I just wanted to throw in my two cents here. We have a raised ranch with a walkout basement, with a large deck off the main floor. Here's a pic from two years ago:

Last summer, we screened in our bottom deck, and added flexible viyl "windows" from the same company. With the addition of an inexpensive propane patio heater, we used the hot tub in the screen room comfortably all winter, even when temps dipped down into the really colds, LOL. (In summation, I think the radiant in the patio is unnecessary...)

We do have radiant heat on both floors of our home, and opted not to go with a forced air system. We also added radiant heat into the attached garage. I've been extremely happy with it. Our flooring supplier would not warranty hardwood flooring, so for budget reasons we ended up with laminate flooring through about 45% of the house, carpet in the bedrooms and ceramic tiles making up the rest. There is nothing quite like getting up on a cold Canadian morning and feeling toasty warm ceramic under your feet!

Carrie

there is no comparison between radiant heat and forced air. once you have the system adding rooms is not that expensive. i used both in floor and baseboard radiant.

Thanks. We do have quite alot of wood floor on our main floor. Radiant heat should not be installed under wood floor or at least it won't be warrantied? Is there any way around that besides doing another floor covering? We have a mix of wood, carpet and ceramic tile, but we probably have 1000 sq ft of wood and I am partial do doing wood there.

We will have radiant heating and forced air. The air is primarily there for air conditioning, but the secondary benefit is air quality issues in the winter as well as being able to bring the house rapidly up to temperature.

The heat pump we are using provides both heating for the floor and for the forced air.

My first post. We are in process of designing an empty nest home in rural Minnesota. We will do a single story approx 1800 sq. ft. with maybe 1400 finished in a full walk out basement. Concerning our home comfort in this climate, I am thinking radiant heat in the basement slab and garage only. Because air conditioning duct is needed for hot and humid summers/ and given budget concerns/ a varied speed forced air natural gas combo unit for the upstairs living area. We expect the downstairs area will contain mostly guest space and my home theater. A heating contractor I met at a Home Show recommended this suggesting heating the basement slab at night with cheaper off peak electricity-- he said the upstairs heating system would be needed a supplement in the coldest weather and would provide air conditioning when needed. We currently live in a 70's style ranch with 2x4 construction. It is cycling between too hot and drafty cool in the winter cold. Better insulation/ maybe SIP construction/better windows- will likely make the biggest difference regardless. I am trying to find a sweet spot in comfort and value. Anyone living in a home set up this way?

shelly k, i ran into the same issue, so i did baseboard radiant heat in the rooms with wood floors. works great and looks european.

I just did basement slab radiant installation. Contractors will charge $3-4/sq foot.If you get your materials yourself from radiantec.com or pexsupply.com you can save a lot of money. DIY will cost about $1/sq foot or less.

Remember: engineered wood and laminate are not the same thing.

Engineered wood is a layer of real hardwood bonded to a core of plywood, and is fine over radiant floors-- Check out 'virginia vintage' and 'kahrs', two excellent products. An engineered wood floor is indistinguishable from real wood because it IS a real wood floor.

Engineered woods can be refinished just like other hardwoods.

Laminates are wood looking and wood based, but the surface you see is merely a photo representation of wood. It's fine over radiant, too.

When we were planning our HVAC we were told that we would likely need supplemental heat if we went with radiant.

If you need supplemental heat you would do hydro-air, not forced air. Forced air uses a furnace, hydro-air uses a boiler. You already need the boiler for the radiant, so going hydro-air would be much cheaper.

A reputable flooring supplier told us we could do radiant under site-finished solid wood flooring if we went with quarter or rift sawn. This was white oak, not sure if it would be different with another wood. I believe you need to acclimate the boards, turning the heat up slowing when the heating season starts.

"An engineered wood floor is indistinguishable from real wood because it IS a real wood floor."

These are pre-finished, correct? Do they have a bevel? Is there such thing as a site finished engineered floor?

Great ideas and suggestions -- keep them coming. You've given us alot to think about and talk with our builder/HVAC contractor.

Thanks!!

We installed radiant in our 7K SF house in no. CA. Part of the home is slab so the PEX tubing was laid in the slab. The remainder is raised foundation and the tubing is embedded in a 1 1/2" layer of gypcrete atop the sub-floor.

