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Old 08-24-2009, 09:13 PM   #1
stoutaholic
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Default Alternate HERMS design



I keep making changes to my brewery setup and today came up with this alternate design. Basically, it places the heat exchanger coil in the mash tun, and then recirculates near-boiling water through the coil to add heat (in order to maintain temperatures). The temperature controller simply switches the pump on and off as necessary based upon the reading from a thermowell inserted into the mash tun recirculation loop. Here are the advantages that I see with this setup:

1. Since it is not switching a high wattage, no SSR is required -- just a simple single-stage temperature controller such as a RANCO ETC-111000.
2. Since the copper coil extends throughout the mash tun, heat is distributed evenly throughout the mash -- no more worries about adding heat at the top and hoping that it evens out through recirculation.

3. No possibility of scorching, like the standard HERMS design.

4. Simple and easy to build. Reliable. The only equipment that could fail in this scenario are the pumps and the temperature controller. No worries about burning out an electric element or your pilot light going out.

The only disadvantage, that I can see, is that it requries two pumps instead of one. But, BFD, because you are saving the money that you would otherwise put into and SSR, PID, RIMS heating chamber or gas solenoid valve (depending upon your method of heat control).

If anyone has already built this, let me know! I'd like to hear how it works (or doesn't).


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Old 08-24-2009, 10:30 PM   #2
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It would have MORE of a chance of scorching (200 degree pipes in the mash vs the wort in pipes submerged in 155 degree water)

Without the PID & SSR you no longer have controll over the temperature of the water in your hlt. (fiddling with a dial on your burner... blah.) (are you going to sparge with that "near boiling" water?)

The water in the pipes when the pump shuts off will continue to give off heat after the pump shuts off.



Its a big step back...



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Old 08-25-2009, 01:54 AM   #3
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You need temps much higer than 212 degrees to scorch wort. If the bottom of your boil kettle only reached 212 degrees, do you think that you would be able to raise 10 gallons to boiling?

I should have pointed out that in my setup I am actually going to use a dedicated HLT to feed the heat exchanger, and a second HLT to provide infusions and sparges. This is why I drew the HLT to be smaller than the mash tun, it only needs to hold a few gallons of water. So I am not trying to control the temperature of the water in the dedicated hot water heater (which I called an HLT). It just has to be sufficiently hotter than the liquid in the mash tun, so that efficient heat transfer will occur. I would just keep it constantly heated. If I kept the flame on and it boiled, that would be fine.

An SSR is only necessary when your temperature controller needs to switch loads that are greater than those for which it is rated. A RANCO controller, for instance, really can't handle much more than 1300 watts (and pushing it to the maximum is a good way to fry your controller). However, in my setup, I am just switching a March pump on and off. So no SSR is necessary. It would switch the pump off as soon as the temperature reached the target. Little additional heat would be transferred after that point, though there could be a small amount of residual heat in the coil -- probably less than the residual heat in the bottom of directly heated mash tun which would reach much higher temps.

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Old 08-25-2009, 03:11 AM   #4
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Ok, my point is not that your design will scorch wort, my point is that I took the statement "No possibility of scorching, like the standard HERMS design." to mean that standard herms scorches. I guess its kinda ambiguous.

you should look at the pol's design. The only part of his system that needs a PID or SSR is the boil kettle, the HLT uses a Johnson fridge thermostat.

When you switch the pump off, the liquid would remain in the lines. That Liquid would have a good bit of thermal mass. FAR more than the thermal mass of the bottom of a pot (unless your pots are incredibly thick)

Lets compare your system to the pols system (not the electric BK, just the two cooler herms)

The Pol.
1 pump
1 temp controller
HLT temp automatic.
3 vessel brew house
less propane

Yours
2 pumps
1 temp control
HLT manualy controlled and an extra vessle
4 vessel brew house.
more propane

also, if you let the HLT boil, march pumps can cavitate and lose their prime.

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Old 08-25-2009, 03:18 AM   #5
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This is not a new concept.

This has been re-hashed here many times.

Standard HERMS cannot scorch wort... so, that is a non issue with HERMS. This is not a benefit to your system as the "issue" doesnt exist in the first place.

A simple JC A419 can switch a 1500W element easy and run a HERMS system with no PID or SSR, I have experience with this. Again, this is not a benefit of your system, as the "issue" doesnt exist in the first place.

