Copper HERMS build. I

[Curly79]

Just finished putting all the pieces together to make my new HERMS. Would probably rather a Stainless coil but I'm going to give this a go to begin with. It's made from a piece of 150mm copper which is 450mm long. The coil is made of 3/8 copper. I'll be using a 2200w keg king element.
I'm going to start soldering it all together this weekend. I'll add a ball valve top and bottom later for filling the vessel with water then maybe insulate the whole thing.

Thoughts? Suggestions? Cheers [emoji482]

 

[Curly79]

Just realised that if I solder the top down I won't be able to get at the probe ever again. Seems to be sealing well but might just sit it there for now. Maybe tape it up.

 

[TidalPete]

You could always solder three or four lugs on the bottom of the cap to make it a snug fit inside the cylinder.
From your pics, there's no need to fill right up to the top with water anyway. Only need to cover the coil.

 

[Curly79]

It's actually not bad just sitting there. Ignore the duct tape I'm eventually going to mount it with two double bolted clips

 

[Mardoo]

Love it! I actually snagged one of those old 9L copper fire extinguishers to use for a quad batch HEX housing.

 

[Curly79]

Fixed it in position and fired it up today. Filled the HERMS and Mash Tun with cold water and pretty much raised the temp 1 degree per minute all the way to 70 degrees. I definitely need to insulate my Mash Tun. The difference in temp between the water returning into the MT and the water in the MT was about 5 degrees. Does this mean I should set the temp controller to 70 instead of 65 for mashing or do I just need to keep the MT itself insulated? Cheers [emoji481]

 

[Mardoo]

I'm pretty sure there's a different answer to the temp setting question depending on whether you insulate or not. Me, I say insulate. It's the most temperature crucial aspect of your brew/wort production rig. Minimizing fluctuation of temperature seems the best way to go. I'm unsure about insulating the HEX. I've initially thought I would, but then it occurred to me that the ability to shed heat from the HEX water might be as important as the ability to raise heat in the HEX water. Not sure. Any great minds care to chime in?

 

[MartinOC]

Mardoo's hypothesis is a good one - insulate as much as you can to prevent fluctuations in the overall system. If you want to get really anal about it, you can even insulate the hoses themselves.

You don't need to monitor the temperature of the HEX water. The critical temperature you need to monitor/control is the exit of your HEX, as that's the hottest part of your system & will dictate survival/denaturing of the enzymes. It looks like you're already ahead of me, as you've got a thermowell there to insert your probe into.

Flow-rate is a biggie, so a 3/8ths coil is probably going to restrict your ability to get a good ramp-rate, but you've got a 3/4" inlet Chugger, so it's probably going to be OK. Maybe think about a 1/2" coil if you get poor results with an actual mash.

I know we discussed this over a beer at your place yesterday, but thought I'd chime-in here in case anyone else is reading & wants to build something similar.

 

[timmi9191]

For me, everything is insulated. Any heat lost is heat that needs to be re-added.

 

[trevgale]

Insulating will improve ramp times, I'm not sure by how much though. I prefer to have a bit of heat loss in the system, it help prevent overshooting.

 

[Curly79]

Im thinking if the return from the Hex is 65 but the water sitting in the MT is 60 then by rights I'm mashing at 60 which is far from ideal. Just trying to get my head around this before I kick the old girl into gear and start producing sub standard beer?

 

[malt junkie]

Enzime activity takes place in the wort not the grain. Therefore you don't want the hottest part of the system higher than your step temp.

 

[Maheel]

out of interest do you need to control the temp of the HEX water or do you just "turn it on"

 

[MartinOC]

Nope, the HEX water just creates the heated environment to be exchanged to the wort travelling through the coil. It can be at boiling point if there's a demand from the system for more heat. The important temperature that's controlled/monitored is at the exit of the HEX coil.

 

[TheWiggman]

You shouldn't ever boil the water in the heat exchanger. If that's the case your coil is too short. Curly's will be fine, and with 3/8" tube you'll get better transfer efficiency than with 1/2". In fact, you could go a 1/3 of that length safely in my opinion and you'll get better flow.

 

[MartinOC]

Agreed. In practicality, the HEX water will never get to boiling point unless the coil is too short or you get a blockage in the recirculation.

 

[mxd]

out of interest do you need to control the temp of the HEX water or do you just "turn it on"

You control the heat of the water by the temp of the wort at exit, or re-entry into the mlt, i use a pid. ForMines in a kettle so if it hits a boil will turn off.

 

[Jack of all biers]

Thermal mass is just that. Mass, not volume. You tested with water without grain, which adds mass. I'm not sure how long you ran it for, but you started it cold and ran it up to 70, so I'm not surprised you had some lag in temp rising the mash tun. I would insulate the mash tun. If your not sure, use a blanket or towels or quilt to start with and see how it goes. If good, then a more permanent insulation solution will be in order. If the temp at your hex exit is similar to the temp at your mash tun inlet, then you won't need to insulate anything else. If not insulate your line first. The hex would only NEED insulation if ramp up times were slow in the hex.

If you ramp up at 70C, you are in effect mashing at 70C.

Thoughts to consider.

 

[Curly79]

Cheers Jack. Yeah I never thought of that. Should be much better with grain shouldn't it. And yes ill definitely insulate the Mash Tun

 

[MartinOC]

If you ramp up at 70C, you are in effect mashing at 70C.

Not sure if I get what you're saying here, so just to clarify:

Curly79 set-up his system for a "dry" run (ie. without grains) to test the potential ramping-capacity of his system. I agree with you that adding grains to the equation will change things & the "actuals" will only come with "test & adjust" fiddling.

If you're monitoring the HEX exit temp., that's the maximum temperature in the entire system. One the whole system has stabilised at the target temperature, THAT is the temperature you're mashing-at & no higher (PID vs. Thermostat [ie. STC] considerations aside).

If I'm reading you wrong, please set me straight here. Maybe we're saying the same thing in different words?