20 gallon boil kettle / Electric BIAB kettle

After years of drooling over other peoples kettles I’ve finally acquired a big stainless brew kettle. No more plastic boiling vessels for me, and I can finally make my electric brewing rig look good, work well and allow for easier cleanups.

I’ve already drilled a 32mm (1-1/4″) hole with a step bit for the 5500w heating element I will be using. I had read reports, for example on Kal’s site about step bits being unreliable for big holes like these, but I had no issues whatsoever. I just used alot of cutting oil/grease and made sure to keep the battery drill steady and the hole came out very nice I dare say. I also drilled another 22mm hole to accommodate a 1/2″ 3 piece stainless steel valve from bargainfittings. I also got a pickup tube with the valve. Here’s what the pickup tube and heating element look like installed in the kettle.

The 3 piece ball valve is connected to a Tee, where the pt100 temperature probe is. Next in line is the pump, which is used during mashing and cooling. More on that later in the post. I have a couple of reasons why I wanted to mount the probe outside the kettle, inline with the pump. First was that I didn’t want to drill another hole into the kettle, and wasn’t sure what placement of the probe would be best.

The kettle has a false bottom, that sites roughly 8cm above the bottom of the kettle. The false bottom is 45cm diameter and was laser cut for me by a friend.

My usual brewing process goes something like this:


  1. Heat up mash water, with false bottom in the kettle and pump running (otherwise the temperature probe would be useless)
  2. Measure and mill grains, using a rather fine crush
  3. Put the grain bag into the kettle, add grains and stir well to dissolve any grain clumps
  4. After 60 minutes mash I do a mashout at 76°C for 10 minutes. It takes about 10 minutes for the temperature of the mash to rise

While mashing the pump is on, recirculating the mash water and ensuring even temperatures throughout the mash. The PID controller keeps the temperature constant within about 0.3°C.


  1. After mashout I pull the grain bag out and hang it up to get as much sweet, sweet wort as I can out of the grains
  2. I remove the false bottom and put the heating element to work. It takes me about 5-10 minutes to reach a boil from mashout temperature
  3. I boil for 60-90 minutes depending on recipe, adding hops, irish moss and other additives as needed
  4. When there’s 15 minutes remaining I connect the already clean (but not sanitized) counterflow chiller (CFC) and recirculate boiling wort through it to sanitize it
  5. At the end of boil the heating element is turned off, wort is pumped through the CFC and chilled. The wort is at pitching temp when it exits the CFC so it goes straight into the fermentation bucket(s) and the yeast is added. This step usually takes about 10 minutes.

So that’s a typical brew day for me using my shiny new kettle. I’d love to hear about your brewing systems in the comments!

Next post I will write about the control box I’m using to control the element.

12 thoughts on “20 gallon boil kettle / Electric BIAB kettle

  1. This is great, I would like to build something similar. Can you provide a detailed BOM and am looking forward to you posting on the control box.

  2. What pump is that? when you are at full boil do you pump/circulate the wort? My March pump pulls in air (from the boil) and losses prime.

  3. I really like your false bottom design, looks very effective.

    But for ebiab isnt the false bottom only there to prevent the bag from sitting on the element? (preventing scorching, catching and tearing or weight on the element) Wouldnt a false bottom with MUCH larger holes help to increase the flow for the pump? Do you ever have problems with the pump pumping too fast and leaving a void under the false bottom?

    Do you find the false bottom is actually needed at all? Thanks for the writeup!

    1. Yeah the false bottom works really well. But you’re also right that the holes could be a bit larger without troubles. I just decided on this design in case I want to drop the bag and mash without it. I’ve had problems with the pump pumping a bit too hard, but by adjusting the bag a bit in the beginning of the mash I avoid those troubles.

      As for needing the false bottom; it’s really handy being able to pump water from under it, and obviously keeping the bag off the heating element.

  4. What kind of bag do you use…..I like the fact that you have it all in one pot, instead of using an HLT, mash tun and kettle. I just got a 15 gallon pot that I was going to electrify and use as my HLT….and already got and converted a 10 gal cooler for my mash tun……but….I may have to go this BIAB route and combine all my stuff and make a setup like yours.

    I have just sent an email to solar project asking about the pumps, and I’m still waiting for some of my electrical components to arrive, so I’m very happy I saw this thread today…

    Thanks for the inspiration!!


  5. Do you have any problems with the eyebolt and the bag? How do you remove the false bottom? I have built a similar system and the only remaining detail is how to remove the false bottom for the boil. I was thinking eyebolt but wasn’t sure if it would damage the bag. Do you have something that hooks into the eyebolt? Thanks.


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