The Eccotemp EM series is the brand's small electric mini-tank water heater lineup — 2.5, 4, and 7-gallon point-of-use tanks designed for under-sink installation or supplementary hot-water service. These are not whole-house heaters — they handle a single fixture or small zone with short pipe runs.
EM models
- EM-2.5: 2.5-gallon under-sink, 120V 1500W, plug-in. Use for kitchen prep sink or single bathroom faucet hot draw.
- EM-4.0: 4-gallon, 120V 1500W or 240V 3000W variant. Sized for bar sink, small bathroom vanity.
- EM-7.0: 7-gallon, 240V 4500W. Larger under-sink or small office breakroom.
Typical applications
Mini-tanks solve the "long pipe run from main water heater" problem. A bathroom or kitchen sink 30+ feet from the central water heater wastes water waiting for hot to arrive and increases heat loss in piping. A point-of-use mini-tank under the sink delivers instant hot at the fixture while the main water heater handles bulk demand elsewhere.
Installation requirements
Most EM models plug into a standard 120V or 240V outlet — no hardwiring required. Cold water supply (compression or threaded fitting), hot outlet connecting to the fixture's hot supply. Most installations include a small expansion tank or pressure-relief provision. Mount under sink, on the wall, or on a sturdy shelf — the unit must be supported above the floor.
Run-time vs full-on heating
Mini-tanks are insulated to minimize standby loss but they're not designed for constant full-on operation. Typical residential use: tank stays full at setpoint, occasional draws trigger element activation to reheat. Setpoints in the 110–120°F range are typical for under-sink applications; higher temperatures increase scald risk and energy loss.
Anode rod considerations
EM models include a small anode rod for tank protection. In hard-water or sulfur-water applications, anode consumption is faster than in larger tanks. Check at year 3 and replace when 75% consumed.
Lifespan expectations
EM mini-tanks typically last 8–12 years in residential service. Smaller tanks cycle more frequently than large tanks (refilling and reheating after every draw), so element life can be slightly shorter than a primary water heater. Element replacement is a $25 part, 30-minute DIY.
When mini-tanks make sense vs alternatives
- vs point-of-use tankless: mini-tanks are cheaper upfront, simpler install (no high-amperage electrical), but they have a standby loss tankless doesn't.
- vs whole-house water heater for distant fixture: mini-tank avoids the energy and water waste of long pipe purge.
- vs continuous-recirculation system: mini-tank uses less energy than constantly recirculating water through long runs.