I would not use anything.

Make some wooden feet or shoes for each leg. Stain or varnish or finish to match the floor. If you are an arteest shape em into a pleasing form.

Put a large stainless steel washer, with a small center hole, under each foot to spread the weight.

One of my favorite old houses had solid walnut planks cut and shaped, with a routered edge molding, for the rads to sit on. The house was 1898, the rads were really fancy so were probably original. This was on old pine flooring, BTW.

Casey

As Sombreuil described, that is how our radiators are set up. Board( don't know what the wood is) full length of the radiator, nicely shaped and edged. Our house is 125+ years old.

I wouldn't worry about it-- you're not going to be moving the radiators around, after all. The only person who will know there might be dimples is the next person to replace the floor in 100+ years.

I agree with rwiegannd, and the person a hundred years from now is not going to worry about it

I agree with not doing anything special, particularly something that would attract attention like tiles, etc. I have a hard time believing that the radiator feet would dent oak very much, if at all, and no one will notice if it does.

They will dent them slightly, but who cares? I would think that there are more important things to worry about.

Thanks for editing. More accurate, of course.

It had visibly radiated out a bit from the feet on my old floor, so why do unnecessary damage to the next one? And a new floor in a different room is actually vinyl, which will really need heat protection based on what happened on the wood one.

I have beautiful inlaid parquet floor in a large bedroom with a *beast* of a steam radiator sitting on it. The weigh literally caved in some of the flooring, crushing and destroying various parts of the decorative inlay that someone painstakingly put in 135 years ago. I'm paying a carpenter to rebuild that section of the floor and you can be damn sure something will go under those feet this time. Speaking as the person "100 years later", I definitely do care and wish they had done something to prevent this.

In another room, I'm replacing a radiator. The flooring is only about 15 years old. Hardwood. It's already dented and burned from the radiator sitting directly on it.

Ask him to cut wooden circles to put under the rad feet using a hole saw. Stained or paint for a snazzy look. Or should I say a "cooler look?" 'Scuse the heating pun.

I don't think the weight is caving in the floor. I think you are getting gradual rotting from heat and possible a bit of moisture. I'd make sure that whatever pads you put under the feet are synthetic...maybe furniture leg cups if you can find ones that will take the heat such as rubber ones in this style which could also contain moisture if there is any:

Over time, my old floor boards actually charred a bit from the heat, which also weakened them structurally.

there is no way a radiator "charred" anyone's floor wood wont even start to char until 250 deg if your radiators are this hot you've got major issues. more likely you are seeing a chemical reaction from the iron

It is a dark spot underneath an object that repeatedly gets hot. So it's understandable to make that assumption. Charring is also a chemical reaction. Chemical reactions are also sped up and intensified with heat. So the lines do begin to blur. I find the very old wood window frames that are on the south side of my house, are dried out and blackened as if somebody took a blowtorch to them. Again it is probably some sort of chemical reaction rather than burning but it sure doesn't look that way.

And yet the black marks were there. Surprised the hell out of me too. Perhaps it was just rot from prior leakage that had accumulated at the feet? Or a chemical reaction is a good guess too. But whatever the reason, the marks were there.

I used 1/4 metal disks about 2.5 inch in diameter, to help distribute the weight better.

Glass Castors were used in my 1893 Childhood home.

I had wooden rectangles cut to fit beneath the feet, but I really like the glass casters idea!