Radiant Floor heating vs Forced air

Mike T., Swampeast MO

Thanks Eric!

You can take this for whatever it may be worth from a mainly a homeowner with ZERO experience with oil, but personally I'd maintain the existing Buderus and let it run until it dies. Given your thermostat habits, boiler size, home size and location it can likely handle "some additional square footage". Snowmelt is, of course, an absolute wild card. Walkways--likely no problem with the existing boiler in anything but unusual conditions. Driveways however...if of <I>any appreciable size</I> probably better served by dedicated boiler(s). Absolute waste to oversize your space heating boiler to handle a snowmelt load unless you're <I>always</I> heating that drive (e.g. class 1 snowmelt).

Ed_40

Radiant floor heat vs forced air

I am currently building a home in the north east. I know and respect the fact that you do not talk about pricing on this web site. Here is my situation. My new house is 5000sq feet plus 2000 feet in the basement and 800 feet in the garage. My builder includes 2 Furnaces, 2 40 gallon hot water tanks, and 2 air conditioning units. I would like radinat heat in all or part of my house, but do not want to have 2 types of heating everywhere, but still need air conditioning everywhere. What options do I have? Is it cost effective for me to trade in my 2 furnaces, and 2 water tanks for a radiant heat system that the heating source can also be used for domestic use? Next if you could touch on the air conditioning, reading about unico, how cost effective is this sytem. Again I respect that you do not talk pricing and quotes. I am just looking for answers that the cost is comparable or one is way more expense or possibly solutions to keep the costs resonable.
Very long and wordy question from a lay person, looking forward to your response.

Ray Landry_2

Hi Ed I would definetly go with the radiant if I where you. your ROI will be huge in that you can run ultra low water temps with a super efficient boiler not to mention a level of comfort that is second to none! I'm not to familiar with the cost comparsion question in regards to high velocity a/c to conventional, BUT I would guess that since your home is new, conventional tin duct will be much cheaper since nothing is finished. high-v is great for retro's. Please ASK ASK ASK questions about the radiant install if you get quotes there are many blow and go installers out that and if radiant isnt done right it's a mess!!! you will also need some type of air exchange system- hrv or erv depending on where you live if you choose radiant.

clammy

radiant is king

In my book the best over all comfort and cheaper long term operational cost is a boiler and radiant is the ticket .Why have to hot water heaters when 1 correctly sized indirect fired hot water heat will be more then enough .You could always use standard a/c air handlers with hot water coils for a second stage if need be,another biggy to me is when you use a furnace and she developes a heat exchanger crack every time your fan runs it distrubites the co through out your home ,something that does not hapopen to hot air system that use hot water coils .Plus the fact that your tile floors in your kitchens,foyers and bath will be warm it's hard to ever get used to a cold floor again.The list of things a hot water heating system can do in my mind far out ways what a forced hot air system can do plus the real fact that most homes using hydronic heating systems use less engerny then homes heated with hot air and i,m not making that up it's in some 1950 ibr booklets aside i believe a burmham booklet states the same .Hot air systems are always cheaper then a good hydronic system and plus most gc love a/c hot air just one set of ducts for it all and it's easier to sell and more money in his pocket .On another note i know if i where to sell my home and move any where i would not settle for a home with hot air andif i did it would shortly be hitting the curb and a hydronic system would be installed peace and good luck clammy

Mike T., Swampeast MO

A well-designed, well-controlled, radiant heating system operating at low temperatures has only one disadvantage--initial cost. So-called "low cost" radiant systems do exist, but they compromise efficiency by operating at high temperature, [sometimes] compromise comfort and are [sometimes] inadequate as well. When choosing a radiant heating contractor ask for AND VERIFY customer references--a good contractor will be just as happy to provide them as the customer will be to "spread the word".

Unico (and similar) high-velocity cooling systems are very nice, unobtrusive and comfortable. They are however VERY expensive compared to traditional ducted systems. While they are sometimes used in high-end new construction, their more common use is in older homes where large ductwork just won't physically fit. As long as you can deal with traditionally sized ductwork, registers and returns, conventional systems will save significant $$$ in new construction. When installed as a cooling only system both the supply registers and returns should be located high on the walls or from ceilings. This enhances both comfort and efficiency. Mixed heating/cooling forced air systems ALWAYS compromise either comfort or efficiency because of the nature of "warm air rising" and the relative size of warm vs. cool air.

