Scorched air strikes back in JLC Magazine

Dave Yates (PAH)

Check it out.

http://www.jlconline.com/cgi-bin/jlconline.storefront/3e47b492004d7a80271a401e1d290643/Product/View/0302intn

I will be sending a letter to the editor.

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Paul Pollets

I'd say

this case "study" ranks as important as the Seattle open system failure. Since John Seigenthaler is a stone's throw from Schenectady, perhaps he could review what they did?? I'd be interested if they used outdoor reset and/or continuous circulation, not to mention zone valves. And why plates? How do plates demonstrate radiant's ultimate efficiencies? I've been saying this for years....when 2 homes are built side by side, with identical loads, one with forced air, the other with RFH in-slab and with an overpour powered by a condensing boiler using outdoor reset and continuous circulation. It would be my opinion that the RFH residence would "blow away" the other home in energy use. Who designed this study? Who built the system?

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Mike T., Swampeast MO

Open Trusses?

They sure look like open trusses in the photo. Wouldn't those be particularly difficult to insulate properly?

That two weeks radiant--two weeks forced air seems particularly troublesome as well. While it is often stated (and I personally believe) that you can be as comfortable at a lower temperature with radiant vs. forced convection that's not enough time for the occupants to really determine their comfort.

Unknown

I believe the RPA already jumped on this study and its flaws and are trying to work with this organization to design a more realistic side by side comparison test. Not sure if they are getting anywhere... not as far as they would have liked if this study was published I'm sure heh..

Dave H_2

NAHB Reserch Center

Is still in the process of reviewing the data. This article in the JLC was printed prematurely as was the data on the NAHB website.

They are still breaking down all of the vartiables.

Here are some detials about the project.
1300 sq.ft. two story home.

Radiant underfloor, The picture from JLC was not an actual install of the Schenectady project, just what was on file.
There is no outdoor reset, two zone radiant, one zone forced air. Radiant heat load calculated at 22,600 BTU's with a 40,000 BTU boiler driving.

Still analyzing the data and discrepancies.

Duncan_2

NAHB website address?

Dave, do you have to be an NAHB member to view those preliminary results? I tried using their search function to find the preliminary results at NAHB.org, and got nowhere.

* Got an NAHB website address? *

In fairness, I thought JLC did a decent job of presenting RPA's case. They devoted a fair amount of space in the article to RPA's objections about possible sources of inaccuracy of the study.

I thought those "plates" in the Adobe Acrobat .pdf format article at JLC looked like thin flashing plates, not the real deal. But I could be wrong.

Dave Yates (PAH)

me too

I'd like more of the details & am also trying to obtain the info.

Good Grief! A 40K boiler driving a split zone with total load of 22K??? Why not just kick us in the warbles while they're at it!

I've done a few Habitat homes too & the labor force is almost always unskilled volunteer based. Keeps ya on yer toes when trying to rough in properly. Materials used are whatever is available via donations. Hydronic heating equipment sounds like something they had in inventory.



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Bill_14

Would either one of these work?

http://www.nahbrc.org/

http://www.nahb.org/

Bill_14

If you know a NAHB member, then...

http://www.nahb.net/login_center/login.asp?url=/default.asp

KCA_2

On an aside..

Were doing a study on all the systems that we've installed against whoever we can get to participate from the forced air side. Granted, the homes aren't alike and the domestic use, room temps, insulation etc. are diferent however, we're finding that the Radiant is ahead by 30-45%. Once I can sit down and come up with a multiplier for the various differences we'll get a better idea. For instance; the Radiant systems are in the low 5BTU/sqft/deg day where the FAG systems are between 7-9.

Granted, some designs are in the 11's or higher. But we didn't install those!! :-)
Interesting..

:-) Kca

frank s

you all forget...........

