Warmup dual wire electric underfloor heating installation – start to finish

Considering the need for cosy feet and a nice ambient rising heat on a cold morning. Well, we’ve fitted a lot of electric underfloor heating systems and thought we’d share a video with you to break down the process. We’ve also included a full timeline description below.

0:08 – 0:23 Scene 1 : Firstly we scrape the floor to remove any past builders material like plaster. We give it a sweep with a soft brush, then we clean the floor with cold water to remove dust and left over bits. 

0:24 – 0:37 Scene 2 : Once the floor’s dry, we give it a final sweep and then prime it. We prime the floor as it is porous. The primer seals the porous surface and allows a good key for the next stage. The primer was purchased from ToppsTiles and is recommended for this use. We use 3 parts water to 1 part primer. If the surface wasn’t porous, we would use non diluted primer applied directly on to the chipboard surface.

0:38 – 0:44 Scene 3 : Next we mixed Toppfix 2 part flexible adhesive and applied it to the chipboard using an 8mm square notched trowel. We do this in a fan pattern for strength of fix. The Toppfix is extremely easy to use as it has a pre measured liquid component that is simply poured into the bucket of powder and using a paddle is mixed till there is no lumps.

0:45 – 0:55 Scene 4 : Now after pre cutting our Warmup heat reflective insulation boards to size (this is done with a standard utility knife), we bed the boards, at single row intervals, on to the adhesive. Here you can see Ste slightly twisting the boards whilst at the same time pressing them down firmly. This is an important part of the process as it ensures a good key between the insulation boards and the adhesive.

0:56 – 1:14 Scene 5 : As a second recommended fix, we install penny washers and screws supplied by warm up. We make sure to pinch the washers down into the boards slightly to have them sit just below the surface of the boards. 

1:15 – 1:51 Scene 6 : As this floor is in a bathroom and will be having a finishing 2 part latex self levelling compound installed over the top, we are guided to silicone each washer and screw fixing. We then scrape across the top to level off the silicone.

1:52 – 2:00 Scene 7 : Now we decided to feather over the edges of the boards and the screws and washers with left over adhesive. This can be done with mastic. This helps prevent air pockets trapping when the levelling compound is installed. We also applied silicone around the entire perimeter of the floor. This created a completely sealed base making installing the levelling compound easier. All were left to dry. We then loose laid the heating wire and taped the ends/returns with a little insulation tape (supplied in the warm up dual heating kits). 

2:01 – 2:16 Scene 8 : When we were happy with the layout, insulating tape was fitted to cover all the heating wire. It was important to pinch the side of the tape for it to fit snuggly as air pockets can make the wire overheat and burn out. 

2:17 – 2:33 Scene 9 : Now it is time to mix a 2 part latex levelling compound ready for pouring. The levelling compound shown is again from ToppsTiles and is absolutely ideal. Like the adhesive, it is a 2 part pre measured combo. Simply pour the 5ltr latex liquid into a flexi bucket and add the powder. This is a great system particularly if you are fitting a levelling compound in sections as we are in the video. The levelling compound will be the same consistency every time. If you have slightly different consistencies which is easily done with conventional levelling compounds the bonding/fusing process between the sections can fail. Leading to cracking and loss of strength. It is important to note that the levelling compound for electric underfloor heating should be 10mm thick. This can be checked at intervals as the compound is applied with some sort of gauge. We actually used a screw driver with a piece of insulation tape rapped round it 10mm from the tip. Very technical stuff. Simply place your gauge into the wet compound after it has been poured, making sure it touches the insulation boards. The compound should just touch the insulation tape around the screw driver. Then wipe and repeat. If the compound doesn’t reach the tape, more compound should be applied. 

2:34 – 2:56 Scene 10 : We always overlap when pouring the levelling compound in sections. This guarantees good fusion. We then work the compound with a trowel to evenly spread it and also pay attention to where the sections meet to again make sure the levelling compound is essentially one. Never over work a levelling compound. The temptation is to mess with it and keep messing with it. Simply spend a minute to work the SELF levelling compound and then leave it alone!

2:57 – 3:00 Scene 11 : Here you can see a sensor probe located in a brass housing. This is cut into the insulation board to drop it lower than the levelling compound. The probe will constantly measure the temperature of the floor and relay that information back to the control thermostat.

3:01 – 3:10 Scene 12 : After the final section of levelling compound has been installed we leave to dry. A quick tip to prevent air bubble in the levelling compound. After the compound has been mixed there will be trapped air in the compound. Simply tap the side of the bucket for a few minutes and you will see the air bubbles come to the surface and the air release. Scrape any stubborn left over bubbles off the surface with a trowel. You will then have a smooth, strong compound ready for pouring. 

3:11 – 3:33 Scene 13 : After a day the levelling will look like this. It is now time to have a part P registered electrician carry out his/her final fix. This means wiring in the temperature control thermostat. I would recommend that you consult an electrician prior to fitting electric underfloor heating. This is to establish an electric feed for the heating so either you or your heating fitter knows where to start the wiring. The heating must not be turned on for two weeks after the levelling compound has been installed.

We highly recommend you read the installation literature that suits your particular installation prior to purchasing any heating. There are several ways underfloor heating can be fitted. 

All the products used in this guide can be found at ToppsTiles inc the insulation boards, warm up dual wire electric heating, adhesive, trowel, self levelling compound and primers.

If you would like any further advice, you can contact us. Warm up also have a technical help facility or you can speak to them on their technical helpline number.

© Copyright 2013 Wes, All rights Reserved. Written For: Fitmywoodfloor

I am a Pergo trained professional installer of 20 years. I've been up close and personal with lots of floors and have the knobbly knees to show for it...Should you have any questions or comments please feel free to add them below. Thanks for taking the time to call by and I hope the information you've found has given you some insight!........................................................................................................................................................................“When you click on links to various merchants on this site and make a purchase, this can result in the site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network, amazon.com, amazon.co.uk, amazon.fr, amazon.de, amazon.it, amazon.ca, affiliate window network.” This statement is to comply with current internet regulations regarding transparency to consumers.

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