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Bensiff 10-29-2011 04:15 PM

Correct power requirements for step mashing
 
I didn't want to hijack Bad Wolf's thread, so here is my pondering...

Can you step mash with 120v quickly enough to make it worthwhile? I'm really wanting to step mash without decoctions or water additions and trying to decide if I should go electric, steam, or direct fire. Electric seems the most economical if I can do it at 120v. For clarification I would want to be able to step mash up to a 10 gallon batch from 104 degrees to mash out temps.

Yooper 10-29-2011 05:29 PM

In my experience, no.

I had an HLT with a HERMS coil, with a 1500w element. It took 90 minutes to get 8 gallons from tap to strike temp. It took more than 30 minutes to go from mash temps to mashout temps, with the water in the HLT starting at 159 degrees in a 5 gallon batch. It was impossible to do, so I got a new HLT with a 5500 w element.

I still have the old HLT with the element in it. I think it leaks, though, since I tried to remove it and I couldn't get it apart. Otherwise, I'd offer it up to someone here on the forum.

samc 10-29-2011 05:56 PM

Same here. 120v in RIMS with keggle was fine maintaining mash temps, but really slow to get to mash out temp.

Bensiff 10-31-2011 12:01 PM

Thanks guys...since the cost of wiring a 220 is prohibitive I guess that means looking at steam or direct fire

shortyjacobs 10-31-2011 01:43 PM

I have a RIMS system with an igloo cooler MLT. The cooler MLT is nice, because it doesn't need much power to maintain temps...this gives me more power to raise temps.

My RIMS element is a 4500W @ 240 element that I run at 120, giving me 1125W. It takes me about 10-15 min to ramp from 152 to 168 for mashout for a 10 gallon batch, (20-30 lb grain, about 9 gallons water in the MLT). I've never done step mashes, so I can't say for sure if that's fast enough for you, but there's another data point for you. I could probably eek a bit more speed out of it by insulating my RIMS tube, which is copper, and therefore dumps a lot of heat as well. Also, my RIMS element is running in PID mode. If you put a PWM in the loop and a DPDT switch to alternate from PID to PWM, you could probably crank the PWM to 100% for ramping a mash, then switch back to PID control once you get near your desired mash temp...give you a lot more speed, since the PID isn't trying to get you there as fast as possible.

So just another data point, but I think it could be possible if you had a 1500W ULWD element in a RIMS tube and an insulated MLT. (Also note, RIMS will be way faster than HERMS in this case, since with HERMS you also have to heat up your HEX water).

clearwaterbrewer 10-31-2011 03:00 PM

Those numbers look correct, I use 25% power on a 4500W element in a RIMS tube on a sankey MLT and it held temp fine and ramped up fast enough for me..

here is my BCS datalog:
http://www.embeddedcontrolconcepts.c...ile.php?id=238

They make 1600 and 2000W 120V elements, you can insulate your MLT if not already... I think you can do it... but definitely RIMS, not HERMS, as it has much more inherent loss and delay, as stated.

audger 11-01-2011 02:15 PM

Quote:

For clarification I would want to be able to step mash up to a 10 gallon batch from 104 degrees to mash out temps.
you forgot to define one important variable- time. how quickly must you be able to get 10 gallons from 104 to 170?

you need to impart 5500 BTUs to 10 gallons of water to change the temperature that much. thats about 1,500w of electricty (@100% efficiency) to do it in 1 hour. 3,000w will do it in 30 minutes. 6,000w will do it in 15 minutes... etc.

mabrungard 11-01-2011 03:05 PM

In my opinion, flow rate through the RIMS or HERMS circuit is the critical variable in assessing if your system can use any more heating power. In my RIMS, unless the flow rate is quite high (really permeable mash bed), then my 120v (1500w) system is adequate on a 5 gal batch. With the PID control sensor mounted directly downstream of the element to prevent overheating the wort, the PID will really turn down the heating potential if that flow rate is not high enough.

