Current Stage: Complete

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Design:

Tub:

  • Grizzly 400 cooler with one hole drilled into the side for a bulkhead fitting & chilled water inlet. I like the fact that the cooler is well insulated. This should ensure the chiller doesn't have to work very hard. The size is great. I think this cooler is going to get popular for cold plunge builders.

Chiller:

  • 1/4HP chiller should be plenty powerful for this. The cooler is well insulated and I'm keeping it in my insulated garage. Hottest recorded garage temps have been 92F in peak summer with 100+ degree temps. I also have the option of adding ice if I want extra low temps.

Filter:

  • I'm using a bigger 4.5 x 10 whole home filter to help increase my flow rate. The larger filter will also ensure it doesn't need to be cleaned as often. I spent the extra money on a clear housing so I can see how dirty it's getting.

High Flow Rate:

  • I'm going to try to use as few fittings as possible to help achieve high flow rate, hopefully no tees or elbows. I will measure flow rate.

Tubing:

  • 3/4" Flexible PVC tubing will be used. This will be very convenient.

Pump:

  • A 1200GPH pump is in range for the chiller and hopefully I can keep the final flow rate high. I will measure flow rate.

Sanitation:

  • H202

Parts List:

Note: I do not endorse or have any affiliation with the sellers listed below. You can find these parts many places.

  1. Cooler
    • Grizzly 400: $1,231.42
    • Grizzly Torrent Twist™ Plug with Hose Connection: $18.80
  2. Chiller
    • Active Aqua 1/4 HP : $612.64
  3. Pump
    • Danner Mag-Drive 12 1200 GPH: $124
  4. Bulkhead
  5. Filter Housing setup
    • Pentek 10" Big Clear Filter Housing with 1" Ports and Pressure Release: $138
    • Housing Bracket (included above)
    • Sediment Filter: Harmsco Calypso Blue 20 Micron Pleated Sediment Cartridge: $25
  6. Tubing
    • FlexPvc 15 feet: $50 (I ended up using 10 feet.)
  7. Fittings
    • You might need to add a few fittings, like an elbow, depending on where you chiller sits relative to the cooler.
    • I ordered more unions than I needed just in case. They are way cheaper than local.
    • Cost of fittings: $37
  1. Filter Housing connections:
  2. Bulkhead connections:
  3. Chiller connections:
  4. Pump connections
  5. Tub Drain connection
  6. Hose connections ( 4 hose segments total)
  7. Pipe Thread Sealant ( Whatever is at local hardware store)
  8. PVC Primer and Glue ( Whatever is at local hardware store)
  9. Tubing insulation ( Whatever is at local hardware store)
  10. 3/4" PVC pipe. You won't need much, but you'll probably have to buy one long piece. You'll need some way to cut this.

Technical Notes:

  1. Hole saw bit size: FlexPVC bulkhead: 1 3/8" . McMaster Bulkhead: 1 5/8"
  2. Flow rate:
    • Without Filter: ~8-9 GPM
    • With 20 micron filter: ~5-6 GPM
  3. Energy usage and cost:
    • Chiller and pump are switched ON 24/7
    • Energy cost: $0.14/kWh
    • Chiller: With garage temp at 82-84F ~$9.20 per month.
    • Pump: $6.85 per month.

    So glad I saw this link on Facebook. This is exactly what I want to build but I needed this build log!

    Added the fittings you will need. Keep in mind you might need a few different fittings depending on where you are placing the chiller relative to the cooler.

      Design:

      Tub: Grizzly 400 cooler with one hole drilled into the side for a water return line. I like the fact that the cooler is well insulated. This should ensure the chiller doesn't have to work very hard. The size is great. I think this cooler is going to get popular for cold plunge builders.
      Chiller: 1/4HP chiller should be plenty powerful for this. The cooler is well insulated and I'm keeping it in my insulated garage. Hottest recorded garage temps have been 92F in peak summer with 100+ degree temps. I also have the option of adding ice if I want extra low temps.
      Filter: I'm using a bigger 4.5 x 10 whole home filter to help increase my flow rate. The larger filter will also ensure it doesn't need to be cleaned as often. I spent the extra money on a clear housing so I can see how dirty it's getting.
      High Flow Rate: I'm going to try to use as few fittings as possible to help achieve high flow rate, hopefully no tees or elbows.
      Tubing: 3/4" Flexible PVC tubing will be used. This will be very convenient.
      Pump: A 1200GPH pump is in range for the chiller and hopefully I can keep the final flow rate high. I will measure flow rate.
      Sanitation: TBD

      So it begins! Should be able to get started in the next couple days.

      Had a setback with the flex tubing, might switch to regular PVC pipe and try my luck heating and bending it. I still don't want to use fittings unless I absolutely have to.

        Thanks for sharing your build plans.

        Mind sharing your thoughts about ozone? I was looking at the diycoldplunge ozone + venturi approach, which seems reasonable, but I hadn't decided if it's needed or not (many plunges don't have ozone and seem fine?).

          acon I was planning on buying a smaller LLDPE cooler, filling it with water, and pumping ozone in 24/7 in order to see what happened. However, I saw that the Modplunge guy is currently doing the same test to see if any problems develop. So the plan right now is to wait to see how his testing goes.

          If I do use ozone I will not plumb it in with a venturi. I will most likely buy a generator with an air pump and then drill a hole in the lid for the ozone tube.

            wintermute I am waiting on my Grizzly to arrive. Going same exact build. What kind of setbacks with the flex?? Mod-Plunge seems to have figured out how to use flex the whole way thru and I would like to do the same.

                acfbob It was just a problem with the order. I'm still waiting to receive it. Flex tubing will be quite convenient to use. Especially because with how I am going to build my plumbing it will allow me to move components around if I want to.

                  acfbob By the way, I hope you make a build log or at least a completed build post so I can see it!

                    I forgot to add one fitting which connects the bulkhead to the union:
                    3/4 MPT x 3/4 MPT OR 3/4 MPT x 3/4 Slip (bulkhead to union)

                    Component connection progress. To the right of the filter housing is the bulkhead plus the exterior connection. To the far right are the two connections for the water chiller that just thread on.

                    Drilled and installed the bulkhead. Look at that perfect fit. 1-3/8 hole saw.

                    All done just waiting for the flex tubing. UPS hasn't updated the tracking in 4 days.

                    Thanks for your updates. I'm a couple weeks behind you (cooler freight delivery is slow), but will be largely following what you've done. Any tips/lessons you learn along the way would be appreciate — all the plumbing stuff is new for me.

                      acon I would recommend practicing gluing PVC together a time or two before you use your build parts. I would also recommend doing your gluing outside if possible, the solvent smell is extremely strong. If you're hung up on any specific thing let me know I can talk you through it or maybe even show you a video. The true test is the leak test which is still to come!

                          Jdlh The only thing I noticed is that the drain plug wasn't perfectly parallel but I don't think it will affect anything. What issues do you have and did you contact grizzly about them?

                            I did the same build been using for a couple of weeks I'm pretty happy with it. Even the same color.