Hayward High Limit Kit, FDXLHLI1930

The Hayward FDXLHLI1930 is the high limit kit for Universal H-Series Low NOx pool heaters in the 150 to 400 range. It is the genuine Hayward part, the same one the heater left the factory with.

What the high limit does

The high limit is a temperature safety. It watches the water leaving the heat exchanger and opens the heating circuit if that water gets hotter than the heater is designed to run. That single component is what stands between a flow problem and a damaged heat exchanger, so it is not something to bypass or jumper out.

Diagnosing before you replace

A heater that will not fire, or that fires and then shuts down after a few minutes, often points at the high limit. Before fitting a new kit, work through the flow side: a dirty filter, a closing valve, a clogged impeller or a pump running too slow will all push the heater into a high limit trip with a perfectly good switch. If flow is right and the heater still locks out, the high limit itself has failed and this kit puts it back.

Ordering

Confirm the model on your heater data plate is a Universal H-Series Low NOx unit in the 150 to 400 range so you get the right part the first time.