HERMS question

I’m hoping to use my HLT as my heat exchanger which is pretty common for a HERMS set-up.

The question I have is this:

I understand that use your HLT water to maintain your mash temp. for 60 min. but how do you increase the HLT water temp. in order to reach mash out temp.? Obviously, you would have to stop recirculating to do this and I’m assuming you would drain the mash tun at this point. Isn’t their a pretty substantial time delay between the time you empty your mash tun into the BK and the time it takes you to get your HLT water from circ. temp to mash out temp. so that you can add it to the mash tun?

Not sure I understand.

There are probably varying ways to do it, but I would keep recirculating while you heat your HLT. The mash temp will rise while you do this, and should stay pretty close to the HLT temp. When your mash gets to mash out temp, drain it and then sparge with the water in your HLT.

I assume you are using some sort of kettle that you can directly apply heat to for a HLT right? If you are using a cooler, HERMS isn’t going to work.

Use a burner under the HLT to heat and/or maintain temps. You don’t stop recirculating; by recirculating you really are constantly “draining” the MLT and pumping the mash liquor through a heat exchanger (in the HLT) back to the top of the mash.

I’ve found that you need the HLT water temp to be 10-15 degrees hotter than the desired heat exchanger exit temp. Run the HLT at about 175-180 when you start to recirculate the mash, and then let the HLT temp drop to about 170 by the time you are ready to sparge.

YMMV, exchanging heat using a coil and water bath is highly variable dependent on numerous factors which are tricky to predict and difficult to control.

My HERMS set-up: http://hbd.org/discus/messages/366/3362 … 1339813504

Thanks guys. This makes sense. Is there a reason you choose 40 minutes before you start raising the temperature of the mash? Aren’t you risking conversion issues by raising the mash temp. that soon?

Also, I intend on using a 10 gallon SS vessel w/my old immersion chiller has the heat exchanger for my HLT. Do you think that this capacity will be sufficent for 10 gallon batches or should I look into a keggle for the HLT?

Usually it’s less than 40 minutes but I definitely let the mash rest undisturbed for at least 15-20 minutes before starting recirculating. It can take a long time to raise temps while recirculating if you are using a copper coil and hot water bath as a heat exchanger. No need to worry about conversion problems as the total volume of the mash that is in the heat exchanger at higher temps represents a very small portion of the mash at any one time. Most of the conversion happens pretty quickly anyway; and is mostly done by the time you are recircing the heat exchanger.

Keggles don’t make the best kettles and no need to acquire one if you don’t already have one sitting idle, a 10 gallon HLT w/ Hx is large enough for a 10 gallon batch. And you can add more hot water to the mash from the BK at the end of the mash to get extra sparge volume if needed.

Your existing immersion chiller will work to some degree, but whether it will be fast or efficient enough is another question; use a long, large diameter coil for best results. Stirring or mixing the HLT also helps with heat transfer.

Thanks for the info.

What size copper coil (length and diameter) do you recommend for a proper heat exchanger? I want to make my HERMS correctly the first time and not skimp on something this important.

Also, have you considered an agitator for your HLT instead of stirring by hand? I’ve seen a few system with this addition.

Last, I was going to gravity drain my mash tun to the BK but it seems that most people fly sparge with their HERMS and therefore, have to regulate their flow in and out of the MT. My HERMS system is being constructed with the primary goal of moving my operation indoors. Increased eff. would be nice but if batch sparging with my system is quicker and a bit less efficient, I’m O.K. with that. I envision using my system to maintain mash temps, improve wort clarity, and make my brew day easier. Do you see any problem with draining the MT into the BK (once mash out temps have been reached) and then adding the sparge water to the grain, recirculating for awhile in the MT to clear the wort and then draining to contents to the BK. Basically, a hybrid batch sparge.


Consider using a 5/8 inch diameter convoluted copper coil 25 feet long for best results. (google convoluted copper coil). Pricey, but probably the best short of using two pumps and a chillzilla type heat exchanger.

I don’t actively agitate my HLT, but I do fire it to add heat to it during the recirc; this help to set up convection currents in the MLT to help keep it from becoming stratified.

