Description
Trade replacement for Rheem standard-NOx, 1.5″ Insulation Tank (Natural Gas, 4″ W.C.) standing-pilot tanks
The Honeywell/Resideo WT8840C1000 is a factory-style gas control for Rheem water heaters that use a 1.5″ insulation cavity. It reads tank temperature through an immersion-well NTC sensor, is self-powered by the pilot’s thermopile (no external wiring), and ships set for a 4″ W.C. natural-gas outlet pressure. CS88xx pilot assemblies are designed for use with this control.
Replaces These Models
- Honeywell / Resideo WV8840C1406
- Rheem AP16910E
- Rheem SP20832E
What it Does Well
Direct Rheem Swap (1.5″ Cavity)
Labeled for Rheem standard-NOx heaters with 1.5″ insulation. Avoid re-piping or bracket changes.
Self-Powered, Standing-Pilot Design
Runs on thermopile output from the pilot flame, so no batteries or 24-V supply are needed.
Integrated Temperature Sensing
Immersion-well NTC probe monitors water up to 221 °F (105 °C) for accurate control.
Water Temperature Limit
Sensors provide a fail-safe mechanism that can control water temperature limit (Temperature Cut-Out [TCO]) function.
Quick Diagnostics
Front status LED provides flash codes to speed troubleshooting.
Key Specifications
| Gas & Regulator Setting | Natural gas; 4.0 in. W.C. outlet pressure. |
| Insulation / Fit | 1.5″ insulation Rheem standard-NOx tanks; upright mounting. |
| Temperature Details | Dial set-point: ~55–155 °F; Sensor rating: to 221 °F (105 °C); High-limit (ECO): temperature-cutoff integral to WT88xx series. |
| Power Source | Thermopile heated by the standing pilot (no external power). |
| Connections | ½ in. NPT inlet × ½ in. inverted-flare outlet (right-angle body used on Rheem OEMs). |
