S0... IT....Happened to me...

[nobadays]

I brew eBIAB in a 16 gallon, 5500W, PID controlled kettle. I always re-circ as I mash being careful to keep the volume throttled down to find that balance between too little and too much re-circ. Thought I had it set pretty well and stepped away for a nature call. Came back a couple minutes later to here my pump pulsating.... Oh NO... lifted the the lid while shutting down the pump and element, to see the mash water near the top of the kettle and think I smelled just a touch of burned grain Stirred it rapidly and got the water level to drop almost instantly and kicked the pump back on. Kept stirring until the mash temp dropped...it had risen from my set temp of 151 to about 160. Definitely too high of mash temp for this IPA but... it is what it is.

First time drying out the pump, came close before but caught it in time. Usually I put 1 or 2, 1" PVC pipes between the bag and kettle wall to act as overflows in case the water level rises like this...just as insurance, of course this time I didn't!

It's all doing well now and I can't smell anything off, no burned smell so I will keep my fingers crossed that all is well. It is a mildly hopped IPA so hopefully it will still be a tasty beer!

 

[nobadays]

Whew! Looks like I dodged the bullet! Just finished clean up and found nothing burned onto the element. There were some very dark "flakes" in the bottom after draining so that was a concern but after tasting several of them I'm sure they are just dark bits of grain - the recipe had 12oz of 40L Crystal - all the dark bits tasted pretty neutral, certainly not burned flakes of grain or hops.

Can bet I will not walk away until I'm absolutely certain my re-circ flow isn't faster than what will drain through the grain bed!! I did answer one lingering question though... My re-circ is through the lid with a silicone tube that just hangs down to just under the "average" water level for my mashes. I have wondered if I was short circuiting with that flow "boring a hole" in the grain bed and shooting right through the bag, not really mixing. Apparently not or I would not have had this problem!

Cheers!

 

[Genuine]

I believe I accidently dry fired my element a good 3 times before it decided to quit. The last time I cleaned it with some oxy and steel wool, then during that brew session it died and crack in half. I don't know if it was because of the way I cleaned it or what. Just ordered another element and I'll have to be careful going forward.

 

[TexasWine]

This is exactly why I have a level gauge in my MT. The level in the gauge gives an immediate indication if your pump rate is out stripping the rate the liquid is falling through the grain. I set the pump flow rate so that the level in the gauge drops no more than a few inches.

 

[augiedoggy]

The issue with sight glasses in false bottoms is they are an easy way to circumvent the hydraulic even pulling action through the grainbed some use and they can introduce air into the bottom of the mt. so for some (not me) they would cause more issues than benefit. This is why you dont traditionally see them on mash tuns. (that and they are fairly useless for reading levels)

I recirculate through a rims back into my mashtun and found as long as I keep my flow rate under 2 gallons per minute ($30 flowmeter inline to see this and also show if there is restrictions) I dont have any issues with stuck flow. I have had very slow flow around 1 gpm though with some grainbills although I have only ever used rice hulls once.

I installed a flowswitch in my rims which kills the heat in the rims as soon as the flow drops below .5 gallons per minute. these can be bought for as little as $10 on ebay but I recently switched to a much better design which is all stainless
https://www.ebay.com/itm/Liquid-flow-switch-sensor-NPT-1-2-inch-female-female-Stainless-Steel-FSS-N1FF-SS/222859334294?_trkparms=aid=444000&algo=SOI.DEFAULT&ao=1&asc=50999&meid=ca51c15af24240c1885237fcb64a239d&pid=100037&rk=1&rkt=1&sd=322723603348&itm=222859334294&_trksid=p2047675.c100037.m2107

This can be wired up very easily as a switch on one of the DC power wires going to your ssr powering your heating element. you can use an xlr connector to connect it to your panel and put a bybass switch on the panel so its not in use during heating and boiling modes... you can put hose barbs on each end or better yet, camlocks and connect it right to the output of the mash tun as orientation is important.
just an option to consider.

 

[golfindia]

You only pull air through the mash tun sight gauge when you have a stuck mash. That is why I put one in mine. If there is no liquid in the sight gauge or it's dropping I turn the pump down. If you suck air through the sight gauge, you're doing it wrong.

 

[TexasWine]

You only pull air through the mash tun sight gauge when you have a stuck mash. That is why I put one in mine. If there is no liquid in the sight gauge or it's dropping I turn the pump down. If you suck air through the sight gauge, you're doing it wrong.