I don’t think the efficiency difference between batch and fly sparging is significant enough to enter into the equation when deciding on a sparge method. Gravity draining the MLT into the boil kettle shouldn’t be a problem, but it will put the MLT up higher, and depending on the size and height of your vessels, may make reaching your MLT for mash-in/stirring more difficult. I also don’t see any problem with batch sparging other than the additional time it takes to re-set the mash after the first sparge, something you don’t need to do if you sparge on the fly.

Finally, it is possible to fly sparge quite fast. This may result in a small drop in efficiency, but I don’t see that as a big deal on a home brew scale HERMS system.

For my setup, I use an old 25’, 3/8" OD copper coil in my old turkey fryer pot. I cannot run the march pump flat out because the mash gets stuck (just using a braid, no manifold). So with the ball valve maybe 50% open, the outlet temp from the coil is about 5° cooler than the water bath. This works out very well for 5 gal batches. It takes about 30 minutes of recirculation to bring the mash from ~150 to ~165 with a HLT temp of 170-180 (I don’t have a controller on this yet so I have to keep turning the electric element on and off).

If we were talking about 10 gal then a larger coil may be in order, just for flow rate. I doubt seriously if I can be ‘copper limited’ with the output of a march pump with this 3/8" coil, you physically cannot pump enough liquid.

The water bath size does not need to be big, it’s just a buffer between your burner and your mash. 5 gal of hot water should be plenty even for a 10 gal beer, which makes a 7 gal turkey fryer pot perfect.

I would not recommend the convoluted copper. While it is technically superior for heat transfer, I don’t think you will be ‘copper limited’ in this application. You can always turn up the temp on the HLT. Plus I like having a smooth bore to make cleanup that much easier, and it’s cheaper.

Keep in mind, this is all opinion from my experience. No comparative testing has been done from me to reach these conclusions, so I may be dead wrong on some of them. :cheers:

This is a critical consideration that has not yet been mentioned. If you are going to recirculate a lot of mash liquor, you need something that is going to allow a lot of flow out of the mash without compacting the mash. Using gravity flow to a grant and pumping from there can also be used to prevent mash compaction within pumping. In my system I use a 1/2 inch hard copper slotted pipe manifold, no compaction issues if you start recirculating gradually, and it flows over a gallon per minute.

Another question along that same line:

I currently use a 120QT. rect. cooler for my 10 gallon batches. My bottom manifold is soldered 1/2" copper tubing that tee’s to (2) stainless mash screens about 12" long (the same sold at NB). Do you think that i’ll need to add additional “arms” to the manifold to avoid a stuck sparge or should this be sufficient?

Also, what are you guys using for adjustable sparge arms on the inlet side of the MT? I’ve been told that this manifold should be adjustable so that the recirculated wort leaches into the top of the mash bed instead of dropping into the mash bed.

The larger the surface area of the sparge manifold the better your chances of avoiding a stuck mash. I start recirculating slowly and gradually ramp up the flow over about 15 minutes to reduce mash compaction. You can try your existing set up to see if it works. If it doesn’t work, you could still get the beer brewed by re-stirring the mash and transferring the spage to the BK manually. It would just take longer and could be a PITA.

For the sparge arm, as long as you keep some water over the top of the mash at all times, you can use anything as long as the return flow doesn’t disturb the mash. I use a length of 1/2 inch CVPC pipe that has two rows of holes drilled on opposite sides to distribute flow across the surface of the MLT. It is shown in this photo:


I use a 3 tier HERMS. I heat my strike water in my BK and I fill my HLT that has a 1/2" stainless coil for my HEX. i just bought one of the stainless immersion chillers from Midwest and cut the stacks off. I use 2 pumps, 1 recirculates the HLT water bottom to top, 1 recirculates the wort. I use a 130qt cooler with a copper manifold. It takes me about 20 minutes to move to mash out. Filling the HLT and using both burners lets me get to the HLT temp while the mash is resting. I really like it, but then again I like gadgets. I can’t say it has made my beer any better than when I used the cooler/stainless hose filter with batch sparging. I would have to say adjust my water made the biggest difference, but i do like the recirculating HERMS. My wort is much more clear and and my break seams better. I added a blending/bypass valve at the entry of my HEX and it has come in handy at times when I needed to cool it down a bit. I do also like being able to gravity feed the MT and the BK.