That this is not about comfort but efficiency, I have done my part in the radiant scheme of things and the customers love it, but when you think about it , in a new home that is properly insulated and weather sealed hot air is gonna hose radiant, you can set back the T-stat 8* when you're not home and have it come up an hour before you arrive and when you walk through the door the "house" feels toasty, maybe not the floors, but the air, try to set back a radiant floor 8* and see how long it takes to get back up to temp.........better get a snickers bar, you won't be going anywhere for a while. A more honest comparison would've been baseboard to radiant. I have to ask why the sour grapes? We are in the heating profession, regardless of it's means of delivery, yeah, so radiant means toasty floors, big deal! Do you want to put the slipper manufacturers out of business? And I'll tell you what, as an open challenge to Dave Yates, If you can find us a place where we can put 2 identical houses up, 1 with radiant the other with hot air, I will design the hot air house, as well as install the entire system free of charge, and we can go head to head. Not because I think hot air is better, I'd much rather have radiant, but because in today's houses hot air is much more economical all across the board, meaning how long will it take you to recoup the additional cost of installing radiant as opposed to hot air?, and, if it proves not to be more efficient, what's there to recoup? If you want to take me on you know how to reach me, remember it's not warm feet or floors, but efficiency.,Don't forget I can add A/C for a fraction of what you can.....can you say total comfort? Just my 2 cents worth. I'd like to talk to you anyway Dave about a radiant nightmare, please email me if you have the time.
Frank

Unknown

partial B.S.

Good reset controllers have setback options too. You might not be able to drop a high mass house 30 degrees but you can certainly do a scheduled setback.

That, coupled with the different in infiltration and stratification and the inherent efficiency of low energy heat transfer *should* mean radiant kicks the heck out of FHA in *efficiency*.

Now for *economics*, the second part of your statement, that's a different story. Since FHA is about 1/3rd of the cost of radiant ya, it can be tough on some projects to claim payback as an option for radiant. That doesn't mean that you aren't using less fuel (environmental benefit) or that you won't be far more comfortable with radiant, it just means bottom line is yes, you might spend less money on FHA on some projects. And I stress the some. AFAIK no one has ever challenged that.

hot_rod

Well!

That's a pretty stern lecture there Farnkie & one that's a tad misdirected IMHO. Just for the record, we do hot air too. There are times where HA is the best choice and other times when HW is far superior. That's part of our job - knowing where to draw the line. If all your "hosing" is based upon is the ability to utilize setback, that's called stacking the deck and has nothing to do with overall system efficiency. I have one hydronics customer who sets his thermostat back to 50 every night! Even on these bitter cold winter nights, his boiler never comes back on.

Cheaper to install? I'll gladly give you that one. More efficient? Nope, won't go along with that one - not willingly anyway, not anymore. Depends upon the installation design and installer's skills. Comfort issues - if customers who've lived in hot air homes that now have radiant are any indication, and I fit into that category, hot air will be just that - full of hot air(G). I can do set back with hydronics & have on multiple occasions.

A few years ago, I'd have agreed with a lot of what you're saying. Efficiencies of furnaces blasted those of boilers. I lamented the lack of USA manufacturers in the high-end efficiency field of hydronics at the RPA banquet just a few years ago. No more though. Now we've seen the advent of boilers from within our own shores that meet or, in some cases, beat the efficiencies of hot air furnaces. So there.

While I can install boilers with true modulation and continue to evenly distribute those moderating Btu's throughout the system, modulating blower speeds in ductwork that's been designed for proper air flow based upon friction loses for specific CFM's goes into the crapper and delivery becomes unbalanced. Unless you add a multiple automated damper system.

So, the game's afoot as far as I'm concerned. But don't come a calling with some hyped up set of figures based upon a flawed installation that's skewed to make the outcome fit what's desired by those pulling strings behind the scenes. Like you've said - take two identical homes and let both industries give it their best shot - in good spirit and with as much comaradie as is possible. Kind of like the current reality shows on TV! Btu Island? First one to exceed 1-million Btu's get tossed off the Island.

