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Staple up radiant

Andruid_2
Andruid_2 Member Posts: 41
Thank you for the valuable posts to the thread by The_Zimmer_House about staple up radiant.



I am currently faced with convincing a friend that his plumber is wrong to bid his project using stapled up tubing.  I will inform him of the decreased efficiency (higher water temps required - not sensible with a mod/con boiler), striping (less comfort and potentially destructive to his hardwood floors), and noise (expanding and contracting pex 'slaps' the floor and squeaks in the staples).



Are there any issues with staple up radiant that I've omitted here?  Why would anyone recommend staple up radiant (besides being the 'cheap method')?  Am I unreasonable to suggest that staple up radiant is nothing more than a hack job (I apologize if I've offended anyone with this remark)?

Comments

  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Staple up radiant "Done Right"....

    is an oxymoron. If the loads were less than 10 btu/sq ft/hour, then this MIGHT be an OK application.



    The reason it is commonly associated with HACK work is due to its simplicity. It's about as simple as it gets. Load the bays up with tubing, throw in an insulation who performance is questionable at best, and is know to degrade over time, hook it to a heat source capable of generating REAL hot water, and by golly, you've got radiant floors, just like on This Old House...



    As long as the end user is TOTALLY aware of all of the issues that you've correctly laid out, and is willing to shoulder those burdens based on cost differential, then so be it. It is really tough for people who have never experienced a herd of crickets running through the floor to understand exactly hour onerous this system and its inherent problems will be...



    The contractor will probably deny that any of these problems really exists.



    You have one chance to do it right. Doing it a second time is going to be MUCH more expensive than doing it right the first time.



    Good luck in your endeavors.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • I disagree

    Striping is associated with plates because most of the heat is conducted through the floor directly over the plates, you get more heat into the room if the floor temperature is more uniform, like with staple up/ suspended tube. I did all different types of radiant and the only noisy bays in my house are the ones with aluminum plates, all my staple up jobs are noiseless, I use plastic staples to support the PEX. I disagree with the output, Radiant Basics tells us that 2 tubes per bay will give us 10 to 20 btu's per sq. ft. while 4 tubes per bay will give us 30 to 40 btu's a sq. ft. so I can assume 6 pipes per bay may give us 50 or more? I run my radiant jobs at low temps, usually about 140 or less, my customers are happy, their bills are low and they have no nails in their radiant to start leaking down the road. I have one job where we had to put quik trac over part of the finished basement and the rest had suspended tube, 4 pipes per bay, residents reported the comfort to be the same in both parts of the house and my lazer thermometer showed almost identical temperature rises when the two were fired up using the same temp water. The most important thing with radiant is to keep nails out of the tubing, this is very hard wth systems other than suspended tube. Nails are what people fear most when they have radiant. Adding more pipes per bay, heating a couple of walls or ceilings, and heating the counters, stairs and tubs will do a far better job than slaping down the sandwich method radiant, and you will be safetly away from nails.



    Thanks, Bob Gagnon
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited June 2011
    Difference in Opinion

    I have never seen a floor stripe using plates. On the other hand seen many with tubing stapled directly to the bottom of the floor. I will say that if your using suspended clips then yes you would not see it either. As for noisy plates that is more of an installation issue vs "plates" in general. Most noisy systems happen when thermostatic mixing valves are used in a set it and forget it application because installers didn't do the heat loss or a proper radiant design. We slam hot water into a ice cold plate. What would you expect to happen?





    To me, any floor that requires more then 120 degree water is not a low temp radiant system. Its a mid to high temp radiant system. Can a mid/high temp radiant system be a low temp? Yes, when outdoor reset is used via injection mixing, modulating mixing valve or a condensing boiler is used as the mix source.



