RIMS RTD temp 2.5 degrees more than mash temp - Is this normal?

[CanAm]

RIMS tube RTD sensor says 152, hand held CDN DT 450X digital thermometer ranges from 149.5 to 149.9 (don't even ask about the Blickman brewmometer on the pump inlet - also claibrated to the RTD & CDN - which reads 144-145)

This was my second batch using the 18 inch Brew Hardware RIMS tube with an element running at 1350 watts. I have an Auber RTD as the temperature sensor, and a CDN hand held thermometer to check the temperature in the mash tun. I checked them against each other and they show the same temperature in the same liquid.

I'm mashing around 22 pounds of grain in a keg mash tun with a SABCO full false bottom and a chugger pump running wide open (once things get stabilized) I'll stop the pump and RIMS element every 15 minutes and stir everything up to offset any channeling that develops.

The 1/2 inch silicone hose from the mash tun to the pump is 2 feet, from the pump to the RIMS tube is 2 feet, and from the RIMS tube to the mash tun inlet is 4 feet.

Question 1) Is this normal?

Question 2) I don't want to raise the RIMS temperature to 154 for risk of denaturing the mash enzymes. How do I get my mash temperature to be the same as the RIMS tube?

Thanks!

 

[augiedoggy]

RIMS tube RTD sensor says 152, hand held CDN DT 450X digital thermometer ranges from 149.5 to 149.9 (don't even ask about the Blickman brewmometer on the pump inlet - also claibrated to the RTD & CDN - which reads 144-145)

This was my second batch using the 18 inch Brew Hardware RIMS tube with an element running at 1350 watts. I have an Auber RTD as the temperature sensor, and a CDN hand held thermometer to check the temperature in the mash tun. I checked them against each other and they show the same temperature in the same liquid.

I'm mashing around 22 pounds of grain in a keg mash tun with a SABCO full false bottom and a chugger pump running wide open (once things get stabilized) I'll stop the pump and RIMS element every 15 minutes and stir everything up to offset any channeling that develops.

The 1/2 inch silicone hose from the mash tun to the pump is 2 feet, from the pump to the RIMS tube is 2 feet, and from the RIMS tube to the mash tun inlet is 4 feet.

Question 1) Is this normal?

Question 2) I don't want to raise the RIMS temperature to 154 for risk of denaturing the mash enzymes. How do I get my mash temperature to be the same as the RIMS tube?

Thanks!

154 wont denature anything... It sounds like you have your rims flow set too high... I run my mash at 1.5- 2gpm flow with my 1800w rims which works perfect and I know other who do this too... a chugger at full power is way to fast to effectively heat in the rims tube. you also get no channeling this way to worry about.

This is one of the reasons I use the smaller dc pumps over the larger ones which are overkill IMO. a homebrewer is better off with slower flow for recirculating, sparging and chilling through a plate or counterflow chiller yet most use a high flow pump and throttle it way down with ballvalves...

 

[CanAm]

Thanks augiedoggy - hadn't considered the flow rate. How much difference do you find between your RIMS sensor and your mash temperature at 1.5-2 gallons per minute flow rate?

By the way, I didn't even know about the smaller DC pumps when I got my chugger. Ah well...

 

[augiedoggy]

Thanks augiedoggy - hadn't considered the flow rate. How much difference do you find between your RIMS sensor and your mash temperature at 1.5-2 gallons per minute flow rate?

By the way, I didn't even know about the smaller DC pumps when I got my chugger. Ah well...

depending on room temps its usually about 1-2 degrees so I set my pid for 1 degree higher than desired. But sometimes more if its really cold in my room since I brew in front of a window with an exhaust fan in it.
this is due to temp lose from the plumbing and MT and I dont believe its enough to effect anything IMO.

The larger pumps have advantages as well like not needed as much filtering without worry of jamming up. but if you account for that the small ones work just as well.

 

[BrunDog]

My 18" RIMS with 1400W element always runs 1-2 degrees higher than the mash outlet temp. The gap slowly reduces over the mash period. This is normal as there is some heat leaking. If you insulate your tun and hoses you might get less leakage, but this could work against you, because if you overshoot for some reason, cooling back down is more difficult.

 

[eric19312]

I think your measurements make a lot of sense and I trust your thermometers because you mentioned they have been calibrated against each other.

If you are controlling your RIMS element with the RTD it is turning on and off to stay at 152 (I guess that is where you have it set).

The wort in your tun is constantly cooling as it passes along the sides of the keg mash tun on the way from the top of the mash to the false bottom. You can reduce this by insulating the mash tun.

If you reduce the flow rate I think you are going to make the issue worse not better. The wort will have longer to cool on its way to the false bottom so will drop further than it is now.

