So my underfloor heating has been slightly intermittent and now constantly displays an error.

It's a fairly simple timer/temperature controller but displays the error 'F1' which according to the manual means "sensor error".

When it's showing F1, it doesn't switch on obviously (presumably as it doesn't know where the sensor is).


I imagine that this was a problem from before I bought the house as nobody made any mention to me that there's underfloor heating!!! I only found it a month ago.


So my question is.. where do these sensors normally mount, and is it a case of me having to rip the tiles off to try and replace it? (not keen).

It's in the kitchen, and the controller is on the wall at the back of the worktop near a fridge... is the sensor usually mounted on the floor just below the controller?

i was reading an installation guide a few weeks back, that implied that the sensor should be wired from a recessed socket box near floor level, and that it should be inserted into a bit of bent conduit that takes it into the heated area. So somewhere below your controller/thermostat there should be a blanking plate, and hopefully, behind this should be something sensor-like.

What kind is it? I guess electrical unit.

I have this in one room. There is an air temperature sensor in the control unit, and a floor temperature sensor embedded in the floor. If you are lucky it might be the air temp sensor.

If it turns out to be the old sensor then, I wouldn't bother trying to dig out the old sensor, just add an additional sensor. Ideally you want to find a place where you can put a new sensor without having to drill a hole in the floor (i.e. where it won't be visible). Also you don't want it too near the wall, as the wires in the heaters don't go to the edge of the room.

Have you got the manual for the system that you have? Google for it perhaps.

Matt

Sensor will be a usual type thermostat wall mounted somewhere, you will also probably have a manifold to, to which the underfloor zones connect, if you have radiators on the same system there will also be a mixing station/blending valve to mix the return temperature with the flow to reduce the water temperature down to around 45 degrees, Radiators have a flow temp around 80 degrees.

The wall sensor modulates the values on the manifold to control temperature.

That's a basic explanation but hopefully you get the idea, search the internet for companies like Velta.

assuming its a wet system of course.

If its electric they do tend to have a temperature probe in the floor somewere

Apologies, didn't realise there were so many different types.


It's an electric unit, no radiators etc.

The controller is mounted in a recessed socket and into the controller at the back are 4 wires, 2 that go to the elements, and 2 that go to the sensor. They just disappear down a conduit from the socket recess (down behind the worktop/cupboards).


http://www.klima.co.uk/thermostat/documents/FHT%20Manual.pdf


That's the same unit as I have (rebranded) and the manual makes no mention of how the sensor is installed!

What kind of sensor is it (I'm wondering whether I can somehow bypass it, even if it's just to manually switch it on every once in a while - the stone is FREEZING). I can probably put a sensor in under the fridge as even if there's a hole there it won't be at all visible.

with a bit of luck that conduit will be bent at the bottom and the sensor will just pull out. I sadly have no idea how to bypass it, but i imagine its dead easy when you know how!

You sir, are a genius (I was reluctant to give it a good pull at first as it didn't nudge, but with your suggestion I just tugged as hard as I could at it and lo and behold the wire with the sensor pulled right out!).


Now.. does anybody know whether these things are proprietary or standard (so i can go and buy another one!)

How many wires does it have?

I would bet its just a thermister... 2 wires... should be about 20p if you can figure out what range and co-efficient it should be... are there any part numbers on it.. give it a gooooooooooogle

It is just a two wire thermistor at the end of a long 2-core wire. No part numbers (it's all sealed within the rubber/plastic plug and I can't cut it open easily).

Replacement sensors with the wire <£10 on ebay - might be the easiest way.

result

dont blame me if it doesnt go back in

hi there i fit these all the time in bathrooms the unit is one of two types one has ambient room tempreture sensor and the other has a floor stat if it is the floor stat unit just buy a n
ew stat and fit it between the grout joints in the floor tiles if it is the other unit just replace the unit

thay also dont have to be wired in in a certan way ok mate

thay also dont have to be wired in in a certan way ok mate

Sorry to jump onto this old thread but I am suffering the same problem. I have an oj microline system and the 2 circuits in my front room have gone down. I have taken off the room control stats and there are 4 cables in the back. A live and neutral feed coming in from the DB and a neutral and live going out down to the floor. Thre is no 5th cable for a floor sensor. Any ideas? I literally jumped out of bed when I red this thinking it was the answer.

The stat is an oj electronics OTN-1999H which is the built in sensor module without floor sensor . Any other ideas. Someone said that the element may have blown but I can't see this. I have never heard of the cables burning out especially 2 loops in the same room. PLEASE HELP ITS FREEZING IN HERE.

[Edited on 30/12/13 by Padstar]