In addition to oruboris' excellent post, here's what I learned about radiant:

1. The optimal pad to use under carpeting is something called "slab foam"...hard to find and expensive but it combines the lowest R-rating with good pad performance. Next best is a corrugated rubber pad. Above all, DON'T use re-bond! And contrary to what you may think, the thickness of the carpeting doesn't have a significant effect on heating performance.
2. A benefit of radiant heating is that the heat in a room doesn't rise to ceiling level as it does with either F/A or baseboard heating. Because the heat is so evenly distributed over the floor, cold air can't get underneath the hot layer of air to displace it and allow it to rise to the ceiling. The result: it's more efficient, keeping the heat where you want it and that should be a real benefit with your 11' ceilings. And because your sensation of warmth is most felt in your extremities, the warmest part of the room is next to your tootsies so you feel warmer even if the thermostat is set at 68 degrees. That's especially important as you age, since your circulation in your extremities isn't as good.
3. You can set heating zones, room by room. We have 20 thermostats (yeah, really!), 6 F/A and 14 radiant. We keep the guest rooms set at 50 degrees and simply close the doors when they're not occupied, a big energy saver.
4. We installed furnaces in our F/A system so we could easily heat the house back up after returning from vacation. We're retired and often travel during the winter so this has been a big help.
5. Initially, our radiant system was powered by a commercial 100 gallon water heater, which also supplied hot water to 1/2 of the house. It crapped out after five years and we discovered that water heaters really aren't made to stand up to the demands of radiant systems. We replaced it with a combination hot water heater/boiler which serves the same function. It was $13K but has a 20 year warranty and has 96% energy efficiency compared to 70% for water heaters.

We have never regretted the decision to install this system. Getting up and night and walking across our limestone floors to go to the bathroom is a delight!

Bob

Sue: You don't need supplemental heat IF the system is properly sized and you don't mind a wait [shorter than you'd think] to raise the temp in your house. I'm using a couple qas fireplaces, but anticipate that I'll probably only use them if I come in from a winter bike ride cold and wet.

The quarter sawn oak thing has some validity: it is more stable than traditional woods. I'm not certain you'd find a flooring company willing to warranty it against splitting, though, and I wouldn't pay this kind of money for a floor without a waranty. I think one consideration is the size of the space-- larger would imply more potential movement.

I know that 'Virginia Vintage' makes a site finished engineered. They are a division of Anderson Floors, so it's possible you could get the unfinished in Anderson's other lines as well.

I *think* Kahrs and some others make engineered floors with essentially no bevel to the edges. If they have a bevel, it is very small, what I'd call functionally invisible. Working from memory on that, though-- been a while since I was looking at these.

Since engineered can be refinished, which would likely eliminate any trace of bevel. I don't know how practical it would be, but it should be possible to lightly screen a prefinished floor with microbevels, and apply a couple coats of new finish to make the whole thing perfectly smooth, if thats your goal.

How long does it take to warm up a house? I've never had radiant heat so I've only used F/A. We like to have the temperatures lower at night in our bedrooms during the winter. Is that difficult to accomplish? Is a timer on some/all of the thermostats necessary to help this?

I read some on the Radiantec website and they are very strong proponents of the high efficiency hot water heater (Polartec) instead of a boiler. Any thoughts on this or experience with this?

Shelly, when you ask about how long it takes to warm up a house, it depends on a) how cold it is to start (e.g., moving a house from 50 degrees to 70 degrees takes more time than 60 degrees to 70), b) how cold it is outside (because the colder the outside temperature, the more heat you're losing through walls and windows as it tries to heat the house up) and c) how efficient your system is (this is a function of such things as how closely spaced the tubes are, the efficiency of your heat exchanger, etc.). But we've found that it can take 8-10 hours to bring the temperature from 50 to 70 in our mild winters, and that's with a very efficient installation. And conversely, if you find yourself too warm, turning the thermostat down won't have an immediate effect, either, because the thermal mass of the floor holds the temperature steady...you typically will need to open a window. We've had to do this on a few occasions during parties, where all those warm bodies and a fire in the fireplace for ambiance has made the house too warm.

As far as set-back thermostats and lowering the temperature in a bedroom for sleeping, most experts recommend against it. While setting the thermostat down at night is an energy saver for other systems, the radiant system wastes energy trying to re-heat the thermal mass each morning so it's suggested that you set your thermostat at one temperature and forget it. And if you want to sleep in a cool bedroom and open some windows to cool the room down, remember that it will take a long time to warm the room up the next morning (unless you've left the radiant heat on all night, which of course wastes energy). We typically keep our bedroom thermostat set several degrees lower than the rest of the house, but not so low that we're uncomfortably cool when we're getting dressed for the day.