In addition to using a radiant heating system that requires low operating temperature, you should give the UTMOST consideration to a condensing/modulating boiler. This provides the unbeatably combination of the ultimate and comfort and the maximum fuel efficiency. At present, condensing/modulating boilers use only gas for fuel--natural or LP. With gas prices that seem almost certain to stay very high, the cost differential between conventional and condensing/modulating will pay back quite rapidly.

With radiant floor heat limit recessed lighting that protrudes into unconditioned (typically attic) space. When installed in soffits (typically kitchens & baths) INSIST that those soffits be built such that they are located in conditioned space. Where recessed lights protruding into unconditioned space "must" be used, make CERTAIN that those little "chimneys" are WELL-INSULATED. The best method (even with recessed fixtures rated for insulation contact) is a sealed "box" of rigid insulation on top of the fixture with other insulation (usually loose fill) surrounding the sides and piled over the top of the insulating "box".

Mike T., Swampeast MO

Cost Reducing Ideas

While wall-to-wall carpet and radiant floors are compatible, the carpet (and particularly the pad) must be carefully chosen and appropriate design changes made. If the carpeting is heavy plush then significantly higher supply temps can be required. This complicates control and reduces efficiency. Floors like stained concrete, ceramic tile, sheet/tile vinyl/asphalt/linoleum, engineered hardwood, natural hardwood and cork are very good for radiant. Small area rugs are no problem, but room-sized rugs may present problems.

All this said, a combination of radiant floors and wall-mounted panel radiators can reduce installation costs significantly. Think radiant in non-carpeted areas and panels in carpeted. The panels will most likely need a hotter (less efficient) supply than the floors, but with careful sizing and the use of Thermostatic Radiator Valves (TRVs), the efficiency hit can be kept to an absolute minimum.

A good radiant heating system is a system for the life of the HOUSE that WILL NOT BE CHANGED WITH "TRENDS" OF STYLE OR FASHION!!!

Consider that when choosing other materials. Tens if not hundreds of thousands of $$$ can be spent on a kitchen and history PROVES that kitchens are SHORT-LIVED. You may think you're building a kitchen that will last forever but I guarantee that it will look "tired" or "outdated" within in single generation! If you (or later owner) has the funds they'll rip out everything you so admired when it was new!!!! Baths are similar but I do confess my love for high-style baths. As long as you consider SERVICE ACCESS as TANTAMOUNT and use the BEST WATER-RESISTANT CONSTRUCTION in a high-style bath, my observation shows that NOBODY will EVER want to upset the luxury and they'll gladly overlook whims of change in fashion.

Eric_25

Radiant

We install a lot of radiant in NH with the high velocity A/C systems either Unico or SpacePak, same concept, If a complete radiant system with A/C is out of your budget the next best thing is a hydro-air system with radiant only where you really need it (tile floors, basement slab, garage, etc.). The installed cost of a high velocity system versus a conventionally ducted system is usually about the same in my book, the HV system itself costs more but the labor is less. The energy savings and comfort level of the radiant or hydro-air system will far outweigh the extra cost in my opinion.

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Mike T., Swampeast MO

While hydro-air does have a place, it requires HIGH TEMPERATURE that significantly reduces the efficiency of condensing/modulating boilers. It's really just "forced air heat" under a different name and still has ALL of the disadvantages of such. While a few here might accuse me of heresy, if you're using forced air heat just use a good, high-efficiency furnace.

Hydro-air and conductive radiant floor heat are incompatible if you want energy efficiency.

Mike T., Swampeast MO

Shoot me if you like Eric, but systems like that will NEVER be able to take advantage of highly efficient boilers. Why not use a furnace and a tank water heater?

stephen_4

Mercedes Benz vs. Skate board

Bob Forand

Check again

The cost of a Unico system to a conventional ducted system is approx 20-25% higher than standard duct. The recent past steel hikes brought this much closer...

Unknown

Hi Ed,

It depends on what you mean by "cost effective". If you're just looking for payback... it probably isn't cost effective. If you're looking for comfort and hoping that the energy savings may offset the initial cost to some significant degree... it very well might be cost effective. However if "cost effective".. i.e. money... is the main attraction, then put the money into your envelope.

Especially with moderate loads (assuming a good envelope), your mechanicals get smaller and cheaper. And all kinds of options open up that make more sense. And since you'll have duct in any case, adding an air exchanger would be fairly trivial to keep good Indoor air while sealing the heck out of your envelope.

S Ebels

Plus the fact

That a Unico system is insulated right out of the box and you have to pay extra to insulate your steel. IF you can find a contractor that will even do it. Definitely not a habit of anyone in these parts.

