Electric Heating Installer Hub

Frequently asked questions

LX Floor Warming

The LX family is perfect for the following floor types:

  • engineered wood
  • laminate
  • tile/stone
  • vinyl 


Note: The thermostat needs to have the floor limit set to 82°F. 

Almost 99% of the time, the reason that an electric radiant floor heating system would eventually stop working a couple of months after installation is because of damage to the cable element during installation. Even simple nicks or cuts can cause the system to fail in the future. Alterations to the floor (if not handled properly) can also inadvertently cause damage to the cables.


  • Take a resistance reading:To ensure the cables have not been damaged, complete a resistance reading on the cable using an ohmmeter or multimeter. The Ohm value of the resistance conductor-to-conductor should be within ±10% of what is printed on the manufacturer’s tag. Measure the resistance of each conductor to ground, and there should be an open circuit. If the resistance value is not within ±10% of what is printed on the tag, or there is resistance when measuring to ground, the cable may be damaged.
  • Check voltage:
    Next, ensure the correct voltage is supplied to the in-floor electric heating cables. Applying 240V to a heating cable that is specified for 120V—known as over-voltage— will cause the cable to overheat and melt, damaging the system. Conversely, applying 120V to heating cables that are specified for 240V will not produce enough heat to maximize comfort. Verify power connection splice placement: If it is determined via resistance readings that the cables have not been damaged, the next step would be to make sure the power connection splice is embedded with the heating cable.
    In order to dissipate heat correctly, the power connection splice has to be encased in mortar. Often, contractors will incorrectly place the power connection splice behind the wall, which does not meet electrical code. At least 3 in. of the non-heating lead should be embedded per National Electrical Code (NEC) 424.41(D). However, a good rule of thumb is to embed at least 12 in. of the non-heating lead. The typical recommendation includes the extra 9 in. because if the power connection splice is not embedded correctly, the connection will overheat and cause damage, pose a fire hazard and ultimately lead the system to eventually stop working. It is always important to follow the manufacturer’s specific installation instructions, as they will vary slightly.

Visit: Troubleshooting electric radiant in-floor heating systems article published in the RSES Journal for more information.

LX Thermostats (general questions)

No. Provide the thermostat with the voltage per tag/or label on the heating cable.

Never supply the thermostat with the wrong voltage as this could damage the heating cable.  

Resolution: Press and hold the standby/reset button until the thermostat display goes blank. 

15A. To add additional heating cables to the same system, a power module is required.

Each power module can handle 15A, and a maximum amount of five (5) power modules may be connected to a single thermostat.  

The thermostat thinks there is a ground fault.

Resolution: Press the standby/reset button on the thermostat. If the message disappears, then this was just a nuisance tripping. If the message does not disappear or keeps coming up, consult a certified electrician in your area.  

E2: External wired floor sensor fault. The sensor is either damaged, short circuited or disconnected.

Resolution: Check the connections of the sensor, if this does not help - the sensor needs to be replaced.

An alternative could be to change the Application to Room (Model code numbers: 088L5130, 088L5137 & 088L5140 only).

LX Programmable Thermostat (088L5130): To unlock the child lock:

  1. Press the OK button to activate the menu.
  2. Then press and hold the Up and Down buttons simultaneously 
    for three seconds. 

LX Touch/WIFI Touch Thermostat (088L5136, 088L5140): To unlock the child lock:

  1. Tap the screen to activate it. Three circles containing dots will be displayed on the screen.
  2. Draw an “L” on the screen in a single stroke without lifting your finger from the screen. Start by touching the dot in the upper left corner, then slide your finger downwards to the dot in the lower left corner, and continue sliding your finger to the dot in the circle in the lower right corner - forming the letter 'L'. If done correctly- the home screen will appear.


Note: The child lock will be reactivated when the thermostat returns to screen saver mode unless it is deactivated under: Menu>User Settings>Child Lock. 

LX205T Touch Thermostats (088L5136, 088L5140)

Top Six FAQs for Electric radiant floor heating

Top six FAQs for electric radiant floor heating

For additional LX troubleshooting support see Troubleshooting Electric Radiant In-floor Heating Systems article - which covers our top most frequently asked questions (FAQs) before, during, & after installation:

  1. The electric cables worked for a while after installation, why have they suddenly stopped?
  2. How long should the system last?
  3. Why is the red light flashing on the thermostat?
  4. How do I determine if the thermostat is operating properly?
  5. I have too much heating cable for the area; can I cut it?
  6. The cable has been damaged. Does the entire floor need to be ripped apart to find the fault?

Published in the RSES Journal, 03/2018.


Contact Us

Phone: 1-888-DANFOSS (326-3677) - choose option #3 for heating

  • Technical support: heating.ts.electric.na@danfoss.com
  • Customer service: heating.cs.na@danfoss.com

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