Robertshaw Electric Hot Water Thermostat EWT1L2-70K ST12-70RS

Genuine Robertshaw 70°C Electric Storage Hot Water Thermostat

Restore safe and accurate temperature control to your electric hot water system with this Original Robertshaw Thermostat EWT1L2-70K / ST12-70RS.

Designed for reliable and precise thermal regulation, this thermostat ensures your water heater maintains consistent temperature while protecting against overheating.

Ideal for replacing a faulty, inconsistent, or non-heating thermostat.

🔧 Technical Specifications

• Brand: Robertshaw (Original OEM)

• Model: EWT1L2-70K

• Cross Reference: ST12-70RS

• Temperature Rating: 70°C

• Application: Electric Storage Hot Water Systems

• Type: Rod / Probe Thermostat

• Condition: Brand New

🔄 Alternate / Compatible Part Numbers

Direct replacement for:

• EWT1L2-70K

• ST12-70RS

• ST12-70

• ST12-70KS

• ST1201133

• ST1204133

• ST1207154

• EWT1L2-523

• EWT1L2-513

• EWT1L2-513N

• EWT1L2-513L

• EWT1L2-540N

• EWT1L2-540NZ

• 1317213

• 20431-3

• WIM270

• W1M-70

• W1M2508

• W1M25085

• W1M2520

• GRIST-70

• 6060605

If your existing thermostat matches any of the above numbers, this is the correct replacement.

✅ Key Features

✔ Accurate 70°C temperature regulation
✔ Reliable cut-in / cut-out performance
✔ Durable high-quality internal contacts
✔ Designed for electric storage systems
✔ OEM Robertshaw quality

🔥 What This Thermostat Does

• Maintains consistent hot water temperature

• Prevents overheating

• Protects heating elements from excessive cycling

• Improves system efficiency

• Reduces energy wastage

⚠️ Common Fault Symptoms

• Water not heating

• Water too hot or fluctuating

• Hot water running out quickly

• System tripping

• Element tested OK but no heating

🛠 Installation Notes

⚠️ Installation must be carried out by a licensed electrician or qualified technician.

Before installation:

1. Isolate power at the switchboard.

2. Confirm no live power to the hot water system.

3. Remove access panel and insulation carefully.

4. Disconnect faulty thermostat wiring.

5. Insert new thermostat probe fully into pocket.

6. Reconnect wiring securely.

7. Refit insulation and cover.

8. Restore power and test heating cycle.

Incorrect installation can cause overheating or system damage.

🏠 Why Choose Robertshaw?

• Over 100 years of thermostat engineering

• Trusted worldwide in water heating systems

• Designed for durability and long service life

• Reliable temperature control you can depend on

📦 Package Includes

1 × Robertshaw Electric Hot Water Thermostat (EWT1L2-70K / ST12-70RS)

Need Help?

Not sure if this suits your system?
Send us your hot water system brand and model number and we’ll confirm compatibility before purchase.

📌 Component Breakdown

Terminal Connections (Top Section):

• Active power enters through the thermostat.

• When temperature drops below 70°C, the thermostat closes the circuit and allows power to flow to the heating element.

• Once the set temperature is reached, it automatically opens the circuit to prevent overheating.

Copper Probe (Bottom Section):

• The probe inserts fully into the thermostat pocket inside the hot water tank.

• It senses water temperature directly via conduction.

• Proper insertion depth is critical for accurate temperature control.

⚙️ Operating Principle

1. Water temperature drops below 70°C.

2. Thermostat closes internal contacts.

3. Power flows to heating element.

4. Water heats to 70°C.

5. Thermostat opens circuit and stops heating.

This cycle maintains stable water temperature while preventing overheating and energy waste.

🛠 Installation Reference (Visual Check)

Before purchasing, confirm your existing thermostat:

✔ Has a straight copper probe
✔ Is rated 70°C
✔ Matches ST12-70RS or EWT1L2-70K
✔ Uses similar top terminal configuration

If your thermostat shape differs (short probe, dual-stage, adjustable dial etc.), send a photo and we’ll confirm.

⚠️ Safety Reminder

Always isolate power before servicing.
Thermostat probe must be fully seated in pocket.
Loose or incorrect fitment can cause overheating or element failure.