Update 9/27/2009: Built a 240V version of the HLT, works a lot better than this one. I’m keeping this page up for reference in order to let people know about the perils of the underpowered 1000W element.
Update 8/31/2008: The electric HLT’s first field run was mildly unsuccessful. The 1000W element heats too slowly for my taste, the PID controller overshoots the final temp by 5-6 degrees, and the agitator motor burned out. Back to the drawing board for this one. The ideas are sound but the implementation needs work – I still dislike prepping my hot liquor additions on the kitchen stove.
To quickly and accurately heat my hot water additions I use an electric hot liquor tank. This idea is not original, I primarily followed this design. My electric HLT has these specifications:
- 5-gallon capacity
- Sight gauge
- Temperature control
- Water agitator
- 120V, 1000W heating element
The relatively small size suites me well because in batch sparging 5-gallon batches my water additions never go above 4 gallons.
Most of the work centered around fitting the heating element into the water cooler. The water heater element has 1″ threads which means a 1 5/16″ hole needs to be bored out. A 1″ FPT > 1″ PVC adaptor sawed in half made for a locknut, and I used a shortened 1″ PVC cap for a safety cover for the wires underneath.
The black goo is non-hardening automotive RTV sealant. In retrospect I wish I had used the hardening kind because this stuff is pretty messy. Because it’s probably not food safe I covered everything with fish tank silicone sealant. Underneath you can see the copper grounding ring which keeps the body of the element grounded.
Finally I drilled a 1/2″ hole across the bottom of the cooler to provide an exit for the cord.
Another hole in the cooler is for my thermocouple and sight gauge. I used a 1/8″ pipe nipple with a tee on the outside and a locknut on the inside. As you can see the interior locknut doesn’t look very pretty and that’s because it’s a sawed-off elbow. The “glass” on the sight gauge is simply a piece of tubing. A 1/8″ compression fitting secures the thermocouple, and its 6″ probe length keeps it sensing well within the HLT. The gasket on the inside of the sight gauge bulkhead is a piece of gasket material RTV’d onto the locknut.
In order to have evenly heated water one needs to keep it moving around. I mounted a small 1700RPM motor to the cooler lid and made an impeller from a fender washer. A motor cover from an ice cream maker keeps fingers out. The impeller shaft is a piece of #10 threaded rod coupled to the motor shaft – I had to put some threads on the motor shaft in order to use a threaded coupling.
The last part is the controller box. The heating element, thermocouple and agitator all plug into this. Controlling the power into the box is a household switch mounted on the front. The PID controller operates a solid state relay which in turn feeds into one half of an outlet, the other half of the outlet is fed by the small metal switch on top. The “controlled” outlet is for the heating element while the switched outlet is for the agitator. The two banana plugs on the left are for the thermocouple leads.
The PID controller, if you’re buying a cheap made-in-China item from eBay shouldn’t cost more than $30-$40. The relay should be less than $10, and make sure you get a heatsink for it.