Probat L12 Gas-fired Coffee Roaster

Ever since we moved back to Emeryville, California from Ohio, I dearly missed having a full-size shop roaster. In Ohio, we had a Diedrich IR-12, basically a 24 Lb. capacity drum roaster from a really great manufacturer. I have little justification for having a roaster, except that I really like to cup coffees roasted by a variety of methods. I think our dedicated home roasting customers like this too, and I had the thought that some might occasionally want to add a pound of roasted coffee to an order to compare the “degree of roast” and cup results with coffees they roast at home. The only change I wanted to make was to avoid the Infra-Red burners -they work quite well but just don’t have the BTU output to change a roast mid-way through, or to chose faster roast profiles on full batches. Diedrich makes their excellent chassis with an open-flame burner, but this time I wanted to go with a gas-fired German roaster from Probat. They are real workhorse roasters with a big footprint, more overall bulk. They take more maintenance and cleaning, but really give the roaster-operator a wide range of choices in terms of roast profiling.

Probat L12:
How I added logging temperature probes to the Probat L-12:
This is how I have the data logging 2 probe thermometer set up in the front of the roaster. Then in the rear, I have a non-logging single probe in the exit airflow of the drum. It’s a setup that gives me exactly the information I need. My only last addition will be a flow-meter (in water column inches) for the gas so I can see exactly where the valve is set, instead of eyeballing the flame.

Travels of an L12: Moving the roaster from its old abode in San Francisco to Emeryville, just over the Bay Bridge, was an adventure. We had rented a truck but discovered the roaster was too tall. So we decided to move it in my pickup truck!

That’s me (left) taking directions from my friend Troy. There were 4 of us to move it.
A roaster on Van Ness, on our way to the 101
It was a lot easier to get the roast out of the truck than into it… … I really, really appreciate having a forklift: 3 hours to load, 5 minutes to unload! Here is the L12 sittin on the shop floor as I prepare to install it.
The roaster was in great shape, but dangerously dirty. I found the vent stack was clogged with just a 2″ opening!
We are actually going to have the roaster on the 2nd floor mezzanine, a “roasting loft. Here’s the space after I ran the gas and electric lines
Here’s the same space looking across from the other side of the mezzanine
Here’s the space after I laid the aluminum plate down -see the shiny spot from the old Diedrich -a much smaller footprint than the Probat.
Attaching the venting -really high-quality Ampco grease duct.
Roasting the first test batches! Actually, I bought several bags of mixed samples to roast up while working out a few problems, and getting a feel for the burner settings (they are a bit different on each roaster).

This is how I have the data logging 2 probe thermometer set up in the front of the roaster. Then in the rear, I have a non-logging single probe in the exit airflow of the drum. It’s a setup that gives me exactly the information I need. My only last addition will be a flow-meter (in water column inches) for the gas so I can see exactly where the valve is set, instead of eyeballing the flame.

More to come…

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