HERMS question...

[Boomer]

My plan is for a single tier eHERMS setup. On my brew stand, I'd like to have a middle tier for a 5 gallon SS pot that I'll use as a heat exchanger with an immersion chiller running through it. I'm going to pump my wort through the chiller and have the water in that pot temp controlled.

How can I alleviate losing all of that wort when I pump to my BK? Correct me if I'm wrong, but if I can't run the pump dry, doesn't quite a bit of it stay in the line between my MLT and BK? I've never used a HERMS system before and have read quite a bit, but this one is stumping me. Can I just look for a target OG then pump a little extra through to clear the line and boil a bit longer?

Thanks!

 

[Getzinator]

I'm confused by your question of single tier and a middle tier. Do you mean they will be stacked vertically, or run horizontally?

 

[Boomer]

Sorry - horizontally like a traditional single tier rig, it'll be 3' tall. BUT, I want to have a "shelf," if you will, at 1 1/2' that will be under the main tier. It'll have my heat exchanger on it with the immersion chiller run through it. HLT, MLT, and BK will all be on the main tier, but the shelf under them will have the heat exchanger on it.

 

[audger]

i dont think he really means another 'tier', but just a seperate HERMS pot somewhere (not the HLT).

what size batches are you doing? 5 gallons is probably going to be too big (er- atleast just unnecessarily large, which has some downsides)... i do 5 and 10 gallon batches and use a 1 gallon HERMS pot and 2kW heater in it. and im building another one for larger batches that is in a 2 gallon pot and has a 4kW heating coil in it.

the reason for keeping it small (the same reason i dont like using the HLT as a heat source) is because you can more precisely control the temperature changes; specifically how quickly you see a change in measured temperature from the time you turn the heat on. that is the benefit of a RIMS where the element is directly heating the wort; there is no lag between when you turn the heat on and the time the wort starts heating. the more 'distance' between the heater and what you are heating, the slower your steps will be. if you arent stepping, but just maintaining temperature, the point is kind of moot.

you can sort of compensate for this 'distance' by adding more power, but obviously it gets difficult quickly. with 1 gallon and 2kw of heat; thats a ratio of 2000w per gallon. to get the same speed out of a 5 gallon HERMS, you would need 10kW of power... and if you used a 10 or 15 gallon HLT as the source... 20 or 30kW- thats not really possible.

Correct me if I'm wrong, but if I can't run the pump dry, doesn't quite a bit of it stay in the line between my MLT and BK?

its not that you cant run the pump dry, its that as soon as air gets in the pump it will stop pumping. that is what stops you from getting it all out. and yes, this is one of the few reasons its not a good idea to use excessively long HERMS coils, like 20 30 or 50 feet (ive even seen longer!). i have 8 feet of 3/8" copper in my small HERMS, and will have 10 feet of 1/2" stainless tubing in the new one. its constantly recirculating so it doesnt need to be longer. the liquid will spend almost the exact same total amount of time in the coil; it will just make more passes thru it.

you can run clean water thru the system at the end, and just stop it before it empties into your boil kettle. that way you can get more sugar out.

edit: +1000 words...
new one:



old one:

 

[Boomer]

FWIW - I just meant I'm using a 5 gallon SS pot - only planning to have 1-2 gallons of water in it. I'm actually looking for a pot the same size of my immersion chiller but haven't found it, yet. I do like the idea of a stainless 1/2" coil and having it shorter. I could make one of those specifically for the rig and just mount it in the pot permanently. I'm going to look into that, thanks!

 

[Boomer]

What do most of you do? I'd like to get as much as I can from the mash. Or, after sparging, is it pretty much not that big of a deal?

 

[luhrks]

I sparge out through my heat exchanger and recirc pump.

No wasted mash or wort, and clean pump, hoses, and hex.

 

[Boomer]

I sparge out through my heat exchanger and recirc pump.

No wasted mash or wort, and clean pump, hoses, and hex.

It just seems like some would be left in the heat exchanger. I'm guessing as long as I take a gravity reading of what's coming out of the line and into the BK and it's fairly low, AND I'm at my target OG, anyways, I shouldn't be too worried about it. I'm only in the design stages of this thing, but this is an obstacle I'm trying to avoid.

 

[Yooper]

But if you sparge your sparge water through the HEX (I do), it rinses the wort out first, and you have just water left in the tubing/pump/coil.

When I stop recirculating the wort, I leave the hoses all connected and just put my HLT through those hook ups instead of the MLT ballvalve, which then goes to the boil kettle. I hope that makes sense!

 

[Getzinator]

You could always try to go the other way with it. Make the other shelf a foot and a half higher, pump the water up through the cooling coil, and once the pump runs dry, hope the downward force of the coil being drained siphons all of it out.

