Does anyone have experience with a radiant system by Warmboard? We are relocating to northern Minnesota and will be building a home. We are considering a log cabin and trying to figure out what heating system would be best. I am concerned about the longevity of a infloor system.
Any advice about forced air vs. radiant would be great too.
Replies
Here's my preference:
1) Heat tubes in a concrete slab
2) Heat tubes in lightweight concrete
3) Heat tubes in Warmboard
I wouldn't install forced air heat in anything I build.
You may need all that ductwork for an air conditioning system tho...
Build on the shore of Lake Superior, and that will eliminate the A/C!
Just wondering why you wouldn't install forced air heating in anything you build - does that include heat pumps? (BTW, I dislike forced air heating intensely and would live in a cold house rather than use it, but I really can't give you a good rationale so I'm hoping you have one that I can use).
We don't use heat pumps at all in our area.
After you live in a home with radiant heat in the floors and experience the comfort level, you will never have a forced air heating system again!! EVER!!!
I don't like the problems with routing ductwork, the noise, the drafts, the variances in comfort levels, the dust problems, the registers on the wall and floor, the chance for contaminates to build up in the ductwork, etc. etc.
I worked for a warmboard distributor and have installed warmboard. I like the product, but it's overpriced.
Insulation will solve many problems with cathedral ceilings in cold climates. Insulate, insulate insulate. The more insulation, the less is required of a heating system, the more comfortable the room is, and the more money you'll save over the life of the house. Insulation is the only major item in construction that will actually pay for itself over time.
If I only leave one thing that you remember, it's to order the warmboard installation manual if you go this route. Additional blocking is required on each sheet under the weaker areas where tube groves come together. It's explained more, as are ways to deal with various problems. Oh yeah, and insulate!
Beer was created so carpenters wouldn't rule the world.
Don, this is a log home. Insulating is a bit limited. You're absolutely correct, but this is one of several reasons log homes are tricky for HVAC design. Log Cathedral Great Rooms are, from a heating design standpoint, a great big red flag.to previous poster, quik trak is not even in Warmboard's league. If Warmboard is overpriced, Quik trak is the biggest rip off ever in radiant, if you judge on a price for performance ratio. I'd rather see someone use extruded plates in the joists than quik trak any day of the week. Warmboard is about 20% more money after you deduct the 3/4" subfloor, probably about half the labor figuring the whole project in, and an order of magnitude more powerful at heat transfer. A project needing 130 degree water in quik trak needs only about 90 degree water in Warmboard and 120 in extruded joist plates (and the joist plates will be cheaper).If you're going to go prefab-panel, Warmboard is really about the only game in town worth playing if it's early enough in the construction process to use it. Otherwise, there are plenty of options, but all of them increase labor to save material costs, so if you're paying for labor they may or may not make sense for a particular application.Of course, installers don't get a markup on Warmboard, so I'm not surprised there is so much resistance to its use. That's a problem the boys at WB are going to have to address at some point.-------------------------------------
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"Warmboard is about 20% more money after you deduct the 3/4" subfloor"
You must be including labor and other costs in this? I got a quote from the NW dist. and he quoted $180 a $heet ,3/4" sub floor is less than $40. It is a great product but way too pricy.
