Radiant floor heat thermostat wire extension?

[CalG]

I put in a floating radiant slab in the kitchen dining room addition years ago.
We have been content to use an air temp thermostat to control the floor hot water circulater.

With humid weather today, we wanted to warm up the floor a bit to drive off the damp. But.. The thermostat didn't work (LUX TX500E)

So I replaced the device with a tecmar unit that allows two remote temperature sensors. The standard remote thermocouples come with 10 foot cables.
That's not near long enough. Can I just twist together an extension cable ? Will there be galvanic EMF at the junctions that play havoc with the temperature readings?

I want to add Floor temp and outdoor temp to the devices internal indoor air temp.

 

[dstig1]

Go ahead and extend. The only point that matters for the thermocouple is the very end where the 2 different metals join together to measure the temp

 

[Roadworthy]

You are correct. If the device in question is a thermocouple there will be a change of potential at every change of wire type. I find myself wondering if you're dealing with thermocouple temperature sensing, though. They are usually used in higher temperature range devices. Check into the technology used for your sensors. Some type of RTD or a thermistor of some sort is more common. On these devices extending the wires should not be an issue.

 

[dstig1]

The radiant floor sensors I have seen have said you can freely extend with regular wire...

 

[Roadworthy]

If you can extend the sensor lines with regular wire the sensors are not thermocouples. Most sensors in common use are not thermocouples. That was my point. Extension wire type is critical with thermocouples and doesn't matter with most other temperature sensing devices.