Anyone out there installed radiant floor heating? I’m thinking of remodeling and adding this to our flat in Shanghai, and just trying to understand this better. How well does your system work, is it a concrete imbedded type or insulated, what kind of floor covering do you use? Any comments, thoughts, links, etc would be appreciated.
We have one at my job. It. Is. Nice. Its copper tubing embedded in concrete. You can also do rubber hose embedded. Works like a charm. I would imnagine that for a home it would be nicest with tile or parquet flooring.
We installed radiant into our basement floor. It’s PEX tubing attached to wire mesh laid out out in loops 12" apart and then embedded in a 2 1/2" concrete pour. It’s not all one continuous piece of tubing - 1000 sq feet of floor has 4 different primary loops. Below the concrete is a special type of insulation that looks like foil backed bubble wrap. A special mixing valve adds water from the boiler and keeps the water temp in the loops at around 100 degrees. In addition to some tile in the bathroom area, we have 1/4" engineered hardwood on top of the concrete. The hardwood flooring was installed with a glue down method rather than as a floating floor to increase the heat transfer through the wood. The wood is also the reason that our mix temperature is a relatively cool 100 degrees. Without the wood we could run it hotter if we wanted to.
It works great- absolutely quiet and no room taken up by radiators. The floor is not cold, but it is not “warm” either - mostly you just don’t notice it. It also provides the most even heat I’ve experienced. The temp in the room is always rock steady at 68 degrees. Be sure you get a thermostat specifically designed for radiant - it has special logic that accounts for the “slowness” of temperature change with a radiant system - otherwise you can have a system that swings between extremes.
Beware the electrical systems - while ok for a small area such as a bathroom, large areas will be cost prohibitive because of the amount of elctricity they use.
Let me know if you have any specific questions!
We had it in the house I grew up in, built in 1957. It was all the rage then. Trouble is, the water pipes broke after 10 or 15 years, which led to “hot spots” and “cold spots” on the floor (you could always find the cats sleeping happily on the hot spots). Since the only way to repair even minor damage was to rip up the floors, it never got fixed.
We had radiant floor heat in our previous home. It was great. I miss it. 
The problem with radiant floor heating done during those years was long term corrosive action between the alkaline bearing concrete and bare copper. Had Bill Levitt known that and applied anti-corrosion wrap to the copper when building his famous Levittown developments (and Willingboro, NJ) the systems would probably still be perking along fine.
The floor heat in the home I owned in Levittown, PA was still working nicely after 25+ years, but I only got a few more before floor leaks were observed, and I had to install radiant baseboard.
We installed radieant in the course of renovating our house. It is the cat’s ass, but there are a couple of things worth keeping in mind:
As regards leaks, the use of highly cross-linked/ Oxygen impermeable (It’s the oxygen that corrodes copper, too) PEX tubing will probably outlast your house, provided you don’t put a nail through it. Like the dickheads who installed the flooring did.
But that’s another story.
In our system, water is constanly circulated through each zone. If the zone call for more heat, a valve opens, and flow to the zone is increased. And vice-versa. This means that you need a constant source of hot (app 100 degree) water. We did things stupidly, with a “hybrid” system, wherein we use the hot water from the conventional forced hot-water system in the remainder of the house. However, when the furnace turns off, so does our radiant heat. Moral of the story; if you’re not going to do the whole house, think about putting in a separate hot water heater for the radiant.
Secondly, radiant heat efficiency will depend what you put on top of it. Tile is good. wooden flooring is less than ideal, but will work. Carpeting is probably not a good idea.
That said, I still love it. My next house will have no radiators, anywhere.
Bizzwire - We’ve got radiators throughout the rest of the house and use the same boiler for the radiant system. Either system (radiator or radiant) calling for heat triggers the boiler. Both thermostats feed into a central controller that controls the boiler. It probably wouldn’t be too big a deal to add that type of “central controller” to your system…
How are radiant systems in terms of cost and fuel efficiency? Any better or worse? Or (which is what I’m guessing) it is more or less the same thing, but a different delivery method?
huh…now that’s pretty rootin’-tootin’ smart…
Radient is more efficient. The whole floor is the radiator. With a standard radiator, the warmest place in the room is near the ceiling. With radiant, it’s near the floor.
