Not getting up to temp

If you have already descaled your Tempra 24 Tankless water heater and replaced the flow sensor, but the high limit switch is still tripping, there could be a few other possible causes of the issue: Malfunctioning thermostat: A malfunctioning thermostat may cause the heating modules to overheat, which can trip the high limit switch. You may need to replace the thermostat if this is the case. Insufficient water flow: The Tempra 24 Tankless water heater requires a minimum flow rate of 0.5 gallons per minute to operate properly. If the flow rate is too low, the heating modules may overheat and trip the high limit switch. Check the water flow rate to ensure it meets the minimum requirement. Electrical issues: If the wiring or electrical connections are faulty, it may cause the heating modules to overheat and trip the high limit switch. You may need to inspect the wiring and connections to ensure they are intact and properly connected. If none of the above solutions work, it may be best to contact a professional technician for further diagnosis and repair. It is unlikely that you would need to replace the entire unit if the issue is isolated to a single heating module.

What Trips?

• the "Actual" electrical circuit breaker?
  
  • Is it GFCI Style?

or...

• Is the high limit switch tripping?,
  • which isn't actually a breaker.
• A circuit breaker is a breaker that toggles as a switch, and to reset it you have to switch the toggle switch ALL the way to Off position to reset, then switch it to on.
  • Same thing if it were a GFCI style, it just has a 'Test' button on the body of the breaker, that button is usually a white rectangular button.
• Some systems have a GFCI breaker that looks totally differnent from above... It's located on the control system itself, very similar to what you may have in your bathroom or kitchen of your home! It will have a 'Test' button AND a 'Reset' button.

A High Limit Switch, acts like a breaker, as it will trip when it senses a temperature greater that it is set for as a safe temperature. Once that temp is breached, it will trip.

So... Which one is tripping for you? What are you resetting to turn it back on?
if circuit breaker, it has nothing to do with the 100 degree temp you mentioned. If that trips,= electrical problem, either a short or overheated electrical appliance (internal wires) aging motor pulling too much current, loose electrical connections generate heat, etc.
if High Limit, then possible overheat of water? Many times, failed thermostat. I already know what you're thinking... But I never saw water get Hot! But... Many times that IS just the case , it's just you never noticed the water hot, and it has been cooling down when you saw it.

ur high limit trip because ur heater overshoots the program setting for the temp replace ur k4/k5 solid state relay for it controls ur temp for the heater.

The error code is HL, not hi
This is telling you the high limit switch is tripping(safety feature)
Lack of flow, corroded heat exchanger, bad high limit switch, bad thermal regulator.....
Take these steps to try and get it narrowed down.
With heater off
Locate the high limit switch, unplug the two wires connected to it, put a jumper wire in between those two wires. Turn on the heater, if it fires you need to wait till it heats all the way up. If if heats up with no fault in the cycle then most likely it's a bad high limit switch, if it continues to trip then thermal regulator, it may need both parts.
If it doesn't fire at all then you will probably need a professional

I would look at fan limit switch. They are normally located in electrical cotrol compartment. If your are lucky you will have one thats adjustable. It would helpful if I knew is your home a mobile or modular home as they usually use a button type limit on fan and hi limit. It sounds to me like you may be having problems with fan limit which controls temp. that fan comes on . Often what happens is that switch scenses temp to turn on and then draws cold enough air on return air to shut back down until temp.rises again.If this occurs when unit first comes on or continues after burner shuts off you can get a limit switch with a higher temperature rating or one that has adjustable temperature range. Hope this helps you.Thanks.

4.34

Sounds like the high limit switch. It is a small round disk shaped part at the top of the heater coil box. If the temperature gets too high then it trips this, after it cools off it resets itself. So either the limit switch is going bad and tripping early and coming back on late. Or the dryer is overheating, maybe the vent stopped up with lint?

If the unit comes on and runs but then shuts down, that sounds like an indication of a high limit trip.

Most, if not all, furnaces have high limit switches that keep a constant check on the temp inside the furnace or air handler. On most systems, once this high limit switch has been made (got to hot), the limit switch breaks control voltage to the heating device (strips, gas, fuel, etc.etc..). The blower motor continues to run until the high limit has dropped in temp and reset itself.

On some models, the high limit is a manual reset, meaning you need to reset the switch yourself or shut the unit off and then back on to reset it.


Check all filters and replace as necessary. Check the coils and fan blades for dirt build-up and cleanliness. Check motor belt (if applicable). If all these fail to solve the problem, then your issue either lies within the blower motor itself not moving enough air for proper heat transfer. Or the high limit switch itself is failing.

If the fan speed is not set correctly and running on low or medium for heat then the high limit could be tripping fan should be running in high speed for heat.