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Low Water Cut Offs (LWCO)

We stock a wide range of LWCO's for gas, oil and steam boiler applications from industry-leading brands, including Hydrolevel, McDonnel & Miller, Taco and others.
Available in low volt (24V) and line volt (120V), auto or manual reset options.
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About Low Water Cut-Offs

Low water cut-off, frequently abbreviated as LWCO is an essential safety component of any boiler heating system. It's primary function is to cut off the power to the burner/heating element if the level of water inside the system is too low. This prevents dry-firing and consequent equipment failures and possible health and safety risks.

Frequantly Asked Questions

Q: What is the difference between manual and auto reset functionality on LWCO?
A: Manual reset controls require manual restart each time in a low water condition, meaning the reset button would have to be pressed to re-start the system once the water level is above the probe. Manual resets are most common for commercial applications and could be required by local code.

Q: What is the purpose of Test button on low water cut-off?
A: Test button allows to test the LWCO for functionality without manually lowering the water level.

Q: Why some LWCO's come with a standard probe, others with short or long? A: Since the probe must be in contact with system water to properly function, it is important so select the right size to ensure it freely contact water when its' level rises or falls. Most low water cut-off probes are standard, meaning they should universally fit majority of applications. Short probes may sometimes be used where LWCO is installed into a standard tee fitting instead of the boiler tapping.

Q: Where should low water cut-off be installed in the system?
A: In hot water boiler systems LWCO is commonly installed either directly in the boiler (if outside tapping is available), in the riser (vertical pipe leading to the boilers' fresh water supply/intake) or the header (horizontal pipe leading to the riser).
In steam systems, the LWCO is installed either in the boiler tapping or in an equalizing line. If used as a secondary (in steam systems), the control should be below the level or primary LWCO, but above the lowest permissible water level (specified by mfr).

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