Help please, newly laid floor not getting very warm

[JaneJ]

Be gentle with me, this is my first post!
Our newly installed ufh and cause of many many more grey hairs (long story involving having to completely remove the old floor and replace)was finally installed and tiled over about a month ago. We used 10mm insulation boards under it and got an electrician to wire it in. All resistance values checked etc at every step of the way. Left it over 3 weeks to dry out etc and when we switched it on, it painfully slowly raised the temp to 7 deg C and no warmer. When I say painfully slowly I mean several hours, we then left it on overnight to see if it would improve but it still only got to a max of 7. Is this right? In which case it has been a complete waste of time and money and more, massive amounts of stress.
I really hope someone can advise? We have contacted the supplier who is being less than helpful.
Thanks for reading.

 

[Gazzer]

Have you got more details, what make was it ? what wattage ?

 

[Stewart]

What's the wattage if the mat.

Is that room temp or floor temp.

 

[JaneJ]

Hi, thanks for looking!
It is the floor temp, the room temp gets up to about 12 deg C. slightly higher if the radiator is on in the adjoining room.
It is a loose cable kit made by thermopads, TR3100 thermostat, ekoboard 10mm

 

[jay]

how was the probe fitted and welcome to the forum

 

[JaneJ]

Thank you 🙂
Ummm, probe fitted into floor, I remember hubby dug out a groove for it?
Forgot to say cables were 65mm apart so wattage 150 I think...am I right in thinking the wattage varies according to how close together the cables are?

 

[Stewart]

How far apart were the cables installed.
Did you put self levelling compound over cable.

 

[JaneJ]

hiya, 65mm and yes we did.

 

[Alan.P]

How big is the floor area, what size kit was installed and have you checked the thermostat settings ?

 

[jay]

is the probe under insulatiom board and do any wires cross over or run near the probe

 

[Stewart]

That's works out at a 150 watt, and should be suitable to heat the floor to 25+ degrees easily. Is the thermostat in the room that's tiled or outside in adjoining room.

 

[Gazzer]

Not really the done thing but I would be inclined to rule out the 3 items that can go wrong, the thermostat probe, the controller and the heating element itself. You can do thisby bypassing the controller and probe. this is done by connecting a plug to the power cable and feeding power direct to cable.
Please note that this should be done by a qualified electrician.

 

[Stewart]

Also.... Are there any heating pipes running near the probe under the floor.

 

[Gazzer]

Also.... Are there any heating pipes running near the probe under the floor.

Good point !

 

[JaneJ]

OK...

floor area approx 7.5m2, cable was from memory 115m, kit was for 6.9-8.8m2

How do you check the thermostat settings? I haven't programmed it, only used it on manual. If I set the room temp to 18-20 deg C the floor comes on and runs constantly but floor temp never gets above 7 deg 9well it did make 8 once briefly!)

I think the probe was grooved into the insulation boards, no wires crossing anywhere and I'm not sure how near to the probe, will have to ask hubby that one.

Thermostat is in the room that the UFH is in

Pretty sure no heating pipes as we took the floor out to bare earth and beyond so pipes would have been fairly obvious even to me!

Hubby did suggest by passing the thermostat, will get the electrician back in.

If the probe was faulty, ie reading a faulty temp surely the floor would get much warmer than it does as it continues to feed power to the cables? I know it is putting power in as my electric watch thingy goes up when it is on and down when it isn't. How would I know if the thermostat was faulty? It doesn't make any sense to me that power is going in but it isn't getting any warmer??

 

[Gazzer]

I really would try adding a plug to the cable and powering direct 1st. This will isolate or highlight the problem area.
As for the probe, was it inserted into a tube or direct int the insulation. Its always better to use the tube as its simply a matter of pulling one probe out and then re inserting the new one should problems arise.

What has the heating company actually said ?

 

[Alan.P]

If you could watch the electric watchdog thing and operate the stat up and down you should see a rise and fall in demand as the stat kicks in and out.

 

[doug boardley]

Good point !

very good point!

 

[JaneJ]

Ok, it has been wired up for over an hour and a half and it is not getting any warmer than it did with the thermostat and probe in the circuit.
HELP! Does this mean the cable is dodgy? It is getting warm but hardly and slowly.
In answer to the watchdog thing, it doesn't kick in and out cos it never gets anywhere near the set temp.

 

[Stewart]

Does that particular thermostat have a separate setting for maximum temp as with some of heat-com ones, also have you tried changing the thermostat to room temp?

 

[Stewart]

Sorry just re- read previous post so please ignore

 

[micko]

Hi,
I would find out from the manufacturer what the resistance value is for your specific kit and get it re checked by your electrician or yourself. If you have the floor directly wired to a plug and the floor is not getting up to temperature. It’s pointing towards a fault with the under floor wiring . sorry

 

[faithhealer]

only thing I can think of now is if the tiles were dot and dabbed so there is poor heat transferance.

 

[JaneJ]

Arrgghhh! does that mean we can't do anything about it? What is dot and dab?

 

[faithhealer]

Arrgghhh! does that mean we can't do anything about it? What is dot and dab?

Hi jane, dot and dab is where the adhesive is put on the tile in 'dollops' (usually one in each corner and maybe one in the middle) instead of full coverage using a trowel. The heat can only pass where the adhesive is, hope you follow. Checked out the manufacturer, seem a big outfit. Would check resistance etc out and get back

 

[maniek]

JaneJ please check one more thing, connect a cable directly to power feed
as Sir Ramic advised, and make sure there is no electric switch in between,
as elec switch with neon indicator if badly wired will give you only 120v on
the cable instead of 240v....

 

[Dan]

Just bumping some threads in the underfloor heating forum. You can now find and search for both electric underfloor heating and water underfloor heating threads. By the way, if you feel some of the threads you want to be seen at the top of the forum need to be bumped back, for the next month or so from now, feel free to do that. Although it's not usually something we allow, whilst we're going through this process of changing over forum software, we see the need for this to happen.