    You still no matter how you install a plateless system give up response time and an even surface temp across the floor.  Do they work. Yes they do and some consumers are happy with this but I've met more that are not.  I've been a part of many jobs where as Mark above pointed out, cost much more to fix then the original install. Most of the time this is due to a contractor not conducting the heat loss or doing a proper radiant design and insulation issues. He uses rule of thumb formulas thinking a system will work.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Bob Gagnon plumbing and heating
    Bob Gagnon plumbing and heating Member Posts: 1,361
    edited June 2011
    Suspended Tube

    Chris, the aluminium plates I use are less than 4" across, that's less than half of the floor surface that is in contact with plates. I notice a large temperature drop between the plates in my house, 5 degrees or so if my memory serves me correctly, that's significantly less heat going into the room than a floor that is uniform in temperature; like my suspended tube jobs using 4 pipes minimum per bay. If the heat from plates is transferred mainly by conduction, that makes sense. I also have a hard time convincing customers to use a manufactured wood flooring, everyone around here wants to nail conventional hardwood down, and good carpenters tell me the nails must pierce the sub floor to have good holding power. Dictating what type of flooring customers should use or dealing with nails and blaming the floor guy is something I want to avoid. Heating multiple surfaces like I mentioned above allow people to use setback and have a reasonable response time. I know many contractors that have installed plates or sandwich method radiant and have had to use supplemental heat, I have never needed supplemental heat on any of my radiant jobs. You can have your cake and eat it too, without worrying about nails in your pipes. The first question people usually ask when considering radiant is "What if the pipes leak between the floors?" With plates and sandwich method radiant, leaks are a lot more likely.



    Thanks, Bob Gagnon
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    edited June 2011
    Bob...

    I hope you know that I was in no way inferring that you or anyone else that chose this method is a hack. I boil it down to the basics.



    I think we can all agree that CONDUCTION is the king of heat transfer, no?



    Your methodology works, obviously, but at what expense? Your systems are going through a lot of gyrations just to deliver comfort, and you are expending a lot of (I hope) expensive labor to achieve the same end, that being good human comfort.



    So, you are a lot further ahead using plastic isolation clips to avoid the cricket issues. Yours is not a true "staple up" system, but instead is a suspended tube system that obviously has to be done from below. How do you insulate in order to guarantee performance? Do YOU actually do the insulation, or are you dependent upon others to guarantee delivery and performance?



    Do you include chiropractic and massage services in your bid/proposal?



    4" OC tubing eh... The tubing manufacturers must LOVE seeing you headed for the warehouse :-)



    I've always known you to be a radiant kind of guy, but didn't realize that you'd actually go to 4" centers to make it work. And putting it into suspension clamps HAS to be more time consuming.



    Most occupants aren't walking around with an IR thermometer. So long as they are comfortable, they aren't paying much attention to the emitting surface temperatures.



    Not all aluminum plates are made equally. There are a lot of knock offs on the market attempting to emulate what Dale Pickard knows how to do, and they fail miserably in their attempts. Hence noisy plates.



    You are obviously good at delivering YOUR comfort to YOUR customers in YOUR way, and I am equally good at delivering MY comfort to MY customers using MY system.



    I've just had a LOT more negative experience with true "staple up" systems, which is what the original poster was addressing. If everyone went to the steps that you go through with your suspended tube system, there wouldn't be nearly as many complaints.



    One only has to look East to Germany and the other European countries, and ask, if tubing from below is such a great idea, why don't they utilize it over there?



    EDIT: As it pertains to "the question", I always counter back that the heating system is only operating at 12 to 15 PSI, and ask them if they lose sleep over the fact that their houses potable water system, which is just as susceptible to nail attack, is running at 70 PSI and can and will do a LOT more damage than the heating system could.



    I always tell the consumer that I will NOT be making a solid connection to their potable water system (I use the PIG) and that NO leak is a good leak in their heating system. That quells any potential nail issues immediately, and puts you into a completely different category than the competition, because you are showing that you have the customers long term best interests in mind and are making an effort to avoid potential issues down the road.



    As for flooring nails being stronger due to their actually penetrating through the sub floor, that is an old wives fable. There is NO advantage to nails penetrating the sub floor. It's just that the nailers have one size fits all nails in their nailers, and as far as they are concerned, the excess nails are what they are. It's like their use of rosin paper. Some will tell you it "stops squeeks". The ONLY reason they use rosin paper is because it makes the wood slide across the floor during installation easier. Period.





    Peace my friend.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    bob

    where are you getting your output information from? for years Uponor has sworn that going tighter than 8" o.c. in a suspended tube didn't provide any worthwhile benefit.