Bingo.

 

[Genuine]

The issue with sight glasses in false bottoms is they are an easy way to circumvent the hydraulic even pulling action through the grainbed some use and they can introduce air into the bottom of the mt. so for some (not me) they would cause more issues than benefit. This is why you dont traditionally see them on mash tuns. (that and they are fairly useless for reading levels)

I recirculate through a rims back into my mashtun and found as long as I keep my flow rate under 2 gallons per minute ($30 flowmeter inline to see this and also show if there is restrictions) I dont have any issues with stuck flow. I have had very slow flow around 1 gpm though with some grainbills although I have only ever used rice hulls once.

I installed a flowswitch in my rims which kills the heat in the rims as soon as the flow drops below .5 gallons per minute. these can be bought for as little as $10 on ebay but I recently switched to a much better design which is all stainless
https://www.ebay.com/itm/Liquid-flow-switch-sensor-NPT-1-2-inch-female-female-Stainless-Steel-FSS-N1FF-SS/222859334294?_trkparms=aid=444000&algo=SOI.DEFAULT&ao=1&asc=50999&meid=ca51c15af24240c1885237fcb64a239d&pid=100037&rk=1&rkt=1&sd=322723603348&itm=222859334294&_trksid=p2047675.c100037.m2107

This can be wired up very easily as a switch on one of the DC power wires going to your ssr powering your heating element. you can use an xlr connector to connect it to your panel and put a bybass switch on the panel so its not in use during heating and boiling modes... you can put hose barbs on each end or better yet, camlocks and connect it right to the output of the mash tun as orientation is important.
just an option to consider.

Now that is an interesting flow switch......didn't know something like that existed. Damnit, another thing to consider adding to my panel build.

 

[BrunDog]

This is indeed the danger of having a temp probe that is physically isolated from the heating element. A flow switch is more necessary in this type of application than in a vertical RIMs tube. In the RIMs tube, even when dry, the element will heat the surrounding air which rises and heats the temp probe, causing the PID (or other algorithm) to cease heating.

I think any application where the *possibility* of overheating can occur should have a backup protection such as a flow switch or auxiliary temperature sensor.

 

[augiedoggy]

You only pull air through the mash tun sight gauge when you have a stuck mash. That is why I put one in mine. If there is no liquid in the sight gauge or it's dropping I turn the pump down. If you suck air through the sight gauge, you're doing it wrong.

To a point I agree with you. the grainbed is in this case though acting as a filtering restriction and your pumpi

But the main reason you would end up with a stuck mash or air under the false bottom would more likely be your pump is simply pumping much faster than the gravity and grainbed can replace the liquid on its own. In which case you either pull air from the sight glass (which wont help in this situation unless im missing something?) or the vacuum from the lack of the relief tube aids in pulling the liquid through the grainbed. In extreme cases this could cause the grainbed to clog, channeling and even damage the false bottom as been reported on here a few times. But, in a close to balanced flow setup the lack of the a bypass can help aid in positive flow.
I dont have an issue and I believe its because I use such a low flow rate speed in my setup. It works great so I see no benefit to speeding it up and dealing with rice hulls and such to counteract the self induced restrictions. I think this is simply because the flowrate of most home brewing pumps are much higher than needed for this type of application and people often think more is better.

 

[augiedoggy]

This is indeed the danger of having a temp probe that is physically isolated from the heating element. A flow switch is more necessary in this type of application than in a vertical RIMs tube. In the RIMs tube, even when dry, the element will heat the surrounding air which rises and heats the temp probe, causing the PID (or other algorithm) to cease heating.

I think any application where the *possibility* of overheating can occur should have a backup protection such as a flow switch or auxiliary temperature sensor.

Depending on the orientation and design of the rims tube a flow switch could be very beneficial.
If the element in the rims isnt long enough to come close to the temp probe or the rims is vertical a temp probe exposed in an air pocket above the element and heating wort would likely not cause the probe to heat up fast enough to prevent damage to the wort and possible scorching. Again I mainly agree with what your saying but I see a lot of long rims tubes here with elements that dont even span half that length and a probe mounted quite a bit away. without flow it would take a bit I think certainly enough time to mess up the enzymes in the wort being over heated even if it isnt likely enough to cause localized boiling.

