RIMS; how hot & what flow rate?

[Vale71]

If you mash at a temperature well below gelatinization temperature you will always risk scorching as even with a well established grain bed you'll have a lot of non-gelatinized particles flowing through the tube. Those are quite sticky and will tend to stick to the heating element and cause scorching.
There is really no point in performing a protein rest since all malt you can buy today will be well modified. The only undermodified malt you can get today is actually unmalted cereal. If you're using a large portion of unmalted adjuncts you should consider doing a separate cereal mash instead of mashing in at a low temperature in your RIMS system as such mashing will be the most prone to scorching as unmalted cereal has an even higher gelatinization temperature.

 

[BarryBrews]

Is that the 400 micron bag from brewinabag.com?

Yes, it's the 400 micron size from brewinabag.com. Guess I've been lucky, 27 brews has left the bag well stained but never a stuck mash. Keep in mind my mash tun is 23 inches in diameter and there is a false bottom.
After dumping the grist I clean the bag using the leaf blower to remove the fine pieces then Dawn clean and thoroughly rinse. No build up going on.

 

[augiedoggy]

So My take on the rims is this... I use the longest, lowest watt density heating elements I can and use a relatively lower flow rate than most. At home this means I recirculate throught a 40" long rims with a 36" long cartridge heater thats 1800w... I recirculate with a 24v dc pump at 1.5-2 gpm and I consistently get between 88 and 91% brewhouse efficiency this way (depending on adjuncts used or not). My rims element surface doesnt have to heat up much more if any higher than the desired mash temp..

I use this same principle at my brewpub where I brew on a 3bbl rims system I made using 2 rims elements and a 6ft long "U" shaped rims mounted horizontally so it fully fills and drains without air or liquid pockets. I use brocontrol there to limit my ULWD 6500w longer (24" maybe?) straight hot water style element to 75% max output ON TOP of my regualr pid control... I also have a 30" long 2200w cartridge "booster" element wired into this rims to help and ensure consistent temps before the temp probe mounted at the rims exit.

We brewed a orange/honey cream ale yesterday and achieved a 92% mash efficiency after sparging.
I recirculate my 3bbl rims at between 3-5 gpm pulling through a 30" diameter false bottom depending on the consistency and size of grainbill.
I do not like to push flow to the max as My experience shows it compacts the grain bed and causes channeling and REDUCES my mash efficiency.

on all my rims setups the elements stay relatively clean with only a minor light almost clear color Gelatin buildup depending on grainbill that wipes off with a damp cloth. Theres no burning or discolored "cooked" protiens on my elements surface and denaturing is not an issue... I think of it as performance of a rims with safety of a herms in this configuration... (I also use flow meters and flow switches to prevent any scorching or localized boiling in the rims. We do sometimes stepmash and we find regardless of modified grains that it makes a difference.

BTW rims and stepmashing with RYE do not go well together! It was the one and only time I experienced scortching at the brewpub and we did have to dump the mash we stepmash with other adjucts such as wheat and oats on a regular basis with no problems.

here are a couple photos, one showing the mash temps and ramping rates of a large mash (It took almost 15 mins for temps to stabilize to rims at 4gpm) and another 15 mins to mash in. you would think that after 30mins much of the conversion has already taken place before the rims reaches equilibrium in this case but its not really the case surprisingly since we still have a lot of control over hitting our numbers and beer body.
The other is an older pic of our rims which has changed a bit since this pic but you get the gist.

 

[kydan47]

So My take on the rims is this... I use the longest, lowest watt density heating elements I can and use a relatively lower flow rate than most. At home this means I recirculate throught a 40" long rims with a 36" long cartridge heater thats 1800w... I recirculate with a 24v dc pump at 1.5-2 gpm and I consistently get between 88 and 91% brewhouse efficiency this way (depending on adjuncts used or not). My rims element surface doesnt have to heat up much more if any higher than the desired mash temp..

I use this same principle at my brewpub where I brew on a 3bbl rims system I made using 2 rims elements and a 6ft long "U" shaped rims mounted horizontally so it fully fills and drains without air or liquid pockets. I use brocontrol there to limit my ULWD 6500w longer (24" maybe?) straight hot water style element to 75% max output ON TOP of my regualr pid control... I also have a 30" long 2200w cartridge "booster" element wired into this rims to help and ensure consistent temps before the temp probe mounted at the rims exit.

We brewed a orange/honey cream ale yesterday and achieved a 92% mash efficiency after sparging.
I recirculate my 3bbl rims at between 3-5 gpm pulling through a 30" diameter false bottom depending on the consistency and size of grainbill.
I do not like to push flow to the max as My experience shows it compacts the grain bed and causes channeling and REDUCES my mash efficiency.

on all my rims setups the elements stay relatively clean with only a minor light almost clear color Gelatin buildup depending on grainbill that wipes off with a damp cloth. Theres no burning or discolored "cooked" protiens on my elements surface and denaturing is not an issue... I think of it as performance of a rims with safety of a herms in this configuration... (I also use flow meters and flow switches to prevent any scorching or localized boiling in the rims. We do sometimes stepmash and we find regardless of modified grains that it makes a difference.

BTW rims and stepmashing with RYE do not go well together! It was the one and only time I experienced scortching at the brewpub and we did have to dump the mash we stepmash with other adjucts such as wheat and oats on a regular basis with no problems.

here are a couple photos, one showing the mash temps and ramping rates of a large mash (It took almost 15 mins for temps to stabilize to rims at 4gpm) and another 15 mins to mash in. you would think that after 30mins much of the conversion has already taken place before the rims reaches equilibrium in this case but its not really the case surprisingly since we still have a lot of control over hitting our numbers and beer body.
The other is an older pic of our rims which has changed a bit since this pic but you get the gist.

Thnx for the extra insight Augie! I’ve ran 2 batches thru with the rims since receiving the responses and I’m dialed in now. I’m using a 3500 watt ulwd element and backing up the power to about 50-60% using a flow rate between 1-4 gpm while setting the output at 160-170. Flow rate varying with mash tun output.

cheers, Kentucky Dan