Devirig 550 Electric Floor Heating Thermostat

I've had the above device installed for 18 months, controlling a heated floor in our conservatory.

It worked well last year, and I shut the system down in March.

This week I've reactivated the unit, with the same parameters, to warm the floor 06:00 to 08:00hrs each day. The unit is not a conventional thermostat, it applies current to achieve a desired temperature at the programmed times. In my case it would typically activate the floor about 05:00 hrs so the temperature target (ambient room temp 18C) was hit by 06:00hrs.

However since using it again this year it applies current to the floor more or less 24/7 with a 50% duty cycle. The Devirig FAQ acknowledges this effect could be for two reasons, see text quoted below:-

[Devirig FAQ Quote]

"1: The times programmed into the thermostat are the times you wish the room to be at the temperature set. The time it takes time to achieve this temperature is added to the start time to ensure the temperature is achieved for the start time set. ie if it takes 2 hours to achieve temperature and the time set is 7am it will switch itself on at 5am."

"2 Another reason could be that the set back or 'LO' setting has been incorrectly set during configuring the thermostat. This is the setting that directs the system to switch back on to offer frost protection. This should be set at -25°. This means that if the temperature drops 25 degrees below the temperature shown on the face it will switch back on. So, if this was incorrectly set to read -5° and the face temperature showing 21°, as soon as the temperature dropped to16° the system would switch back on.

This becomes more of an issue when the thermostat is set to operate on floor sensor as the readout is a comfort setting between 1-10 , with each number relating to 5°.

If the user were to turn the thermostat to 10 to 'try' and get more heat they would effectively be asking for 50° and even if the Lo setting was set at -25° the system would switch back in when the floor temperature dropped to 25° which would not take long particularly in the winter months."

[End Quote]

Needless to say I've fully investigated point 2.

The conservatory ambient temp without the floor heating has been 14 C at night, and about 17-18 C during the day. I can't believe therefore that the floor needs to come on at all until 05:00hrs ish. I can't seem to apply a 'hard reset' to the unit, it has a battery back up, but that battery is soldered in, and the back of the PCB is inaccessible.

I can't find anything (other than the text quoted above) on Devirig's website that gives any more information about the unit.

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experience or help would be appreciated, failing that I'll ring them on Monday.

Reply to
Mark Carver
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