I'm no scientist, but I'd say it's worth a shot.

 

[luhrks]

+1 what Yooper said, and I should have articulated.

Process:
1. Stop mash recirc.
2. Close MT drain valve.
3. Disconnect hose from MT out, connect to HLT out.
4. Connect new hose from MT out to BK in.
5. Open HLT valve, engage pump.
6. Open MT valve.

Congrats! You have now pushed your sparge water through your hex coil, pump, and hoses.

 

[Boomer]

So you're pumping from the HLT through the HEX into your MLT to sparge and directly from your MLT to your BK?


Ding ding ding! Thanks for the help/input.

I was trying to justify SS QD fittings everywhere. Just did.

 

[Yooper]

So you're pumping from the HLT through the HEX into your MLT to sparge and directly from your MLT to your BK?


Ding ding ding! Thanks for the help/input.

I was trying to justify SS QD fittings everywhere. Just did.

YES- that's exactly right.

But keep in mind that even if you don't- there is actually very little wort left in the HEX and tubing anyway. It seems like it would be a lot, but it's not, maybe a quart or less. I can't remember now, but I measured it a couple of years ago by draining it all via gravity into a pitcher. It was so much less than I thought it would be that I laughed at myself.

In my case, I have a CFC and I leave a few ounces of wort behind there, but after measuring the HEX amounts I realize it's almost nothing. (Same size coil for the CFC and the HEX).

I still sparge through the HEX, though! It actually helps rinse/clean the HEX because I'm using 170 degree water for the sparge, and by the time the sparge is over all of the sticky wort is long gone from the HEX.

 

[Boomer]

YES- that's exactly right.

But keep in mind that even if you don't- there is actually very little wort left in the HEX and tubing anyway. It seems like it would be a lot, but it's not, maybe a quart or less. I can't remember now, but I measured it a couple of years ago by draining it all via gravity into a pitcher. It was so much less than I thought it would be that I laughed at myself.

In my case, I have a CFC and I leave a few ounces of wort behind there, but after measuring the HEX amounts I realize it's almost nothing. (Same size coil for the CFC and the HEX).

I still sparge through the HEX, though! It actually helps rinse/clean the HEX because I'm using 170 degree water for the sparge, and by the time the sparge is over all of the sticky wort is long gone from the HEX.

I like it. I want the system to be designed so I can pump a cleaning agent through the entire thing. I only want to have to dump grain, everything else will handle itself as much as possible. This seems like a step in the right direction. I'll be using a plate chiller so flushing the HEX will clear out all the wort except what's left in the MLT and the line between the pump and BK. I can live with that!

I'm gonna try to get it all fabricated and welded/bolted together this 2 weeks off and then handle all the wiring on my next 2 weeks off. I hope to have a fully automated single tier eHERMS by the beginning of June (I work 2 weeks on 2 weeks off).

 

[JRems]

If you are using a smaller vessel for the hex, why not fill it with something other than water? Like oil? Wouldn't it heat better?

 

[Boomer]

If you are using a smaller vessel for the hex, why not fill it with something other than water? Like oil? Wouldn't it heat better?

I don't really know how to answer that other than I don't want to. I guess I can't say whether it'd be good, bad, or indifferent - it's just one more substance I don't want around on brew day. I'll have plenty of water, and IF there is any mixture, I'd rather have water mix than oil.

 

[Dog House Brew]

So how thick are your mashes when you are recirculating? I've read all kinds of opinions on this. Just wondered how thin people are mashing. I have a stainless coil in my HLT (keg) and have been thinking of moving it to a smaller pot and using less volume of water to heat.

 

[rockytoptim]

new one:

At Audger: Where did you get your SS coil made and whats the OD of the built coil? I have a 2 gallon cooler that I have a 3500W element in. I currently have copper but would like to go to stainless.

 

[MaxOut]

I sparge out through my heat exchanger and recirc pump.

No wasted mash or wort, and clean pump, hoses, and hex.

I Do This ^^ No waste.

 

[mux]

I sparge out through my heat exchanger and recirc pump.

No wasted mash or wort, and clean pump, hoses, and hex.

Good idea.

 

[Yooper]

So how thick are your mashes when you are recirculating? I've read all kinds of opinions on this. Just wondered how thin people are mashing. I have a stainless coil in my HLT (keg) and have been thinking of moving it to a smaller pot and using less volume of water to heat.

I go with 1.33-1.5 quarts/pound generally.

 

[luhrks]

1.5 to 2.0 with some rice hulls just in case.

If it's a Heff, 2.5 with 2 pounds of rice hulls.

