ThermoMate ES400 4 Gallon
A 4 gallon plug-in tank for a kitchen sink. Ariston and EcoSmart sell 4 gallon tanks for less with longer warranties.
Amazon $220.99$220.99
4 gal1,440 WPlug-in
3.2/5
A low-priced 2.5 gallon plug-in tank for a single sink, with a six-year tank warranty. It is the value pick among the small tanks.
- 2.5 galTank
- 1,440 WElement
- Plug-inPower
- 6 yearsTank warranty
Check price at Amazon$159.99
Price checked November 9, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Cheapest 2.5 gallon tank here with a six-year tank warranty
- Plugs into a standard outlet with the relief valve already fitted
- Thermostat goes up to 161 °F, hotter than most mini tanks
Cons
- Wider than most 2.5 gallon tanks at 14.25 in square
The Ariston Andris RS family
Every Ariston Andris RS model we rank, smallest first. Ratings compare each against its own size.
| Model | Tank | Rating | Price |
|---|---|---|---|
| Ariston Andris RS 2.5 Gallon (this one) | 2.5 gal | 3.2/5 | $159.99 |
| Ariston Andris RS 4 Gallon | 4 gal | 4.0/5 | $169.99 |
| Ariston Andris RS 8 Gallon | 8 gal | 3.4/5 | $209.99 |
How it scores
The rating comes from 5 measured or published factors, each scored 0-100 against fixed reference points for its size. How we rank explains each one.
Specifications
| Model number | ANDRIS RS 2.5U 1.4KW |
|---|---|
| Heating | |
| Tank capacity | 2.5 gal |
| Element | 1,440 W |
| Voltage | 120 V |
| Current | 12 A |
| Electrical connection | Plug-in |
| Recovery (maker figure) | 6.8 gal/hr at 90 °F rise |
| Thermostat range | 65 to 161 °F |
| Price per gallon | $64 |
| Installation | |
| Dimensions (H x W x D) | 14.2 x 14.2 x 10.8 in |
| Weight | 15.5 lb |
| Water connections | 1/2" NPT |
| Relief valve included | Yes |
| Wall bracket included | Yes |
| Warranty | |
| Tank | 6 years |
| Parts | 2 years |
Alternatives in this size
GE 2.5 Gallon Point of Use
A 2.5 gallon plug-in tank with an eight-year tank and parts warranty, the best-covered small tank here. Good for a single sink where you want it to last.
Amazon $205.26$205.26
2.5 gal1,500 WPlug-in
Rheem Mini-Tank 2.5 Gallon
A slim 2.5 gallon plug-in tank from Rheem for one sink. It matches the Ariston on warranty but costs more.
Amazon $218.99$218.99
2.5 gal1,440 WPlug-in
Compare
Compare the Ariston Andris RS 2.5 Gallon with any other mini tank water heater →
More from Ariston: every Ariston product ranked.