew heat exchanger I decided to just modify my chiller instead of making a chiller.

I started by finding some band clamp heaters that would fit around my coils. I got mine on ebay but these can be had from McMaster Carr as well. In order to get full contact with the heaters I rolled some 0.040" aluminum to fit around the coils, underneath the heaters. This allows the heaters to not have any airgaps underneath them both improving heating efficiency and reducing hot spots that could prematurely burn out the heater. This also effectively reduces the energy density and imparts heat to more of the coils.

I wired my two heaters in parallel to a boil controller that I had lying around that I was going to use for a RIMS build, but currently was only being used as a pump switch and temperature display. I figured the eHERMS operation would be a no brainer since it does not require much energy to keep wort warm so I wanted to test how much heat I can impart to the water side of the heater exchanger. I fired it up and my two elements pulled about 1450 watts. I started moving some water through it and was pretty impressed by how hot it got. I still wondered how I could make it more efficient.

I had some heat conductive tape lying around that I thought would be good to put under the rolled aluminum. In theory this should increase the heat transfer area to the coil by evening out the surface of the coils. In turned out that it was difficult to get the aluminum roll around it properly and I may have ruined some of the wraps because it kept sticking and stretching as I was getting the roll on but I decided to go for it and test it out. The temp was higher than before but I had no way of knowing if this was better because I was just collecting temperature and flowrate data and analyzed it afterwards. You can see my results below.

The biggest issue I had with this other than the exposed electrical contacts was the fact that I was losing of heat to the air. I needed to insulate this heat exchanger so I made a quick trip to Home Depot to see what I can get. I ended up getting a fiberglass pipe wrap roll and some aluminum tape. This was a big mistake because I was dumb enough to wrap this while I was sitting on the couch in front of the TV and ended up covering myself, my couch, and my floor in fiberglass.

My final tests showed some decent progress. I cranked down on the valve so I was only getting a little trickle but that water came out hot hot hot. This insulation helped a little bit, but the outside was still very hot to the touch meaning I'm still losing to much heat.
I analyzed my numbers and was really impressed with the efficiency I was getting. I soon realized my numbers were not accurate as I was taking my initial temperature at the faucet, when in reality that water traveled through 25 feet of hose in a 72 deg F room before entering the heat exchanger.

I think soon I will do a test run with all my gear set up. I am still working to figure a few things out and I can update this thread with more tests and pics.

So thanks for reading my build diary. I posted this because I would like to get some suggestions on what I should do to insulate this thing better and make it safer so I dont shock myself or burn my house down. I also dont know what I should call this heat exchanger. Chermller? Chillherm? HERMCH HEX? I don't know you tell me.

 

[BrunDog]

Interesting approach. You mention sparge water heater... this doesn't look to have enough power to heat water for on-the-fly sparging... was that your goal?

 

[JadeAug]

Interesting approach. You mention sparge water heater... this doesn't look to have enough power to heat water for on-the-fly sparging... was that your goal?

Yes that was the goal. Theoretically it should be able to heat on the fly if I slow the flow down enough. The only valve I was using was the one on my expanding hose and it doesnt handle partial open very well. If I used the current configuration it should be able to heat water from 45 deg f to 170 deg f at 0.3 l/min. That would take about an hour to get 4 gallons so the best option to make it an on the fly sparger is to get a higher watt heating element or start with warmer water. One thing I have thought of was dumping extra sparge water in a bucket with an immersion chiller and have my hose water run through it to preheat.

I only have one vessel for heating water so currently I am heating my sparge water while I mash, drain the mash tun in to a bucket, batch sparging in the mash tun and then dumping the wort back in to my kettle for the boil.

What I would like to do is have my mash tun fly sparging while slowly filling my kettle from the mash tun. I don't want to my moving around buckets of hot sugar water in my kitchen so Im trying to get my brewery setup so all I'm doing is turning valves after the initial setup.

 

[BrunDog]

I've done a lot of research and trials with on-demand sparge water heating. I've even gone so far to design and [shameless plug] sell a custom RIMS heating element for this purpose.

Your math sounds about right... I heat from about 75 to 170 with ~3700W of power (5500W @ 67% net power) to achieve ~1 l/min.

I honestly appreciate your design and effort but do believe the singular line of contact (band heater internal surface contact along a spherical coil) is non-ideal for effective heat transfer, and could lead to issues long term. Obviously you realized this and tried to mitigate it with conductive tape. Band heaters around a long pipe might be more effective (external RIMs). Or consider a large cartridge heater inside a pipe (@augiedoggy has done this successfully) which is relatively low cost and effective due to liquid contact area.

That said - keep up the fight! I have no idea why anyone needs an HLT when you can heat on demand!

Also, if sparging is the goal - there are other ways to do it. You can gently place all your BK heated sparge water on top of the mash. It will not mix due to it's temperature and lower gravity than the sugar water below it. You can also place non-heated sparge water on top, though it may mix a bit more. Remember you are just trying to rinse the grains - the water doesn't need to go in as fast as it leaves. Fly sparging dogma says it should but that's an old wive's tale.

 

[Mybuddypete]

Remember you are just trying to rinse the grains - the water doesn't need to go in as fast as it leaves. Fly sparging dogma says it should but that's an old wive's tale.

I've been learning this the hard way recently as I recently added a Blichmann auto sparge and lost about 5% efficiency. I used to drain the mash until grains were exposed and then using a basic sparge diffuser would fill sparge water on top of the grain bed. Then I switched to the auto sparge to keep a steady sparge level. I'm going to go back to my old method and abandon the auto sparge.