UFH - whole mat is not heating up.

[ianmorrison9]

Hi,

i am hoping someone can help me, as this is my first post but in desperate need of some advice.

we have installed electric ufh and had it tiled, but when installing we to remove the cable from the mat and coil it around to fit in the remaining space. The mat was tested before tiled and everything was working.
However now its been tiled the area in the corner where there is more than normal amount of cable (it hasn't touched or crossed) it is very hot, but the rest of the mat does not seem to be heating anywhere near the amount it should.
Are electrician thinks that the heat may be getting pulled to the area of most cable and missing the beginning of the mat out? is this possible and if so what options do i have? the area that isn't heating does not feel like we have any underfloor heating which is very disappointing.
We have spoke to the suppliers and they advised not to shorten the cable, but is this them just covering themselves, because are electrician thinks it could work by not pulling as much power to that area? Has anyone ever shortened or cut their mat cables.

the area that isn't warming as efficiently does have a poor sub floor compared to the rest of the room, could this have anything to do with it also?

any help and advice is greatly appreciated?


Ian

[nybor62]

did you use insulation boards you could be loosing all the heat into the floor , thus not generating up into the tile

[diamondtiling]

Your electrician sounds like a bit of a chancer, is he qualified? You cannot shorten the cable and it sounds as though it has been wrongly installed, the minimum gap is usually 55mm and you should not go below this. Have you installed the probe near to this excess of wires?

[Stewart]

Electrician doesn't know what he's talking about. You will have a hot spot due to the amount of cable in the one area as there is more cable to heat a smaller area and due to this, you will be unable to get a evenly heated floor. Also, as above, if the probe is in this area, it will cause the same problem, as the hotspot area will heat up quicker

You could try changing the setting on the thermostat to room temp only and see how it heats up then.

[Dave]

The coiled section is creating a hot spot and will burn out eventually.. it should not have been installed if too long.

[andy8758]

Hi,

we have installed electric ufh and had it tiled, but when installing we to remove the cable from the mat and coil it around to fit in the remaining space. The mat was tested before tiled and everything was working. All you test is that the cable has a set resistance (as described in the instructions). This measurement lets you know that the cable is undamaged - it does not tell you that everything is working.
However now its been tiled the area in the corner where there is more than normal amount of cable (it hasn't touched or crossed) it is very hot, but the rest of the mat does not seem to be heating anywhere near the amount it should. With the cable installed too close to itself, it is heating itself - i.e. overheating and ultimately it could burn the cable out - this is a fire risk and it must not be used until that fault is rectified.
Are electrician thinks that the heat may be getting pulled to the area of most cable and missing the beginning of the mat out? is this possible and if so what options do i have? the area that isn't heating does not feel like we have any underfloor heating which is very disappointing. No (properly qualified) electrician would give you that advice. Electricity flows through the cable, and the flow causes the cable to become hot - it does not miss the sparser areas to reach the denser areas - this is utter rubbish.
We have spoke to the suppliers and they advised not to shorten the cable, but is this them just covering themselves, because are electrician thinks it could work by not pulling as much power to that area? Has anyone ever shortened or cut their mat cables. The correct way to install UFH is to accurately measure out the (0.5m) widths of the mat, across the room, and to order no more than that length - i.e. order a smaller floor area not a larger - then you have to plan where not to lay the mat, i.e. where you can live with a cold floor area.

the area that isn't warming as efficiently does have a poor sub floor compared to the rest of the room, could this have anything to do with it also? The cable heat radiates evenly in all directions from the cable. If you lay it on concrete, it is putting as much effort uin heating the concrete as it does heating the tile. So you should lay the cable on insulation board (laid on top of the concrete) - this then reflects the radiated heat up through the tile, and stops the cable heating the concrete (or wood) floor.

any help and advice is greatly appreciated? I am sorry but you must remove the tiles and UFH mat and start again.


Ian

Always read the instructions and follow them exactly - hope the above advice is followed - I know it is not helpful to you - but you cannot use the UFH as installed because of the risk of overheating of the cable.

[Dan]

Or just tile over it all again starting with insulation, then the right sized mat, and then tile. Cheaper than pulling it all up and redoing I'd guess.

[jay]

as above would be interested to know were probe was positioned and how

[ianmorrison9]

Hi,

thanks so far for the replies, thought i'd best respond and provide some more information.

The hotspot is nowhere near the probe.

the room (kitchen/diner) has 2 mats, the larger mat in the dining area is on backer boards and heats up evenly, the smaller mat in the kitchen area is only on a 1mm mat (new product from tiling shop) as the levels were different so couldn't fit backer board, the excess wire from this mat runs around part of the perimeter infront of the patio doors (will this be cooling this area down) and into the corner were the hotspot is.

surely people order larger size mats than they need and install them with extra wires in one area. how likely is it to overheat, it is probably covering an area of no more than 0.5sqm. (if that)

is taking up the tiles covering the small mat and replacing the only option, i am really worrying about this overheating, but how likely is this, also the cost of taking up the tiles and replacing is going to be significant (they were very expensive tiles)

how easy are tiles to take up and whats the likelyhood of taking them up without breaking them?!

any responses and advice would be greatly appreciated.


Ian

[Sir Ramic]

It will depend on how well the tiles were fixed and how long they have been laid.
Where about in the country are you?

[ianmorrison9]

the tiles have been done for no more than 3 months, we are in Liverpool, think the tilers used plenty of adhesive!!!

[Sir Ramic]

I would think that you wouldnt lift the tiles without breaking them.

Only asked because I went to school with an Ian Morrison....its not you...lol

[andy8758]

Hi,

thanks so far for the replies, thought i'd best respond and provide some more information.

The hotspot is nowhere near the probe. The wall thermostat can be set to measure from probe only, probe and air temp, air temp only, or not take account of temps at all. If the thermostat takes account of room temp - then the hotspot may be affecting that reading. In any event the hotspot is always going to be "hot" whereas a properly functioning ufn system will make the tile feel mildly warm to the touch - not hot.

the room (kitchen/diner) has 2 mats, the larger mat in the dining area is on backer boards and heats up evenly, the smaller mat in the kitchen area is only on a 1mm mat (new product from tiling shop) as the levels were different so couldn't fit backer board, the excess wire from this mat runs around part of the perimeter infront of the patio doors (will this be cooling this area down) and into the corner were the hotspot is.

surely people order larger size mats than they need and install them with extra wires in one area. how likely is it to overheat, it is probably covering an area of no more than 0.5sqm. (if that) - no never buy too much, always buy less than floor area - you really cannot place wires closer than manufacturers recommendations - generally that is at least 50mm from walls, obstructions and other cable. Your retailer should always recommend buying less.



how easy are tiles to take up and whats the likelyhood of taking them up without breaking them?!

any responses and advice would be greatly appreciated.


Ian

Ian, I am sorry but you really seem to have misinstalled this heating system. The flow of electricity generally generates heat. Electrical installations are governed by BS7671:2008 commonly called the 17th Wiring Regulations - one of the regs is that you must install the appliance/accessory/installation according to the manufacturers instructions. The regs also include common issues affecting the safety of electrical installations - one of which is to reduce the risk of fire caused by incorrect instalklation of electrical installations. If you have a fire in your home now - your insurance company may refuse to cover you because of this. From what you are telling us the installation is not doing what it should - so the safest thing to do is rip it out and install it correctly.