HERMS Coil

What is more important for maximizing heating during recirculation.....internal diameter (allowing more mass of fluid to heat) or increased length of the coil or both?

 

Don't know for sure, but jumping in here so that when someone with heat exchange knowledge comes along I'll find out. That said, my guess would be that it's mostly about surface area and if you get there with a larger diameter or a longer tube, the results will be the same.

 

I had some left over 3/8" OD tube but just 10 ft & it's not quite doing the job. Perhaps 20 ft would do better or 1/2" x 20 ft? Recirculating 25 gal mash tun.

 

I use 50" of 1/2 inch SS and it works well. See theelectricbrewery.com for more info. that's what we use on our systems. Hope this s helps

 

Do you just let your coil sit in the temperature controlled HLT & have the wort pumped through the coil? Am I understanding this correctly?

 

you got it

 

I use 50' copper, 1/2" OD, 3/8" ID. It may be overkill, but can use it for a wort chiller as well. Wouldn't want to pump through a smaller ID tube, seems chances for getting clogged with grain husks/chunks would be too high with anything smaller.

 

Many people put the temp probe at the HERMS coil output, which is arguably a better way of doing it. You do not want to control the temperature of the HLT, do you? No. Ultimately you want to control the temperature of the mash. If you put the probe at the HERMS coil output, that is what the system will do. I went a little further and put my probe at the inlet of my mash tun so I know that the wort that goes into my mash tun is the exact temperature I want.

 

+1 to kevink

 

Infidel, do you have your coil installed through side walls of bk? Could you keep it in the bk while boiling & then use for cooling? I am using just an MT & bk w/no sparge method.

 

Sorry, going to have to do a -1 to what kevink wrote above.

The temp of the wort exiting the HERMS coil will always be (or should be with a good coil) the same as the HLT water temp.

The danger with decoupling the probe from the HLT heater by putting it at the HERMS coil output us that if you stop the recirc then the HLT heater will skyrocket to try and keep up.

Instead, I put my HLT temp probe in the output of the HLT and recirc the HLT continuously to keep an even temp throughout the HLT. The wort exiting the HERMS coil will then always match the HLT temp no matter how fast or slow you pump through the HERMS coil.

I put a second display only probe at the output of the MLT to show how long it takes the mash to get up to HLT temp when ramping.

Note: In process control systems such as ours that involve fluid recirculating, temperature monitoring is usually done in the plumbing instead of in the kettle. This helps avoid temperature misreads due to stratification (layering).

(This is not an issue in the Boil Kettle as the violent boiling action continuously stirs the wort to ensure an even temperature throughout the kettle.)

Stratification is most likely to occur in the Mash/Lauter Tun. A temperature probe placed in the grain through the side of the kettle would only be measuring one location. We would not know when the entire grain bed is at the desired target temperature as it heats slowly from top to bottom. By placing the probe at the kettle output we ensure that the entire mash temperature is being monitored. For example, when we increase the Hot Liquor Tank temperature to 168F to perform a mash-out, the water in the Hot Liquor Tank will reach 168F before the grain in the Mash/Lauter Tun. It is only when the Mash/Lauter Tun also reads 168F that we know that the whole grain bed is at 168F. Placing the probe elsewhere would not provide us with this accuracy.

Kal

 

Why do you stop the recirc?

 

When I mash in (for one).

Kal

 

I control my mash temp in the same manner as Kevin K. IMHO, I don't think it makes sense to control HLT temp - it is controlling an indirect variable. I control the temp of the wort as it returns to the MT. I monitor the temp of the wort leaving the MT.
As far as mashing in goes, when the water in my MT reaches strike temp, I turn off my HLT elements and close the valve on my HERMS pump. I then mash in, resume circulation, and turn on my HLT elements. I do not stir or recirculate the water in my HLT.
Obviously, there is more than one way to skin a cat and I am sure Kal's approach will work as well.

 

Yup - whatever method you choose has to match the process you use. Obviously we use different processes so different means of controlling the temperature make sense.

Kal

 

Does the vume you are recirculating matter with length fir your coil? I'm recirculating around 25 gal.

