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The HydroStatModel 3150 Universal
Temperature Limit and Low Water
Cut-Off for Oil Fired Boilers

Replaces Cold Start and Triple-Action Aquastats®*
    • Install it on existing immersion well for full temperature functionality, or
    • Install it on an Electro-WellTM to add low water cut-off protection

Simple dial-type temperature and differential settings.

Easy to wire - uses the same terminal designations as common   Aquastat models.

Dynamic Temperature Display

Four on-board diagnostic indicating lights.

Saves time, materials and wiring.

*Aquastat is a registered tradmark of Honeywell International

The versatile new HydroStatModel 3150
can be used in two ways.

By installing the control on an existing immersion well, HydroStat can be used as a universal replacement for common Aquastat models. Whether it’s a cold start or a tankless coil boiler, HydroStat will provide all the temperature functions of the control being replaced.

Or, install HydroStat on a Hydrolevel Electro-WellTM (sold separately) to automatically activate the low water cut-off function. With HydroStat you can add low water cut-off protection to new or existing installations without the added time and cost to install a separate control.

Dial Type Temperature and Differential Settings
Allows for quick and easy adjustments.

Dynamic Temperature Displays.
This 3-digit LED display continually indicates boiler temperature. Whenever the high limit, low limit or differential temperature dials are turned, the LED instantly changes to display the setting temperature. For a quick reference, the LED will scroll through the current temperature and differential settings each time the HydroStat control is powered up.

Easy to Wire.
HydroStat uses the same terminal designations as common Aquastat models. This makes field replacement
fast and easy.

Four On-Board Diagnostic Indicating Lights
Indicates HydroStat is powered and the temperature function is active.

Illuminates any time the boiler is off on high temperature limit.

Only illuminates when the HydroStat is providing Low Water Cut-Off functionality. This function is activated by installing the control on a Hydrolevel Electro-Well. This LED will not illuminate when installed on a standard immersion well.

Indicates a low water condition in the boiler.


To enable HydroStat's low water cut-off function, Electo-Wells are available in three sizes to replace standard immersion wells. Remote mounting kits are also available.