I'm comparing material cost only. Once you correct for the difference in pipe, manifolds, and subfloor. Quik trak is ROUGHLY a bit short of $5/sq foot in materials, and Warmboard, subfloor corrected for .87/sq ft for 3/4" plywood (less than you're paying, apparently? I ran the numbers last summer so maybe the price increased), is between $5.40 and $6.00/sq ft. The tubing and manifolds do make a difference between these two installs; quik trak is 7" o.c. max (roughly) 225 ft loops, and Warmboard 12" o.c. max (roughly) 300 foot loops.That's distribution cost only.. no mechanical room components. But it is apples to apples. And the warmboard, even with custom routing, should install quicker. and perform RIDICULOUSLY better.If it's too late for Warmboard, then Raupanel's performance is excellent, but all the other prefabs will have similar labor costs and material costs will vary widely with desired performance.JMHO, of course :D but that's how it comes out when I ran the numbers.I should qualify my statements... not every project needs warmboard or Raupanel's output. If it's a very well insulation home with low loads and appropriate floor coverings, you can get nice low temps out of quik trak or the other second-tier prefabs out there. But the higher the loads, the thicker the floor coverings, or the lower the desired water temperature... and I hope that temp is desired to be low these days... the more it makes sense to use a better method.-------------------------------------
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Since we're making comparisons...just for fun:
For the die-hard DIYrs out there with good knees, good tools, and some smarts about how to rip and move sheet goods around, and given a light to moderate heat loss of, say, 15 BTU/sqft/hr, I wonder how the material costs for a DIY plated sandwich would compare with Warmboard?
Sq ft cost of thin plates/extruded plates = ?
3/4" CDX = .80/sqft (or plug your numbers in)
The labor is hard to figure....what would you figure man hours per sq ft, assuming the plywood is delivered, to rip 4X8 sheets into 12" strips, cut the end grooves, and get it all screwed down with plates in the grooves? Maybe a tradesman will pony up with some numbers here. On my project, I didn't keep track of the DIY hours.
Then I suppose for apples to apples against WarmBoard, you'd have to factor in the installed cost of the original 3/4" subfloor. Since mine was put in by my framing sub, I don't have a break out for it. Any rough numbers out there, gents?
I know you wouldn't have the continuous aluminum that WarmBoard has, but then you wouldn't really need it with only 15 BTU/hr would you?
You know I'm a big proponent of DIY sandwiches, johnny.If you take labor costs out of the picture completely, then Warmboard doesn't make sense unless you really need top performance for some reason... say, you want to power the whole system with solar hot water so you need the lowest water temps you can get. This is the way for many who wish to go entirely sweat equity because they are cash poor. Of course there are a lot of middlers too, who want to put in sweat equity but also want to save time, so the balance varies project to project.But.. again material only.. Light sandwiches run roughly $2.50/sq ft and heavy Thermofin U sandwiches about $3.50/sq ft. Radiant ceiling, about $1.30 :Dvery rough, but apples to apples to my previous ballparks.-------------------------------------
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Edited 2/14/2006 4:16 pm ET by NRTRob
I did mine for more like $1.25 in materials....$1 each for 6" X 16" thin plates, 600 spread out over 1600 sq ft. 50 sheets of ply @ $25.
What I'm really looking for is some rough estimate on the labor to rip, locate, and screw down the sleepers.
So you pro framers and carpenters out there, how many man hours to rip a 4X8 sheet of 3/4" CDX (or OSB) into 12" X 8' strips, then locate them with 3/4" spaces between them and put 180° turns at the end grooves (some route the end grooves, some just pattern cut them with a jigsaw...your choice) and then screw them down.
Then locate and staple or nail down aluminum plates....this last step is really quick, say 1 hour per 200 sq ft.
Edited 2/15/2006 8:52 am ET by johnnyd
that's a good ply price, but it doesn't look like you included any other components in your number? the numbers I gave include everything through pipe, manifold and fittings. Of course Your Milage May Vary based on brands and pricing etc.-------------------------------------
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Oh I misunderstood:
"I'm comparing material cost only. Once you correct for the difference in pipe, manifolds, and subfloor. Quik trak is ROUGHLY a bit short of $5/sq foot in materials, and Warmboard, subfloor corrected for .87/sq ft for 3/4" plywood (less than you're paying, apparently? I ran the numbers last summer so maybe the price increased), is between $5.40 and $6.00/sq ft. The tubing and manifolds do make a difference between these two installs; quik trak is 7" o.c. max (roughly) 225 ft loops, and Warmboard 12" o.c. max (roughly) 300 foot loops."
OK, so including Mr PEX barrier, Safeway - 8 port manifolds including zone valve actuators bumps the sq ft cost to $1.95...call it $2.00. We're getting close.