But you should insulate the mash tun and then you can probably reduce the flow rate. For me I run a direct fire tun so I can't really insulate. I keep my flow pretty high and my flame very low to keep temps stable.

 

[CanAm]

So BrunDog and Eric, what are your thoughts on setting your RIMS tube (or direct fire) for 153-154 to get a mash temp of 152? A risk for enzyme denaturing and having the final gravity too high?

 

[Bellybuster]

your differences are based on heat losses. Not uncommon for a degree or 2 to be lost in even short tubing, you just have to know it and compensate for it.
154 does not pose any risk for denaturing as said above.

 

[CanAm]

Awesome guys. Thanks!

 

[eric19312]

So BrunDog and Eric, what are your thoughts on setting your RIMS tube (or direct fire) for 153-154 to get a mash temp of 152?

Personally I don't worry about the temperature in the mash tun. I focus on the temperature of the wort leaving my pump and flow at a decent rate and pretty much same flow rate every beer. Wish I could measure flow rate could use it in recirc and in lautering.

I try to dial in recipes on my system. I brew a batch at 151 (meaning 151 at the pump exit). Ferment it out and see how it does. If I want a bit more body or sweetness in that recipe next time I brew it I might go higher. If I want a bit dryer I go lower but if I go lower I usually will go a little longer too.

So my 151 is not really going to match your 151. But I am guessing it is close enough to use as a starting point, after that you have to find out what works best on your system for a given recipe.

A risk for enzyme denaturing and having the final gravity too high?

No risk at all. What you risk is a slightly less fermentable wort but you will absolutely get as much conversion at 154 as you get at 151.

 

[BrunDog]

So BrunDog and Eric, what are your thoughts on setting your RIMS tube (or direct fire) for 153-154 to get a mash temp of 152? A risk for enzyme denaturing and having the final gravity too high?

As stated above, my RIMS runs a degree or two higher. During the mash I will occasionally update my RIMS temp to get my mash temp where I want it. No denaturing to be worried about unless your flow drops too low.

I do have a flowmeter on my rig and try to keep the flow about 6+ qt/min.

 

[augiedoggy]

I do have a flowmeter on my rig and try to keep the flow about 6+ qt/min.

As do I I find it and my flow switch in my rims very useful... more than once I have shut off my rims pump and forgot to kill the rims element... the switch does it for me and I dont have to risk dry firing or burning the liquid in the rims when this happens.

 

[eric19312]

As do I I find it and my flow switch in my rims very useful... more than once I have shut off my rims pump and forgot to kill the rims element... the switch does it for me and I dont have to risk dry firing or burning the liquid in the rims when this happens.

Tell me about your flow meter please.

 

[augiedoggy]

Tell me about your flow meter please.

got it on ebay... there are links and pictures in my build thread linked below in my sig... sorry its long and I made a lot of changes throughout the thread.

 

[Bobby_M]

The effective mash temp, if you could ever calculate it, is temperature over time across all volumes. Even if small volumes are heated a little warmer for a 2 seconds, then cooled back down, it's like it didn't happen. Enzymes don't denature instantly.

If your mash (the thick mass in the tun) is about 150F and the RIMS output is always 152F, I think the average is about 150.2F. You just need to learn what your offset is (which likely changes seasonally if you brew in a garage) and account for it. If you find the beers to be more or less fermentable than target, adjust next time.

 

[eric19312]

got it on ebay... there are links and pictures in my build thread linked below in my sig... sorry its long and I made a lot of changes throughout the thread.

Awesome thanks. I've ordered this one:
http://www.ebay.com/itm/331353079740
0.2 - 2.4 GPM

I read in the fine print it is rated to opperate 0-65C
that is 149F

I am guessing your experience is they are working fine a little hotter than 149 but I don't think I will circulate boiling liquid through it.

 

[augiedoggy]

correct I use up to 170 degree liquid.

 

[BrunDog]

2.4 gpm might not be enough. Chugger/March puts out almost 7 wide open (no restrictions) and if you recirc fast-ish it will be off the scale, of if not it might end up inducing a restriction and unwanted pressure drop.

 

[CanAm]

Even if small volumes are heated a little warmer for a 2 seconds, then cooled back down, it's like it didn't happen. Enzymes don't denature instantly.

Thanks for chiming in Bobby. I didn't realize the enzymes could tolerate elevated temps for a brief period.

Thanks a lot to all the other posters - I'm going to up the RIMS temp two degrees on my next batch.

 

[CanAm]

Update after three brew days:

With a mill gap of 0.039 the mash was getting stuck, recirculation rate was dropping, and the mash was loosing heat through the uninsulated tun faster than the RIMS tube could replace it. This explained the 4+ degree differential between wert exiting past the pump thermometer and the RIM set point.

