No hot water

Contact their Support direct. It may be low water pressure.

https://www.eemax.com/products/eemax-flowco/spex3512

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Technical Support Tankless Water Heaters Eemax

The EEmax must restrict the flow of water in order for the elements to have more time to heat it.

Heavy current required for instant hot water may be switched via a relay or contacter which may be faling. One way to diagnose may be with cover off and careful listening and visual inspection, but a risky process for inexperienced DIY'er's ??. Pro time?

Water heaters have thermostats so that you cand adjust the temperature of the water. Temperatures above 120 degrees can pose a scald hazard.

Call the rep!

It runs off 220v, meaning there are two "hots" and a ground. The 190tc uses TWO sets of 220v at 40amps each. Instead of only having one dbl throw breaker, you need 2. Having said that... the white wire "should" be the same as the black wire and can be connected which ever way you like

Iam guessing your using it faster than it makes hot water. May need a larger unit or a second one,in the system

The boiler temperature setting is kept at a position lower than you need. Go to the boiler. There will be a small box with a knob. The knob generally has 3 settings marked. Cold or Vacation, warm and Hot. If you inspect it closely you will also see a rd dot marked on the body. If my guess is right, the red mark and warm align in your case. Turn the knob a little towards the hot. However, test your setting after a little time and adjust to the best setting that suits you.. If your temperature controller is in good working condition, water could get really hot. So, tely everyone in the house that you have changed the setting to hot. Other wise you know, severe scalding could occur. If this did not work you may need to change the thermostat. The element seems to be work because the water is heating up at least a few degrees.

you can check elements with a meter to see if they are any good. how old is heater?