Sounds so simple ! It sounds to me that you use 3 burners? Do you mainly do 10 gal batches? Say if your HLT is at 160, a little above your mash temp, and your recirculating through the coil,how long does it take to raise the temp 10*. I understand that if you turn your burner up full blast, it will get there faster, But with your experience, what is your technique? Also, do you tend to overshoot often?
With this system I generally do 10 Gal AG batches, sometimes 15 or 20 if I go Partial Mash. In the process of building a 5 Gal AG eBIAB system cause weekend outdoor brewing just doesn't happen often enough. :mug
I actually only use 2 burners. Let's call them B1 and B2, 1 is a Blichmann, the other...well....is not. The Blichmann is WAY better. I put the HLT on B2 and heat to about 158 but it varies a little depending on my mash temp and the weather. This weekend it held me at a perfect 152 Mash which was my target (Belgian Pale if you were wondering).
B1 gets the MLT until I get to strike temp and then I dough in. I have 2 sawhorses that I set up behind the burner perpendicular to each other to make a nice sturdy platform. Once I dough in I move the MLT onto the horses and put a reflectix wrap on it. I brew with a friend so it is not a big deal. We have tried to move it before adding the grain and all that weight, but it is too hot on the bottom from the burner for the wooden horses so the extra few minutes with the heat off is perfect and we are only moving it a foot and at the same height. At this point I had been moving the BK to B1 so that I could heat while sparging. (See below for change)
Then we drop the IC into the HLT, vorlauf the mash and hook up the pump as I said previously. I had to watch the temps in both places for several brew days to get the feel for it but now I can manage the temps well. I can generally hold the mash to within a degree of where want it. The speed of the pump matters alot. I shoot for about 6-8 degrees over mash temp and then faster for colder days where I lose more heat and slower for warmer where I don't need to pass the wort through the HLT as much. I would love a valve to divert around the HLT, but only going so far right now.
To raise the temp I was doing it by cranking the HLT up, but to be honest.....that sucks. It takes about a minute per degree or so which means to get from 152 to 168 is 15 minutes and then if you want to hold it there you have to wait again......I just don't have the patience for that. I was shortcutting and not letting it get all the way up. The last two brew days I made a change. Instead of putting the BK on B1 after the MLT was off as I said above, I put a canning pot with about 3 gallons of water on it. Took that up to just below boiling and at Mash Out time dumped it right in. Heating that up during the mash is no problem as it is a small volume and B1 kicks it. Now the drawback to that is that I have to stir it in to avoid cooking any particular areas of the grain due to the high temp. This means that all the wort clarity that I got from the recirc was thrown out, but I get right to 168 recirc for 10 minutes and start sparging.....fast....easy....and my efficiency has been solid. I am drinking the first batch done that way which is a Porter and I don't notice anything cloudy about it all, although it is a Porter so it can be harder to tell. We will see how the Belgian turns out.
One tip is to stir the HLT often so that you get good heat exchange and try not to open the MLT often but when you are learning your setup you should use a stick thermometer to check areas of the mash to make sure that you are keeping it consistent. Once I got comfortable with that I have started to trust my main front mount Thermometer, but I still double check it at least once in the middle of the mash.
One tip is to stir the HLT often. I also leave the lid off and the flame low, although I still have to turn it off once or twice during the mash. I realize this wastes a little propane, but I am looking for consistancy. I don't want to be always losing heat and then having to bring it back up, by promoting heat loss with the lid off and the flame low I can almost get a balance. I wish I could turn the flame down a touch more and I might be able to really dial it in.
Long winded...but hope that helps.