Underfloor heating control problem

[Greyspur]

I have had electrical underfloor heating for 4 years. 5 mats each with an Aube TH132 control unit and Aube PB130 base. The largest controls a mat of approx 21 sq metres and it doesn't work.

When the control unit switches on after a minute or so the LCD display fades and goes blank, resets and the floor will not get warm. I swapped the control unit to another mat and it works fine, but a new unit on the original base/mat has the same problem - blank screen, no heat and then the display reads as if it has been turned on after initial installation.

All other mats are OK, so I think maybe I need a new base unit? Also the resistive load on the base should not exceed 3450Watts at 230V (max 15A) and I wonder if that may be the reason it has failed. I have read that a contactor and a snubber may be needed, but have no idea whether my system has them or where they might be sited. I am tempted to buy another base unit and wire it in, but wonder if this is a DIY proposition?

Sorry for so many questions but any advice would be helpful, thanks Mick

 

[ProDave]

It sounds to me like there might be a supply problem. High impedance joint somewhere, so as soon as the load turns on, the voltage drops and the controller turns off and re boots.

What are your skills and what test equipment do you have? you might need to call an electician if you don't have the right kit or experience.

 

[wozz]

I would gues with 21m your controller is over or near that 15a max, if no contactor.

 

[kme]

And I`ll bet that you DO have a contactor (can you hear a "thud" sound when the controller calls for heat?)

But the problem is generally caused by EM interference from the contactor coil, upsetting the logic in the controller. Snubber capacitor will be required, across the contactor coil.



KME

 

[NozSpark]

I would gues with 21m your controller is over or near that 15a max, if no contactor.

I did a 25m set up and managed to get away with a 16A thermostat,,, but IIRC that was only a 120W/m kit

 

[M107]

Have you one of these hiding away anywhere

Underfloor Heating from Floor Heating Ltd

Give Duncan a call at the linked site, he will sell snubbers on their own.

 

[Adrian]

What is a snubber?

 

[steptoe]

a capacitor that takes the spike out of the load switching.

 

[kme]

Which is connected as close as possible to the coil, across the coil itself.

 

[Adrian]

Thanks