Sorry, my bad. Now after reading it again I see you were comparing WB to Quik trak.
Jeremy
Since it is a log structure, with essentially a fixed R value for the walls, it's even more important that all the insulation possible is placed in the ceiling, floors, and any interior walls that would help, such as insulating the walls around a utility room bordering an exterior wall, or garage (if those are stick framed). Too often roofs are framed with too little space for a decent amount of fiberglass and the owners are building too cheap for spray in foam.
As log structures typically do terribly on blower door tests, it's even more important to seal and insulate.
For those builders who specialize in log structures they often are selling and competing on price and the asthetics, with little thought to energy efficency.
One of the 4,000 sqft mountain homes in the ridge top development we were building in used over 600 gal. of propane a month during cold snaps. Just looking at the roof construction it was easy to see why--no air barrier combined with t&g on the ceiling and very little fiberglass insulation in a 9-1/2" deep roof cavity.
Beer was created so carpenters wouldn't rule the world.
After you live in a home with radiant heat in the floors and experience the comfort level, you will never have a forced air heating system again!!
Amen.
Beer was created so carpenters wouldn't rule the world.
I agree with Mr. Bo Jangles on all fronts but will point out one main difference of using Warmboard compared to a pour: The Warmboard heats up the room much quicker, which makes sense in a vacation home but not a full time residence. The water temp is different for Warmboard compared to inside a pour (a little cooler in the Warmboard because it's closer to the finished surface and is not heating up much mass), so to avoid two mixer setups stick to one installation method. What kind of finish floor material do you want to use?
Forced air is so inferior to in-floor radiant I wouldn't normally speak of them in the same breath. Radiant is silent, luxurious as it is warm on the feet, perfect temp at heart and head level and cooler above head level, very even heat distribution throughout the house, it is also invisible and you can install baseboard all the way around and push furniture right up to the wall. Forced air is noisy, moves dust all over the house, produces very inconsistent temps and the peak of your ceiling will be the warmest part of your house. Once you live with a radiant in-floor system you can never go back. It is definitely worth the added expense compared to forced air.
I'm considering Warmboard in a retrofit application on one of two 400 sq ft floors. For the other floor the radiant tube would be stapled up under the existing floor (t&g sub-floor + t&g floor, both pine). This discussion makes me wonder whether the Warmboard will be so much better than the staple up that I'll end up needing different water temps on each floor. Would I be better of with a less efficient system on the first floor to match that of the second (Warmboard on the second floor is not an option.)This is a small space and will have spray foam insulation all around, so I expect it to be pretty tight.
Would I be better of with a less efficient system on the first floor to match that of the second
Here's a little food for thought. A certain amount of heat is going into, and being drawn out of, the pex loops. Warmboard helps to focus that heat in one direction, thus cutting down response time to heat that area. If your crawlspace is unheated this makes sense, but for many areas of a home directing heat directly up doesn't make a difference in the amount of heat required overall.
well, it also dramatically lowers your water temps required to achieve the necessary rate of heat transfer, beyond the response time issue. Not saying it's necessary to do that here, just pointing out it does more than speed response time for the sake of completeness.-------------------------------------
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well, it also dramatically lowers your water temps required to achieve the necessary rate of heat transfer, beyond the response time issue.
Correct me if I'm wrong, but aren't you reffering to the rate of heat transfer to the target room, while the total rate of heat transfer is unchanged if a heat reflector is used or not. The reflector isn't creating more heat, it's simply directing it.
It is true that there has to be enough heat transfer to the target room, but if that minimum rate can be reached without heat reflectors, and the area below the target room is also heated, that overall nothing is lost.