Thanks. Interesting.
Most US systems use tubing imbedded in about 2 inches of concrete. I think usually in a new home. the concrete acts as a heat trap, and takes a few hours to heat up.
Others use high density foam insulation, that’s an inch or so thick. The water tube is in a frame on top of the foam. This style is popular in Japan, and also for existing homes where there isn’t so much space between the concrete slab the house is built on and the flooring. These floors heat up in about 15 minutes, so it’s not necessary to keep the heat on all night or most of the night.
Anybody have an understanding of the advantages/disadvantages of the above two systems? We are considering both.
Also, I’ve read that 5/8 inch size tube is the minimum size for reduced water flow resistance. Smaller tubes require more pumping action.
Will probably install towel rack radiators in the bathrooms. Warm/dry the towels and add extra heat to the bathroom.
Looking at doing an entire flat - about 1500 sq feet. Kitchen and bathrooms will have ceramic tile, and rest of the house wood floors. Not sure if will use sythetic wood designed for radiant heating or real wood that’s also designed for radiant heating.
Planning to use a gas powered water heater. Actually several different brands will accomodate both a radiant floor heating system as well as heat water for home usage.
Another question is will I need additional radiators as well or will the floor heat the flat? BTW, as per normal construction in Shanghai, the walls/ceiling are not insulated. (We’re also thinking of ripping out the windows and replacing with double glazed windows).
Shanghai has about 4 months of cold weather where you want heating. It freezes a couple times per year but never gets really cold. Relatively high humidity though, so 40 degrees with high humidity = bone freezing cold.
i saw www.warmfloors.com in residential architecture magazine. interesting product.
you do have to be careful of what you put on top of the rad. floor. you don’t want anything that would insulate the floor.
Coupla things…
Check out Stadlerviega.com They have a system of aluminum-backed panels with grooves cut into them which you can put over (or under) most standard construction; a slab is not necessary at all. You can also put radient tubing in your wall, although this is not the most efficient way to do things.
Also, it’s a very minor nit-pick, but you don’t “pump” the liquid through the tubes, you “suck” it through; on one side is the high pressure supply pushing, and on the back end is a pump which does the pulling. Smaller tubing will definitely offer more resistance (think of sucking a milkshake through a coffee stirrer versus a garden hose; which one’s easier?)
My parent’s house (built in the fifties) had the pipe in concrete setup. They had a big leak once and the fix involved jackhammers and concrete dust throughout the house despite efforts to seal the room off. Other than that, day to day, it was a satisfactory method of heating. There are some hot spots but I don’t notice them unless I’m barefoot.
You can get plywood grooved for PEX. A heatsink is more effecient but more costly. Something else to consider: percieved comfort. Don’t have the figures in front of me but if you are standing on a warm surface the ambient air can be a few degrees cooler with no noticable effect.
I installed a RHF in a house in Taos, NM. Bed of sand, copper tube and sand, house brick (herringbone pattern) flooring with sand in between the joints. That was 11 years ago and it still works great.
Some these articles are pretty technical and may only be useful if you are designing your own system, but they have lots of good info about pump sizing, controller placement, zone control, etc.
http://www.taco-hvac.com/products.html?view=AllFileList¤t_category=170&selected_infotype=1
Interesting. I hadn’t thought about this in years (we moved out in '77). The floors gurgling in the winter . . . Walking barefoot into the bathroom and yelling “YEOW!” when you walk onto a red-hot spot . . . Or step on a cat guarding the red-hot spot . . . Ah, memories.
I’ve put this in my house. It’s really a great thing. I should mention that it’s not concrete that is used though. It’s special stuff that was designed to radiate heat. The most expensive part of the whole operation for me was the plumbing involved. Hooking this stuff up to the boiler is NOT a DIY project. I did almost everything else myself, though and I got the materials for free since my mom works at the manufacturer.
You’ll want to be careful about this sort of generalization.
Around here slab foundations are a rarity rather than the norm, and most radiant heating systems (a bad descriptor, in my opinion) are retrofits to existing homes.
It would work great in my house and be really easy to install, because I have a full basement under a single story ranch with hardwood and tile throughout, and no carpeting.