What is a low water cutoff?
A low-water cutoff is a mechanical device (usually a float switch) that is used to turn off the burner or shut off fuel to a boiler to prevent it from running once the water drops below a certain point. If a boiler is “dry-fired” (burned without water in it) it can suffer rupture or catastrophic failure.
How often should a low water level cutoff be tested?
The low-water cutoff should be tested at least weekly. pump and monitor the boiler water-level.
How do you test a low water cutoff probe?
You can determine what the unit is sensing by using a voltmeter set to the AC scale. With water above the level of the probe and power to the LWCO, touch one lead to the end of the probe and the other lead to probe lug . Using a resistance chart, convert the voltage reading to resistance.
How do you reset the low water pressure on a boiler?
Open both valves, to allow cold mains water into the system (you should hear it) Wait for the pressure gauge to read 1.5 bar. Close both valves, one after the other. Switch the boiler back on and, if needed, press the reset button.
How many types of low water cut outs are there?
two main types
There are two main types of low-water cutoff devices.
Where do you put a low water cutoff?
As a primary LWCO the level mark of the LWCO should be placed for mounting between 1 3/8” to 1 ½” below the boiler’s cold water line which will establish the boiler’s normal operating range.
At what pressure does the cut off function?
Low suction pressure cut-off controls are available that will automatically shut down stationary fire pumps that receive water from municipal water supply sources when the water supply pressure reduces to 140 kPa (20 psig) or lower at the suction side of the pump.
What does a low water cut off valve do?
To help prevent damage and possible injuries, boilers are fitted with low water cutoffs (LWCOs). These devices are intended to detect the low water condition and shut down the boiler. The burner remains off until the water returns, then the burner is allowed to fire normally.
Can a low water cut off be bypassed?
It should only be done under authorized conditions, and the jumper should be removed immediately after use. This is not a failure mode, however, it is the cause of many low water conditions. If the low water cutoff is frequently causing a trip of the boiler it should not be overridden because it is a safety device!