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temperatures not equalizing
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dp Brewing Company



Joined: 08 Jul 2013
Posts: 649
Location: Midwest

Drinking: Black Sheep NEIPA, Rye Not Today, Kick of the Irish

Working on: RIS Barrel Aged


PostLink    Posted: Thu Jun 07, 2018 5:45 pm    Post subject: Reply with quote


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It is normal for my setup to have the HLT get up to temp faster than the MT while recirculating. I normally have to set my HLT a degree or two higher than my MT because of heat loss in the hoses. Or at least I assume that is the reason.

Sounds like your two systems are at least a little more accurate now. That is good. Hope this feedback helps others that might have the same issue. I was waiting to see if Kal would respond. He knows a lot and is very helpful about these systems and PID's.

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kal
Forum Administrator


Joined: 12 Dec 2010
Posts: 9839
Location: Ottawa, Canada

Drinking: German Lager, Electric Hop Candy Jr, Scottish 70/-, Janet's Brown, Maibock, Kolsch, Russian Imperial Stout, Black Butte Porter

Working on: West Coast Blaster (American Red IPA)


PostLink    Posted: Thu Jun 07, 2018 8:48 pm    Post subject: Reply with quote

dp Brewing Company wrote:
It is normal for my setup to have the HLT get up to temp faster than the MT while recirculating.

Yup - normal, as the HLT heats up first, which the heats up the MLT. There's a normal lag. This is why I like to have an MLT temp probe on the very output of the MLT. It's the last place to heat up. Once it's at temp, you know the rest of the MLT is too.

Quote:
I normally have to set my HLT a degree or two higher than my MT because of heat loss in the hoses. Or at least I assume that is the reason.

Having a HLT to MLT temperature lag is a very common issue. Using parts that are different from the ones I recommend in our build instructions can cause this. To minimize the difference, make sure to:

- Calibrate both the MLT and HLT temp probes per the instructions here: http://www.theelectricbrewery.com/control-panel-setup (Unless both are calibrated with a known accurate thermometer at the mash temp, you don’t know if what you are seeing is accurate).
- Make sure to set up the PIDs per the instructions here: http://www.theelectricbrewery.com/control-panel-setup
Use the thicker walled hoses I recommend here: http://www.theelectricbrewery.com/hoses
Thicker hoses will lose less heat. Most people do not use these thicker hoses. Try to minimize distances as well.
- Set your mill gap crush per the recommendations here (0.045 to 0.050"): http://www.theelectricbrewery.com/grain-mill
You want to mill looser for good flow, not tighter.
- Use the pumps I recommend here to ensure adequate flow: http://www.theelectricbrewery.com/pumps
- Run both pumps at 100% open when mashing. To get good flow without any channeling use the kettles I recommend here: http://www.theelectricbrewery.com/kettles-overview

Users have reported on our forum and by email how they were seeing a temperature differential between the MLT and HLT and were able to make it go away by swapped out their hoses and pumps for what's recommended in the build instructions. A quote from one of them:

"I had originally tested the HERMS with the thinner 1/2 ID silicon and had my pumps setup with the inline heads (long story). I was landing about 1-2 degrees cooler in the mash kettle. I swapped out the pump heads for the front inlet and swapped out the silicon with what you recommend and I now hit the same temp!" - Todd W.

Other things that are sometimes done differently that can cause a differential:

- Make sure the heating elements are wired correctly and being fed 240V and not 120V. Running heating elements at 120V will result in 1/4 the power you expect. You can check this by looking at the amp meter. A 4500W element will draw 18.8 amps while a 5500W element will draw 22.9 amps.
- Brewing in a very cold location may cause the MLT temp to drop slightly by the time it reaches the MLT temp probe.

This question gets asked a lot on the forum too. These threads may provide further hints:

http://www.theelectricbrewery.com/forum/viewtopic.php?t=25474
http://www.theelectricbrewery.com/forum/viewtopic.php?t=26722
http://www.theelectricbrewery.com/forum/viewtopic.php?t=30387
http://www.theelectricbrewery.com/forum/viewtopic.php?t=28283

Kal

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barney the bear



Joined: 15 Oct 2014
Posts: 37
Location: Linköping, Sweden


PostLink    Posted: Thu Oct 25, 2018 10:36 pm    Post subject: Reply with quote

I had issues with my SWA-2451 PID from Auber. It is a PID with a built-in timer. The temperature (PV) always stopped and
was hold three degrees Celcius above the set value (heating). I contacted Auber a had a long discussion with them.