Do not let anyone sell you a fiberglass duct board, duct system. The contractors that use the stuff can talk all they want but I consider it a health hazard and have walked away from two jobs where the GC or architect required it.

Radiant will always be more "expensive" unti you start trying to quantify the worth of a truly comfortable house. I've been in lot's of new forced air homes that had the stats set on 72 and the owners were running around in sweaters. Not so in a properly done radiant house.

Brad White_51

Unico HV versus LV Conventional

Bob-
I recently designed a condominium AC system which came in over budget. Contractor proposes a Unico/Aspiration principle system as a VE item. Made sense to me.

Granted the Unico duct (spiral good for 6 or 10 inches, gasketed smooth LR fittings etc.) may cost a bit, the total amount of sheetmetal is much less on the supply side of things. Thoughts?

Thanks
Brad

JimL

Good point on the \"expensive\".

A t-stat on 72 in a radiant house would probably be unbearable. If you are a 70 kinda guy then you'll probably find 66 on the stat to suit you just fine. As far as energy savings,Although you'll read anwhere from 10-50%++ savings are typical, we stay away from quoting a number as I have no idea what their habits are. There will certainly be a life-cycle savings over FHA or baseboard but that number will vary on location, construction,etc, etc. I was told at a recent seminar that every 1 degree lower on the stat = 3% fuel and for every 3 degree drop in water temp = 1 % fuel. Does anyone concur with that? As opposed to discussing any percentage savings, I though that this would be a reasonable comparison most people would understand.
I realize that looking at the budget, the comfort thing is somewhat intangible to most and ceratinly understandable. The new home is a huge undertaking and there always seem to be a million things more important. BUT...After the first heating season in the 2500 SF, 2 zone FHA builders special house however, the comfort thing tends to become very real all of a sudden.
Trying to "sell" radiant to someone who's never experienced it is certainly the challenge in this profession.
It is so true that you don't miss what you never had. I can tell you this though...and I'm sure most will agree... nearly everyone I've ever met that had an experience with a well designed radiant system, would never consider anything else. Ever. Period. They really feel that strong about it.
COMFORT
Efficiency
COMFORT
Ease of Zoning
COMFORT
Freedom to put furniture wherever you want.
COMFORT
Heat the walls in your shower and whirlpool surrounds
COMFORT
Warm you towels and your Toes
And finally, did I mention COMFORT?
Get it designed and installed by a PROFESSIONAL, not the builder. It's a big investment, yes, but one that will not lose value when you drive it home.
I often wonder how over the years we have been led to believe that unless we spend 3 mo. salary on that diamond
, we don't "really" love her. I thinking of running local ad stating the same about radiant.
"Show her how much you "really" love her this Mothers Day, by giving her the best heating system money can buy". Or..."Bring in your tax refund and we'll match it on the radiant heating system of your choice..." And there's always the "Push, pull or drag in your old heating system....." Anyway, I digress..Good Luck with your project Ed.
Jim L.

Unknown

hydro-air water temps

in response to Mike T's assertion that hydro-air systems must run at high water temps to work and are thus incompatible with condensing boilers, this is simply untrue. look in any high-v (Unico, Energy Saving Products, Air Link etc.) design manual and you will find multipliers to size your coil for whatever water temp you choose. lower temps mean you will need a larger coil is all, simple.

Weezbo

Sounds like you need to find someone who you can trust,

for the many issues that you may find to be overwhelming in getting the project finished. Being your own G.C. is painful to your sub contractors,one good General Contractor will save plenty headaches for everyone.

Insulation is Paramount in the equation. are they offering Optima,Spider, Spray foam,foam board, tremcoed vapor barrier ,clean tidy work with All wiring ,mechanical,Plumbing wall penatrations,window,door,plates, sealed?

A Mechanical Contractor of your choice might be extremely costly in many ways however,...to aid you in that choice this site has Find a Professional,check it out Ask your General Contractor for his input and meet the Mechanical contractor he has a good working relationship with. now, should it happen that they are one and the same individual Bingo! You are in the right realm,go home say a quiet prayer of thank you and call it a beautiful day.

Costs are not easy thing to discuss however,when you have someone working with you who is considerate of the physical and financial comfort into the future you have someone certain of some very specific requirements and standards of quality that need to be incorporated in the home. The long term value of the decisions while somewhat open to interpretation is nt something micro designing by internet site and sight unseen would be real sound advise to give you. So,...

