EcoSmart ECO MINI 4
An inexpensive 4 gallon plug-in tank for a kitchen or utility sink. Its warranty is a year shorter than the best small tanks.
Amazon $165.92$165.92
The EcoSmart ECO MINI 4 is the better mini tank water heater overall, rated 4.0 to 3.2. The EcoSmart ECO MINI 4 leads on value, warranty and features. The EcoSmart ECO MINI 4 costs $55.07 less ($165.92 vs $220.99).
Prices were last checked November 9, 2026. Product prices and availability are accurate as of that date and are subject to change; the price and availability shown on Amazon or the retailer's site at the time of purchase apply. As an Amazon Associate we earn from qualifying purchases.
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
Which should you buy?
- Choose the EcoSmart ECO MINI 4 for value ($41.48 per gallon ($165.92, 4 gal) vs $55.25 per gallon ($220.99, 4 gal)), warranty (5-year tank, 2-year parts vs 3-year tank, 1-year parts) and features (plugs into an outlet, relief valve included, wall bracket included vs plugs into an outlet, relief valve included).
Scores side by side
Each factor is scored 0-100 against the same fixed reference points for every 2.5 to 4 gallon mini tank water heater; a clear win is highlighted. How we rank explains each one.
| Factor weight | EcoSmart ECO MINI 4 | ThermoMate ES400 4 Gallon |
|---|---|---|
| Overall rating | 4.0/5 | 3.2/5 |
| Value 30% | 96 $41.48 per gallon ($165.92, 4 gal) | 60 $55.25 per gallon ($220.99, 4 gal) |
| Warranty 30% | 48 5-year tank, 2-year parts | 24 3-year tank, 1-year parts |
| Heating power 15% | 20 1,440 W element | 20 1,440 W element |
| Features 15% | 100 plugs into an outlet, relief valve included, wall bracket included | 75 plugs into an outlet, relief valve included |
| Tank size 10% | 100 4 gal tank | 100 4 gal tank |
Specifications
| EcoSmart ECO MINI 4 | ThermoMate ES400 4 Gallon | |
|---|---|---|
| Heating | ||
| Tank capacity | 4 gal | 4 gal |
| Element | 1,440 W | 1,440 W |
| Voltage | 120 V | 120 V |
| Current | 12 A | 12 A |
| Electrical connection | Plug-in | Plug-in |
| Recovery (maker figure) | 24 min max | - |
| Thermostat range | 50 to 140 °F | 50 to 149 °F |
| Price per gallon | $41.48 | $55.25 |
| Installation | ||
| Dimensions (H x W x D) | 18.2 x 12.3 x 12.7 in | 14.5 x 14.5 x 12.9 in |
| Weight | 21 lb | 19.8 lb |
| Water connections | 1/2" NPT | 1/2" NPT |
| Relief valve included | Yes | Yes |
| Wall bracket included | Yes | - |
| Warranty | ||
| Tank | 5 years | 3 years |
| Parts | 2 years | 1 year |