If they were reflectors, you'd be correct, however that is not the function of the aluminum in Warmboard or plate systems. They are conductors, not reflectors, allowing the tubing to have much greater conductive heat transfer directly to the bottom of the floor or subfloor. This means in two side by side applications, one with conductive aluminum and good pipe contact to the aluminum, and one without, the one with will actually transfer a LOT more heat at an equal water temperature. A reflector would only be able to refocus heat already radiated from the pipe. conductors actually allow heat to be transmitted faster from the pipe. conduction is king of heat transfer!-------------------------------------
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How do you suggest maximizing the contact? In the recent RFH article in FHB by Rick Arnold he was squirting silicone into the quik-trak with the tube. Is silicone a good heat conductor? I wouldn't think it would be, but couldn't explain why if you pressed me on it. Are there other ways to maximize the heat transfer to the plates?In the case of staple up, I see people stapling those plates pretty tight on the tubes. I would think that would give good contact, but might make noises as things warm-up and cool-down, not to mention long term wear on the tubes. What do you recommend?My house has some sections that will be staple up, and others that will be laid on top of the subfloor, so I'm curious about both. Before anyone suggests it, gypcrete is out. Old floor, not engineered for it.-Rich
If you are using regular Pex in a system such as Warmboard, they recommend a bead of silicone along the bottom of the entire run.
If you are using pex-al-pex tubing, you do not have to use the silicone.
Part of the reason for the silicone is heat transfer and part of it is to prevent noise when the tubing expands.
Pex-alum-pex has a rate of linear expansion that is about 1/10 that of regular Pex, so that is a big factor in keeping the noise down.
The more rigid pex-al-pex is well suited for systems where the tubing is above the floor and easy to bend.
silicon is a band-aid for a poor fit. in quik trak, it's used because otherwise you have next to no contact between the pipe and the aluminum. It does conduct but not as good as aluminum does.You get maximum contact by using good plates/products that are manufactured properly.We recommend, in underfits, stapling the heck out of the plates if they are lightweights. You address expansion other ways, such as by using dynamic mixing like variable speed injection or a motorized mixing valve. Or, by using PEX-AL-PEX, though that's harder to work with in joists. Or, use heavy extruded plates.Or, let there be noise ;)-------------------------------------
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One thing I would say is with a Log cabin in northern minnesota, with your inevitable cathedral great room you will, in all liklihood, need more than just radiant floor in at least a portion of the home.
Warmboard does outperform lightweight concrete or gypcrete.
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<Warmboard does outperform lightweight concrete or gypcrete.>
I'm not sure I would agree with that. If I were concerned about radiant floor heating supplying enough heat for a large home with cathedral ceilings, Warmboard would not be my first choice. Gypcrete would be my last!
We live and build in the frozen North, and we build large homes with many lofts and high ceilings using only radiant heat in the floor and use all of these methods.
I consider the concrete slab and lightweight concrete to be much more comfortable systems. The Warmboard is limited by its 12" tubing spacing so the only variable is the water temperature. This can become a real problem if you have hardwood floors and can't bring the water temperature up to where it will supply enough heat for the space.
I don't think there is anything as comfortable as a nice warm concrete floor. It's like having a multi-ton radiator. Warmboard has no mass to speak of.
One of the advantages of Warmboard is its ability to generate heat in a hurry as the previous poster pointed out. It also cools off quickly, so it requires a constant source of heat to keep it at the right temperature.
If I could post a picture with this **^##** computer, I would show you many examples of very large homes we built that are heated only with in- floor heat.
We are meticulous on our detailing for air sealing and insulating, so that does make a big difference.
Are you saying that you often have trouble heating a big home with only the Warmboard? This interests me because I have never built an entire new home using it. I have found it to be "on the edge" in terms of being able to keep up with the demands we usually have for heating in the additions where we've used it.
Edited 2/13/2006 5:01 pm ET by BoJangles
Once again I completely agree, and would add that I think radiant in-floor heat is the perfect choice for a great room or a room with cathedral ceilings. In-floor heat puts the heat just where you want it, within six feet of the floor, higher up the heat dissipates (or radiates, or something happens to it) and temps get cooler. Second floor loft spaces do need their own heat source because of this. Maybe if you had forced hot air a loft wouldn't need it's own delivery system, but that's a small matter. Another important factor with in-floor heat is the cat absolutely loves it. Maybe I disagree about gypcrete, I've poured it a few times and have always been satified with the results. Mr. Bo, what is your complaint about gypcrete, isn't it just like light weight concrete with gypsum instead of pumice or some other lightweight mineral.