    140 in a typical suspended tube is about 15 BTUs/sq ft. that would satisfy many heat loads without supplemental, but you better be doing load calcs if you're going to run that kind of a limitation.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    Leaks

    Mark, Rob have you ever come across a system that the tubing actually leaked? The thought process of thinking that the tubing will burst and leak is just wrong. I personally in 20 yrs have never seen a PEX radiant system develope a leak in the tubing itself.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Andruid_2
    Andruid_2 Member Posts: 41
    edited June 2011
    Tubing leaks long after install

    Chris



    I have come back to repair a hole in the tube that developed after a year or so.  Granted, it was no fault of the tubing.  A pair of distribution lines had been run up the stud, and a sheetrock nail had somewhat missed the stud and found the tubing instead.  The nail sealed the hole and the system ran leak-free for a long time.  Then the nail rusted out and sprang a leak.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Inadvertent leaks...

    Chris, other than a 10 year old snowmelt system with a 1" piece of exposed PEX, I too have never seen a random leak in PEX tubing. There is usually someone with a tool of some sort responsible for the leak.



    I once worked for a guy that wen we were doing sleepers for hardwood, would "violate" some of the sleepers to get into and out of the grids. We warned the hardwood flooring guys NOT to use rosin paper, and they did any way. They snapped chalk lines showing the centers of the sleepers and hammered away.



    One year later, we got a call from teh HO that the floor was warping, showed up and found that a staple had rusted out that was embedded in the tube. We fixed it. ABout 6 months later, another leak showed up in a different spot. Seems the hardwood flooring guys had hit our tube all over the place wherever we went through the sleepers.



    Unfortunately, the HO was a lawyer, and needless to say he was NOT a happy camper. He finally brought in an arbitrator who decided that the GC and the HW floor sub had to post a cash surety bond equal to the total floor replacement costs, and if one more leak popped up, the HO had the option of ripping it out and replacing the complete in floor part of the system. If at the end of 20 years, the tubing had sprung any additional leaks, then the GC was allowed to cash out the surety bond with interest.



    I left that company, so I don't know if the HO cashed the bond or not.



    I'd also seen a job where the finish carpenters nailed a 3/4" PEX line in a wall with a finish nail, and it self healed and held for 10 years before the nail rusted out and it started leaking. It was an occasional vacation home, so it did a LOT of water damage.



    Live and learn.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    hits are not that uncommon

    in overfloor methods. Bob is right that the joists are safer. I have seen nails seal their own holes and rust out years later on a few occasions. it's not common, but it can happen for sure. good luck going back to a finish floor installer 3 years after installation with a warranty claim....
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Mpj
    Mpj Member Posts: 109
    Staple Up

    Mark,

    What is wrong with using red rosin paper for radiant installations? I heard not to use tar paper because of possible smell but never red rosin paper.

    MPJ
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    Rosin paper makes it hard to see the

    marks that indicate where the pipes are. Like throwing knives with a blindfold on. Most of us would not do that. As for leaks after the fact. I got a call for a leak in an apartment building built in the late 1970's or early 1980's. One of the first screw jobs for hanging sheet rock in the area. Well they got the main sewer stack with one screw. By the year 2000 it had rusted out enough to leak. It was a 3" copper stack.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    What Charlie said...

    One can not see where the sleepers have been violated with tubing crossing through them, and they take hits.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Staple Up/ Suspended Tube Output

    Rob, I get my information on the btu output of closer tube spacing from Radiant Basics, the design section, page 172 figure 8-6. Wouldn't it make sense that more pipes per bay would deliver more heat? Where did you get the information from Uponor swearing that heat output would be limited to 15 btu's a sq ft.? Think about the infrared pictures that are out there dissing suspended tube; showing 2 lonely pipes per bay, with small orbs of heat emanating from the pex. If there were 4 or 6 pipes per bay, the orbs of heat overlap and create a uniform heating surface across the surface of the floor, better  than with plates. This whole industry seems hellbent on 2 pipes per bay and I don't know why. I asked John Barba in Wirsbo boot camp in Minnesota if more pipes per bay should give you more heat output and he said it would, but he said you can't bend the pipes into a tight enough radius to get more pipes into the bay. I asked Siggy at a radiant class in New York the same thing and he agreed the more pipes will give more heat but it cost more to buy more pipe. I have no problem buying a few more rolls of pex to increase the system's efficiency by lowering water temperatures, and to quicken response time and to eliminate the need for a supplemental heating system. But remember the floor is only part of the system. I heat a building using the "Whole Building Approach" like the LEED standards. With suspended tube you have a lot of home runs and I use those in strategic places in the walls with aluminum plates, this along with heated kitchen counters, stairs, ceilings and tubs, contribute to the heat load within the heating envelope, with a more average temperature throughout the home, and at the same time keeping the floor system away from nails, giving my customers the best system to avoid nails and problems in the future. 



