Herms Design

[fraser_john]

Sisalation paper, where do I get that?

 

[kirem]

clark rubber have the stuff I used.

 

[Yorg]

Don't insulate the container.
If you are using a PID and expect it to autotune - using an insulated container - and presumably insulated mash tun and hoses - you will overshoot and never come back down. Your autotune will not work, becuase your HEX will keep adding heat into your circulating wort even powered off, since there is so much thermal mass in the water reservoir and no ability for the system to shed heat. It makes hitting target and setting the right parameters and getting the dynamics of the system right quite difficult.
Controlling temperature is easiest when there is an ability to move up to the target (heat addition) and move down to the target from above (heat loss). With responsiveness both ways, controlling the system is easier.
The only issue with not insulating is that it is less efficient, energy usage wise. Measured in cents and carbon emmissions.
That said, insulation from the HEX to the tun should be substantial to eliminate another vairable of the differential between what is exiting the HEX and what your mash tun does.

for HEX in the HLT type systems the issues are different.

Cheers.

 

[schooey]

:huh: Dude... you're wife is going to have kittens when she sees that dress of hers wrapped around your mash tun...

 

[fraser_john]

:huh: Dude... you're wife is going to have kittens when she sees that dress of hers wrapped around your mash tun...

LOL, that made me smile! Its actually a 4" polyester roof insulation batt that I had my wife sew up a cover for, its got a zipper and all in it so I can zip it off when I wash the tun. Very good insulation.

 

[technocat]

Don't insulate the container.
If you are using a PID and expect it to autotune - using an insulated container - and presumably insulated mash tun and hoses - you will overshoot and never come back down. Your autotune will not work, becuase your HEX will keep adding heat into your circulating wort even powered off, since there is so much thermal mass in the water reservoir and no ability for the system to shed heat. It makes hitting target and setting the right parameters and getting the dynamics of the system right quite difficult.
Controlling temperature is easiest when there is an ability to move up to the target (heat addition) and move down to the target from above (heat loss). With responsiveness both ways, controlling the system is easier.
The only issue with not insulating is that it is less efficient, energy usage wise. Measured in cents and carbon emmissions.
That said, insulation from the HEX to the tun should be substantial to eliminate another vairable of the differential between what is exiting the HEX and what your mash tun does.
for HEX in the HLT type systems the issues are different.

Cheers.

Yeah I endorse what you are saying here after running water trials and subsequently two brews with my new HERMS. However I have found my overshoot in the MT is only a couple of degrees so I have countered this by turning the pump off early in anticipation. I have stripped off the insulation on the inlet side of the pump and only retained it on the outlet. I am still in the process of logging the parameters of the PID so to fine tune and take away the manual control aspect. The only problem I have is my 1800 watt element in a 16L vessel is not giving me a fast enough rise time when ramping up temps. This I intend to replace with a larger output.

Cheers
BN

 

[fraser_john]

Not sure that overshoot is going to be a problem. If the PID has been properly auto-tuned, then its logic takes into account the rate of heating, loss, errors etc. So being insulated will not be any issue at all.

Based on Yorgs concerns I decided to run a test.

I insulated the HERMS roughly with a carboy cover (cut up sleeping bag). Then I re-tuned the PID. Overshoot was 1C and it settled back to 40C within seconds. I then changed my PID to show one decimal place and overshoot was actually only 0.2C. It then settled back to be +/- 0.1C for the whole thirty minute 40C rest.

Overshoot is not an issue for a well tuned PID.

 

[kirem]

If the PID parameters are set correctly then the heating system should not overshoot. That is one of the fundamentals behind implementing a PID algorithm into the control system.

A system that requires a loss (in this case a heat loss) to maintain control is pretty poor engineering especially with PID enhanced control implemented.

I have the heating system including heat-exchanger, hoses and mash tun all insulated and I don't get overshoot.

I use the aubins PID temperature controller Model: SYL-2352P

 

[fraser_john]

Just finished my first mash using the new HERMS setup. Very happy with the unit. With the Auberins PID (SYL2352P) and an insulated container, it overshot by a minimal 0.2 degrees during the mash. Mas was a four step mash including the mashout step at 76c.

Big plus for Emmanuel at Stainlessstuff.net. For Aus$210 including shipping, this is a great unit!

 

[hsb]

Old thread - just wondered how this HEX was holding up, looks good. Any other aspects you would have changed upon reflection?
Also, what are you using to block the drain tube when it's in use?