The water does not heat up

these units have an inlet filter i would check that first, 2nd i would turn on 3 hot water sources and see after doing see if it corrects last try resetting the unitit. the 3 - 220 circuits are for the heating elements.

heater or circuit failure /short --and no on water in chambers causing heater problem --

Air contains water molecules. Cold air has a lot more than hot air does. When you heated all that cold air the moisture was squeezed out in much the same way water accumulates on the window glass when hot air interfaces with cold.

With heater running put your hand by the exhaust and see if the air being expelled is hot. It will be if heater is producing heat. Depending on the size of the pool this heater can take some time to heat the water.

you didn't specify whether it was electric or gas, so i'll assume it's gas. Clean or replace the thermocouple that the pilot light heats. Yes it could be the thermostat as well.

sounds like it is a plumbing problem with water supply to heater . clean filter on inlet of water supply

Did you turn the breaker completely off, then back on? When a breaker trips it is in a middle position, and nust be turned off to reset it, then it can be turned back on.

I am assuming that everything was fine and then all of the sudden available hot water usage time dropped.

On a dual heating element hot water heater it can be

1. Internal tank loaded with sediment (drain and purge from lower garden hose fitting)

2. Thermostat or element problem with ONE of the 2 heaters. (Trouble shoot element thermostat)

3. Check Circuit breaker for partial trip of the breaker.

HL is normally a "high limit" fault. If your filter is clean and you have sufficient flow, you may have a faulty high limit sensor. It should be mounted on the heater itself. The high limit sensor shuts the heater off if it senses excessively hot water. Check to see that you have sufficient flow, clean the filter, and make sure the filter pump is running. If everything else is running properly, you may have to replace the high limit sensor.

has the unit every been cleand you can check the it in the service door