    Thanks, Bob Gagnon
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    the uponor info

    was at wirsbo training years ago (also John Barba). the quote was something like "While we would LOVE to be able to tell you that more pipe helps, it doesn't". I assumed that there is a diminishing return as once the mass is heated up, transfer slows down appreciably, and even adding more capacity wouldn't raise the output by that much. for instance if two pipes can get you withing (made up number alert!) within ten degrees of your water temp in the joists... then adding two more might get you more output, but every degree you raise it kills 10% of your transfer. there is definitely a diminishing return which you can see with any MFG's output charts for concrete... the jump in output from 12" to 9" is much larger than the jump from 9" to 6", for similar reasons.



    so while you will technically get more output, I don't think it's necessarily all that much, which I think is implied in your responses from John and John... technically yes, but not enough to be worth it.



    Also, that radiant basics info is pretty limited stuff. It doesn't even differentiate between plateless and plated joist applications even though they obviously have VERY different water temp requirements. I wouldn't use it as a basis for design, personally.



    Uponor has published output charts for 8" o.c. joist heating which shows 15 BTUs/sq ft under R1 finish floor (wood) requiring about 140 degree water temps. I've never seen anything that would contradict this in the real world. I don't normally design hotter than that, so I consider that a max value for "primarily low temp" operation. it's arbitrary though.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • I Disagree With Your Assumptions

    Rob, the chart in radiant basics backs up your info on pipe spacing with two pipes per bay as being about 15 BTU's a sq ft. yet you disagree with the same chart that says you get 30 to 40 BTU'S a sq ft with double the piping in that bay. I don't get it. I don't always trust charts but my real like experience has backed up the figures in this chart. I have done suspended tube jobs with 2 pipes per bay and other jobs with 4 and 6 pipes per bay and I can tell you without a doubt the output is much greater. I don't agree with your assertion that John Barba, and Siggy's comments to me implied anything other than what they said. John said you would get more heat output, but can't bend the pipe that tight, this was an easily solved piping problem and Siggy said you would get more output, but that buying more pipe cost more money, I have no problem spending more money to get a better job. You did notice that John Siegenthaler's name is listed on the cover of Radiant Basics as it's Author, the same book that contains the chart we have been talking about. When you tell people that staple up doesn't work, (when you are talking about 2 pipes per bay) that would be like me telling people that plates don't work (because the installer left out half the aluminum plates), or like saying baseboard heating doesn't work, (because I have seen many jobs with not enough baseboard to meet the heat load), like with any job it has to be done correctly to work.



    Thanks, Bob Gagnon
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • NRT_Rob
    NRT_Rob Member Posts: 1,013
    I am not sure what you are looking at

    but the radiant basics I am looking at says tube below subfloor is only 15BTUs/sq ft under carpet and pad at 140 deg F. that's a plated application, not a plateless application, judging by the water temps. I was talking about under wood, which radiant basics would say is 110 deg F... definitely not plateless.



    Siggy advocates for plates pretty strongly at almost every turn. So while pipe would cost more, he usually advocates for a solution that would cost EVEN MORE than the pipe. He's not one to cheap out of a good solution to drop water temperatures. He's not ruling out a great way to drop water temperatures because of some additional pipe. At least... I really, really doubt he is. I think it's much more likely that the effect is there, and he speaks precisely, but it's small and not worth the extra expense. Much like doing 2" on center pipe isn't helpful compared to 4" or 6".



