What is a low water cut off on a boiler?
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.
What is a low water cut off valve?
Low water cutoff valves are installed on all steam boilers, most commercial heating boilers, and some home heating boilers (hydronic or hot water heating systems). As water level drops the arm moves down and ultimately trips a mechanical switch that operates an electrical contact to turn the heating system off.
How many low water cut outs are required on a boiler?
Some jurisdictional authorities require two functioning low-water fuel cutoffs on each boiler. In addition, the second low water fuel cutoff must be equipped with a manual reset in many instances.
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 often the low water cut off is tested?
The low-water fuel cut-off should be tested on a regular basis, either weekly or monthly. The frequency of testing should be increased when large amounts of makeup water are required.
Where do you put a low water cutoff?
Primary LWCO Installation: 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.
How many types of low water cut outs are there?
There are two main types of low-water cutoff devices.
How does a low water cut off probe work?
Probe Style LWCO A probe uses the boiler’s water to complete an electrical circuit. As long as water covers the probe, the electronic circuit will be maintained. If the water level drops below the probe, the circuit is broken, shutting down the burner and protecting the boiler.
Why do I have to keep adding water to my boiler?
Yes, adding water too often brings in oxygen, minerals and chemicals all of which are bad for the boiler. The worst thing on a steam boiler is chlorides. One chlorides start eating out the boiler you cannot stop it. Chlorides will normally eat away at the top of the boiler.