HERMS loop Vs counter flow

[Cain Harland]

I'm looking at putting together a HERMS rig. It will probably be single tier so have 2 pumps. Given that during mash 1 pump will just be recirculating the HLT water I have been thinking why not do away with the HERMS loop and use a counter flow chiller instead, an all metal one. With the HLT water in the outer loop and mash in the inner. There is probably very little in it in terms of price by the time you buy the extra valves, bulkheads and compression fittings for the HERMS.

Can anyone give me a reason why this is a bad idea and a traditional HERMS loop would be better? Eg is the outer loop going to have toxic shit in it because the cooling water usually goes down the drain so I wont be able to use it for sparge.

I would probably find a suitable old pot or something and set the chiller in it in expanding foam to stop it acting like a heat sync in the air. Will probably insulate mash tun too either with wooden slats like a barrel or by placing inside a slightly larger pot (the cheapest thinnest one I can find) and filling the gap with foam.

Also I  go the HERMS loop way then for cooling how much less efficient is cooling by running the wort back through the HERMS loop while running the garden hose into the bottom of the HLT and out the top. Rather than cold in, hot out like counter flow or immersion, its cold in mix out so clearly less efficient, but would it make any real difference or do I just waste a little more water?

[Barry]

Roughly an hour to raise a mash from 66deg to 75 (so for a mashout)?

Going to be very interesting putting this to the test. If real world results are anywhere near that long then I'll be refactoring my system PDQ.

Thanks for the maths, fascinating.

[Cain Harland]

I'm assuming both those are for straight copper pipe. Do you have ones for stainless HERMS loop and convoluted copper CFC? Also what does doubling the volumes do to the curves

[Adam Sparks]

My 2 cents……..

For a HERMS coil in the HLT You don't need 50 feet if your doing 20L batches. Depending on the size of your HLT, most of a 50 foot coil will not be submerged after you dough in.

In my situation I have a 50 foot stainless coil in a 100L HLT. For a 20L batch I fill my HLT right up and only use half the liquor to brew. I then use the remaining 50L to CIP once Im done but its overkill. Its really better suited to 40L batches

I think the counterflow chiller would work just fine but I would definitely get 50 feet because cooling will be an issue with any less in summer. I also have a coil hard plumbed in my kettle which is frivolous, but saves time on brew day!

Stainless coils are best purchased from here Even after shipping the price is pretty good and you won't find cheaper in New Zealand.

[Barry]

50' counterflow chillers might be a bit hard to come by.

A process change can get around the HLT being empty after dough in: you transfer strike water, refill HLT and heat to recirc temp whilst recirculating as if you were mashing. When all the things are at correct temp you dough in.

All sensible advice though, thanks Adam. I am very curious to see whether my CFC will do the job or whether I'll be in the market to upgrade my HLT with a coil.

[Cain Harland]

Any idea about what shipping would be on on a 50' 1/2" coil?

[Blake Jones]

Im no expert but i dont think its the best idea. The whole point in herms or a heat exchange is to have a large thermal mass of water to trasfer heat to the wort. Having it in a CFC you will have a large temp diff between the hlt and water in the cfc and not having the thermal mass there will make heating the wort much slower, think of it like the wort is trying to cool the hlt water as much as the other way around. If i was you i would go to a heat exchanger herms system like paul wicksteed to scott bennison, pauls is a very fancy one if your that way inclined, scotts is more basic but does the job. I have seen some people do it cheaply with a 5 litre urn, put a PID onto the urn element and run a copper coil inside the urn. Unlike using the HLT the is a much smaller volume of water in the urn so decoction mashes are easier as temp can be ramped quicker. And unlike your CFC idea there is no heatloss as the element is in the heating medium.

[Barry]

Yeah plenty of people have tried it and reported good results. I'm not flying into this blind.

[Cain Harland]

Surley you still have the large thermal mass in the HLT you just cycling it through the CFC.

[DMAC]

I also think that you still have a large heat mass with the CFC provided you pump enough water through it -which it appears you would. In fact, would the heat exchange be more efficient because the counter flow chiller would have non laminar flow through both wort and liquor parts whereas the HLT method would only achieve non laminar flow in the heat exchange coil? (because the flow outside the coil is the slowly circulating water in the tank). From what ive read achieving no laminar flow is very important to heat exchange. Sounds like David could run the numbers and answer this question...(or correct my assumptions)

[Cain Harland]

I think you are right  and I'm guessing per length of coil if the is enough flow (and there should be) on the HLT side counter flow is more efficient its just a matter of there being a lot more coil when its in the HLT.

[Cain Harland]

Anyone got an opinion on on chilling by pumping wort through HERMS loop while bottom filling HLT with the garden hose at about the the rate water will flow out the whirlpool arm 1/2 way up?

If I go this way I will put a whirlpool arm on the bottom valve too facing the opposite direction to the one 1/2 way up it will mean the HLT won't drain completely (whats a couple of liters of wasted water) but will mean both in and out flow cause whirlpool action while either top or bottom filling.

Its going to be less efficient than counter flow or immersion because the cold water going in is being mixed with the warm product of the heat exchange and the mixture is flowing out rather than the cold pushing the hot out as with the other 2. The real question is will it take for ever or just waste a little extra water.

The other 2 options without purchasing any extra gear would be.

1)Take the first bit of heat out this way then dump a bucket of ice into the HTL and recirculate the water.

2)Bring a small volume of water to boil in HLT to serialize then empty (maybe use for cleaning mash tun), run cold water through HERMS loop, transfer wort to HLT then whirlpool in HLT.

Having separate HERMS loop and chiller seem unnecessary to me since they are more or less the same thing.

[nofizznofoam]

im not sure exactly what your hlt is going to look like with whirlpooling....but in the herms system I have the coil is fixed inside the hlt.

 

 pm me and i'll give you my number if you want to chat....i'll try to explain here

 

during mash, one pump circulates the mash.  hlt full of water to very top, kept generally at 2deg above mash temp.

 

I do a mashout....so raise HLT temp to 77 and let mash get up to 75.  then I use the HLT water for the sparge.  I have a second pump which is used just to pump the sparge water from HLT into the top of the mash tun.

 

there is just enough water left in HLT after the sparge to cover the fixed element, once finished pumping I turn the HLT up to 100c.

 

I circulate a few times during the boil to ensure the coil is sanitised

 

with 5 mins to go I shift the HLT halfway out the garage door so its on a lean, drain hot water and start hose running flat out in the bottom of the HLT and it overflows out the garage door.

 

at flame out start the pump and cool wort to 18c around 20 to 25 mins.  in winter I can cool to 10c in approx. 30.

 

I just recirc back into the boil kettle.  I have tried once to pump for a bit, then once the return wort is at say 20c start pumping directly to fermentor and this is definitely faster but its a drama that complicates things, and you couldn't do a whirlpool.