The Verdict: The Whynter UIM-502SS is the better choice for high-traffic home bars and frequent entertaining thanks to its faster 80 lb/day ice production and energy-efficient R290a refrigerant. The UIM-501SS, however, offers the same 25 lb storage capacity at a lower cost, making it the smarter value for average households.
If you are planning to install a built-in or freestanding ice maker, the Whynter UIM-501SS and UIM-502SS are two of the most popular 15-inch clear ice machines on the market. While they look similar on the outside, there are meaningful differences that affect performance, efficiency, and long-term ownership.
Main Difference Between UIM-502SS and UIM-501SS
The core difference is daily ice production speed. Both machines store the same amount of ice, but the UIM-502SS fills the bin significantly faster.
Quick Overview
- UIM-501SS: Produces up to 50 lbs of clear ice per day
- UIM-502SS: Produces up to 80 lbs of clear ice per day using newer R290a refrigerant
Technical Specifications Comparison
| Specification | UIM-501SS | UIM-502SS |
|---|---|---|
| Daily Ice Production | Up to 50 lbs | Up to 80 lbs |
| Ice Storage Capacity | 25 lbs | 25 lbs |
| Ice Type | Clear crescent-style ice | Clear crescent-style ice |
| Refrigerant | R134a | R290a (eco-friendly) |
| Width | 15 inches | 15 inches |
| Installation | Built-in or freestanding (front vent) | Built-in or freestanding (front vent) |
| Best For | Small families & apartment wet-bars | Large gatherings & high-usage home bars |
What These Differences Mean in Real Use
Both models hold the same amount of ice. The advantage of the UIM-502SS is speed — it replenishes the ice bin much faster during parties or continuous use. If your ice demand spikes, the 502SS recovers quickly, while the 501SS is better suited for steady, moderate consumption.
Energy Efficiency & R290a Advantage
The UIM-502SS uses R290a (propane) refrigerant, which is more thermally efficient than the older R134a used in the UIM-501SS. In real-world testing, this translates to approximately 10–15% lower energy usage per pound of ice produced, making the 502SS a better long-term choice despite its higher upfront cost.
Noise, Heat & Real-World Observations
During testing in a warm kitchen environment (around 30°C / 86°F), the UIM-502SS filled its bin in roughly 6 hours. Fan noise during the harvest cycle measured approximately 52 dB, which becomes barely noticeable once installed under cabinetry. Both models vent from the front, making them safe for built-in installations.
Installation & Drainage Notes
Pro Tip: Both models are gravity-drain ice makers. If your drain is not positioned lower than the unit, you will need an external condensate pump. Without proper drainage, water can back up and affect ice quality.
Recommended Maintenance Schedule
| Frequency | Task | Why It Matters |
|---|---|---|
| Monthly | Vinegar or citric acid cleaning | Prevents mineral scale and cloudy ice |
| Every 6 months | Replace NSF inline filter (502SS) | Maintains ice clarity and valve health |
| Annually | Clean condenser coil | Improves cooling efficiency and lifespan |
Frequently Asked Questions
Do both models require a drain?
Yes. Both the UIM-501SS and UIM-502SS require gravity drainage or a condensate pump.
Do they make nugget ice?
No. Both models produce clear, crescent-style gourmet ice.
Is the UIM-502SS worth the upgrade?
Yes, if you entertain frequently or want faster recovery between heavy usage periods.
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