Originally Posted by Diesel Dan
I'm sure the water heat in the floor would be the most comfortable option, but yes, you would pay a premium for that in both parts and labor. And I would worry about leaks, and the fact that if it did develop a problem, you may have to tear out your whole conversion to fix it. I spent the day in my bus the other day, and it was 25F outside. My portable propane heater kept me from freezing, but it was like 90 degrees at the ceiling and it felt like 50 degrees at the floor. My floor is barely insulated at all, so that is a large part of the problem, but I have to admit I was fantasizing about how wonderful it would feel to have in-floor heat.
I think its pretty doable, and definitely far less than $4000. Depends on size I guess and just how much you feel like running... But if you just did the main isle with 6-8 strands you're not talking that much in material. You wouldn't want radiant floor heating under your cabinets/appliances anyway.
As for leaks, get the whole system up and running and pressure test it. Make sure it can hold pressure overnight, etc. Then you should be good to go unless you do something to physically harm it. Put as many connectors as you can in an accessible location, just in case. But people install this in closed house walls all the time and it lasts longer than your bus probably will.
You can actually get by with cooler overall cabin temps and still feel comfortable when you have a nice warm floor to walk on.
As for the op, just noticed you're throwing in the skoolie towel. Not sure how you think a sailboat is going to cost less to own or maintain though. And you're right, you could get a crappy trailer and a crappy tow vehicle for less, but it wouldn't be as cool as a skoolie. Your choice tho, follow your gut.