Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Help choosing radiant panel system

BeZeBeZe Member Posts: 3
Hello and thank you for this great forum. I have been reading posts and trying to decide between Sunboard and Warmboard (both S and R) for our second story addition (new build) and existing first story (remodel), roughly 1200sq ft on each floor. I'm north of Seattle so it does get cold, but not very cold for very long. I was hoping you might be willing to give me some additional insights to help in my decision.

Our initial quote from Sunboard was for the "gold" version. I've seen Sunboard generally recommended on here and it is a lot more budget friendly than warmboard. However, I read in a helpful post "Do not be fooled by Warmboard's cherry picked comparison videos , such as their Warmboard / Sunboard comparison. Although they used a Sunboard product that was unfortunately named " Gold" which many would take as being the best , it is not . Sunboard Gold is a panel that does not have the aluminum or graphite coating through the groove as Warmboard does have . .... Sunboard Silver is in fact a through the groove coating application and WILL outperform the Warmboard products . Ask me how I know . If you are seriously considering WB for your project I urge you to look at Sunboard ."

I will inquire about the Sunboard silver, but I suppose my question is whether there is a clear benefit to WB that would make this a preferred option, or if it is just as, or nearly as good to go with a more budget friendly option, (especially if SB silver is similarly priced to gold)? WB has great customer support which would come in handy for my contractor who has worked with neither SB or WB.

I know there are other similar products available and I have chosen to avoid those with built in foam insulation as they contain added chemical flame retardants which I'd like to avoid.

Does anyone find that one is a better performer in the long term? Thank you so much for any advice and for all the advice I've already read! Beth


  • hot rod_7hot rod_7 Member Posts: 9,140
    Apples to apples? Look carefully at the spec. The thickness of the wood and aluminum varies between the WBs and SBsilver. The aluminum thickness determines the hold of the tube and ability to move heat energy across the panel and to some extent the strength of the panel.
    I have not used either of those models but I have used brands with thin foil coverings and they do not hold up to construction traffic.
    I have a good track record with the original WB structural panels, they perform great and hold up well during construction.

    The Warmboard R is a structural floor sheathing at 1-1/8" thickness, not an over the top product.

    Shipping cost has a lot to do with your cost also. If the product is manufactured close by that is a cost factor.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GordyGordy Member Posts: 8,677
    edited August 2017
    Warmboard-S is stuctural, and Warmboard-R is remodel panel 13/16" thick vs 1 1/8" thick.

    One thing to note is warmboard uses strictly 12" center tube spacing where sunboard, and others allow for tighter tube spacing options. There are situations where tube density is beneficial.
  • hot rod_7hot rod_7 Member Posts: 9,140
    Aluminum is the key to good energy transfer. I noticed both WarmBoard products cover the entire sheet with heavy gauge aluminum. Looks like the SunBoard only has aluminum on the straight sections. That leaves all the loop ends in just the wood panel.

    The load of the room dictates how much floor output you need, under the right conditions either product would get the job done. Plenty of bare tube systems heating adequately out there. Probably many not so well :)

    Here is an example of how not having the aluminum, or routering through it changes heat transfer.

    The front 1/2 is bare Warmboard, the back 1/2 has carpet over it.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Rich_49Rich_49 Member Posts: 2,515
    Hot Rod said : " Aluminum is the key to good energy transfer. I noticed both WarmBoard products cover the entire sheet with heavy gauge aluminum. Looks like the SunBoard only has aluminum on the straight sections. That leaves all the loop ends in just the wood panel. "

    When speaking of aluminum to aluminum this is quite true , nobody could argue . Sunboard offers a graphite covered panel also . This is what we use exclusively . Thermal conduction of graphite is far superior to that of aluminum . Tubing density as mentioned earlier is also a good reason to use Sunboard , this allows for lower temp fluid use . Remember also that before heat goes to where the people are the mass must be heated . Sunborad also produces a 3/8" tubing panel which can be very beneficial to keeping head of circuits above many circulator pump performance curves which is always good .

    I have used both products in several installs . There is no benefit to using WB over Sunboard unless you require the structural properties of the WB product . In similar homes in the same geographical area I can say that I have been able to use lower water temps with Sunboard than WB . All things considered , price , performance , labor , comfort , Sunboard is my choice .