Opened up the mill gap to 0.060 and increased the mash volume from 8 to 9 gallons for a 21 pound grain bill. Flow rate was much better maintained with a 1 degree difference between pump and RIMS thermometers. I stirred it 3-4 times and the longer the mash went on the more compacted the grains became. But temperature was pretty constant. 80% efficiency to kettle

Kept mill gap at 0.060 and decreased the mash volume from 9 to 8 gallons for a 21 pound grain bill. Flow rate was not as well maintained with a 2 to 4 degree difference between pump and RIMS thermometers (too much to be explained bu heat loss through three feet of silicone tubing IMO). I stirred it 4-5 times and the longer the mash went on the more compacted the grains became. It required frequent stirring toward the end of the mash. Even more so that the above brew day. 88% efficiency to kettel but frustrated as there was a lot of stirring needed to maintain full throttle flow.

Plan for next week - keep mill gap at 0.060, mash volume 9 gallons for 21 lbs grain, mash for 45 minutes, stir two or three times, and see where I land.

 

[BrunDog]

60 thousands is pretty wide. I recently reduced my gap to about 0.038" and started to get some sticking mashes. I learned the key is to start recirculating a bit slow. You can then ramp it up. I don't stir much if at all once doughed in. Also, if you don't, condition your grain, and mill slowly, you should as that will help.

 

[CanAm]

Conditioning. Huh, I'd heard of it but never looked into it. Definitely will do that on my next batch now that I've seen some pics of grain milled with and without being conditioned. And it's a hand crank so milling fast isn't an option

How long do you take to throttle up your pump? 1/4 open for... etc.

Thanks for the great tips Brundog!

 

[augiedoggy]

well I'm not sure why I dont have problems but I'll chime in on what I do in hopes that it may help...
I have my gap at ? (see below) and I use a motorized grain mill with doesnt go super fast but way faster than a hand crank.

I dont condition my grain. and never have

I add my water to the mash tun before doughing in.

I have a flow meter which shows I recirculate at 1.8 gpm give or take .2 gpm

I use a triple filtering false bottom which consists of a false bottom , a bazooka tube under that and a12" section of finer stainless braid inside of theat which I feel I need because of the small dc pumps I use...

I never have any recirculation issues I have do just over 60 different brew sessions this way and never a hint of a stuck sparge.. I brew 6 and 100 gallon brews.

My opinion is if you want to recirculate at some high rate for some reason you need to increase your filtering surface area somehow to allow better drainage

and my rims RTD does read a degree or 2 higher than the one at my MT exit


EDIT** just checked my gap and although I cant find my feeler gauges I was almost able to put two credit cards between the rollers so whatever that thickness is? (I would say 1.5 credit card thicknesses)

I have my beersmith set up for 75% efficiency but usually end up higher than that with 60 minute mashes and fly sparging.

 

[blizz81]

My opinion is if you want to recirculate at some high rate for some reason you need to increase your filtering surface area somehow to allow better drainage

Kind of in the spirit of the above quote, I started using a BIAB bag in my keggle and haven't had any flow issues since. Prior to that I was using a jaybird level 1 false bottom + handfuls of rice hulls + conditioning grain (which I still recommend every chance I get - cuts down on grain dust when milling, fluffy husk material left for grist giving better filtration, doesn't really take much effort / time).


I generally dough in, let things settle for a couple minutes, then start to open the outlet on my March. Once flow starts, I might nudge the valve a very tiny bit further open. Probably generally at about 45 degrees. I was running a 0.028" crush for a long time with no problems after the BIAB bag...for my last brew, opened up to 0.0385". In regards to the original question on the thread, I generally set my PID to one degree higher than target mash temp, and the mash will usually stabilize at about a half-degree lower than PID.


You shouldn't need to stir your mash at all. I can see the necessity if it's having flow issues, but if you're worried about channeling, I've found even running a silicone hose back in through the top of the vessel and coiling it around the outside seems to work fine in that respect.

 

[augiedoggy]

I agree with not having to stir and also starting the pump low and ramping up.. I do that too.

 

[CanAm]

Thanks for the tips!

I'm using a SABCO full false bottom on my keggle mash tun and was getting around 70% efficiency into the kettle. I thought I was getting channelling as most other users of similar mash tuns were reporting greater efficiency. I was using a silicone hose coiled around the top of the mash and having about 1 - 1.5 inches of water above the gain bed. At this time I was direct fire heating the bottom and was only measuring the temperature of the wert leaving the tun. Don't remember letting the mash really sit after doughing in, and pretty much opened up my chugger pump all the way soon after. No slow ramp up.