You'd be screaming bloody murder if I installed a furnace so grossly oversized and then slammed it for not performing well in a national publication. When the dust clears on this particular installation, I'll bet we'll find lots of oddities that render the so-called "findings" in the JLC article all but useless as a valid comparrison between HA & HW. That's where the sour grapes are coming from. If they want a real fight, untie my other arm!

Comfort isn't part of the overall efficiency picture? Yeah, since when? It is in my book.

Upfront costs an issue? Well then, let's not forget to include replacement costs for the furnace that lasts an average of 15 to 20 years! The boiler at our shop will be celebrating her 74th birthday this year.

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Jackchips

My, my

aren't our danders up.

I don't think either one of you has made your case. You both state anecdotal data, not facts. Come on men, let the contest begin. There must be enough folks in both trades (and many Daves who do both) to put up the design for equal houses, find a builder and put the challenge to work for a whole heating season.

Sure there would be obstacles, especially agreeable homeowners, but if you get the right people we could get facts, not statements.

hot_rod

We

can easily run the numbers in our heat loss programs for - let's say a great room with an 18' vaulted ceiling.

My Rheem RHVAC furnace sizing program will indicate more Btu's are needed than will my radiant programs. While the vaulted ceiling room will be more dramatic than other flat ceilinged rooms, there will continue to be a slight edge with radiant. Overall, the Btu ratings will favor the radiant system (at least as the programs are designed). Has more to do with how the heat is delivered than the actual heat loss of the structure (without any particular heating source), IMHO, and lots to do with how buildings lose heat and where the greatest heat loss takes place within the structure.

All that's left, if we concentrate on equipment efficiencies without losing that focus, is the equipment itself. We can both match the other's numbers in that arena.

So, if I have to produce fewer Btu's to perform the same function and our equipment is in a dead heat (pun intended), I wonder who would ultimately win.

My dander's not up, I used my head & shoulders just this morning(G). I will freely admit that I don't like cheap shots that masquerade as factual reports in national media that's designed to deliberatey mislead folks. Even if radiant were to lose to hot air, which I sincerely doubt would be the case in a real study using well designed and installed systems (for both), it wouldn't be by 22%. In the same token, I wouldn't expect to see radiant whallop hot air by that wide of a margin either. Truthfully, I'd expect to see a fairly close efficiency with the edge going to radiant. However, if comfort becomes a contributing factor then radiant will surely win the day. I've lived with standing cast iron hot water (3), hot air (4, 2 of which I designed and installed), standing cast iron steam (2), HW baseboard (2) and radiant (1). My personal experience tilts the scales in favor of hydronics with radiant topping the list for the ultimate in delivered comfort.

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hot_rod

It ain't over till...

I thought the JLC article was fair in acknowledging the "weak points" in it's report. The RPA has, and will continue to work with any, and all groups that report "partial facts" regarding the pros and cons.

We really need to ally with the air side and do our best to include, not hammer them. We need better in-roads to those associations, as well as the reporters sent to "do the story"

After all the RPA was founded as an education, not for profit enity. This task should be right "up the alley" of what the RPA excels at. Give it some time the gears are turning as we speak The manner in which we respond is as important as the response, I feel.

Just the facts! Now where did we place the facts, again?


hot rod

Earthfire

NAHB

In MY humble opinion The NAHB & their research center operate as a block to improvement in home owner comfort and convenience. They fight improved and safer codes, they fought ADA,they fought and killed the requirement for real 3 ft. wide doors in houses and wide enough corridors to walk down, and they seem to work on the principal of cut the corner as much as we can, grab the money, and let somebody else hold the bag( exp.Dryvit type stucco,Good product shoddy production builder installations and misapplications.)According to an almost constant mantra eminating from them,people can't afford better.They prey upon an uninformed suseptible public that sees the pretty flash and is unaware of the substance that should be in their homes. We have all walked into buildings and shuddered at the defects while the prospective new owner is gushing with anticipation of how pretty it looks.The builders ,their sales people & other staffers are driving beamers ,lexuses,and other pricey vehicles, while the "tradesmen" that are creating their wealth are on the average driving an old beater and trying to get one more house roughed in today so They can try to pay their bills. The only fair way to run a comparison is SIDE BY SIDE identical projects with identical locked up setpoints and run an annual comparison. There are builders that do build a guality product and give their clients and trade partners a fair and honest shake, but they are not the norm.For me anything the NAHB sponsors or endorses is to be approched with a large grain of salt. Just MY humble Opinion after 30 some years in and around the construction business

Dave Yates (PAH)

The deck was stacked with aces dealt in advance to one player!