 

No, the volume shouldn't matter. What would matter is the speed at which you are sending wort through and the length of the coil. If the length/speed are sufficient to allow equalization of the wort temp with the HLT temp before the wort exits the coil you can have all the volume you want waiting to enter the coil. What volume will effect is how fast temperature changes are made. More volume takes more time to change temp.

 

15.5 gal batches......need approx 15 gal for mash & 10 gal for sparge using HERMS coil, will a 30 gal pot with 28 gal total water &13 gal left in HLT after mash water be enough to keep the HERMS working efficiently or do I need 40 gal pot?

 

I think the key here would be how much of the coil the remaining 13 gallons covers. Any idea on that?

 

OK, second cup of coffee and brain is working marginally better now....

One alternative is to top up the HLT after you have pumped the needed volume into the MT. The only real problem with this method is you will have to add more salts if you are adjusting the water. You will obviously have water left over, but you can use that for cleaning.

Another alternative is a dedicated HERMS vessel and a dedicated HLT. The HERMS vessel will have a smaller volume, maybe 10 gallons, with the coil always submerged, and you will use your HLT like anyone else. Probably the best possible scenario except that it requires another vessel, another heater, another PID.

 

As you are kind of hinting at another issue of having a large volume in the HLT is that it will take longer for it to react to temp changes needed for step mash if you are doing that. This is another reason it would be nice to have a smaller dedicated HERMS vessel if you need a large volume of sparge water. As you pointed out though you would potentially need additional equipment.

 

I got ya! So for reg 3 vessel mashing, what size vessel for MT w/strike water of 15 gal & 46 lbs grain for a 15.5 gal final batch?

 

I believe that would take up close to 19 gal in the mash tun. There are a bunch of good calculators here. http://www.rackers.org/calcs.shtml

 

Why not fill the MT with 15 gallons of cold water and fill the HERMS HLT with with 15 gallons of cold water (or 10 or whatever you need to cover the coil and provide you with enough volume for sparge)? Recirc the mash water so both the HLT and mash water heat up at the same time. Dough in when you are slightly above your target mash temp.

 

I was thinking about this on the way to work today. There shouldn't be any problem with this method at all, except I would probably just dough in at mash temp. That way I don't forget to lower the temp on the PID, or make some other mistake that makes me overshoot the sac rest temp. The HERMS coil will bring it back up quick enough.

 

Yes, this will work. However, it could take longer to ramp up from cold (we'll say 70F or lower) water to mash in temps using the HERMS. Your HLT would get to temp much quicker and then hold while waiting for the mash tun.

Directly hearing with an element full on would likely be quicker, even if it was the full volume.

For a 11 gallon batch, I personally heat 12 gallons in my HLT and then my strike in volume my BK. That way both of the smaller volumes are being directly heated.

 

OK, I think I get it. To confirm. You put the volume you will want for sparging in your HLT. You put your strike water in your BK. You heat them both seperately, and when you get to strike temp, or maybe a couple degrees above, you pump the water from your BK to your MLT? That's a really good solution. You have twice the heating power, so you are actually saving time. I have a "back to back" panel so I can run both elements without any problems. I like this solution a lot, thanks!

 

I just thought of another good point to this method. I don't have a sight glass on my MLT, and I don't think most people do. But I have one on both the HLT and the BK. Heating up strike water in the BK means easy and accurate volume measurements.

 

Heating both at the same time would definitely save time. My method above only applies to someone who can only fire one element at a time (my case). I have a 5500 watt element in the BK and a 5500 watt element in the HLT, but only a 30 amp panel. I don't know what size panel the OP has. I just assumed 30 amp for some reason.

 

That's a pretty safe assumption as it is by far the most common. I wanted the flexibility so I went with the 50A back to back setup. If I could get my electrician buddy over to hook up the circuit I could start actually using the thing

 

Do you all have a temp probe in the MT or recirculating loop. Mine is currently in the recirculating loop & having a hard time picking up the correct temp no matter where I put it. If I place it coming out of the coil return to MT it reads hotter than set point but rest of water in MT is lower than set point. Then if I have it coming from the input, it reads lower than MT volume. It I put it directly in MT water, it reads closer to where it is on a manual temp probe. Think I will install through wall of MT.

