Underfloor heating gone mad (Warmup 3iE)

[PerranOak]

I have electric underfloor heating in the bathroom (Warmup with 3iE thermostat) that has been working perfectly for over nine years.

Today, the temp is reading 31.5C when the heating is off and the floor is cold to the touch.
There are no errors showing, nothing has happened (no bumps, power cuts, etc.) and there are no other obvious problems.

Could someone give me a clue of how to assess what the problem is please. I guess it could be the thermostat unit (easiest to fix), the floor temp sensor (pricey and tricky to fix) or the element (cold bathroom from now on!).

Cheers.

 

[muggles]

Probably the thermostat, I've replaced no end of faulty ones. Awful things. Floor sensor and element are easy to check with a good quality multimeter

 

[Taylortwocities]

Yes. You need a multimeter. Disconnect the element and the probe. Measure the resistance of both and report back what you find.

The probe should show between 8 and 12Kohms
The element reading will be somewhere between 20 and 300 ohms depend on the mat size

 

[PerranOak]

Hi,
The probe is 13.5ohms and the element is 87.6ohms (a small bathroom).
So the probe is knacked then?

 

[Taylortwocities]

Hi,
The probe is 13.5ohms and the element is 87.6ohms (a small bathroom).
So the probe is knacked then?

Are you sure it’s 13.5 ohms and not
13.5 Kohms?

If you are certain, then you could set the 3iE to be air sensing only. Then see if things work better.

hint. It’s an option in “set heating target” in the menu.

 

[PerranOak]

Sorry, I didn't look at the display properly!

I just measured it again and it is 13.36kohms, that is kilo-Ohms.

The floor temp was 18.6degC - roughly. I think the probe is an NTC10K.

What a fool.

P.S.
Mine is a very old one with no "air" option - worse luck.

 

[Taylortwocities]

So, as previously mentioned, it’s a fair bet that the 3iE Has gone to join the angels.
You don’t necessarily need to get a Warmup one as a replacement. But it must have a floor probe facility.

i got one of these when my Warmup died. Perfectly adequate and more intuitive than Warrmup.

 

[PerranOak]

Cheers mate, thank you.

Just to be clear: it’s the “box on the wall” not the probe in the floor that has died, has “joined the choir invisible “?

 

[Taylortwocities]

Yes. The box with Warmup 3iE written on it. It’s the subject of this thread!

 

[PerranOak]

True, true, I deserve that. As you say, “sometimes it’s useful to have an idiot around”!

It’s just that I think of a “thermostat” as being both the controller and the sensor together.

Replacing the box is a far better option than the probe. Cheers.

 

[PerranOak]

Hi, me again, sorry to be a pain.

I had asked Warmup about the situation earlier and they finally got back to me!

They say that even though the probe's resistance measurement looks ok it is still at fault. They got me to change the target to air temp (I was wrong, mine does have "air capability") and see what it said: it gave about the right temp. This, they say, means that the "box" is ok but the sensor has failed.

So, should I still buy a new "box" and try it?

Cheers.

 

[Taylortwocities]

Hmm, seems unlikely if the probe tests a correct resistance. But, here’s the bottom line:

replacement floor probe £5
Replacement thermostat/programmer £50-100

which do you want to try first?

 

[PerranOak]

Yes, that’s what I thought and I wonder how “technical” their “technical staff” are anyway.

Indeed. However, a floor probe would be mightily expensive to re-embed in the floor; especially as the boss would want all the tiles re-done. New floor? Gulp!

 

[Taylortwocities]

Yes, but buy a probe, just tape it to the floor, switch on and see what happens.

In fact you don't even need to tape it to the floor. Its just to determine if WarmUp's furloughed advice is correct.

 

[PerranOak]

Oh right, yeah, durr. Cheers again mate!

(“furloughed advice”, like it, gonna use that)