    I have lots of respect for siggy, but honestly I don't find radiant BASICS to be very good basis for full design. I think he'd be quick to acknowledge the limitations there too... though why he isn't differentiating between plates and plateless apps there, I can't say as that seems to be a pretty major oversight and very confusing to new designers.



    I've never said staple up doesn't work. I said it works in low load situations, or with high temperatures. and all the information I have says more pipe doesn't help enough to change that point of view.



    We have disagreed on this one for a long time, and we will continue to do so it seems. fine by me and best wishes to you, I just wanted to see if you had info that was compelling on this. I wouldn't say you were unreasonable. Just that we disagree, based on the info presented.



    Next time you talk to siggy, ask him HOW MUCH more output you should expect in this situation. I bet you'll find the answer dissapointing. though you would definitely get faster response times out of dense pipe, I don't think steady state performance is that much better.
    Rob Brown
    Designer for Rockport Mechanical
    in beautiful Rockport Maine.
  • Interceptor
    Interceptor Member Posts: 46
    broken staples!

    I just finished tearing out a 10 year old staple up system. About 10% of the staples were broken and several others had completely fallen out. This left the tubing hanging and rubbing on whatever was in the way (nails, plumbing, wiring, etc.). I don't know for sure what brand the staples were, but the tubing was Rehau Raupex. The system was extremely noisy and required 170 degree water. I can assure you that it's no fun to fix a botched radiant system and it's cheaper to do it right the first time.



    I never felt any striping nor could I measure any with an IR thermometer.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Stress....

    I don't think there IS a staple on the market that could withstand the continuous expansion/contraction associated with the cycling of the heating system.



    This methodology has never had a high rating in my book. Too many problematic systems out there to my liking, inexpensive or not.



    As a matter of fact, I DID have this system in my own home, and was not impressed. I was running it through my 40 gallon water heater, turned to max temp setting, and it barely knocked the chill off the floor. When I took it down, there was a bluish green slime growing inside the pipe, and I decided that I would NEVER expose my customers to that potential. I replaced it with a closed loop system with extruded aluminum plates, and it works fantastic.



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Michael_6
    Michael_6 Member Posts: 50
    underneath is for retrofit only

    New construction should always be done on top of the subfloor CONDUCTION IS KING. IF you have to go under (retrofit) always use heavy gauge extruded plates and foam below. People make the mistake that pex tubing is radiant heat. Pex tubing is just an excellent conduit for delivering heat to emitters while keeping the heat in. You need a radiator to extract the heat or embed it in concrete or create a fake thermal mass heavy gauge aluminum. Nothing beats being in contact with the finish floor, nothing.
  • What Beats Radiant in Contact With The Subfloor

    Nails, That's what will beat a radiant system in contact with the sub floor. Conduction is fine, but an 83 degree floor is an 83 degree floor whether you heat it with plates, sandwich method or suspended. I'm not a big fan of suspended tube when you only run two pipes per bay either, has anyone here, that is knocking staple up, ever run more than two pipes per bay? We have outside temperatures near 15 below here, and I never use supplemental heat, how many of you can say the same thing when using plates and the sandwich method?



    Thanks, Bob Gagnon LEED AP
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • Greg Maxwell
    Greg Maxwell Member Posts: 212
    Staple up

    We have been designing radiant jobs since I've been with our company, and that goes back to 1984. Is it the most preferred method I'd use? No. But, until money is no object, staple up will continue to be a widely accepted method. If done correctly, it is very comfortable, very efficient, and problem free. First, have a competent company design the job for you. The #1 problem I see, is that people do not do the proper heat loss/layout they should. If your room needs 35 btu per sq ft, and you can only deliver 15, you have problems. Radiant loves square footage. The more, the merrier. If yours is limited, you may have to resign yourself to the fact that you will need supplemental heat. Once you have a proper layout, use transmission plates. With plates, you should only need water temps of 140 or less. Probably less, but every job is different. I have heard stories of striping, but for the most part, striping is caused by an error on water temp. its more likely that you will have noticeable variations in floor temp, but again, not if designed properly. Rehau's new transmission plate is awesome, only 1 plate for the bay, instead of two. Also, floor covering is very important. I cant tell you how many jobs I've been involved in where the plan was for hardwood, so the water temps were again, 140 or less, then the homeowner added carpet. That completely negated the heat transfer, and resulted in an under heated room. Not the fault of the radiant. You will not ruin hardwood floors with radiant, unless its done wrong. Hardwood is not as great a conductor as tile, but is way better than carpet, and by far is the largest used floor covering I see. Get a competent flooring company to lay the floor, and tell them ahead that its going to be over radiant. there's nothing worse than all those nails having to be cut in order to install the tubing. The tubing may squeak, if the water temps are too high, or the tube is not installed properly, and now Rehau has a new tubing with a different coating on it, so it will not make the noise of the old tubing. If staple up is designed and installed properly, the homeowner will have nothing but high marks for the installing company.
  • Hutch7
    Hutch7 Member Posts: 2
    Engineer