Go to the RPA site, download the PATH report and read it carefully. Radiant lost that game before the first hand was played. To even remotely claim this is a comparrison of efficiencies is a sick joke.

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Duncan_2

Efficiency, comfort, the truth...

You’re right Frankie, The study IS about efficiency, not about comfort. It’s about finding a more energy-efficient way of heating your home. Judging from their website, the NAHB seems to be into green building, and wise use of energy (and other) resources is a part of that. Then again, after reading Earthfire's post, maybe I need to have another look.

Radiant heat has long been touted as the most efficient heating system, compared to all others. Supposedly, this is why it’s used so widely in Europe, where fuel prices are much higher. Personally, I’m not so sure many, or even most radiant systems deliver this promise.

Especially not staple up, where heat transfer BY CONDUCTION is limited to heated joist space AIR that can carry heat to the subfloor at only 0.018 btu/cubic ft.

And conduction is a big part of the heat transfer package.

Heavy extruded plates increase heat transfer by conduction, in effect, by increasing the area of warm-tube-to-floor contact. Embedded systems contact 100% of the tube surface, which offsets the somewhat poorer conductivity of cement. It’s ALL limited by the floor covering.

I think Dave and the RPA’s issues are very real ones, and points well taken: comparing a GOOD forced air system to a POORly designed radiant floor system is hardly a valid comparison. If the forced air heating system is reaping the benefits of of a previously heated warm slab, the results are skewed. Everyone who’s lived with a radiant slab knows it continues to emit heat for days after the heat's been turned off. A heating plant sized twice as large as the load will be MUCH more wasteful than a properly sized heat source. If we are comparing apples to oranges, let’s at least not compare rotten apples to ripe oranges. Those of us who’ve been in the biz for any length of time know there are poorly designed heating systems of every type out there.

I’m after the truth, I could care less about who "wins". If one type of (well-designed) system is scientifically proven to be more energy efficient than another, SO BE IT! And let it be advertised as such, citing the authoritatively recognized studies which back up the statements.

It’s about putting good information out there and letting the consumer make an educated choice. The same goes for life-cycle cost.

Some will gladly pay more for the superior comfort radiant heat provides, regardless of the cost. Some won’t. Just like we make car buying decisions. Economy? Comfort? Speed?. But claiming and selling energy efficiency as a benefit when it’s not really there is not only unethical, it could hurt the radiant floor business as a whole.

Just the facts will do fine standing on their own. Good job stirring the pot, Frank! Dave, I love watching you stick to your guns, and good job pointing out what may not have been immediately obvious!

Yip YO! Let 'er RIP! Get on the horse and let 'er BUCK!!!

Heatermon

This is the reason

why we never sell radiant as a system that "will cut the fuel bills in half". I totally agree with PAH that it's about comfort. From what I see in this report it's about two system that were thrown out and arbitrarily measured (yes, I know how Habitat works). PAH also points out that it takes a professional to know when, where, how and why we use the different systems. I have ran into too many homes with vaulted cielings, different elevations, large expanses of glass, etc. to know that forced air isn't the BEST. I have also ran into too many staple up systems without plates or insulation, tube spacing of 12" and more, 1/2" tubing runs of 500' and more, to know that hydronic isn't always comfortable, efficient, or affordable. We just have to work as Professionals to recognize the differences and install the BEST system for the situation. With that being said, I would like to see 2 homes, both two story, 4,000 sq. ft., with 20 ft. vaulted cielings in the living room and a wall of glass. In one, Install 1/2" tubing on 6" centers, insulated underneath, 200 foot loop lengths, overpoured with ceramic tiles and wood floors, heated by a fully condensing gas fired boiler, controlled with outdoor reset. In the other, install a "basic" forced air system and see who is more comfortable and saving money on the heating bill. It just goes to prove the point "Figures don't lie, but liars figure".