Here are some of the answers:

"This controller might not the best for home brew application because the power output won't be zero percent when PV - SV <= 0. The residual output does not reduce to zero until PV - SV > 5°F. So, we would recommend you use our EZBoil controller DSPR120 or even DSPR310D (which has the brew timer in boiling mode). These are specially designed for home brewing. "

"The control algorithms on this controller is different from our other controllers. For SWA-2451, when PV=SV, the output percentage is 10% not 0%. In other word, if the output percentage needed to stabilize your system is less than 10%, there will be an temperature gap between the steady temperature and your set temperature. You can try to set this controller under manual mode (section 4.3.4 in page 5 of instruction manual), and measure the output percentage needed to stabilize the temperature at your set temperature. If it needs less than 10%, then this residual output is the reason. Our other controllers don't have this feature.

According to control theory, the ideal system should take 25% power at steady state. If the heater is too powerful (<10% power at steady state), the system is going to be very difficult to control. If the system take more than 75% power at steady state, it will be too slow to response, Most oven will need about 15-40 % power at steady state.

For this situation, you can try set the Set Temperature 3 degrees lower. For example. if you want 65 degree C, you can set the SV at 62 degree. , Or you can add a 3 degree input offset (parameter SC), but you have remember. "

"Good insulation may contribute to this issue, but the main factor is that water has high heat capacity and a big tank of water doesn't loose heat or drop temperature fast. And this controller is more suitable for other applications. When our customers use this controller on their powder coating ovens, it works fine.

For beer brewing, I recommend you use our EZboil series controller DSPR120 or DSPR310D. Not exactly PID controllers, but the control algorithm works perfectly. And these are specially designed for home brewing. Features available on these controller are not available on other PID controllers. "
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AwakenedBrewer



Joined: 04 Aug 2017
Posts: 21
Location: Norfolk, NE


PostLink    Posted: Thu May 23, 2019 2:36 pm    Post subject: Reply with quote

Sorry to revive an old thread but thought this might help others if they are still having this issue. I believe this is what Kal mentioned someone else having a similar issue and getting new parameters from Auber.

http://www.theelectricbrewery.com/forum/viewtopic.php?p=324600#324600
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siestakey



Joined: 10 Mar 2017
Posts: 48



PostLink    Posted: Wed Jun 05, 2019 2:10 am    Post subject: Reply with quote

Thanks for linking this. I have been gone for work and haven't brewed in quite a while. I was able to get some time this evening to take a look. I had purchased the 3 piece ball valves a while back and finally swapped out with the linear flow valves. I immediately noticed a major difference in flow rate as well as getting the water moving. It is normally a 5-10 minute fight to get the flow going and this time it worked immediately on the first try. I was blown away. I thought for sure this would improve the other issue I've been seeing with the temperature differential.

I set the PID values 40/350/2 and t=2 on the HLT and MLT. I'm still seeing a 2 degree offset between MLT and HLT. I thought at this point it might be an issue with the MLT probe. I pulled it out and put it in a cup of water with a Thermapen and both read the same temperature so I reinstalled the MLT probe. I started recirculating through the HERMS coil and measured the temperature at the outlet of the hose in the MLT and I am seeing exactly what my HLT is set to (wasn't seeing that before). The water in the MLT in the center is a degree cooler, so I can only imagine it is cooler at the outlet and what is being reported is accurate. I let things runs for 20 minutes and the temp never comes any higher - always 2 degrees cooler at the output.

I then checked the HLT water temperature and probe and both are the same as the Thermapen.

I ran out of time tonight, but when I get back home, I'm going to verify the other PID settings listed here: http://www.theelectricbrewery.com/control-panel-setup

I am also going to run another autotune since I swapped out the Linear Flow Valves to see what my PID settings are after that.

Depending on all those results, I may just set my HLT 2 degrees warmer than my MLT desired temp but for some reason this is really bugging me.
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siestakey



Joined: 10 Mar 2017
Posts: 48



PostLink    Posted: Tue Jun 11, 2019 3:34 am    Post subject: Reply with quote

Everything checks out as far as configuration goes and I'm still seeing the 2 degree offset. I'm going to let this one go and set my temp accordingly.
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