I find my efficiency drops otherwise.

 

[MaxOut]

i dont think he really means another 'tier', but just a seperate HERMS pot somewhere (not the HLT).

what size batches are you doing? 5 gallons is probably going to be too big (er- atleast just unnecessarily large, which has some downsides)... i do 5 and 10 gallon batches and use a 1 gallon HERMS pot and 2kW heater in it. and im building another one for larger batches that is in a 2 gallon pot and has a 4kW heating coil in it.

the reason for keeping it small (the same reason i dont like using the HLT as a heat source) is because you can more precisely control the temperature changes; specifically how quickly you see a change in measured temperature from the time you turn the heat on. that is the benefit of a RIMS where the element is directly heating the wort; there is no lag between when you turn the heat on and the time the wort starts heating. the more 'distance' between the heater and what you are heating, the slower your steps will be. if you arent stepping, but just maintaining temperature, the point is kind of moot.

you can sort of compensate for this 'distance' by adding more power, but obviously it gets difficult quickly. with 1 gallon and 2kw of heat; thats a ratio of 2000w per gallon. to get the same speed out of a 5 gallon HERMS, you would need 10kW of power... and if you used a 10 or 15 gallon HLT as the source... 20 or 30kW- thats not really possible.

One advantage of building a bigger HERMS or placing a HERMS in your HLT is so you don’t have to build a bigger one later. Another advantage of having a HERMS in your HLT is one less vessel to build, heat and clean. By the time you figure the cost of a suitable pot and heat source for a small HERMS you could probable buy extra coil to fill your HLT so costs would be similar.

You can adjust your water level in a larger HERMS and use as little or as much of the coil you want. A larger HERMS has more mass and more conductive surface which equals more capacity to maintain temps during a single step. If you are doing multiple steps and need to ramp temps quickly you empty your water in the HERMS to a level that you have the capacity to heat quickly. I have a 48’ HERMS coil in my HLT and generally do two step mashes with ease. I fire the HLT full of water with a 90K BTU banjo and it has the capacity to heat a 10 gallon mash from 148* to 168* in 10 min. Usually about 6-7 gallons actual pre-sparge volume. I use one pump to circulate the water in the HLT and the other runs the wort through the HERMS and back to the MT. I just dont see the advantage of building a small seperate HERMS when you have a 3 vessel system and all ready heating the HLT.

 

[audger]

...I just dont see the advantage of building a small seperate HERMS when you have a 3 vessel system and all ready heating the HLT.

if you are specifically going for cost savings or trying to cut down on number of parts, it is easier to have everything all in one. i like being able to hold my HLT at a certain temperature for sparging, while sending runoff thru the HEX to preheat on its way in to the BK; or sending incoming water thru the HEX to heat faster on its way into the HLT; or being able to heat the HLT up to sparge temp while also stepping the mash... theres some personal preference to it.

i look at it like the flywheel on a car. a big heavy truck flywheel (HEX in the HLT) with a lot of mass will keep the engine running at a specific steady RPM. it will resist changing speed as the load on the engine varys, at the expense of being able to rapidly accelerate/decelerate.

the flywheel on a sports car is usually very light (thermal mass of a descrete HEX). the engine idles rougher, and you have to closely match the gas pedal to clutch or you risk stalling (aka- carefully tune your PID). however you can shred thru the gears (step mash) with great speed.

but as long as your engine (the heating element) can keep up with the load anyway (heat lost during mash), theres no need for a bigger flywheel (greater thermal mass in the HEX) to keep the temperature constant.


as your example- you use a 90,000 BTU burner to step 10 gallons at 2 degrees/minute. i use 6,800 BTUs worth of electricity to step 10 gallons at 1 degree/minute (7% of your energy input, and 50% of the performance). i could double that (to a 4kW heating element) and match your temperature rate change, while using only 15% of the energy.

At Audger: Where did you get your SS coil made and whats the OD of the built coil? I have a 2 gallon cooler that I have a 3500W element in. I currently have copper but would like to go to stainless.

sorry i just saw that question. i bought the steel from NYbrewsupply and rolled it myself. the OD is about 7 inches. i did have to build a tubing roller to make those... if you wanted to supply the materials and pay shipping, i could make one for you. shoot me a PM.

 

[luhrks]

as your example- you use a 90,000 BTU burner to step 10 gallons at 2 degrees/minute. i use 6,800 BTUs worth of electricity to step 10 gallons at 1 degree/minute (7% of your energy input, and 50% of the performance). i could double that (to a 4kW heating element) and match your temperature rate change, while using only 15% of the energy.

Might want to check your math. He's getting 2x the performance for 2x the BTU's expended, or 1x for 1x when you upgrade.

