Forced Air vs Radiant In-Floor

orangeTO · April 2010

Just wondering if anyone might have a quick answer to this.

We're contemplating building our own home (approx. 3,200 sqft) and we're stuck on the fence between going the 'traditional' route of using a forced air gas system with a/c or going with an in-floor radiant system throughout with a high velocity a/c system.

Does anyone have a quick pros & cons breakdown for each system? As well, does anyone have an estimate as to what is the cost difference between each system based on square foot area?

Thanks in advance!

jack z_2 · April 2010

Radiant vs hot air

We built a house(3500 square feet) about five years ago. We decided to go with radiant infloor heating (Viega climate panels on the top of the sub floor) and a separate AC system. It was a LOT more money but in my opinion worth every dollar. We used spray foam insulation(Icynene) and a fresh air ventilation system. We are in the country(northern PA) and only use about 500 gallons of oil for the heating season. The comfort is amazing; the house is warm with absolutely no drafts. I haven't regretted spending the money for one second. If I built another house(never going to happen) I would absolutely use radiant heat again.

jp_2 · April 2010

your choice!

which do you prefer?

don;t care? hot air will cost less.

want a dollar figure? pick a number out of a hat......... whats the cost difference between a good car and a cheap car ? everyone will tell you something different.

jp

orangeTO · April 2010

please elaborate

jack z....you say it was ALOT more, but what are we talking about?...25% more?...50% more?...100% more than the forced air system you were intending on using?

As for what I prefer?...I've lived in homes only with forced air gas and never experienced first hand in-floor radiant....so I don't know if I necessarily "prefer' radiant to forced air.

I'm willing to live with forced air but I'd like to consider radiant in-floor, as I said initially, I'm looking for some help explaining its pros, cons, cost differential, its lifecycle costs etc.

So I assume 'jp' you refer to the radiant in floor as the 'good car' and the forced air gas as the 'cheap car'?.....why is that?

Jamie Hall · April 2010

I don't have a horse in this race...

being a steam man -- but I've worked with both. There are advantages to each; I'll start off by saying that, of the two, I prefer the feel of the radiant floor. However, that is a personal preference.

The radiant floor is -- or should be -- utterly silent. The forced air can be very quiet, but rarely silent, even when well designed and installed (if poorly designed... !).

The forced air can raise the apparent temperature of a room very very quickly. Radiant floors respond more slowly.

Radiant floors are warm, and they warm everything in the room very evenly. Forced air floors are not warm (they can be downright cold), and objects in the room may not be as warm. Also, it is remarkably hard to get really even heat distribution with forced air (again, this is a matter of design and installation).

It is easy to add whole house air filtration and humidification to forced air; in fact, it is almost necessary. Humidification and filtration aren't as necessary with radiant, but if you want them they are harder to install (although with your idea of a high velocity a/c system this becomes moot -- put the filters and humidifiers on the a/c system and run it as required).

It would be very hard to state a cost difference in numbers, or even percent. Modern radiant is very easy to install -- but then, so is forced air. I would be inclined to say they'd be about equal, but the high velocity a/c will be an add on to the radiant, while with the forced air some of the cost (the ductwork and fans) is already there.

Not sure that that's particularly helpful...

EricAune · April 2010

pros/(not so many)cons

Comfort is best packaged in a properly sized and installed radiant system. Overall room temperatures are more even when utilizing a radiant in-floor system than compared to a forced air/ducted system where most of the energy is concentrated at the ceiling level (hot air rises).

Minimum dust, dander and allergen circulation are the major health benefits associated with a radiant system.

Outdoor temperature sensing appliances that directly decrease operation costs by matching the heating load based on the heat loss. On average, properly designed and installed radiant systems will operate 20-30% more efficiently than a forced air system; delivering the heat where its needed at a rate matching the needs of the house.

Multiple zones allowed and encouraged. Radiant systems are more flexible when it comes to zoning. Room-by-room zoning, floor-by-floor zoning or anywhere in-between.

Maintenance required annually, the same as any mechanical system. Mileage may vary.

Cons: Often humidity control maybe needed depending on your climate

Radiant cooling, although possible, is often cost prohibitive lending need for a separate cooling system. I prefer to use duct-less mini-splits (air source heat pump).

Hope that helps.

jp_2 · April 2010

comfort??

well for starters, comfort is in the eyes of the beholder.......radiant is nice, FA is fine too, depends on whats truly important to you. many here think radiant is the only form of comfort, a little biased. myself, i prefer a wood stove hands down.

a lot depends on your floor coverings too, nothing beats radiant for a tile floor, but if you like carpeting and big rugs, don't bother putting heat in the floors.

think about passive solar, use some free heat from the sun.

you should experience radiant for yourself before making a decision. then if interested, find a contractor and get a quote.

I see no real pros and cons, they are both JUST heating systems....... for me there are no pros and cons to eating ice cream, but for some people there are.

Eric, can you document this 20-30% savings over FA? that's a big number.

Steamhead · April 2010

There's no way

forced air could ever equal the comfort and efficiency on a water-based system, unless the latter was poorly done.

JP, he probably means duct leakage- 20% on a good day.

