Another HERMS design question

So, I'm thinking about how best (read cheapest) to go the HERMS route with my brewing, but to be honest I don't really know that much about it, save what I've been reading up on here in the forums. I'm trying to design something that uses the equipment I already have to the greatest extent possible - I'm not too worried about automation, etc. I want to have control of my mash temp, both for holding and raising for step mashing. I only have one burner. I mash and sparge using coolers, one with a false bottom, obviously, and I've got both a immersion and a counterflow wort chiller, and a temperature controller. I've got one pump at the moment, but am going to add a second so I can go single-tier and fly sparge.

At first I was going to use a single pump and the immersion chiller, but it seemed like setting the kettle water temp would have to be pretty precise, or you'd overheat the mash, or at the very least, denature a portion of the enzymes that were in solution in the wort that went through the chiller. So then I thought I'd use the temperature controller on the outlet side of the immersion chiller to control the pump, which would mitigate the problem by reducing the amount of wort that would be heated too high, but then I wouldn't have continuous recirculation (I'm not sure how important that really is, though, since I've been fine with a standard non-recirc mash up till now). Finally, I settled on using my counterflow chiller as the heat exchanger and water in my kettle as a heat source. The wort would be continuously pumped through, and a pump from the kettle through the heat exchanger would be controlled by a temperature controller reading the wort outflow temperature, so there would only be counterflow against the wort when it needed to be heated. This would seem to make the temperature of the water in the kettle less critical. I would probably also put valves after both pumps to set flow rates to reduce how often the kettle pump would cycle on and off. I've attached an image of what I mean.

I'm interested in any observations about this method people may have. Will this effectively control mash temps, and allow me to do steps easily by adjusting the temp controller settings? Will it be fairly kettle-temperature insensitive? Or will the restart delay on the temperature controller keep the pump from cycling effectively to maintain steady temps? Will this cause excessive scaling in the counterflow chiller, or are the passages inside (it's a Blichmann Therminator) too small for the inevitable grain bits, causing them to get stuck? Or any of a thousand other things I may not have thought of?

Any help/suggestions would be most welcome.

I think control over the temperature of the water you're exchanging heat with is a fairly critical part of HERMS. Yes, you can shut off the pump - but at that point how much of the mash has gone through? Then you'd need to stir the mash to get the temperatures uniform across the mash. Not effective IMO.
Why do you feel like you don't have good control over the water temp in your kettle? How do you heat your sparge water? Is that not accurate enough for strike?

Okay, I went back and re-read your post..at least this way you're maintaining re-circ, which as benefits as to the clarity of your wort by basically being a constant vorlauf. Still not sure how well that will work though.

I guess I misspoke - it's not that I don't have control over my water temp, it's more that I think it might be tedious to be frequently refiring the burner to keep the sparge water at the right temp for the length of a mash, and there's always the risk that I forget about it at some point and the sparge water temp goes too high.

There shouldn't be too much risk of overheating the mash water, even if the sparge water got up to boiling (accidentally, of course - I'm just thinking worst case scenario) with this method, I'd think - the amount of sparge water that would be circulated would be minimal, since the valve leaving the sparge water pump would be set for minimal flow, and the wort would first encounter the overly hot water at the tail end of its flow through the chiller, quickly notifying the temperature controller that it was well warm enough, and shutting down flow.

The biggest worry, the more I think about it, is the size of the channels inside the counterflow chiller. I'm thinking about abandoning this idea for that very reason. The last thing I need is for a piece of grain to get stuck inside the counterflow chiller - even if it doesn't block flow entirely, I may not know it's in there, and it would be a potential source of contamination on the cold side. I think I'll have to build my own recirculation circuit.

In designing a recirc system, it seems like the ideal would be a large volume of hot sparge water which is used in a counterflow system with the wort. By minimizing the volume of water in 'contact' with the wort, you minimize the chance for overshooting temperatures, and maximize control, since you can basically insert a fairly precise amount of heat into the recirculating wort. So maybe a separate counterflow chiller (not a plate one like the Therminator, but a spiral one). Thoughts?