The burner's rated for 90k BTUs - per hour, but the burner's only engaged for 10 minutes or 15k BTUs.

 

[MaxOut]

Might want to check your math. He's getting 2x the performance for 2x the BTU's expended, or 1x for 1x when you upgrade.

The burner's rated for 90k BTUs - per hour, but the burner's only engaged for 10 minutes or 15k BTUs.

Thanks Luhrks, and if I filled the HLT half way I would use even less energy to do quicker step mash. As for saving energy I fill the HLT and that water is used to sparge with. After mash out it is the perfect temp. No wasted water.

Although I see some advantages to having a separate HERMS in your case it just doesn't make sense for me. I use a tankless hot water heater to supply water up to 180* so I've got preheating water covered. Pre heating the wort going to the BK seems a little redundant during sparge. I usually wait until I'm half way done sparging before I even start to heat the BK so the entire volume reaches a boil at the same time. Makes it easier for me to estimate boil off.

 

[luhrks]

I actually do the exact same thing. I use my HLT to preheat strike water, step mash, sparge, and then use what's left to clean.

 

[audger]

Might want to check your math. He's getting 2x the performance for 2x the BTU's expended, or 1x for 1x when you upgrade.

The burner's rated for 90k BTUs - per hour, but the burner's only engaged for 10 minutes or 15k BTUs.

my math is fine. both numbers were rate of change per hour. he uses 90k BTU per hour to step 2 degrees per minute, i use 6800 BTUs per hour to step 1 degree per minute.

i suppose it might have been clearer if i had said

i use 6,800 BTUs worth of electricity [[per hour]] to step 10 gallons at 1 degree/minute

if you are doing how many BTUs are used in 10 minutes, he uses 15,000 BTUs to change 10 gallons by 20 degrees; I use 1,200 BTUs to change 10 gallons 10 degrees. better?

also if you are looking at efficiency- ideally, it takes 830 BTUs to heat 10 gallons of water by 10 degrees. I use around 1200, or 30.8% more than ideal (~70% efficiency). if you use 15000BTUs to heat 10 gallons of water by 20 degrees, that is 88.9% more than ideal (1660), or ~11% efficiency.

 

[MaxOut]

my math is fine. both numbers were rate of change per hour. he uses 90k BTU per hour to step 2 degrees per minute, i use 6800 BTUs per hour to step 1 degree per minute.

i suppose it might have been clearer if i had said


if you are doing how many BTUs are used in 10 minutes, he uses 15,000 BTUs to change 10 gallons by 20 degrees; I use 1,200 BTUs to change 10 gallons 10 degrees. better?

also if you are looking at efficiency- ideally, it takes 830 BTUs to heat 10 gallons of water by 10 degrees. I use around 1200, or 30.8% more than ideal (~70% efficiency). if you use 15000BTUs to heat 10 gallons of water by 20 degrees, that is 88.9% more than ideal (1660), or ~11% efficiency.

Still not fair comparisons on efficiency because I'm also heating up to 13 gallons of sparge/cleaning water at the same time with the same BTU’s where you are only heating 1 gallon. You are only comparing one particular step. As I stated before if I wanted to step quickly I would empty the HLT to 2-5 gallons. With similar amounts of water in our heat exchangers I’m sure efficiency would be similar. I like the stability of having a large volume in the HLT and need it for sparge anyway. Comparatively you are heating your sparge with a separate heat source and a separate vessel. How long does it take to heat your sparge and strike water how many BTU’s? I can heat strike water with the Tankless Hot Water Heater (THWH) from well water temp to 170* at 4 gallons per minute over 90% efficiency.


Example of brew day-

• Fill BK with strike volume right below strike temp with THWH
• Use burner on BK to bring to exact desired strike temp.
• Fill HLT with 13 gallons of water at mash temp with THWH
• Use burner on HLT to bring to exact desired temp.
• Once water in BK is at strike temp transfer strike water to MT
• (At this point I’m about ten minutes into my brew day and over 20 gallons have been heated to over 150 degrees)
• Start recirculation of wort through HT/EX and start recirculation HLT
• Mash out by heating HLT to 170 degrees continue recirculation until temp is reached in MT
• Move output from MT to HLT and use pre heated water in HLT to flush HT/EX and sparge into MT.
• Pump wort from MT to BK during sparge and start BK heat once all sparge water is added to MT.
• Boil in BK cool through plate chiller or HLT filled with ice then to fermenter.

I brew mostly lagers and will circulate through the HT/EX filled with ice after the plate chiller help get me to my desired 50 degree pitch temp in one pass another reason I opted for the larger HT/EX vessel. I’m not knocking your design but it’s not for everyone.