Hello, thanks for all your replies and for reading me.
I may be a stubborn builder, but I decided to go ahead and buy "warm tiles" radiant heater from menards ( I already gave it back). It's just a roll of several feet of wire. I tested it and I judged it as too much hazzle. Perhaps doable, but with the low output, having to install it under the plywood floor, considering the heat loss from below the plywood , and the safety risks that involve drilling a hole under the plywood and breaking / perforating the cable. Or even spilling water may be a safety risk in this case. I gave up on that.
But didn't give up on having my feet / the floor cold.
SO I got myself these heated rubber mats, for 25.99 each:
The name is "Heated mat foot warmer"
http://www.amazon.com/gp/product/B000079896
I got it 15 days ago and I am loving them!!!!
I tested 2 and then decided to get 4 of them, so I can heat more or less all my van's floor.
My floor ( see my build thread) has half inch of polyisio under the plywood, which breaks extremely well the cold. Right now is ten degrees outside and the mats are still at 125 degrees (I have a multimeter with thermometer).
There are several advantages on these ones that made me consider them:
- They are water proof, which makes them safer to use, the seller even recommends them to melt snow.
- No installation! just plug, put them on your floor, and enjoy!
- Super slim at only 1/4 inch. I didn't want to lose the ability to stand up in the van. I didn't!!!!
- I could even walk bare foot and be very comfy.
I am still testing them, will be testing them this winter, and these are my observations:
- You can read all the amazon reviews, they are useful
- they reach their maximum warmth in about 45 minutes.
- the 6 mats that I got are not enough for warming up the van. . I still need the ceramic heater. I would imagine that 10+ mats may be enough to replace the ceramic heater perhaps... But both combined are an excellent solution that warms everything !!! IT is so cozy (62) in there when outside is 28 degrees. and I not even half way done with my insulation build!!!!!, Moreover, since my feet were warm, it didn't feel like 62 degrees. it felt like more!!!
- I am testing them running all night and day to see if they make any kind of bowing / warping on my cdx plywood floor. So far, after 24 hrs of continuous run no signs of damage on my plywood. (but it's been below freezing the past 24 hrs) The seller didn't recommend this on top of wood but I am doing my own test.
- each one consumes 90w, so you could use up to 18 mats in a regular house connection ( 15 amps).
I will post more details in my build thread (slow but hopefully successful conversion) by this spring.
Everyone stay warm.