The Scotsman SC20-A is a 20-inch coarse pre-filter that sits on the water supply to a Scotsman ice machine and captures large particles and sediment before they reach the primary filters. It serves owners and facility managers running commercial ice machines, and it also suits residential use.
This guide covers a first-time Scotsman SC20-A installation, which takes about 5–30 minutes. Keep the filter on its replacement schedule, covered in the SC20RC20 replacement guide, because an expired filter stops protecting the primary filters and the ice machine and lowers water and ice quality.
Safety & Preparation
Start by confirming the unit is the SC20-A and not the shorter SC10-A. The SC20-A stands 22.44" tall and takes the SC20RC20 filter. The SC10-A stands 12.44" tall and takes the SC10RC40, so the filters are not interchangeable.
Next, check that the ice machine matches the SC20-A's rating. Scotsman sizes it as a single system for cubers up to 650 lb (295 kg) and for flakers, nuggets and nugget dispensers up to 1,200 lb (544 kg), with a maximum flow of 10 gpm.
⚠️ Supply & Operating Limits
Plan the Location
The SC20-A measures 5.16" W x 5.5" D x 22.44" H and ships at 11 lb in a 6" x 6" x 26" carton. Pick a spot on the supply line ahead of the primary filtration and the ice machine, with enough room for the full height of the unit and clear access for filter changes.
SC20-A dimensions and inlet/outlet positions
Make sure the water lines reach both ports. The connection order is covered in Step-by-Step Installation.
🚰 Inlet
3/4" FNPT, on the left side of the head. Takes the incoming water supply.
🧊 Outlet
3/4" FNPT, on the right side of the head. Feeds the line toward the ice machine.
Have Everything Ready
🧰 Materials
⚠️ Safety Precautions
Step-by-Step Installation
These steps take a Scotsman Aqua Defense coarse pre filter installation from a dry supply line to a flushed, leak-free system.
Common Installation Mistakes
Check these points before and during a Scotsman SC20-A installation. Red cards mark things to never do. Amber cards mark mistakes you can prevent or fix.
Never fit an SC10RC40 or an SSM Plus or AquaPatrol Plus cartridge in the SC20-A. It takes the Scotsman SC20RC20 filter.
Never run the system above or below its rated pressure and temperature ranges. The limits are listed in Safety & Preparation.
Water has to enter on the left and leave on the right, following the arrows on the head. If the lines are swapped, shut off the water and reconnect them as shown in steps 3 and 4 of Step-by-Step Installation.
A fitting that isn't fully tightened will leak at the port. Shut off the water, tighten the connection, and check it again after the supply is back on.
A tight location makes the tall unit hard to fit and filter changes hard to reach. Check the space against the dimensions in Safety & Preparation before connecting any lines.
A filter that isn't fully seated can leak or cut flow. Shut off the water and reseat it following step 5 of Step-by-Step Installation.
What to Expect After Installation
When the supply is restored in step 6 of Step-by-Step Installation, run water through the system for several minutes to clear trapped air. Some air or sputtering at the start is normal, and it should clear as water keeps moving.
Once the flush is done, check the system against the two columns below:
✅ What You Want to See
🔎 Worth a Second Look
🟢 Ready for use: no leaks, steady flow, and the air has cleared. The SC20-A can now supply the ice machine.
If anything in the second column shows up, shut off the water and recheck the connections and filter seating before restoring the supply. More fixes are in Troubleshooting & FAQ.
Write down the install date. It starts the schedule in When to Replace Your Filter Cartridge.
Official Product Resources
Scotsman's SSM Plus and AquaPatrol Plus spec sheet covers the SC20-A coarse pre-filter's dimensions, maximum flow, connections, rated machine capacity, and operating requirements.
When to Replace Your Filter Cartridge
Replace the SC20RC20 filter every 6 months, or sooner with heavier usage, poorer incoming water quality, or a noticeable drop in flow. A loaded filter restricts flow to the ice machine and stops shielding the primary filters.
These three checks help set the timing:
The baseline schedule, counted from the install date.