 

I followed Kal's setup and have my temp lead on the MT outlet.

 

You got it.

 

This means that your PID is not controlling the temperature correctly for some reason. It has nothing to do with where the probe is. It should work perfectly in that location. Have you auto tuned?

It reads hotter than the MT because it takes time for the entire volume of the MT to catch up to the temp of the water you're adding to it. That is normal.

Do not put the probe in the MT. That is one of the worst places to put it (the outlet of the MT is also a bad place). You will be super heating the mash water in the coil because the PID will be using the lower temperature of the mash and overcompensating. What you can do is put a thermometer low in the MT or at the outlet of the MT so you know when the entire mash volume is up to temp.

Sort out the problem you're having with the probe at the MT inlet and you will be fine. You could also put the probe at outlet of the HLT, but you might as well strive to be as accurate as possible and put it where the temp really matters- going into the MT.

 

If it were me I would control the PID/Element with the probe in the HLT. Monitor at the return to the MT to adjust your rate of flow. Adjust the temp at the return point either by adjusting the rate of flow through the coil or by adjusting the temp of the HLT. Then have a probe low in your MT to know over all how your are doing with your mash temp. That probe is the one that should be at your desired mash temp. If you can't maintain the temp there you either need to look at adjusting the amount of insulation on your MT or adjust the temp/flow of the HLT to adjust the temp as it enters the MT to compensate for heat loss. This is where I will be running 3 of my 4 probes. The 4th being in the BK.

Everyone does this a little different though.

 

Yes, everyone does it differently. I don't understand why you would go through all of this, though, when you could simply use the PID to do what it is designed to do, which is control temperature! You should not be controlling temps with valves. With the probe at the MT inlet, you can have whatever flow rate you want and the PID will make the temp exactly what you set it to be. No fuss, no muss. No offense, but your method seems a little too imprecise and a little too hands" on" for me!

 

Well for starters, I am not using a PID but rather a BCS 460 which has 4 temp inputs and the display will show all temps at the same time. Since these are all the points were would want to monitor that is where the probes are going. The reason I mention controlling temp with the valves comes down to the fact that flow rate can come into play depending on the length and diameter of your coil in the HLT. Personally 25' 1/2" copper which is on the short side of things compared to what others have done. If your wort is flowing too fast (my March 815 PL-C is rated to 8GPM) your wort may not be in the coil long enough to reach desired temp. By restricting the flow from 8GPM down to where the wort has time to reach desired temp you can better control things. It is also needed to make sure the wort is flowing through the grain at the right rate. Once set though it would he hands off. It isn't like I would be constantly be fiddling with valves to do a step mash for instance. I would just bump the heat in the HLT through the programming of the BCS and the MT will follow. If I wanted to control the HLT off the probe in the MT return, I can. Couple clicks of the mouse will change it around. I don't plan on that though. If your flow is moving properly and your wort matching the temp of the HLT you are going to control everything there.

As for why I plan on controlling the HLT based off the reading of the HLT vs MT return, mainly because I will see temp changes quicker there and again, as long as the flow is slow enough to heat the wort sufficiently going through the coil, it won't matter. The benefit is that depending on the flow rate you may overshoot your temp a bit controlling just from the input. I do agree totally agree that if I only had 2 places for the temp control probe being either the input or output on the MT. The output would be the least desirable. Over shoots like you say on the input are going to minimal.

A lot of this depends on processes and equipment. For instance if you have 50' of 3/8" copper coil you would have less issues with needing to throttle back the flow as the coil will cause quite a bit of restriction alone. If you are not doing a step mash, you would be simply looking at maintaining temps and odds are it isn't like you are going to be having to make up for a ton of heat loss. So that wort going through the coil would likely only be looking at a couple degrees of change.

 

I am interested in the BCS controller. So this connects ti a laptop & then to a box with the wiring & SSR's? Is there a software that you need to have it display?

 

OFF TOPIC, but I just noticed you are in Mattawan. I graduated from Mattawan in 2001, living in San Diego now.

 

I am not a native but moved here 4 yrs ago. You brewing in San Diego?