There is no way hot water heat could be a fire hazard. It is much less than the temperature of boiling water! Even the most flammable of gasoline soaked carpets would have to be around 500f to ignite. We have hydronic heat under regular maple hardwood (15 year old system) and it is zero problem. Your mileage may vary depending on your system, but think of it this way -- the water under our floor is like max 100f (the floor only gets up to 80f), and our house gets close to 100f on the hottest of sunny days (no AC up here in Canada although I came close to the breaking point this summer). So I can't really see how the heating is more harmful to the floors than everyday life. Slightly related: my uncle was chiding me for the 'safety hazard' of letting my curtains drape over my hot water radiators. I was like 'What are they going to do, slightly warm my curtains to death like a gentle beam of sunlight?' Well, I was more polite in person. But seriously. This post was edited by robotropolis on Mon, Nov 25, 13 at 22:41

I had the problem of sliding furniture on my wood floors. I found that using Rubbermaid (or other brands) of shelving "liner,"which comes in rolls, keeps them from sliding. I don't remember the exact name, but it is the kind that keeps dishes from sliding on cabinet shelves. It is a very thin rubber. I buy it in the beige color that matches the floor most closely, cut it double the size of my furniture legs, then fold it over so it is doubled. (it sticks to itself better than to the floor). There is no real "sticky stuff" on it, it's just very non-skid. Keeps the furniture where I want it and is not really visible at all.

One room I did wood and one room I left old carpet and replaced with new carpet later when I was doing another carpet project. I left the carpet in a room that had a sliding closet door because the closet floor was completely concealed. In the other room with bifold doors the closet flooring was somewhat visible with wood because the doors were high enough to open above the old carpet and the wood floor was lower so you could see in there a bit even with the door closed. There was also no physical separator between the room and the closet like there was with the sliding track so it didn't make any sense to leave the carpet.

Shipping is expensive, but I received them very quickly. Backings are made from latex and nitrile rubber (Multi-grip), see the link for a description of two types. They stay very flat, no curling, and have a very low profile. I have them on all three of my exterior doors. The great thing about them are that they can easily be machine washed in a normal washer and drier. They are not bulky! I went through a couple of those expensive gel mats which both curled after a couple years which made them look bad.