Using electric element to control mash temp

[mbernhardt]

Several months ago I set up my 10 Gal igloo cooler with a rancho digital controller, a pump, and a ultra-low density heating element to keep my mash at a steady temp. The igloo on its own always lost several degrees over the hour, probably because I liked to stir it once in a while to mix the enzymes around.

I have the 4000w element running on 120V, which means that its only actually generating 1000W and doesn't burn the mash. I have the probe measuring the temp of the wort as it leaves the igloo. The element heats my mash about 1 degree per 30 seconds. But the Ranco probe is so slow to adjust that by the time it thinks I've moved from (for example) 153 to 154, a fast thermometer in the mash says it's like 159. So I get these huge swings.

My thoughts are (1) find a much faster probe which has a resistance scale compatible with the Ranco; I haven't been able to find one. (2) Get a much smaller heating element so it heats slower, giving the probe time to catch up. Or (3) go back to the old way.

I can find a 1500W 240V element, which at 120V would be only 375 watts. This should heat very slowly. But it's high density. At this wattage, does it even matter what the density is?

 

[Bobby_M]

I don't know much about the ranco's design, but perhaps the electronics are not even set up to look at the probe all that often. In other words, the resistance of the thermocouple may be changed but the controller doesn't care.

Do you have the ranco's probe in direct contact with the mash or is it in a secondary thermowell?

 

[augiedoggy]

im confused? the heating element is in the mashtun , in the mash? that wont work very well for even temps if thats the case (besides other issues it will cause) you would be better off using the element in an external containers like a rims tube or a herms setup.... I had my temp probe on the exit path of my cooler mashtun and I got large swings in temp too with my herms unit... when I switched to a rims I put the temp sensor at the bottom by the rims tube fluid exit and an analog thermometer at the exit of my MT... now the system works flawlessly and temps stay within a degree or two always...

 

[pizza_man]

Several months ago I set up my 10 Gal igloo cooler with a rancho digital controller, a pump, and a ultra-low density heating element to keep my mash at a steady temp. The igloo on its own always lost several degrees over the hour, probably because I liked to stir it once in a while to mix the enzymes around.

I have the 4000w element running on 120V, which means that its only actually generating 1000W and doesn't burn the mash. I have the probe measuring the temp of the wort as it leaves the igloo. The element heats my mash about 1 degree per 30 seconds. But the Ranco probe is so slow to adjust that by the time it thinks I've moved from (for example) 153 to 154, a fast thermometer in the mash says it's like 159. So I get these huge swings.

My thoughts are (1) find a much faster probe which has a resistance scale compatible with the Ranco; I haven't been able to find one. (2) Get a much smaller heating element so it heats slower, giving the probe time to catch up. Or (3) go back to the old way.

I can find a 1500W 240V element, which at 120V would be only 375 watts. This should heat very slowly. But it's high density. At this wattage, does it even matter what the density is?

I have a RANCO on my converted freezer and it works great as a freezer controller.

But they suck at managing mash temperature because of the time it takes for heat to move through your mash. You need a PID to run your mash tun, something like a MYPIN TA4-SNR.

With a RANCO your element is 100% on until your temperature reaches your set point and by then the temperature right around your heater is 10 - 20 degrees hotter. That heat moves through your mash, heating the whole batch up. Then everything cools off until the RANCO turns back on and starts the cycle all over again.

With a PID your element starts pulsing less on and more off as your temperature gets close, then it varies the amount of on time to maintain your mash temperature. But even with a PID you need circulation which is why I am going to add a RIMS tube to my cooler mash tun.

 

[mbernhardt]

auggiedoggy, so are you maintaining the temp of the wort from the mash, or the hot water that it circulates through? If the latter, how do you collect the wort that's in the coil when mash is done? I'd thought about doing it this way but once the wort has cleared the pump I couldn't see an efficient way of getting the remainder that's stuck in the coil. I'm making 5-gal batches so it's not trivial to lose that much first runnings.

pizza man, I do have constant circulation with a pump, which is why the temperature variation was so frustrating. I guess a controller that pulsed instead of steady on would also let it heat more slowly without having to replace the element.

But maybe I'm not clear about my original question: Ultra Low density elements have a larger surface area and therefore spread the heat over a larger area of mash, reducing the chance of burning it. But I was wondering if it even matters when I'm looking at only 375 watts of heat- only 1/3 of what I'm using now. That might heat slowly enough that I could keep the current Ranco.

 

[AnOldUR]

An electric heating element directly in the mash can work fine, but recirculation probably won't be enough to evenly distribute the heat. In my opinion, you need two things. Constant mixing while the element is on and a way to control the intensity of the element (I use a router control).



edit:
fix . . . I use the A419 for temperature, but a router control for intensity.

 

[mbernhardt]

Also with that MYPIN PID, you also have to have some kind of relay to handle the power to the element, correct? What are you using?