Build an Indoor Vent Hood

When you decide that you’re ready to brew inside the comforts of your home, you will need to find a way to exhaust the condensation from your boil. You could go out and buy a commercial kitchen vent hood, but most of them are usually a far reach from a homebrewer’s budget.

When I was putting the final touches on my semi-automated electric Heat Exchange Recirculating Mash System (eHERMS) I had trouble finding a good venting solution to fit within my eHERMS build budget. I decided to build one using a 4-inch (10-cm) inline fan to remove the boil condensation from my basement brewery, but I still needed to find a reasonable way to collect this condensation for the fan. After looking at multiple gas grill hoods, stainless steel sinks, and commercial vent hoods I finally came across a 30-quart (28-L) stainless steel mixing bowl. With an idea in mind I measured the difference in the diameter of the mixing bowl and my boil kettle and found the bowl would be wide enough to catch the moisture from the smaller diameter kettle.

The next step was trying to figure out a way to mount the inline fan to the mixing bowl and how I was going to mount my new vent hood above my boil kettle. I decided that I could hold the mixing bowl against the fan by connecting three hose clamps together and tightening them against the bowl. I then fabricated a mounting bracket to fit my fan with slotted angle steel. There are many different ways that you can mount the fan to the bowl and mount your vent hood assembly above your boil kettle. Be creative and feel free to modify my instructions.

Everyone’s venting needs may be different. I built this hood only to remove the condensation that is produced during a 60- to 90-minute boil for a 10-gallon (38-L) batch with a 10% per hour evaporation rate. My brewing system is all electric so my goal was not to remove any exhaust gases that are produced when using propane or natural gas as a fuel source. I also do not heat my hot liquor tank (HTL) above 185 °F (85 °C) or remove its lid when heating water so I was not concerned about the condensation produced from it. My vent hood is mounted about 14 inches (36 cm) from the top of my boil kettle. I use a 5,500 watt heating element that is set to 65% output from my PID controller during the boil.

Tools and Materials

4-inch (10-cm) inline fan
4-inch (10-cm) semi-rigid aluminum duct
30 quart (28 L) stainless steel mixing bowl
(6) hose clamps
Exhaust vent
Food-safe silicone sealant
Slotted angle steel
Nuts, bolts, and screws
Hand tool set
File or emery cloth
Gasket tape
Variable speed fan controller (optional)