It takes just 1 AHT mat to enjoy Caravan Cosiness

Case Study of DIY retro-fitting AHT electric underfloor heating in a Caravan

The floor width varies from 0.75 metres between the bench seats, to 1.3 metres between the entrance door and the fixed furniture opposite, with a length of 4 metres.
Installation materials:
Heating mat (0.5m x 4.0m)
Earth net (1.0m x 4.0m)
Multi strand earth wire (3m2 x 3m long)
Low tog (0.8 tog)
carpet underlay (1.2m x 4.0m)
13 Amp plug fitted with 3 Amp fuse
Duct tape
Optional:
3mm thick reflective under mat insulation (1.0m x 4.0m)
Low tog (up to 1.8 tog) carpet (1.3m x 4.0m)
3 Amp fused spur neon illuminated switch to match existing electrical fittings
Appropriate multi strand flex wiring for spur connection
Room thermostat to control temperature

Notes:
The AHT heating mats are supplied with approximately 5m of wire for connection to supply the circuit, and it is necessary to establish the best position for the switch before fixing the mat(s). AHT Amorphous metal ribbon heating mats are normally supplied in 0.5m width up to 7m long in increments of 0.5m. Three heat outputs are available 100Watts/m2, 120Watts/m2 and 150Watts/m2. We chose a 0.5m x 4.0m mat with a heat output of 150W/m2 giving a total heat output of 300Watts. I chose to use a reflective underlay (3mm thick felt with a reflective foil top, normally used under laminate flooring) and to stick the mat to the foil top.
I used two loose fit carpets as the template for the shape of the underlay.

Method:

1. With the underlay fitted, the mat was laid out centrally along the length of the underlay. When I was satisfied with the position, I stuck it to the foil face.
   
2. We laid cables along the floor outside of the mats to the location of the connection point.
3. Next we made a temporary connection to allow the mat to heat up for a short period (i.e., 5 minutes). This was to test that it worked, and to help it to lay flat.
4. Using the same two loose lay mats as templates, I cut the earth net to shape and installed it on top of the heating mat.
5. We attached the earth cable at a suitable location and laid it so that it followed the other two cables. We then taped all 3 cables into place.
   
6. Using the same two loose mats as a template, the low tog carpet underlay was cut to shape and placed waffle-face down on top of the earth net.
7. At this stage, because the upper surface of the low tog underlay was beige coloured Hessian, the loose lay carpets could be placed into position without looking out of place. However, we decided that the carpet was to be fully fitted. We therefore cut the carpet to shape and fitted it using the two loose lay mats as a template.
8. We connected the 3 cables into the 13 Amp plug fitted with 3 Amp fuse, then commissioned the system.

Summary:
Our experience has been that the AHT Amorphous underfloor heating creates such cosiness that our caravan became the meeting place of all our friends and neighbours!