Space conditioning basically has facets that need to be well considered in order to "shine".for my dollar radiant is the way to go once the building envelope is "dialed in"
passive design (orientation,surroundings) and passive designe products within the structure all may cost a dime buh well worth the considerable value added to your home.

speaking of value The Wirsbo Residential Firesprinkler living water system that is connected to each of the water fixtures in your home is a great investment to protect your family and possessions from fire.

Having more than one Boiler or more than one point of use water heating devise on the domestic is surprisingly not unheard of in homes over 5000 sq feet .recirculating,on demand,push button,heat sensors and a variety of computer and or telephone security and lighting and mechanical systems coupled with home entertainment monitoring systems are also available and are considered investments.

While i happen to like oil heating systems there are alternatives that can be integrated such as direct vented propane appliances(fire place,modulating condensing boilers,electric)for examples. the more i think about your question the more i can think about it i would like you to take a look at Healtyheating.com. encapsulated in the site is a clear picture of accurate information that you can See:) Oh. Visit the Kangaroo though a dilapidated looking chap, he is very sensitive

Dave Yates (PAH)

I'm a living walking talking.....

believer. I lived with forced hot air for many years & as a contractor, they were installed correctly with good air filtration and humidity control. Still couldn't match the comfort I'd experienced with a hydronic system that had standing CI rads in my parents home or the baseboard heating I'd had in one of my first apartments. When we built the home we're in now, I wanted radiant. Not because I knew so much about its benefits, but because my customers who have 1930-40's era radiant raved to me about their systems and cried (literally) when the copper-tube systems, installed just after Levittown, failed and we had to install either BB or forced air. Now I'm one of them. You can have my radiant system when you pry it from my cold dead hands - but you'd better hope I was the last survivor in this home or you'll have a fight on your hands!

I'll never live in another home that doesn't incoprporate radiant heating - no matter what it costs up front. If it cost more to operate, which it doesn't, I'd still have radiant. If it were bad for my health and FHA was good, which studies have shown (see healthyheating.com) is exactly the opposite, I'd still have radiant. If my wife craved FHA over radiant, which - than the Lord she doesn't cause I'd sure miss her, I'd still have radiant! If she were looking over my shoulder right now, I'd have at least died in a radiantly heated home!

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Gordy

Table pounding

I resemble that remark! Could not have said it better Gramps Pahs.

Gordy

nick_7

ho $0.02

If you are putting in conventional AC ducts, it is no biggie to throw a hydrocoil on. Remember that in the NE there will be a bunch of days where the temp outside is about 61 and damp in the mornings where you will want a touch of heat on to warm up and dry things out, but then the temp will go up high enough during the day that you will want AC. High mass radiant floors can't kick in quick enough to give you that touch of heat when you want it and then will give off heat during the day when you will want to turn on the AC to cool off and reduce moisture again. Also, is this a second/weekend home, or are you away alot during the winter? you will be want to use setbacks that high mass radiant may have trouble timely adjusting to. Panel radiators may be your better bet for the radiant portion than floors.

Mike T., Swampeast MO

Have looked at such design manuals. Problem is that unless there's a variable-speed blower and the ability to control such in a hydronic system it's difficult to take full advantage of supply temperature reset. This is especially true when combining hydro air with nicely conductive radiant floors where an 80°-90° supply temperature is not at all uncommon in rather common weather. The efficiency of a condensing/modulating boiler is defined by the emitter with the highest temp and flattest curve requirements.

On the other hand there are now furnaces with highly staged flame, variable blower speed and outdoor reset with proportional indoor feedback. I've yet to see a hydro-air system with such facilities. Please enlighten me if I'm wrong.

Unknown

You can control mass. You just have to control it properly.

Mitch_4

forced air

"...another biggy to me is when you use a furnace and she developes a heat exchanger crack every time your fan runs it distrubites the co through out your home... "

Just to point out that most forced air systems are negative pressure in the heat exchanger area by design, and the heat exchanger cabinet is under higher positive pressure, will ikely force excess air into the chamber and out the exhaust, and not the other way around.

Mitch

clammy

fha

Not to sound crabby but is this true with in shot type burner used with combustion fan as on most modern hot air systems .I only say this because either way your duct is moving air that is in your home rioght,as with a boiler the distrubition system moves water not air .Not being crabby just asking .I started my carreer as a plumber then hvac res/com/gov.defense building then strickly a/c and wet steam heat just trying to push the point thathot water system are supior to forced hot air peace and good luck clammy

Mike T., Swampeast MO

Regarding Air Temp & Relative Comfort

I regularly spend time each day with three heating systems: "near radiant" via very large iron rads with thermostatic radiator valves (TRVs); "true radiant" via floors with heavy conduction plates; and forced warm air. None use daily setback.