Rickie, I shouldn't have been so blunt about the Gypcrete. It's just that I find the lightweight concrete to be much better suited to our needs. It seems to react much better to the heat tubes and is cheaper and much less susceptable to damage during the construction process.
Since you are basically taking up the same space with either the lightweight concrete or the Gypcrete, I prefer the concrete.
Others may prefer Gypcrete for their own reasons tho....
I am saying that the loads in cathedral spaces, especially in log homes with lots of glass, can often be too high for *any* radiant floor to do alone comfortably. Radiant has limits. You can only get the floor so warm before you start blowing your wood floor warranties, or make it so hot it's uncomfortable to stand on. Warmboard can get you to maximum outputs at a lower water temperature than any other in floor method, however, and that includes slabs.Mass has nothing to do with why radiant is comfortable. Warmboard achieves the same output as slabs with a lower water temperature; that is the basis of my statement that it outperforms. Also you eliminate the thermal flywheel you have to deal with in higher mass systems.Mass is a *storage* mechanism. Not a transfer mechanism. If you are designing to store passive solar gain, then mass is what you want. If concrete is going down anyway (like a slab on grade house or a basement), then use it, it works fine. But mass is not what makes a radiant system work well. Thinslabs can work fine as well, but they do not perform *as well* as Warmboard does, even with its 12" o.c. spacing. The reason is, aluminum conducts far better than concrete.You make a good point about the cool down speed though, and that's why a PWM thermostat should be used. Makes the heat very consistent.I'm not trying to slam slabs; they can be quite effective and we use them all the time. But warmboard *is* superior from a performance standpoint. Edit: also, I should qualify the cathedral space comment. radiant is best in cathedral spaces due to reduced stratification. But the volume of the heat load in such spaces is also often quite fearsome and often does require supplemental heat.
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Edited 2/14/2006 11:14 am ET by NRTRob
<Mass has nothing to do with why radiant is comfortable>
I totally disagree. You can achieve almost exactly the same heat output per square foot by using concrete with a closer tube spacing. Therefore, when the two systems are operating they "feel" the same to the person in the room.
It's when they shut down that you notice a big difference. Warmboards lack of mass allows it virtually no capacity to store heat. You can sit on a Warmboard floor and feel almost immediately when it shuts down. This characteristic makes it not nearly as comfortable to the occupant as a concrete floor radiant system which continues to give off heat long after the water flow stops.
It is the ability of concrete to maintain this constant flow of heat that sets it apart from any of the other products.
If you have two systems (Warmboard & concrete) that are capable of the same heat output per sq. ft./h , they will perform the same when they are operating. The heat loss in the home is basically constant, so it stands to reason that you are going to have more peaks and valleys in temperatures and less actual BTU's supplied in an hour by a system like Warmboard that doesn't provide any heat at all during the off cycles.
The only way you can match the comfort of a concrete system is when the Warmboard is operating continuously.
I think Warmboard has its place, but for the utmost in comfort, nothing beats concrete.
