Thanks for responding. So that I am clear on this. When you have a large temp change the PID doesn't just turn the element on all the time, but cycles the element to prevent scorching.
Is it better to have a gas fired burner for large temperature changes in a step mash or will a RIMS system do good on its own?
On my RIMS - a 4500W 240V element running on 120V (IIRC) and running in a RIMS tube slightly longer than the element by maybe 4", it will raise a mash consisting of 22 - 27 pounds of grain mixed with water at 1.25 qt/pound ratio a little slower than a degree per minute.
To raise mash temps from 150f to 168f usually takes 20-30 minutes - about the time it takes to get my sparge water to 170f...
My only caution in using a larger wattage element to step quickly is in regard to the local temp of the wort going past the element. I have a 5500W element that I can switch between 120VAC/240VAC so that I can quickly heat up water to strike temps but then step and maintain temps at 120V/1375W. If I try to step or maintain wort at mash temperatures using the higher power setting I will locally boil the wort around the element since the temp rise at the element is huge. The case may not be the same at 4500W, I'd have to dig out my heat transfer books again but my guess is that it is.
My step time from 140F to 150F mash temps with mash thickness of 1.5qt/lb and about 8 gallons of water takes less than 10 minutes and I've never had a problem, just make sure you're looking at the mash temp and not the outlet temp of the RIMS tube.
Your long rise time is because you are only getting 1125 watts out of your 4500 watt element. Run at full 4500 watts of power and your rise time from 150F to 168F should be 5 - 7 minutes. One degree every 1/2 minute would be pretty good.
I have a 2000 LWD 120 volt element and I can rise the temp 1 degree every 45 seconds for a 10 gallon batch. My mash tun is insulated, this does make a difference.
I also have an insulated MT - it's a hot water tank blanket.
I am using a keggle and at first I was not able to raise temps very quickly and had a hard time holding a temp without a lot of fluctuations. I wrapped it with reflex insulation, bubble wrap with an aluminum type covering, put it in the bottom, and put a 2" foam board on top as a cover. Big change.
Me happy now.:fro:
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