The "true radiant" in the "reading room" is suprememly comfortable--even with my pants down. This year the "reading room" was in the deeply setback (constant setback) and even at 59F I was still reading...

I truly and honestly find that my temp differential for the same comfort is 4F between the "near radiant" and forced air spaces. With the same activity level and, 66F with the "near radiant" feels the same as 70F with forced air--and that's with very light (or no) clothing. At 61F in the
"near radiant" my comfort at low activity was fine with a medium-weight sweater with sleeves down. At 66F in the "near radiant" space, the sleeves of even a light sweater are pushed up. 70F feels uncomfortable, 72F has me removing clothes and putting the ceiling fan to high. (Even at the low temps this year, the 4-speed ceiling fan runs constantly on low.)

Mitch_4

hi Clammy

I know your not being crabby...I enjoy many of your posts, and have learned immensly from your hydronic knowledge.

Essentially almost any modern forced air system with an inducer is placing the heat exchanger in a negative pressure zone. Because you "pull" the products of combustion. An easy way to tell is the pressure switch that proves venting. If it is a negative value, then the negative pressure in the H.E. must be greater (More negative) than the switch setting.

I agree that water systems are going to be much safer than forced air in that respect however. CO in your baseboard, or radiant floor tubing is not going to be a danger to the HO.

Peace to you Clammy, keep up the info.

Mitch

Rich_18

JIML

'Show her how much you love her' Thats great! LOL

Eric_25

I do it in my own house

Mike, I run a similar system in my own home in NH. I run hydro-air on the second floor and radiant on the first, I sized my air handler and ductwork to run low water temps. max 160 min 115 and a low fan speed in the winter. This system runs a water temp. below 138 any day the outdoor temp is over 15-20 degrees F which is the bulk of the winter in central NH.

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Mike T., Swampeast MO

Does sound rather reasonable, but a few questions.

Am I correct to assume that you're using little (or no) daily setback?

Are you using a condensing/modulating boiler?

What type of heat transfer system for the radiant?

Not terribly unusual for a nicely conductive radiant panel system in an efficient shell driven by a condensing-modulating boiler in a quite cold climate to max around your minimum...

Derek Moore

radiant and A/C

Ed,
You did not say where you are.

I have radiant heat throughout my home. Hi velocity air (Space Pak) and a Buderus indirect Hot water maker. I have snow melt on my front path (approx 250 sq ft) and the front steps. I have 2 Buderus boilers that are staged and use reset to maximise the efficiency of the system. 90% of the wirsbo tubing is in gypcrete. Coldest month last year was October, we had 3 snows (melting) cooking, dryer etc. gas bill was $650. total sq ft is 8000. I have 26 zones. average indoor temp 72 (I like to be warm). I will change the boilers to condensing (Buderus GB series)in the next weeks and track that next season to see the actual efficiency which I believe will be enough to make the change. One room is 26 feet high and very cosy. There are no drafts anywhere and no dust particles floating in the air when the sun shines in. The A/C is quiet and comfortable.

Up front cost is of course higher, but built in to your mortgage over 30 years. The monthly costs are MUCH lower.

There is only one problem to my mind with radiant. If you have it in one room, you will want it in all of them.

You will not regret the move. I have lived with hot air, baseboard, cast iron baseboard and radiators, as I have experimented with heat over the last 30 years. There is no substitute for the best.

It is significant to note that in Europe, where fuel costs are much higher than here in the U.S. There are NO hot air systems as they are considered totally inefficient.

Good luck with your project, think it through. Check out your potential installers thoroughly. Make sure your project is in their range of capability. If you need advice go to wirsbo and have them recommend someone from your area. We have a great network and help each other. Competition to get the lowest price in radiant is practically non existant. Remember the lowest price put 7 astronauts in the ocean

Derek Moore

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Eric_25

G105-28

I do not use any daily setback

I am currently using a ten year old Buderus G105-28 85,000 Btu oil fired with a Carlin .65 nozzle @ 140 PSI to heat my 2800 Sq Ft contomparary home, I will, sometime soon, probably add a mod/con GB142 or Vitodens as an alternate or additional source as I am adding some snowmelt and some additional square footage this year.

I use Wirsbo double plates under my wood and carpeted floors with joist hangers under the tile for one water temp.

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