Saturday, February 4, 2012

Practical Heating of Hot Liquor for HERMS

I have long used my hot liquor tank, heated by propane burner, with a copper coil heat exchanger to raise the temperature of the mash in my cooler tun.  The high BTU propane burner and heat exchanger do a great job of bringing my mash to strike temp.  The pump is connected to a temperature probe in the mash tun.  When strike temperature is reached, the pump is shut off and the mash stops recirculating and stops heating.  At this point I have to reduce the heat or turn it off to ensure I maintain the hot liquor at 170F to be used to raise the temperature of the mash for sparging.  This sparging raise (or other mash steps) involves very low heat to the hot liquor/heat exchanger that is turned off or on as needed.  The only drawback is that if the temperature of the hot liquor is not monitored closely, it sometimes raises to 190F or higher (have even brought to a boil with a good degree of neglect).

Although this is manageable, this got me thinking about using a heating element as opposed to propane.  This way, I could use a temperature probe heat controller to regulate the temp of the hot liquor and maintain 170F during mash heating steps.  I started investigating this option and found it to be unnecessarily complex to solve.  To convert the hot liquor to electrical heating element with the kind of heating power I get with propane would require me to install a 220V outlet.  Not something I relish doing myself nor paying someone to install.

This made me start to consider a much  more practical solution - Why not continue to use propane for the heavy duty heating and only use controlled electrical heating element for the relatively low heat required to maintain the hot liquor during steps in heating the mash?  This would allow me to use a lower wattage 110V heating element that could be plugged directly into my currently available electricity on the system.  A 110V element should provide sufficient heating for this purpose.  So, I have decided to add to the system a 110V heating element and temperature controller.  Rather than going through the side-wall, I think I will use the lid to suspend the element into the water.  Why drill another hole in my expense stainless steel pot?

There are lots of options on how to accomplish this.  One complete solution is the Brewer's Best Brew Heater. This is a complete heating element with 110V cord and plug and is suspended from the edge of the pot.  This thing even has an analog dial to control vessel temperature (empirically).  This heater will give 2200 watts which should be sufficient for this task.  Alternatively, there are lots of inexpensive drop in electric heaters for agriculture and marine applications.  But with these, I would also have to add a Ranco type temperature controller as well.  Maybe the premade system would be the most practical approach?

I will post an update once I have implemented this change and let you know how it goes.