You've got a decent point with the peaks and valleys, but any good radiant system is using at least PWM thermostats and outdoor reset temperature control. Concrete or any other radiant system benefit greatly from this.. and many concrete jobs require more (slab sensing, indoor feedback) to deal with the flywheel. If you just set a warmboard system to 110 and hook it up to a bang-bang thermostat, then yeah, it's not going to be great for a large portion of the year... just like *no* radiant system will likely be great with that kind of control, except perhaps a basement slab with little to no load variance.If you use PWM w/outdoor reset... a very small expenditure compared to the distribution system... then your heat will be extremely even in either case. Mass compensates for more lackadasical control, in that respect... or it can bite you in some homes with wide temperature swings. also, you cannot achieve the same output with concrete at a tighter spacing. For a "typical" 20 BTUs/sq ft, wood floor, 70 deg room temp 6" o.c. slab weighs in at 105 degree SWT, and you can drop that another 15 degrees with Warmboard. That's a full sized slab, btw. Thinslabs are higher. That's an esoteric difference in some systems, admittedly. But it is a performance increase. With thinslabs, I've seen several in which Warmboard allowed for the elimination of supplemental heat in higher load, carpeted rooms.So... I agree and disagree ;) All radiant systems can be controlled properly to provide excellent comfort. This in some cases may be easier in mass and in some cases is much harder in mass. But the mass itself is not what determines the comfort or effectiveness of the radiant... it's the control, matched to the distribution system it is controlling.-------------------------------------
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This is a fascinating discussion to a newcomer, who is currently sketching out my custom retirement house (before handing over the sketches to a pro.) I'd really like to use radiant floor heating, perhaps fed from a ground-source heat pump. Along with spray foam insulation. (More $ up front, but better insurance against future shocks during my fixed-income years).
But I will also need some AC in the summer, in these NC mountains---about a third of the degree-days are over 65. So it seems that I may need air ducts, air-heat exhanger, etc. in addition! I'm willing to spend a little more up front, but this is getting ridiculous... is there some better way to combine these technologies? Thanks.
Combine radiant heat and A/C? Nope.
You can have both, of course, but your cool air will have to be ducted.
But I will also need some AC in the summer, in these NC mountains---about a third of the degree-days are over 65. So it seems that I may need air ducts, air-heat exhanger, etc. in addition! I'm willing to spend a little more up front, but this is getting ridiculous... is there some better way to combine these technologies?
A high performance shell will both pay for itself over time and greatly reduce the need for ac, perhaps eliminating it in your case. Something approaching R30 in the walls and R60 in the lid, combined with soffit overhangs to cut down on summer heat reaching the windows.
As the heating/ac requirements go down, so does the up front costs for the mechanicals, further making the idea doable.
Check out http://www.nahn.com/mtsiproj.htm for some actual small homes that were built and compared with traditional construction. Very interesting.
Cheers,
Don
Beer was created so carpenters wouldn't rule the world.
Thanks for the tip, IdahoDon. I've been vacillating about super-insulation, thinking that the payback might not be worth it, but if it can eliminate some mechanicals then that might make it work.
I'm pretty sure that Montanans can get by without AC (I grew up there) but it's a tougher prospect here in Dixie- too much humidity! But it may be possible to get by with only a couple of window units, or a small mini split duct system.
'preciate it.
gpr
This sounds crazy, but you can get a lot of great information on basic super insulated houses in hot climates from Habitat for Humanity. If you ask at a local chapter for the name of the regional building science guy he may have a few good sources of information or a person to contact.
Super insulated houses are becoming more popular with Habitat since it reduces the total cost of ownership of homes over the long haul. It's funny how the cheapest route long term is generally thought of as more expensive.
Anyway, Habitat has a lot of experience dealing with all sorts of building science issues within easily built structures.
Beer was created so carpenters wouldn't rule the world.
Concrete with radiant is more comfortable than either Warmboard or 1-1/2" of gypcrete. All it takes is sitting down on the floor while having lunch in a house that uses the three systems.
Beer was created so carpenters wouldn't rule the world.
Absolutely!!!! We have now built over 150 homes with in-floor heat and I have lunched on the floor of every one of them.
There is no comparison to a nice warm concrete floor. My Jack Russell terrier will back me up on this since she is right by my side every day as I eat lunch.
Edited 2/14/2006 9:23 pm ET by BoJangles
You have a Jack Russel Terrier? I knew there was something I liked about you.
Once you've owned a Russell, you'll never go back! ;)
The Wirsbo quicktrac product is a nice alternative to Warmboard.