Looking for a "fair" assesment,

I om the Heatermon

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frank s

alright...maybe not hose

Look fellas I was just stirring the pot, FYI, I would certainly rather live in a house with any other type of heat other than forced air ANY! And Dave.... as far as replacement costs for furnaces, I just replaced the old octopus gravity return hot air system in my brothers house circa 1912, and it was still working, how long will his 90+ last??? I don't know, I'll talk to you in 20 yrs, and you let me know when you replace the 74 yr old clunker you have and let me know how long the new one lasts, unfortunately they don't make things like they used to, When I replace an old steamer that's the size of a railroad car I say "they don't make things like they used to.....thank God!"Have a good day
Frankie

hot_rod

Stiring the pot

is a good thing & I, for one, enjoy the banter.

I was pretty shocked to read the PATH report and find their testing parameters were so flawed. Tain't worth the paper it took to print it out. I'm putting my copy in the bathroom so I can recycle it as is richly deserved(G).

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Mark Hunt

AIR VS. WATER

I have seen alot of poor systems out there on both hydronic and forced air installs. How much ductwork on the forced air residential side, do you ever see sealed with duct mastic? You can bet that if you had as many leaks on a hydronic heating system as those on a "normal" forced air system, you would have quite a unhappy customer on your hands. How many forced air systems out there including those being installed as we speak, are starved terribly for return air. How are the systems sized, for heating or cooling? Where are the registers placed, high or low? Yes, cooling is easier to add but it is always at a compromise of the two. Where in the country do you live? Do heating degree days or cooling degree days rule? I do not buy into the "numbers or percentages" we so often use in this field. Afue's , system efficiencys, combustion efficiency's all are great things, but affected by so many different variables many of which we cannot even measure or duplicate the laboratory conditions that brought about the so called number. That all being said let us ask a few questions. let us make sure that the house is tight with the appropiate building air standard. Which can store and hold more heat energy, the mass of the building structure or the air within it? Which is going to be less expensive, Maintaining structure temp or maintaining air temp? If both installs are done properly with the same features, ie zoning,how far apart is the price going to be? We heard about the cooling feature but what about making hot water with your furnace? The advances in the technology of our field has created some awesome equipment, two stage variable speed furnaces, high efficiency condensing boilers all great stuff. But in the end the comfort level of hydronic heating always wins. It cannot help it because it is the laws of physics.

John Ruhnke1

The study from the NAHB website, Boiler out of tune!!!!!

The problem with the radiant system was that the boiler was under fired. It says so if you read inbetween the lines of the report. Here is the study everyone is talking about. The system was RTI staple up with plates. The boiler was a slant Fin. The problem is AFUE. AFUE is a big joke, it is a huge misconseption. As flue temps go up, fuel bills go dowm. As flue temps go down AFUE goes up. This boiler had an adjustable gas valve on the boiler. They set the gas valve for the lowest setting because the house was rated in btu's at the lowest setting. This underfired the boiler by a huge amount. THe flue temps will be low and the oxygen percent will be high! Underfired boiler! THE UNDERFIREING CAUSED THE FUEL BILLS TO SKYROCKET!! Jim Davis has proved this. I am certified in combustion analysis and if they let me tune the boiler I will guarentee that I will gain back the 22% and then some!!!!
http://www.nahbrc.org/tertiaryR.asp?TrackID=&DocumentID=3489&CategoryID=1505

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hot_rod

dag nab it!

Wish I'd thought to include that in my letter to the editor I sent to JLC earlier today. PATH has some 'splanin to do Lucy.


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