Underfloor heating fault

[elephant]

Hey guys,

its actually my sisters electric under floor heating, think she got it put in about a year ago, no problems and been working fine.

About two weeks it tripped the RCD (FCU off kitchen ring) and keeps tripping, around time it tripped my sister had washed tiles but she said with ALOT of water.

Dont have tester yet but plann IR test in it, but wondering if there is any logic in water somehow seeping down to heating mat and causing fault??

will keep you updated when get chance to test it propperly but jus wondered if anyone had any similar experiences?

thanks.

 

[m4tty]

Sounds like water must be getting down to it mate. You need to test continuity/IR L&N to E?

Wait to see what the others say.

Cheers

 

[wozz]

where in the country are you elephant?

 

[m4tty]

Good Luck !If its any help, a mate of mine had an underfloor fault on electric heating caused by bad tiling some 9 months after install and the rcd then started tripping.

From memory he phoned his insurance up and a firm came in and disconnected the underfloor, they put a black box on the underfloor cable going into the floor (i imagine a large voltage and current down the cable to burn out the short) They then used a thermal imager to detect the hot spot through the tiles from the fault underneath, took one tile up, repaired the fault and relayed the tile - all fixed and still working today....

I didnt see any of this though some some facts may have gotten twisted a little...

The company wasent warm up was it mate. Ive heard that one too. Cheers

 

[elephant]

in scotland.

yep thats what planned to do matty, if did a L-N, would need to do it at 250v instead of 500v?

thanks.

 

[Doc Hudson]

It does sound like damp has bridged across part of the element.

Doc H.

 

[m4tty]

in scotland.yep thats what planned to do matty, if did a L-N, would need to do it at 250v instead of 500v?

thanks.

No mate you shouldnt test IR L to N as it should be a dead short as live goes in and neutral returns out. You should test the continuity of L-N and it should be as per the instructions.

The IR test is checking if anything is leaking to Earth from the L or N.

Also I always test at 250V first to make sure its clear before giving it 500V

Hope that helps

 

[Robin Spark]

in scotland.yep thats what planned to do matty, if did a L-N, would need to do it at 250v instead of 500v?

thanks.

You can only do L/N to Earth as its a heater element ie continuous so you would get 0 meg if doing L- N unless their was a total break in the element.

Oops just sort of repeated same as Matty, however his explaination much better!

 

[elephant]

ha! yeah that makes total sense!

so could simply be the moisture that caused the problem?

cheers.

 

[m4tty]

The tiled and grouted floor should not let anything leak down to the ufh mate. That problem needs sorting after the ufh is ok. Prob water is bridging the heating cable and the earthed grid

 

[elephant]

what you think the chances are of it drying out and the fault clearing?!...

 

[Zeespark]

It may dry out and be fine for a time, but alone wont solve the problem, it will keep returning until the problem is fixed correctly.

AndyGuinness

 

[Manator]

In reality any fault should be identified and corrected before any permanant/serious damage can occur. The test method described above "black box" I would assume is a constant dc voltage devise which can be used with thermal imaging to find an hidden fault.

 

[NozSpark]

I had a number for a UFH repair man not long ago... if it's anywhere it's in my van ATM

From what I remember it wasn't cheap... more than the cost of the kit, but less than the cost of replacing kit and flooring!.... knocking on

 

[ElectekAir]

Like you said it was working before it may just be moisture what you could do is remove the RCD for a while this will allow the cables to dry out then return to the RCD after a few days.

Obviously the down side to this is if there is actually a fault then you will irreparably damage the system so use the above solution at your own risk

This is only something that you should do after testing cont ect...

 

[Larnacaman]

Correct Manator, ....this and similar systems, are used to find high resistance faults and for common maintenance checks in continuous process industries....

Maybe a little more sophisticated than the thermal imagery mentioned here, but the principle is very similar...

 

[elephant]

for anyones interest,

after few weeks, the UFH would go for 5 mins without tripping, from before when was only 20 secs, so kept it on for 5 mins then off for a min-did this for an hour or so and its done the trick! must have def been moisture causing fault. Glad tried this before had been replaced! thanks to all for advice.

 

[Doc Hudson]

Thank you for the feedback, it is always good to hear how ongoing problems are resolved or not.

Doc H.

 

[Adrian]

I cant believe any of your answers to your post

you must stop using the under floor heating if that rcd fails you could be electrocuted

waiting for it to dry out and stop tripping the rcd is irresponsible

there is a fault/ damaged insulation on the mat and the water and tripping rcd is an indication of this fault ,don't be stupid get it fixed before someone is hurt

---------- AUTO MERGE Post added at 21:15 ---------- Previous post was at 21:13 ----------

In reality any fault should be identified and corrected before any permanant/serious damage can occur. The test method described above "black box" I would assume is a constant dc voltage devise which can be used with thermal imaging to find an hidden fault.

or could it of been an isolation transformer