I finished my control box and rigged up some plumbing for this heater tube. It's running quite well with the tap-water wet run out in the garage. Haven't put it to the ultimate test of a brewday quite yet. I still need to wrap up the plumbing, rig a sparge arm, and take care of a number of other miscellaneous items.
It seems to be heating from tap temps (~80*F) a bit more slowly than the 1440W eHLT cooler conversion that I built. I guess that's to be expected with the lower wattage and reduced insulation on the keg MLT. Still, I have no doubt it will be able to maintain a nice, stable temp throughout the mash once I get the PID settings dialed in. A few more tests are needed to tell if it will have the oomph necessary for step (ramp) mashes.
At first I had issues with very
poor flow rates. With ~3.5ft. of 1/2" hose from the MLT out valve to the pump, ~3ft. of 3/8" hose to the heater tube/temp probe setup, and another ~6ft. of 3/8" hose feeding back into the top of the MLT, the flow was trickling out at a pathetic dribble. At that point I didn't even feel comfortable firing the element for fear of losing prime and burning it out. But, I cut out the excess 3/8" hose where I could, reducing the total length by about 4ft., and it's now flowing great...much, much faster than I'd actually want to recirculate during the mash. So that answers the question about adequate flow rate.
I ended up putting the thermocouple probe in a brass tee about 4" downstream from the heating element, so I'm pretty sure I'll get accurate measurements without any issues.
As for the wort scorching, I'll report back after I have a chance to brew with this setup, but I'm not anticipating any issues.
Below are a few pictures.
Control Box. I'll admit I didn't put a whole lot of thought or planning into this, but I tried to arrange it to be easily expandable for my eventual conversion to an all-electric setup. Right now the top left switch controls main power to the box, bottom left is for the pump, bottom right kills the hot leg to the RIMS element. I realize that some parts of the box are water resistant and others, well...aren't. It's still a work in progress.
MLT. Obviously this is a temporary setup. It's in the garage brewery storage area. I'm working on a more convenient arrangement. Control box is perched on top of the eHLT. RIMS element is protruding from the keg handle...I kinda like it there. It's out of the way but needs to be securely mounted. The zip tie is holding the brass tee from moving. Thermocouple wire (small yellow one) is wrapped around the back of the MLT. I might lengthen the short hose between the RIMS element and the brass tee to avoid a kink in the future. The probe end and swagelok fitting for the thermocouple are from Derrin (Welcome to Brewer's Hardware
). I need to figure out how to make this more permanent/waterproof as the masking tape currently holding it in place is probably not going to last very long.
Between receiving the tube heater and rigging up this test, I assumed that it would be a nice setup, so I pulled the trigger on a few more of these. I now have four of these RIMS tubes. One is already spoken for but I might be willing to let one or two go if anyone wants to create a similar setup. I also have a bunch of extra SSRs and a few PIDs.