Why is my spa not heating? What does LF mean? This is a very common problem, and fortunately there are some simple solutions.
Luckily, your spa may be smarter than a fifth grader. It can sense when there is a reduction of water flow passing through the heating system. When this reduction of water flow happens, your spa is designed to shut down the heating system, protecting itself from overheating or burning up altogether.
The most common culprit is a dirty and clogged filter element. To troubleshoot this, take the filter(s) out of your spa completely. Be sure there is nothing floating in the spa water that could get pulled into the plumbing, i.e. leaves, scumballs, etc. Turn the breaker to the spa OFF, and then cycle it back ON. Keep your filters out of the spa, and determine whether the LF error code has disappeared. If it has, close the spa lid and check back in a couple of hours to see if the spa has heated. If the dirty filter(s) are returned to the spa, the condition will repeat itself. Either replace the spa filters with brand new ones, or clean your existing filters with a filter and cartridge cleaner from your local spa store. Rinsing the filters with just water isn't going to do it.
Have you just refilled your spa? If the spa was working fine prior to a drain and refill, but now it isn't, chances are you have an air-lock. If your spa is equipped with a priming mode, turn the breaker OFF and ON. This may do the trick. If not, you must open the access panel on the spa, and locate the correct pump. Some spas have independant circulating pumps, and some use the jet pump on low speed to circulate and heat the water. If you aren't sure what pump it is, try to see if there is a pump that is just humming. Chances are, that is the one. The air must be bled out of that pump by the drain plug or by loosening the PVC union that connects to it. The spa should be powered down before you loosen any pump plugs or unions. Once the air is let out of the pump, it will operate correctly. Thus the LF error code should not appear once the spa is powered back ON.
Is your water level low? Top the spa off to correct level, and cycle the spa OFF/ON.
Is there a screen in your spa that hot water comes out of? If your spa is equipped with a circulating pump, there is a screen-like fitting in your hot tub that bubbles and/or hot water comes out of. Sometimes solids, leaves, hair, etc. can clog this return fitting. They can be removed and cleaned, and should be each time you drain your spa. There is no problem removing this screen when the spa is filled. Grab your suit and jump in! Depending on the make of your spa, you may need a screwdriver.
Does your spa have a pressure switch? Some older spas, and even some new ones have pressure switches. They are usually 1-2 inches in diameter, round, and attached in some fashion to your heater. they may have 2 plastic "flags" that protect some wire connectors. If all else has failed, and your spa is equipped with one of these troublesome components, you probably need a new one.
These suggestions will solve 99 percent of all LF issues. If you have any other questions or problems, please call us at 734-668-7665.