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

We used an epoxy paint with the paint flecks so as to resemble terrazzo over our radiant heated shop floor that we put in. Ourselves. Embedded in the slab. We wanted the best transfer of heat possible for a building containing tonnages of steel machines and automobiles. Do research thermal lag. It's one big drawback. One thing that the engineer obsessor other half researched to death was that the floor covering materials and home layout will determine the loop spacing, length, and how many zones you will need. A system designed for wood will need to have a different temperature than one for concrete or tile, which are more efficient at radiating the heat. There isn't a one size fits all solution. But be SURE that your system designer and your engineered wood floor manufacturer are in synch with the requirements.

Glad we now agree that 85 is an established threshold that radiant floor designers use as a recommended maximum for floor surface temperature. Foot contact with the floor makes the second way high temperatures lead to discomfort. 85 is evidently too hot for those expecting warm feet and will definitely lead to uncomfortably hot room temperatures, in efficient homes. There still seems to be confusion regarding water temperature and floor surface temperature. The temperature of the floor surface will be lower than the water temperature in the tubing. The water temperature entering the tubing loop from heating appliance, will be warmer than the temperature exiting loop, on its way back to the appliance to be reheated. The only mention I made of water temperature was that 125 seemed too high for an efficient home. Perhaps not for a long tubing run with short spacing but I still think it seems high and engineers generally don't like long tubing runs. I've personally installed tubing on a spec of mine and for other builder friends. We installed short runs with wide spacing for better zoning and they were for efficient envelopes. Few ended up being hooked up to an actual appliance. Why spend that money when the required AC can handle the heating too. The "at" which I corrected to "near" room temperature comments were in regards to floor surface temperature, which is a widely accepted fact for those involved in efficient construction. From All About Radiant Floors: "Why isn’t my floor warm? Homeowners who look forward to walking barefoot over warm floors are often disappointed by homes with in-floor hydronic heating. That’s because these floors are rarely as warm as most homeowners expect." From that article's case study (keep in mind difference of water temperature and floor surface): “On the design heating day [the coldest day of the year], the water flowing through the tubes in the floor will only be at 85 degrees,” said Robb Aldrich, an engineer at Steven Winter Associates" From energy expert Alex Wilson's article describing a level of home performance between passive house and international code minimum: "in a highly insulated house (and I’m talking about a really tight house with at least R-40 walls, an R-50 ceiling, and triple-glazed low-e windows), such a tiny amount of supplemental heat is needed that a radiant floor needs to be kept no more than a few degrees above the air temperature—or else overheating will occur. If a concrete-slab or tile floor surface is maintained at 72 or 75 degrees, it will likely feel cool underfoot—since it’s at a lower temperature than your feet. So you may not get that delightful benefit of a warm floor surface.

From personal experience, not technical point, of view, I love LVP. We have hydronic radiant heat throughout (and three large dogs in a snowy climate). On the main floor and upper floor, our tubes are set in warmboard which I understand is more efficient than a staple up installation. The tile in the bathrooms is the warmest underfoot and the carpet in the bedrooms is the least warm underfoot. The LVP in the rest of the house is in between. All three heat about the same, but are in different zones so not an apples to oranges comparison. I keep the bedrooms cooler. LVP has been great with the dogs — no worries about water bowls and tracking in snow. I wet mop often. I love the look of tile, but after having it in the kitchen in my old house for more than 30 years, never again. I cook a lot and occasionally for several hours at a time and tile was really hard on my back. The difference is amazing. My back hurt so much more at 45 cooking in my old kitchen than it does now at 65 on a softer surface.