Switch for Underfloor Heating is over-heating

Bricriu

I have underfloor heating in my house.

The on-off switch for it heats up a lot, and after being on a while the switch begins to turn black and even starts to melt inside.

I've gone through two switches, and now realise that I need a heat-proof switch.

Are heat-proof switches available or is there another remedy for this problem?

meercat

Where is the switch located exactly

is it rated to take the power from your underfloor heating elements

post a photo of the switch

magicbastarder

yeah, i was thinking the same - i'm certainly no expert, but if your switch is getting hot enough to start melting itself, the solution should not be to just get a fireproof switch!

JustJoe7240

Even though its controlling a heating circuit, The wiring shouldn't be heating. I'd be guessing there's probably a loose connection somewhere. If not at the switch then further down the line passing heat up the conductors

Bricriu

Lads, many thanks for replies. See photo of back of switch.

Switch is located 3 feet up from slab (foundation containing underfloor heating wiring).

Re: 'is it rated to take the power from your underfloor heating elements?' I'm not an electrician, so can't answer that. The electrical work was carried out by a fully-qualified, experienced electrician.

When I removed the switch, there was no evidence of loose wiring to the points shown in above photo.

Here is the wiring to and from to the points shown in above photo:

Nout: Red Wire to Slab.

Lout: Red Wire to Slab.

Lin: Live Brown wire from fuse-box.

Nin: Neutral Blue wire from fuse-box.

Earth wire from slab and fuse-box were going to earth point at lower left part of photo.

I hope that is clear. Go raibh maith agaibh.

10-10-20

You'll always have a small amount of heat coming off switches, it's normal to a point as each connection and contact-point has a tiny resistance and depending on the attached load you'll get heat coming off each connection and switch contact point. Consumer units (fuse boxes) would commonly show a temperature-rise of a few degrees on the external surface when under load, it's only a problem when the heat is excessive or one breaker is showing more heat than others for the same electrical load. If the switch is burning out or the wiring melting the insulation, then it's obviously a problem alright, but you need to know what the load is (in watts) so that you can effect a repair. There are higher rated switches out there for showers and immersion elements (20A instead of 13A) and these might be a better option long-term.

A few questions: Roughly what temperature do can you feel on the switch after the heating has been left running for a number of hours? How many for these switches do you have on the property and what rating does the breaker for that circuit have? Does the one switch operate all of the downstairs under-floor heating or how is it setup? Is the switch contained on a board or wall alongside other switches and devices or is it alone on the wall?

mickdw

Get an electrician. That's a 13 amp switch. Maybe it should have a higher rated switch which are available or maybe there is another fault.

Without professional knowledge it would be dangerous to make any changes.

20/20

What type of electrical underfloor heating have you got ? Why is the switch not a thermostat , how do you regulate the heat of the floor.

meercat

https://www.boards.ie/discussion/comment/121557353#Comment_121557353

^^^^^This ^^^^^^

there should be a wall thermostat (with a built in probe buried with the elements) to regulate the heat. Otherwise the element will burn out prematurely if it’s on constantly.

without knowing the size of the buried heating element it’s impossible to tell if the spur outside you pictured is capable of taking the load required

an electrician with the right meter could test it for you (clip on amp meter)

Bricriu

Poster here with answers to the following questions from above:

Roughly what temperature do can you feel on the switch after the heating has been left running for a number of hours? Bricriu: don't know as I don't have a thermostat, but it gets hot.

How many for these switches do you have on the property and what rating does the breaker for that circuit have? Bricriu: three; two others for immersion - bottom and top. Can't see a rating for that circuit.

Does the one switch operate all of the downstairs under-floor heating or how is it setup? Bricriu: no it doesn't; their are three zones: this one which covers three rooms, second covers utility-room, and third which covers downstairs toilet and bathroom.

Is the switch contained on a board or wall alongside other switches and devices or is it alone on the wall? Bricriu: Alone.

meercat

So this switch covers 3 rooms

that’s probably at least 3 different elements (mats)

its probably overloaded

1 can you post a photo of the wiring that actually connected into this switch

2 can you confirm that there’s any thermostatic control of these mats.

Bricriu

Meercat: No, it isn't three different elements; it is one, and I have located the specifications for it: 230 V 2295 W 130 m 18w/m 23.1 ohm.

I have described in detail above the wiring that connected into the switch (see photo and list of connections above).

Thermostatic Control: Can't answer that.

Thanks for your help.

wandererz

That switch should be connected to a Thermostat with a timer. That way you can set the times that the heating comes on and at what temperature.

There should also be a temperature probe that goes from the thermostat to under the floor to read the temperature.

"230 V 2295 W 130 m 18w/m 23.1 ohm"

^^This sounds like the specs for the electrical cable that was used to supply the electricity to the heating matts. A roll of 130mtrs with a max load of 2295Watts.

The underfloor heating element should not be capable of 2295W.

Each of my matts is only 100W.

wandererz

What type of flooring do you have and what type of underfloor heating matts/element??

Daniel son

No thermostat, elements running full load, the only control seems to be someone switching system on/off. Really need to get someone to add control to that system for you and your property safety.

wandererz

@Bricriu Do yourself a favour, hop onto the Amazon and purchase 3 or 4 of these space heaters. They are on sale at €70 at the moment and you will have it by Thursday or Friday.

In the meantime switch off the underfloor heating until you get a proper electrician with experience in electric underfloor heating and thermostatic controls to advise you.

Otherwise you risk burning down the property or even electrocution if for example someone tips over a glass of water.

https://amzn.eu/d/536rgfQ

meercat

https://www.boards.ie/discussion/comment/121561936#Comment_121561936

I’m surprised that there is only 1 element covering 3 different rooms .

they usually come in a mat format

if there is only 1 element it would make it difficult to fit and wire

the switch you have shown should be capable of taking the load from 1 mat with the specifications you have given

can you upload a photo of the cables connected into the switch as requested. This is to see what size the feed and load cables are. A clip on amp meter will give an exact total load.

thermostatic control. You say you can’t answer that

can you answer this

is there any way to regulate the temperature of the underfloor heating or is simply on full or off

wandererz

@Bricriu Further to my above comments, the following is a picture of my setup in one of the rooms.

Isolator switch at bottom that can be used to knock off power feed from mains, and thermostat at top.

This is replicated for each room.

meercat

https://www.boards.ie/discussion/comment/121562203#Comment_121562203

That’s a thermostat above the switch so you do have control over the temperature of each room

edit. Sorry I didn’t realise this wasn’t the o.p I was replying to

Bricriu

No, this system has no thermostat to control the heat; it is an On-Off switch only.

I have contacted the electrician who connected it, but as people know, getting an electrician to call in this area (Co. Galway), or indeed most areas, is not easy, as they are so busy.

Thanks for all your help/Go raibh maith agaibh.

meercat

https://www.boards.ie/discussion/comment/121564435#Comment_121564435

That’s not good for the longevity of the mat or any areas with tiling/grout

wandererz

https://www.boards.ie/discussion/comment/121564435#Comment_121564435

You really don't want the same guy again because he doesn't know what he is doing.

Post a request on this site and you should get a few calls:

https://www.tradesmen.ie/index.asp?ref=bar&n=tradesmen.ie&v=ratedR&gclid=EAIaIQobChMIkfL1rPTAgwMVPZNQBh1cuQD7EAAYASAAEgLxBPD_BwE