We are putting in hydro radiant heat. YOu could also use electric pads. We're running our own tubing through radiantec.
maybe someone here can give a suggestion about the AC

Here is a link that might be useful: infloor radiant heat

There are so many ways of doing radiant hydronic heat-- products like 'warmboard' are probably the most expensive, while stapling the tubing to the floor joists is the cheapest route. It's also the least efficient, since the heat will have to penetrate more layers before it gets into your room...

I think what you may need to do is this: contact a PEX supplier in your area, ask if they do complimentary engineering. Some [most, I think] will look at your location, plans and specs [insulation, etc] and calculate how far apart your pipes will need to be, how big a boiler, etc. They usually do this for the heating contractors, so you may have to have at least a preliminary relationship with one in order to get some numbers going-- plus, you'll probably want the contractor to do the install and pressure testing anyway.

If you're pouring a slab, installing the pex tubing is something you can do but you need to be certain of your layout and insulating under and around the slab.
I installed pex tubing before I had my slab poured and it was there for 3 years before I had it hooked up. It works great here in New England.

We are doing our own radiant and we found that the pex costs at the big box stores are much cheaper than radiantec. We got our Dunkirk boiler free because
they tore down a 3 yr old has when they put in the nascar track here and they let us have it . We were a sub on the job . We are going to install the pex ourselves . We figure for our 6600 sf house the pex , manifolds , etc. should be
about 4k . We are having ductwork for a/c put in attic for efficency and that should cost 4-5k for whole system . We are only a/c ing 3800 sf of space . So we should be able to get by with one unit.
You can do calculations to see how much pex you will need per square foot . I think radiantec has a calculator for that . Then just figure your
manifold design and layout . Get prices for all the items , add a boiler quote
and you should be good for heat . As for your a/c - I think it's better to just get a bid from a local contractor. You really won't save much doing that yourself.

We just had our radiant heat finished. Our builders walked out before our home was finished. Although it was not a pleasant experience it was better for us once we realized their boiler choice would have cost us a fortune to heat our home. That one went back to the supplier.
We have our radiant installed below the floor because that was the way it was initially installed by the builder. Installing the pex is labor intensive. If you can install that part yourself I am sure you will keep the cost down. It was more cost effective for us to finish it the way it was started even though it possibly best installed directly under the floor.
The heating contractor we hired installed a Buderus heating system. It is quite impressive. We are now waiting for an insulation quote to finish the install before we start the radiant.
Good Luck!

Thank you all! I think we're going to go for it. We'll install the pex ourselves. Our plumber friend said he has installed a few, it's just not very popular around here. Doing the a/c ourselves was never a consideration! ;)

We'll have a gas fireplace that can act as supplimental heat if we need it on those days where the weather gets unpredictable.

I could have written this post. We're doing this exact thing. Since you have to have air handling for the A/C, it didn't cost much more to have the furnace added to the system.

We installed the PEX ourselves and it was pretty easy and I think it was cheap. DH will do the hookup and manifolds and all that whenever we decide to put it into use. Since we're not sure how we want to heat the water for the system yet, it will sit dormant until we make a decision and implement it. Until then, our forced air furnace and fireplaces will do the heating. You can read all about it in our blog, linked below, if you're curious.

Here is a link that might be useful: Blog

Two sets of load calculations are needed to see if it is worth it. You may end up just doing some floor warming only.

Sizing systems by square footage is a no-no

We also have done the forced air heat and A/C along with the radiant floors. It's been nice to be able to fire up the hot air when the floors haven't had a chance to warm up enough during the warm days/cold nights weather. (Just in the last couple of days we've had 90-degree days and 45-degree nights.)

During sustained cool weather, the warm floors are fabulous!

We have radiant throughout plus F/A heating and A/C. We use the F/A heating after coming back from vacations in the winter because the lag-time to heat the house from 50 degrees to 70 degrees with radiant can be eight hours. And we put thermostats in virtually every room, allowing us the flexibility to leave rooms unheated (or set lower than other rooms) when they won't be used for awhile.

Our radiant is partially in slab and partially in raised foundation, where it was stapled to the sub-floor and covered with 1 1/2" of gypcrete. It's important to carefully lay out your walls and cabinets and avoid going under them to keep nails from penetrating the PEX. Also, make sure you have closer spacing of tubing adjacent to window walls and doors. The system should be kept under pressure with a pressure gauge attached throughout the construction process to ensure that leaks can be detected.