SABCO recommends a crush between 0.045" (approximately 1.5 credit cards) and 0.060". As I was getting a stuck mash I opened up the mill to 0.060" hoping for larger husks and therefore better flow.

My plan for Tuesday is to mash in and let things stabilize for 10 minutes, then, as advised, slowly increase the pump rate. (blizz81 - do you mean that you slowly nudge your pump open until you get to 45 degrees? If yes how long do you take to nudge it that far?) I'll keep an eye on temperature leaving the RIMS tube and leaving the tun.

Question 1: What is the benefit of not stirring the mash?

Question 2: What is the lowest flow rate that you can turn on a 1250 V RIMS tube without scorching the wert?

 

[blizz81]

(blizz81 - do you mean that you slowly nudge your pump open until you get to 45 degrees? If yes how long do you take to nudge it that far?) I'll keep an eye on temperature leaving the RIMS tube and leaving the tun.

Question 1: What is the benefit of not stirring the mash?

Question 2: What is the lowest flow rate that you can turn on a 1250 V RIMS tube without scorching the wert?

1) Recirculating is more or less an automation for stirring. I guess you might theoretically knock some stuff loose via stirring a bit more than simply by pulling liquid through constantly, but I think in terms of real-life applications, as long as you dough-in well and avoid big balls of grain, recirc is going to accomplish what you want. (And then you're not disturbing the set filtration bed by stirring).

2, and an answer to my "45 degree" mention) Your chugger is probably similar in performance to my March. I guess for me, I get to probably a little short of 45 degrees before I get any wort pulling back up. By the time this is happening, flow is already going at a fairly decent clip, though I don't have a flow meter / that's a "by the eye" assessment. So the "slowest" I can flow...doesn't seem very slow. And that's generally about what I run at for the whole mash...I might open it a tiny smidge further.

I could see if you weren't using something like a Chugger, you could get down to a trickle if you wanted. In my experience that's only happened on my March when I've had lautering problems pre-BIAB bag. Someone can chime in on exact flow rates as far as still being safe to energize your element...generally when I had flow issues, it was a pretty quick and obvious ramp from "normal" to a trickle, and I'd shut the element off manually when I saw it happen.

 

[CanAm]

Gotcha as to stirring and flow rate.

And you obviously can't argue with results. But I'm scratching my head as to how a BIAB in addition to a false bottom would provide better flow than just a false bottom. I would think that at least some of the small pores in the bag would become blocked and decrease the flow if compared to just a false bottom. But your experience says otherwise. There must be a reason but I can't figure it out.

 

[blizz81]

Gotcha as to stirring and flow rate.

And you obviously can't argue with results. But I'm scratching my head as to how a BIAB in addition to a false bottom would provide better flow than just a false bottom. I would think that at least some of the small pores in the bag would become blocked and decrease the flow if compared to just a false bottom. But your experience says otherwise. There must be a reason but I can't figure it out.

Just increased surface area, as augie mentioned. BIAB guys are able to crush down to powder and not have lautering issues. I know others that recirculate are doing it on the forums - saw that and figured it was a cheap and simple option. I think some people have mentioned still running into flow problems and having to lift the bag off to release the suction, and then they're ok. I've done probably 14 5-6gal batches with the bag (incl a 24.50# imperial stout, and a couple batches with a lot of wheat) with no rice hulls and haven't had one issue yet. I do still use my FB more as just elevating my bag above the drain now.

 

[augiedoggy]

Gotcha as to stirring and flow rate.

And you obviously can't argue with results. But I'm scratching my head as to how a BIAB in addition to a false bottom would provide better flow than just a false bottom. I would think that at least some of the small pores in the bag would become blocked and decrease the flow if compared to just a false bottom. But your experience says otherwise. There must be a reason but I can't figure it out.

But there are so many more pores in a bag than a false bottom has... Think about it... Even though more plug up, flow is still better because of the increased amount of holes and surface area thats not steel between less holes, More can still get through .. My triple filter set up acts as a stage filter... ones really course and the second catches whatever gets though the first and the third catches the finer stuff that might still mess up my pump... Eventually the course filter does all the filtering once the grain bed is stable and the wort is clear.

1.8-2gpm is actually a pretty good amount of flow for recirculating. it prevents clogging of the grainbed and channeling from occuring in my opinion.

 

[CanAm]

Well, if it works it works. That must be the reason. Yet another great thing about homebrewing - so many methods that turn out good beer.

I don't have a bag so I'll try the 10 minute dough in, slooowwww recirculation rate increase, 2-3 gal/min flow rate, try not to stir, and see what happens.

Results to follow brew day next Tuesday.