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Around five years ago, as part of a loft conversion, we installed a small shower room with electric underfloor heating.
The controller is a Time Guard TPT88 that caused nothing but trouble. Initially worked ok but then started to go into a cycle of heat on/ heat off, clicking constantly during a heat demand signal.
I managed to get a new unit under warranty and this worked ok for six months or so before returning to the clicks fault.
Time Guard are no longer trading and even if I was prepared to, I can’t find a another unit to do a straight swop.
The controller wiring seems fairly standard with all these controllers but the thermostat probe seems to be a possible problem.
The time guard one is 110k ohms.
Is this likely to work with any other controller or will the resistance of the probe be calibrated to the controller?
If they are specific, what would be the worse that could happen? That the temp reading isn’t indicative of the floor temp. That being the case, would it simply be a case of altering the upper and lower trigger temps to fake readings, but based on actual surface temperature?
I’m not sure at this time how easy it is going to be replacing the probe....
At a guess that’s a 100k NTC thermistor. Wasn’t about 22 degrees when you tested by any chance?
I wouldn’t be at all surprised if other controllers used the same, 100k thermistor is a common value.
Pretty sure timeguard are still trading?
You can pretty much use any controller. I use and recommend Devi on our installs as they’re easy to use and don’t have many problems with them. We probably fit 30-40 a year.
Don’t get the rotorary controller though, they were a pain. You want the basic one or the touch screen if you go Devi. The touch screen one has a set up wizard and will set itself to the probe that’s installed.
Don’t try to replace the probe unless absolutely necessary, it’s a difficult job depending on how it’s been fitted.
Mine uses a Resistance thermometer,PT100. I'll wager yours is the same. They are not system specific.
Thanks for the replies here, curious what the relevance of 22deg is though. Is this something that affects the function of the time guard model.
Blazin, I don’t suppose you could link me to a suitable model as it is a bit confusing, whether they be for probe and air, just air etc.....
Standard function should be fine, just to come on daily, in the morning and evening for a few hours.
Basic - these come set up for floor only which is all I ever set floors for anyway as it's mainly in bathrooms. but can be altered to air, not sure if it will do both (can't see why not mind)
Fancy - These can be set for floor, air or floor&air,
Hey rockhopper,
i mentioned 22degrees as a 100k rated NTC thermistor will measure 110k ohms at 22 deg. The resistance will change with temperature and that’s how the controller knows the temperature of the floor. It’s called a 100k thermistor because that’s the resistance at 25 degrees.
Senor j mentions his uses a PT100 that is 100 ohm at 0 deg, that controller would not be compatible with your 100k thermistor.
im assuming of course you mentioned 110k because you measured your probe with a meter.
The touch screen one I linked above knows what probe is fitted and sets itself accordingly.
Thanks blazin, basic looks ok.
Goldfish, I haven’t measured it, that was extracted from the specifications I found on other forums looking for advice.
The schluter branded thermostat I recently installed allows probe calibration through the interface.