Replace the filter right away if flow slows noticeably.
Busy machines and sediment-heavy water load the filter faster.
To keep that schedule without tracking dates, the 12-month SC20RC20 subscription is a set-it-and-forget-it option.
The genuine replacement for the SC20-A is the Scotsman SC20RC20, sold in packs of 20 so later changes are already on hand. For the replacement steps, see the SC20RC20 replacement guide.
🔎 More from Scotsman: See the full Scotsman collection, with ice machines, water filter systems, and replacement cartridges.
How to Maximize the Lifespan of Your Filter
A few routine habits keep the SC20-A clean, reachable, and working as it should:
- Log every change: record the install date and each replacement against the schedule in When to Replace Your Filter Cartridge.
- Inspect between changes: check the ports and housing for leaks and watch for reduced flow.
- Stay within the rated ranges: keep pressure and temperature inside the limits in Safety & Preparation.
- Keep the area clear: leave open access around the unit so filter changes stay quick.
- Use genuine Scotsman SC20RC20 filters: they are made for the SC20-A.
- Protect the primary filters: a clean pre-filter keeps them from clogging early.
Troubleshooting & FAQ
Which filter does the SC20-A use, and how does it differ from the SC10-A?
The SC20-A uses the Scotsman SC20RC20 filter, sold in packs of 20. The SC10-A is the shorter 12.44-inch model and uses the SC10RC40 filter instead, so the two filters are not interchangeable. The full comparison is in Safety & Preparation.
What connection sizes does the SC20-A have?
The SC20-A has a 3/4-inch FNPT inlet and a 3/4-inch FNPT outlet. Port positions are shown in Safety & Preparation.
Which ice machines is the SC20-A sized for?
Scotsman rates the SC20-A as a single system for cubers up to 650 lb (295 kg) and for flakers, nuggets and nugget dispensers up to 1,200 lb (544 kg).
Why is the SC20-A leaking at the ports or housing after installation?
A loose fitting or a filter that is not fully seated is the usual cause. Shut off the water, tighten the connections, confirm the inlet and outlet are not reversed, and reseat the filter before restoring the supply. Related causes are in Common Installation Mistakes.
Why is flow low right after installation?
A partly open supply valve, a poorly seated filter, reversed connections or air left in the line can all reduce flow. Open the valve fully, check the connections and filter seating, and finish the flush. The flush is covered in What to Expect After Installation.
Why does air or sputtering continue after the flush?
Some air at first is normal. If it keeps going after the flush, shut off the water and recheck the connections and filter seating.
How often should the SC20-A filter be replaced?
Replace the SC20RC20 filter every 6 months, or sooner with heavier usage, poorer incoming water quality or a noticeable drop in flow. Replacement options are in When to Replace Your Filter Cartridge.
Can the SC20-A be used on untreated or unknown-quality water?
No. Do not use it on water that is microbiologically unsafe or of unknown quality without adequate disinfection before or after the unit.
Product & Replacement Options
These related products cover other pre-filtration and main filtration needs on ice machine lines. The full Scotsman collection has more:
The 10-inch coarse pre-filter, 12.44" tall with a maximum flow of 5 gpm. It takes the SC10RC40 filter.
View Product →Replacement filters for the SC10-A, packed 40 to a box.
View Product →A single SSM Plus water filter system for ice machines, with half-micron filtration and a maximum flow of 1.67 gpm.
View Product →🧊 Shop Scotsman Ice Machines & Water Filters
Never Run Out of SC20RC20 Filters
The 12-month SC20RC20 subscription keeps replacement packs coming with auto-delivery.
Conclusion
Installing the SC20-A comes down to six steps, laid out in Step-by-Step Installation. With the water off, position the unit ahead of the primary filtration, connect the inlet and outlet, and seat the filter. Then restore the supply slowly, flush the system, and confirm every connection stays dry.
After that, log the install date and follow the schedule in When to Replace Your Filter Cartridge. When a change is due, use the Scotsman SC20RC20 filter.