You're basically describing a RIMS system, except that's not a large amount of water... Since you seem to not like the idea of using your HLT for recirc, it sounds like RIMS is more your thing.

There are people using CFC and plate chillers as HEX, I'm not one of them - but maybe someone will speak up on their experience with that and how well it works for them.

Have you considered going with an electric or partial electric setup?

For my HERMS I use a 10 gallon cooler for my MT, a 5 gallon cooler with a 1500 watt 120V heating element for my HLT, and a 2 gallon cooler with 1500 watt 120v heating element and copper tubing for my heat exchanger (HEX). Mine is controlled by a BCS-460, but you could do the same with other temp controllers. I constantly recirculate during the mash and I measure the temp of the mash as it exits the HEX and returns to the MT. The small volume of the HEX means it responds pretty quickly when maintaining and/or increasing mash temps. I have more details on my blog if youre interested, http://www.microbusbrewery.org/2009/03/herms-equipment-mash-tun.html

Looking at the problem, these are the variables that can be fiddled with: amount of available heat in the heating water, and amount of wort contact with the heating water. Each of those can be broken into a few of sub-variables: the amount of available heat can be varied by adjusting the temperature delta, time, or volume of the recirculating heating water, and the amount of wort contact can be varied by the same three variables (in theory). Different RIMS and HERMS systems target one or several of these variables

Adjusting the temperature delta by adjusting wort temp is obviously counterproductive (cooling the wort so it's temp is raised more by the recirc water won't get you to a higher temp, and defeats the purpose of the whole system, to maintain steady mash temps). And adjusting the time of contact for the wort side can't be practically fussed with too much - you want a pretty steady flow for good clarity, so unless you can adjust the length of the tubing exposed to the heating water (difficult to design, especially to automate), that variable will pretty much stay fixed. The volume of wort that is in contact with the heating water can be adjusted by using a bypass valve, but again, I think automation of this would be out of my price range.

So we turn our attention to adjustments to the heating water's variables. Adjusting the temperature is feasible, but only to an certain extent within my self-imposed constraints - I don't want an automated burner, for cost and safety reasons (maybe I'm being overly paranoid on that, but that's me), and constantly adjusting the temperature as heat is extracted by the wort and lost to the environs sounds like too much of a pain (though maybe that would only involve a couple of brief burns during a standard 60 minute mash, any people experienced with doing this?). But I could adjust the time and temperature variables at once by adjusting the flow rate of the heating water through the wort or a counterflow chiller - the slower the flow, the fewer BTUs will be put into contact with the wort for transfer, and vice versa. Keeping the volume of water in the heat exchanger small allows for the greatest control of the total number of BTUs you're putting into the heat exchanger

Has anybody done a system where you recirculate water from the HLT through an immersion chiller in the mash tun? You could still recirculate the wort solely for clarity, but the heating would take place in the tun instead of outside it. I'm not sure where you'd measure the mash temp to get the most accurate reading for metering the heating water flow in this setup, but it seems like it would work in theory.

foolsgambit said:

Has anybody done a system where you recirculate water from the HLT through an immersion chiller in the mash tun? You could still recirculate the wort solely for clarity, but the heating would take place in the tun instead of outside it. I'm not sure where you'd measure the mash temp to get the most accurate reading for metering the heating water flow in this setup, but it seems like it would work in theory.

Click to expand...

Sounds interesting...similar to a steam jacketed tun. Seems like you could end up with some temperature variations in your tun unless you stirred the mash (at least periodically) but then there wouldn't be any point in recirculating for clarity.

I figure the recirculation might take care of much of the temperature variation issue. The liquid holds much more heat than the grain mass, so it should level out if you get good even filtration through the grain bed - and I'm not sure, but the copper piping might lead to a little more channeling, though that would be along the piping, thus helping distribute the heat more evenly. But then you'd have channeling issues when you finally did sparge at the end. But I'm thinking any issue with this would be minor.

You can get by with one pump and do what you want. Just put a valve on one pump, and use gravity a little bit. I'm very pleased with my setup. And I doubt I'll ever go back to gas. Electric is a lot easier and a lot better temp control.

https://www.homebrewtalk.com/f51/brewkart-ditches-countertop-brutus-205427/