I will be increasing the size of my mash tun and increasing my heating capacity to 4500w with 240v power. That power increase will be contingent on moving enough water past the element. But, at least I'll have the ability to apply that heat to the system when the mash allows it.

audger 11-01-2011 05:13 PM

that is a good point. however much power you can put into the RIMs tube, your pump needs to be able to circulate the water fast enough so you dont overshoot your max temperature (170*).

the maximum flow rate of your system should be a known variable, so then all you need to do is calculate how many watts will heat the water by how many degrees in one pass. lets use some easy numbers like
10 gallons of mash, 2000 watt heater, and 1gallon per minute flow rate...

2000 watts is going to raise 10 gallons of water by around 82 degrees in one hour, or 1.36667 degrees per minute (total). at 60 GPHour flow rate, its going to circulate the entire volume of water 6 times over the hour, or once every 10 minutes. so in 10 minutes, were assuming (for simplicity) that all of the water will make one pass thru the RIMS tube. in 10 minutes (one pass) there should be a 13.6 degree temperature change.

so you can reasonably expect that the maximum difference between input and output temperature (one pass) of the RIMS will be around 13 to 14 degrees on a 2kW element, at 100% power and 1 gallon per minute flow rate.


now how do you figure out how much power is the most you can use?
ignoring the limits of element size and reasonable wiring requirements- to figure out the maximum element wattage you can use, you find the maximum temperature change (170* minus 104* starting temp = 66*). so the maximum you would want to heat your water in one pass at any time would be 66 degrees, or else you would be overshooting, or never be able to run at 100% power (meaning your elements are overkill).

66*-change in one pass(10min) = 396*-change/hour
10gal x 8.3lb/gal x 396 = BTUs required for the change in temperature
=32,868 BTUs
=9626 watts

*i know its not possible to get water to 396 degrees, the formulas dont consider boiling points of specific liquids, or other non-linear things like that. we are only calculating rate of change, not specific temperatures

so at 1GPM, to heat the water by 66 degrees in one pass thru the RIMS you would need about 32,868 BTUs/hr, or 9626 watts of power. you can use simple math to scale any of the variables up or down.

clearwaterbrewer 11-01-2011 07:44 PM

Quote:

Originally Posted by mabrungard (Post 3444682)
In my opinion, flow rate through the RIMS or HERMS circuit is the critical variable in assessing if your system can use any more heating power. In my RIMS, unless the flow rate is quite high (really permeable mash bed), then my 120v (1500w) system is adequate on a 5 gal batch. With the PID control sensor mounted directly downstream of the element to prevent overheating the wort, the PID will really turn down the heating potential if that flow rate is not high enough.

I will be increasing the size of my mash tun and increasing my heating capacity to 4500w with 240v power. That power increase will be contingent on moving enough water past the element. But, at least I'll have the ability to apply that heat to the system when the mash allows it.


I have a very free-flowing mash recirculation, and I cannot go much above 25% power on a 4500W (just single 12" loop, not ULWD) RIMS element at mash out without having localized boiling/cavitation/whatever shake all the lines... This is with the PID temp sensor in the exit of the rims tube and PID set to 170.

with lower temps, I can go much higher, but 25% with a slight restriction after the element seems to raise it just fine... Luckily, I am using a BCS that each 'process state' can have a max duty cycle, I can have 50% for mash, and 25% for mashout

system specifics:
I have a 15 gal sankey MLT with full 15" false bottom, and a 5/8" dip-tube, 1/2" full port valve with 1" tri-clovers, 2.5' long 5/8" ID hose, march 809HS with 1" tri-clover adapters, 1/2" IDx 2' hose straight into the end of a 1.5" diameter, 14" long tri-clover RIMS tube with a 90 degree 1" tri-clover exit going to a 3-way valve that is where I add restriction or redirect to BK..


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