If you subsequently add carpeting, surprisingly, neither the thickness nor the density of the carpeting is a major consideration in adding R-value but the pad definitely is. Best bet is "slab foam padding". Definitely DON'T use rebond! And if you anticipate adding carpet at some point, recognize that that room will likely heat at a different rate than adjacent rooms so it would be best if it's put on its own thermostat. Finally, ensure that the tack strip across any doorways is glued down rather than nailed, to prevent punctures.

Lastly, take detailed photos from all angles of the PEX before you pour your slab. And you'll need to determine whether your pump and other metallic elements of your system will be all brass or not. If not, you'll have to install a type of PEX that has an oxygen barrier to prevent rust.

Best of luck. You'll love the system!

Bob

Placing the PEX for radiant heating is relatively easy. What's not so easy is determining if this is a waste of money for you. It was for us.

1.)We live in the South, where the cooling season is longer than the heating season. Very little chance of payback unless you operate the system for longer periods. The smart boilers needed to accurately control a system in a temperate climate are pretty spendy and complicated and not very DIYable.

2.)We have wide temperature swings, sometimes daily, which magnifies the slowness of the "thermal mass pendulum." We see this just with our heated bathroom floors (separate system). It's going to be 42° tonight, so turning on the heated floors will feel good. You have to think about that a couple of hours in advance, because it takes that long to warm up. By the time they're warm, they're too warm for most of the timeframe except for that brief period that was 42°. The next day when the swing is back up to 60° and the floors are still 80°, the bathroom is too hot and needs a window opened for comfort.

3.) We insulated the new addition so well that a plain 110 volt 1500 w spaceheater can keep it 60° in the winter, and a 2 ton AC in the summer. If we'd put the money we spent on PEX towards additional insulation (we just used 2x6 construction with "standard" type insulation instead of the new high tech products) then the simple addition of the forced air furnace would have been more than sufficient for truly comfortable heating in the winter.

For many people who have a long heating season and awkward spaces that forced air isn't comfortable for, radiant heating can work "miracles". For people in warmer climates, or in climates with great daily temperature fluctuations, a radiant system is very often not the best choice for either comfort or the pocketbook. Do your research well, and don't get caught up in the hype thinking it's a "must have". It isn't. And, it's sometimes even a drawback to comfort. We've never fired up the radiant in the addition. We've never needed to, even in 0° weather. And the bathrooms do work wonderfully well (imagine 6 cats lying on their backs in bliss!) but are also inefficient monetarily and for true comfort when confronted with wide temperature swings in a day. They are great when the temps say in the 40's and below for extended periods of time, but that't not how our winters here operate. It's 40 for a couple of days, then back up to 55°, then down to the high 20's, then 70° (must be Christmas day!) and then you have a 50° drop into the teens and on down to 0°. Radiant isn't very efficient or comfortable with weather like that.

Thank you all for your comments and advice. We are taking it all into consideration. It's definitely a luxury and not a necessity, so we are looking at it in that way. Kinda like granite countertops. ;) But we are still leaning toward doing it b/c we do have a decent winter of 40's as average with considerable days lower than that. Added to the fact that we won't have the expense of additional flooring materials and we're approved for quite a bit more than we are planning on spending, it is certainly within our budget.

Thanks again, I love this site! I've been reading for days!

We're in Atlanta, GA. We're going to use hydronic infloor radiant heat primarily because it's a much cleaner heating system for asthmatics like me. (And because DH wants toasty toes.) Entire house will be tiled with porcelain tile. Again, very clean/non-allergenic. (And easy to clean.)

In the master bath, an in-wall commercial grade electric forced air heater to heat it up fast and efficiently.

With tight construction, you need a mechanical fresh air supply system. So we'll install an HRV. That needs ductwork, and we need central AC, so we'll tie those systems together. (Central AC doesn't bother me like the central heat does--my doc says it's from not heating what dust there is in the ductwork.)

As long as we're putting in the central AC, why not add a furnace? We are. It'll be backup heat mostly. I can tolerate it for short periods of time in case of a sudden chill. Or if we have a problem with the hydronic. (I can't be around fireplaces.)

I also need backup AC, so we're installing two multi-unit Mitsubishi Mr. Slim systems. Each outdoor compressor supports 2 iindoor (wall-hung) units). We have these now and they're wonderful and efficient and quiet. In spring and fall they'll be used for all our AC needs rather than the central AC.

The central AC and furnace will have a variable speed motor and that needs to be run all the time to support the HRV--oh and the central air filtration system with HEPA and carbon gas/odor filters.

Oh, and Icynene insulation under the roof and in all walls, and the appropriate glazing in our pultruded fiberglass framed windows-- so none of that precious energy gets wasted.

We're into health, comfort and convenience. We're getting older. It's a luxury/necessity. And we far prefer it to granite countertops, which we will have no money left for.