Why the Pebble Flow shower runs cold: EcoSmart ECO 8 tankless heater flow-rate limits

Quick update on the hot water issue:

I did some more digging after talking with Pebble Support. The Pebble Flow uses an EcoSmart ECO 8 tankless water heater, which is rated at roughly:

• 1.0 GPM with 50°F inlet water • 1.2 GPM with 55°F inlet water • 1.4 GPM with 65°F inlet water

The factory-installed Kohler showerhead can flow up to 1.5 GPM. That means in colder areas (like the Pacific Northwest), the showerhead can actually exceed what the ECO 8 is capable of heating at full flow.

I tested this myself and it lines up perfectly:

✅ Lower shower flow = stable hot water ❌ Full shower flow = water cools off

So if you're having trouble getting hot showers, try running the shower at a lower flow rate instead of opening the valve all the way. I'm also looking into whether a lower-flow showerhead or an inline flow restrictor around 1.0 GPM would make the experience more foolproof.