Electric underfloor heating just stopped heating

[DITryer]

I have an Aube TH232 programmable thermostat for my bathroom underfloor heating. It stopped heating the floor over Christmas. There's continuity in the underfloor wiring and the sensor seems to check out too. The unit looks like it's working, and you can hear it switching; just no heat. I've tried contacting the manufacturer to enquire whether it's likely that the switch just isn't making contact anymore but am not getting a response. It's at least 14 years old as it was there when we moved in. Just wondered if anyone had any technical knowledge that could help?

 

[ericmark]

It's a get the meters out job. But first two types of electric under floor heating, simple resistive wire, and chemical. Looking at age, likely resistive wire type, the chemical was out back then, but when I wanted to fit it in a bathroom, found the chemical type did not have a built-in earth screen, so would need an earth screen laying over it when used in a bathroom.

With the chemical, no need for under floor sensors, it is self-regulated, but with resistive you need pockets, and floor sensors.

I would hope any electrician could test it. But as a DIY job, the problem is the cost of the test equipment, and the question is, if worth buying, or just get an electrician?

 

[DITryer]

It's a get the meters out job. But first two types of electric under floor heating, simple resistive wire, and chemical. Looking at age, likely resistive wire type, the chemical was out back then, but when I wanted to fit it in a bathroom, found the chemical type did not have a built-in earth screen, so would need an earth screen laying over it when used in a bathroom.

With the chemical, no need for under floor sensors, it is self-regulated, but with resistive you need pockets, and floor sensors.

I would hope any electrician could test it. But as a DIY job, the problem is the cost of the test equipment, and the question is, if worth buying, or just get an electrician?

Thanks for responding. I have a multimeter and have proved continuity in the resistive wire and also to the sensor; they both appear ok.

 

[ericmark]

I have multiway to measure current. These are the easy-to-use method, but these

today also measure it, plus using my old multimeter

I select an easy method, depending what I am working on. The red and black meter in the first picture has a NCV (non-contact voltage) option, this is handy to see if something is dead, before removing screws needed to access terminals, but what it will not do is test a neutral.

You have to use some common sense, even one of these silly things can help, if no other loads or inputs, it would not work for me due to solar panels, but then the solar panel software can also help.

The problem I found is under floor heating takes so long to warm up, so looking for some faster way to test, be it a full-blown tester, or a neon screwdriver, but also need to test the neutral, and NCV, or neon screwdriver will not test the neutral.

Ohms law

put finger over one required, means we can look at a 690 watt heating mat, divide by 230 volts, and we know that's 3 amps, and 230/3= 76 Ω so we can test the mat with an ohmmeter. And at 760 Ω we know something is wrong, 0.3 amps or 69 watts is not going to heat up anything much. And less than 18 Ω is likely to trip something (13 amps).

The problem is if there is a break in the mat, finding out where, it would need special equipment, and even if we do find out where, unlikely it can be repaired, this is the problem I found, the builder had damaged the mat, so the only real option was to lift it all and start again.

So I can see what I used when, can see where the washing machine went on, must tell wife off about that, 5:30 am too late, off-peak ends at 5:30 am, then I can see when I made first cup of coffee, 12:42 and second cup of coffee, 15:48 talk about big brother watching me.

I found the UFH was useless really, it did not live up to expectations, lucky we had a towel rail as well, and this is the real problem, how much is repairing it really worth?

 

[Harry Bloomfield]

Thanks for responding. I have a multimeter and have proved continuity in the resistive wire and also to the sensor; they both appear ok.

Your next check, is for mains voltage, across the element terminals, when the unit is supposed to be turned on.

 

[DITryer]

Will double check with my multimeter this evening (when I've finished trying to fix the washing machine - but that's for another thread ).