Even though you are recirculating your wort... you have a REALLY HOT coil insulated by plenty of grain. You will still have HOT and COLD spots, it is inevitable.

I dont see where this is an improvement over a standard HERMS. It seems like over-engineering, to simply over-engineer. I dont see a single advantage.

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Old 08-25-2009, 03:22 AM   #6
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Quote:
Originally Posted by Orangevango View Post
Ok, my point is not that your design will scorch wort, my point is that I took the statement "No possibility of scorching, like the standard HERMS design." to mean that standard herms scorches. I guess its kinda ambiguous.

you should look at the pol's design. The only part of his system that needs a PID or SSR is the boil kettle, the HLT uses a Johnson fridge thermostat.

When you switch the pump off, the liquid would remain in the lines. That Liquid would have a good bit of thermal mass. FAR more than the thermal mass of the bottom of a pot (unless your pots are incredibly thick)

Lets compare your system to the pols system (not the electric BK, just the two cooler herms)

The Pol.
1 pump
1 temp controller
HLT temp automatic.
3 vessel brew house
less propane

Yours
2 pumps
1 temp control
HLT manualy controlled and an extra vessle
4 vessel brew house.
more propane

also, if you let the HLT boil, march pumps WILL cavitate and lose their prime.
Fixed that for ya.
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Old 08-25-2009, 12:00 PM   #7
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Does the coil go in after dough in? If not, would the coil hinder the dough in process and breaking up dough balls? Would there be enough space between the sides of the MLT and the coil to stir well enough to break up or move smaller dough balls where you get to them?

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Old 08-25-2009, 03:18 PM   #8
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I never meant to imply that HERMS scorches. I was saying, "like a HERMS, there is no possibility of scorching" or "there is no possibility of scorching, just as in the standard HERMS design."

I think it is pretty likely, though, that you are going to have more even heat transfer with this system. It is distributing heat to multiple layers of the mash, so there are no issues with stratification. And then the water is also recirculating. That has to produce more even temps than depositing pre-heated wort at the top of the mash and relying on recirculation to transfer that heat throughout the mash.

Regarding the residual heat from the coil, at the point that the pump stops, a good portion of that heat will already be transferred to the mash. The water in the coil would have already transferred some of its heat. The water in the coil will still be hotter than the mash, but would this really have a significant impact on the overall mash temperature? If it was enough to even raise the mash temp a half-degree, then it follows that we would have to recirculate only for a couple seconds in order to raise the mash temp back to its setpoint. Clearly this is not the case. The thermal mass of the heat exchanger is small relative to the mash itself. So residual heat would not be significant.

Quote:
This has been re-hashed here many times.
Any links to previous threads? This is what I was trying to find out.

Ok, perhaps the JC A419 does not require an SSR for a 1500 watt element. My RANCO does. And if you are trying to control any SIGNIFICANT amount of heating, you are typically going to need an SSR. A 1500 Watt element would be the bare minimum that most people would be using for a RIMS or HERMS.

The only additional equipment required for this system is an extra pump and relatively small pot, as opposed to, say, a solenoid valve, ssr, rims heating chamber, or whatever you are using for a typical RIMS/HERMS. The heat exchanger coil can be added after dough-in and then later reused as an immersion chiller. So if you already have an immersion chiller, you could use it for this application.

Also, to clarify, it does require 4 vessels, but not 4 burners. The boil kettle just scoots over and uses the burner that was used for the hot water heater. You are not going to be using the boil kettle while recirculating.

I didn't know about cavitation with boiling water, never tried to pump it before, so that's good to know. I would have to keep the hot water heater just below boiling. That shoud be feasible by adjusting the flame to the right output. Whether the water temp it is at 190 or 200 doesn't really matter, considering that I am just using the heat exchanger to add small amounts of heat to make up for whatever it lost during recirculation.

Anyway, since it is so simple to implement and I already have the equipment on hand, I'm going to build it and test it, as that really seems like the best way to evaluate the system. Obviously there could be an extended argument about the benefits and disadvantages of each system. There are several issues I have encountered with the standard design, and this is an attempt to avoid those issues.
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Old 08-25-2009, 03:42 PM   #9
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One other advantage to the system: If you overshoot your temperature when adding an infusion and don't want to add more water, you can use the heat exchanger to cool down the mash, by simply dumping the hot water and adding cool water (and possibly ice) to the dedicated water heater.



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