I'll tell you why the flow switch really pays for itself in my application. If I forget to turn the damn rims power off on the control panel it does it for me every time. In my first vertical rims which was only an 800w 15" long copper rims with a 10" cartridge heater and a temp probe about 3 inches from the end of the element I did in fact forget to turn it off and even though the rims was mainly dry the element stayed on and scorched the liquid that remained on the element surface and at the element base. the whole batch was a dumper when I ran sparge water through the rims without realizing it.

 

[BrunDog]

I agree a flow switch is good in any application. It should probably be added by every builder no matter the application - any direct heat method gets a confirmatory flow signal allowing or inhibiting the controller from heating.

Air coming back through the sight gauge is a very reall phenomena. It may not happen to everyone in any application. The pressure difference is what will decide the fluid column height differential, and if that height exceeds the delta between the lower sight gauge port and the liquid, it will draw air. Again, a flow switch resolves this.

On my rig, which is admittedly more complex, I leverage the automation to enable an "Automash" switch. When on, the mash volume measured by the thermostatic pressure sensor (to determine mach volume) gets watched. If it drops below a certain window, the proportional valve limiting the recirculation is slightly closed. If it goes above a certain window, it is slightly opened. It works amazingly well, but the interesting factor is how the mash "porosity" evolves through the mash period. At the beginning, it is really sticky, but by 15-20 minute mark, I can almost flow full speed. The difference is flow rate is something like 6-8 quarts per min. So in theory, once you get past that initial period, you should be able to let it loose.

 

[augiedoggy]

Yes as you know brundog I use pwm speed control on my dc pumps and I always start the pump up and about 25% power and go up in increments for the first 5 mins until the grainbed "sets".. Maybe I should try climbinging slower to see it it effects my average flow speed but I dont have problems very often. when I do get slower flow its usually the grist being finer or containing some adjunct which makes it sticky.

 

[nobadays]

Texaswine... usually I am setting there checking the levels and can tell pretty quickly if the wort is starting to build on top of the grain. I had walked away so sight tube or no the results would have been the same. Not sayinb a sight tube isn't a good idea, I just wouldn't have been there to see it anyway..

Auggiedoggy ... a flow switch is a great idea. I need to look into this. Thanks!

 

[delium55]

The issue with sight glasses in false bottoms is they are an easy way to circumvent the hydraulic even pulling action through the grainbed some use and they can introduce air into the bottom of the mt. so for some (not me) they would cause more issues than benefit. This is why you dont traditionally see them on mash tuns. (that and they are fairly useless for reading levels)

I recirculate through a rims back into my mashtun and found as long as I keep my flow rate under 2 gallons per minute ($30 flowmeter inline to see this and also show if there is restrictions) I dont have any issues with stuck flow. I have had very slow flow around 1 gpm though with some grainbills although I have only ever used rice hulls once.

I installed a flowswitch in my rims which kills the heat in the rims as soon as the flow drops below .5 gallons per minute. these can be bought for as little as $10 on ebay but I recently switched to a much better design which is all stainless
https://www.ebay.com/itm/Liquid-flow-switch-sensor-NPT-1-2-inch-female-female-Stainless-Steel-FSS-N1FF-SS/222859334294?_trkparms=aid=444000&algo=SOI.DEFAULT&ao=1&asc=50999&meid=ca51c15af24240c1885237fcb64a239d&pid=100037&rk=1&rkt=1&sd=322723603348&itm=222859334294&_trksid=p2047675.c100037.m2107

This can be wired up very easily as a switch on one of the DC power wires going to your ssr powering your heating element. you can use an xlr connector to connect it to your panel and put a bybass switch on the panel so its not in use during heating and boiling modes... you can put hose barbs on each end or better yet, camlocks and connect it right to the output of the mash tun as orientation is important.
just an option to consider.

Hi Augiedoggy,

Do you have a wiring diagramm of your flow switch to your rim.
I ordered one of this switch for my futur 2 x 5500W Biab.


Thank in advance.

 

[augiedoggy]

Hi Augiedoggy,

Do you have a wiring diagramm of your flow switch to your rim.
I ordered one of this switch for my futur 2 x 5500W Biab.


Thank in advance.

Well the flow switch is wired inline to make or break my rims ssr power (its wired to allow the negative dc voltage/ground wire to complete the circuit when theres enough flow, if my flow drops too low it kills power to the ssr to prevent scorching and my flow meter is the visual analog type like this.
https://www.ebay.com/itm/NEW-Dwyer-...2-0-5-5-GPM-water-1-2-MN-LFM-NIB/152808792842