As for Radiantec's hot water heater recommendation, I'd suggest you ask them two questions: 1) What's its efficiency (this rating is required by law)? and 2) What's its warranty and does the warranty offer a full replacement or only pro-rata replacement credit? It's a matter of economics and if you buy cheap on the front end, only to be faced with higher energy bills and maintenance expenses, it may not be such a great deal. Before replacing my water heater with a water heater/boiler (Phoenix by Heat Transfer Products), I calculated the seasonal cost of heating the house, projected the potential savings going from 70% to 96* efficiency, took into account water heater replacement every five years, and figured the net present value using my cost of capital (OK, that last part was because I have a finance degree ;). In any case, in MY case, having a boiler (in my case, hot water heater/boiler, because it heats hot water for the house, too) was a cost-effective solution.

You can get additional info at the link below, which is a forum populated by radiant floor installers. Either post questions as you're doing here at GW or simply conduct searches on subjects you're interested in.

Sorry for the long post but this can be a complicated topic for the uninitiated.

Bob

Here is a link that might be useful: Radiant Panel Association Forum

The HVAC sub for our house was *awful*. He must have slept through the class on calculating how to heat spaces. We had to retrofit our north-facing rooms with under-floor tubing off a tiny boiler. This causes the wood floor in one room to buckle slightly between two boards -- goes back to level in summer when the heat is off.

This is lovely, even heat. I'm not sure how we'd like it if we didn't also have the gas forced air throughout that is *humidified*. We need the forced air ducts for A/C anyway.

How wonderful to have such great technical resources here!

This is not technical, but opinions after living with radiant floors for several years:

One thing to remember is that we must adapt to a difference in how we think about heating. With F/A, wood, radiators, etc. we have a tendency to look at the outside thermometer registering cold, and then turn up the inside thermostat. Or maybe we walk by a window and feel cold seeping in -- and turn up the thermostat to compensate. That's often habit, but the habit is based on the fact that most houses are/were poorly insulated and often let cold or drafts into the living area -- so if it's cold outside our subconscious says oooh, it's gonna get cold in here, turn up the heat. You almost have to live with radiant flooring to really realize that one just doesn't need to play with the thermostat. If your house is well-insulated (and to an amazing extent even if it's not well-insulated) you set the thermostat for the temperature at which you are comfortable, regardless of what's going outside and you leave it there.

And another thing which is rarely addressed is the fact that many (most?) people set the radiant flooring to 75 and are on the warm side of comfortable regardless of whether or not it's frigid outside. No matter what your source of heat, it takes less energy [and less $] for 75 than for 80°.

Yes, if the cat stands in an open door peering out at a snowstorm there will be frigid draft coming in... no matter whether you have F/A or radiant. The difference is that F/A will have to warm up that cold air with more not-very-warm air and meanwhile you have both cold and F/A warm air blowing around you. Brrrr. With radiant, you have --and keep-- warm feet which physiologically makes you feel warm because the temperature of the floor has not changed. Yes, the open door's cold air is mixing with the warm air but it isn't blowing onto you to make you feel cold.

Talking about vacations -- or a length of time away from home -- should take into consideration that radiant flooring does not make any ultra-high demands on its system. Radiant is meant to *maintain* an even temperature, not jerk it up with a blast of heat like other heating methods. So it makes sense to turn off a furnace while you aren't home because a furnace requires a blast of heat to warm the volume of air; long blasts for lots of warmth and short blasts when there isn't much difference between ambiant and desired air temps. Unless you are going to be gone for lots longer than it takes to cool-off followed by heating-up the radiant flooring, it does not make sense to change its temperature. Modern houses with radiant flooring are almost always considerably better insulated than their F/A counterparts, and it takes days not hours to cool off.

And last, there are often comments about the length of time it takes to "warm up the house" with radiant heat. Especially if one lives in an area with a great variety of temperatures. Ah, excuse me, but if I'm comfortable at 75° what difference does it make what the temperature is outside??? If the house is highly insulated and draft-free it makes very little difference whether it's 10° or 50° outside. In my area outside temperatures with daily 40-degree variations are common for weeks at a time, regardless of season. Okay, not so common in the summer, but we don't need heated houses in August. On the rare occasion that it gets umcomfortably warm inside, I open the window. Low-tech but effective. Oh yeah, in July and August I turn on the A/C, not so low-tech, but effective. The point is, 75 is 75 is 75 and if your feet are happy at 75 it doesn't matter what temperature the outside air is. A 'warm house' is a side-effect of radiant because its main purpose is keep you comfortable, that is, maintaining your comfort with an even temperature.

Always get yourself an HVAC consultant. Someone that will look out for your best interests. Get someone that can lead you through the process. You need to know what questions to ask and what the answers should be.

Radiant is like everything else. If not done correctly it will not work properly.