TonyS · April 2010

Enough on the heat side

After installing many ductless a/c units over the last decade, I installed a samsung ductless a/c inverter in my own home last year after tearing out my central air. quiet, heat pump for cool nights,super efficient, zoned, dehumidification mode, no fiberglass particles blowing around your house. Duct is filthy!

jp_2 · April 2010

got numbers guys????

eric,

have you Actually measured temperature differences from floor to ceiling on FA?

the numbers might surprise you, it has something to do with the "forced" in forced air.

steamhead, seems the FA efficiencies are pretty high these days? I read a comment by hot rod that suggests they are pretty even. i generally trust his comments.

yes i agree duct losses can be high, but isn't that why some guy invented "duct tape"?

radiant is nicer, but I really haven;t been in a FA house and said "oh my god" this is so uncomfortable. keep in mind we should be talking about a highly insulated house with new construction.

Steamhead · April 2010

Doesn't matter how efficient the furnasty is

you still have to move the air to the rooms, and that's where the efficiency problems are. Try these links:

http://oikos.com/esb/28/duct_losses.html

http://oikos.com/esb/44/forcedair.html

jack z_2 · April 2010

Radiant vs hot air

I think what you should do is get some estimates from qualified contractors. I would start with the find a professional ads on this website. There are many different ways to do radiant heat - tubing above the subfloor, below the subfloor, type of boiler, control strategies, etc. Only a contractor doing an estimate for your house can give you an accurate idea of what it is going to cost.

After five years of living with radiant heat I don't think there are any cons. The system is dead quiet, the warm floors (especially in the bathrooms) feel wonderful to your feet, and the system is fairly inexpensive to run.

We have carpeting in our bedrooms. Most of the major carpet manufactures make low R value carpeting and padding. This info is very easily obtained. Make sure the carpet installer selects a padding designed for radiant heat.

Building a house is a difficult undertaking. There are literally hundreds of decisions to be made. I think it is easier to justify upgrades that can be seen such as going from particle board cabinets and formica countertops to fine wood cabinetry and granite countertops or from vinyl flooring to ceramic tile.

After five years my wife and I feel that the insulation upgrade to foam and the radiant heat were the two best things we spent extra money on. They are going to give us a lifetime of increased comfort. I think it would be almost impossible to retrofit this house with these items if we didn't incorporate them in the initial construction of the house.

If you have any more questions or want to know anything more from a homeowner's perspective, please don't hesitate to ask.

jp_2 · April 2010

duct losses & PEX losses

interesting Steamhead.

it spoke about duct heatloss conductive, that sounds the same as PEX loss or supply line loss. this has been an old agurement around here, that a losses in supply line cancel because they are in the structure. I always disagreed.

but if you count conductive heatloss down the duct, you have to count heatloss down the supply line.

the articles seems to point to poor design and installation, good article all the same. I'll re-read it , but it didn't seem to talk about efficiency of a properly running system, they have ecm motors too now.

lets compare apples to apples. the Wall has seen its fair share of poorly operating and not operating radiant systems.

CMadatMe · April 2010

Pro Radiant All the Way

First the numbers are in the heat loss. You need roughly 35% less energy to heat a home radiantly vs forced hot air. There is very little to no convection in radiant compared to forced hot air so your infiltration is much less. In radiant we keep the heat you are paying for where you need it most to maintain comfort. At your feet to your head. In forced hot air systems we stack the ceiling and I don't know too many people that are 8 to 10 feet tall.

In radiant we have more control over comfort hands down and we can modulate our system water temps based on the loss of the structure in combination with outdoor temp and indoor temp. While forced air type systems may try they just cant be fine tunned as well as radiant or any low temp system.

With all that said and dependent on budget you may want to look how that home you plan on building is layed out. You may want the foyer/entry, kitchen, master suite and great/family room radiant and use panel rads for the other rooms as they work real well at low water temps when sized properly. Also when looking at radiant you really need to pick out the heating plant and figure on how that is going to play into your control strategy.

There are so many variables that can be used in a low temp hydronics home and that is its biggest advantage over forced hot air. Find a good low temp hydronics contractor and a good HVAC contractor and come up with what plan suites you and your home.

As for cost. I could quote this job radiantly 10 ways from Sunday. It's all dependent on what you want and while many can give you advice the final decision is yours.

Wayco Wayne_2 · April 2010

2 systems vs. 1

Cost will be a lot more for the radiant floor. FA systems combine A/V with heating so one system does both. With a radiant floor you have to provide a heating system seperate from an A/C system. Radiant floors also cost more than FA systems so your looking at more than 100% difference in the cost. I also believe that Radiant floor systems are superior in comfort and economy. Spray foam insulation also superior to anything other insulation. Superior things often cost more but may be worth it on the long run. I have had a radiant floor in my house for years but didn't really get to enjoy it until this Winter when I was home for several months after surgery. The comfort my radiant floors gave me in that time of feeling ill paid for itself easily. If you plan to retire in this house make it radiant floors. WW

LarryC · April 2010

How about in ceiling radiant?

Is there a significant difference in operational costs between a floor versus a ceiling installation of radiant heating? I am assuming there are some additional significant installation costs due to the hassles of fighting gravity during the installation.

Does the lack of a additional layer(s) between the emitters and the occupants, allow lower operating temperatures?

Forced Air vs Radiant In-Floor

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