    I've not visited any of the radiant heating forums in several years; however, I remember Mark and Bob from years back.  Both of you have a lot of practical experience.  My experience using radiant floor heating is only in a few super insulated houses (SIP houses).  These houses do not need much heat.  One house uses 125 degrees F supply water temperature and has staple-up AND expensive Thermo-Fin heat transfer plates.  Used the heat transfer plates in front of large windows and the bathrooms.  The heat transfer plates were installed exactly as owner of Radiant Engineering instructed.  They do make a little noise when the house has been warmed by the sun during a cold day (solar heat gain) and then the hot water heat comes on as the sun is setting.  The staple-up never makes a sound even listening from the crawlspace or unfinished basement.  There is noticeable striping with the Thermo-Fins because the gaps between the hardwood flooring boards is wider right above the heat transfer plates.  In between the plates, the gaps are small.  Flooring above the staple-up had evenly spaced gaps between the planks.  Also, with bare feet, you can feel warm flooring right above the heat transfer plates and not any where else.  This house is easy to heat during the coldest weather in Montana.  I know the heat output is not much from 125 degree F supply water, but the house is so well insulated it needs little heat.  Another house in Bondurant, Wyoming (-50 degrees F) most winter nights, also built with SIPs has suspended tubing and the water temperature is closer to 140 degrees F and the radiant floor heat does the job on the coldest periods of Winter.  Of course, this is not a low temperature heating system.  This system was installed about 20 years ago before low temperature heating system became so popular.  Being afraid of nails, I prefer suspended tubing with good insulation below.  If the house is not insulated well, then I would stay away from  nailed down hardwood floors.
  • Hutch7
    Hutch7 Member Posts: 2
    edited August 2012
    Well Insulated House - Staple-up or Suspended OK.

    I agree.  Done correctly in a well insulated house Staple-up or Suspended works well.  Comparing heat loss number to the heat output of the under floor tubing 8" o.c. the heat output per square foot had to be over 10 BTUs/SF with the boiler supply temperature set for 125 degrees F.  Also, the 125 degrees F supply temperature is correct.  Heating nice hardwood floors excessively reduces moisture content causing shrinkage and noticeable separation gap with wider boards.  I don't see much difference in board shrinkage if the BTUs/SF is the same, whether using suspended or heavy heat transfer plates.  Except with heat transfer plates the wood will shrink more where the aluminum is directly below and in direct contact.  This is not much of an issue with 3 inch wide flooring, but becomes more noticeable with 5 inch and larger widths.  Thermo-Fins were expensive in 1998 and I suspect they cost even more now.  Super insulating a house is also expensive, but it is money in the bank over the long term.  With utility costs rising and predicted to increase 10X over the next few years, better to use more insulation in new construction.  For example, a 2,000 SF SIP house (8" walls and 12" ceilings) with a moderate amount of high quality windows, located in central USA should not have more than 10,000 BTU/HR heat loss during mid-winter.



    Of course, no one uses obsolete fiberglass insulation any more.  That stuff allows heat convection since air can circulate in the walls when it is used, whereas closed cell insulation short circuits heat convection.



    In response to an earlier post, I agree that adding more tubing would seem to be a  diminishing return at some point.  Probably non-linear, such as double the number of tubes in a bay would not double the heat output as the number of tubes increased beyond 2 per 16 inch bay.
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