    Stay away from the Gold and use the Silver for best results and certainly use the graphite product
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC 732-751-1560
    Serving most of New Jersey , Eastern Pa .
    Consultation , Design & Installation
    Rich McGrath 732-581-3833
  • BeZeBeZe Member Posts: 3
    Thanks for your replies! Hot rod, I appreciate the thermal camera shot along with its explanation- those are always non-intuitive to me.

    I've been mulling this over, as undecided as ever! Thanks for pointing out the aluminum thickness, I assume this would affect both the comfort and energy efficiency, but as far as efficiency goes, I wonder how many years it would take to make back the large difference in upfront cost?

    I've been looking for data comparing graphite and aluminum and came across this link.

    The results state "The graphite sheet - #1, measured 6" wide x .020" thick and clearly demonstrated the worst heating performance achieving an average temperature fully 32 °F less than the circulating water temperature. The graphite sheet is significantly oversize relative to the outer dimension of the copper tube, creating an air gap as large as .040".

    Is this low performance due to the air gap? If so, I assume the Sunboard graphite option does not have an air gap but are there data to show it out performs aluminum in a radiant heat application?

    I found this news article stating that this particular graphite sheet has a heat conductivity 5 times greater than copper which sounds promising.

    Any suggestions for where I can find direct info on graphite vs aluminum? It feels like graphite is more of a gamble since there aren't many using it, but maybe it's just relatively new? Many thanks again.
  • GordyGordy Member Posts: 8,677
    Conduction is king in heat transfer. Without a tight tube to heat transfer plate connection you lose that conduction.
  • hot rod_7hot rod_7 Member Posts: 9,140
    edited September 2017
    The graphite is a tough material to form into a transfer plate. The challenge is developing and maintaining a tight tube connection.
    I worked with a graphite manufacturer and radiant company years ago to try and develop a radiant application, we struggled with that "connection" Any space at all, even the thickness of a hair reduces, actually eliminates conductive transfer.

    Graphite is basically a flake or particle so it needs to first be bonded to a backing, we eventually used a product with a self stick adhesive on one side, and even then a plastic tensioner had to be added to keep the grip tight, at that point it became more expensive to produce than the best aluminum transfer plates and still a weaker grip.

    I have not used any of the SunBoard products so I cannot speak to the tube grip compared to a product like Warmboard or ThermoFins.

    I'm not sure for moving heat energy from a PE tube to a floor assembly that you see a huge difference assuming you could keep that constant tube grip, no doubt graphite is the better conductor, used mainly in electronics like the back or your computer, where it is encapsulated in the plastic of the screen backing.

    My experience shows the transfer plates with the tight grip and the thickest aluminum work the best.

    The thinner gauge of the SB aluminum may be why they went with a 8" tube spacing to get good spread across the sheet, and obviously cost. You buy aluminum by the pound :)

    Most important is the load calculation and design, assuring that the unencumbered floor surface can cover the design day heat load without excessive, above 82F surface temperatures.

    Here is another opinion, granted from an "aluminum" guy.

    And some testing done at Virginia PolyTech back in 06

    I don't know of any 3rd party testing comparing the various graphite to aluminum? Possibly the companies promoting graphite transfer products have some test data.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GordyGordy Member Posts: 8,677
    Here is an interesting unbiased study by Virginia Tech of various radiant panel assemblies. Unfortunately SB is not in this study.

    It is a good read however.
  • GordyGordy Member Posts: 8,677
    Another output comparison short version. Again unfortunately SB is not on this chart.
  • IronmanIronman Member Posts: 4,732
    Here's another from Rehau that we use a lot and works great:
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • GordyGordy Member Posts: 8,677
    What I like about that plate is the exposed tubing is at least to the aluminum portion of the plate verses down to nothing, or the insulation in the joist bay.
  • BeZeBeZe Member Posts: 3
    Thanks so much for all your help! I ended up going with Warmboard primarily because it can get wet while the Sunboard products can not. It's been getting wet and holding up pretty well so far but hopefully we'll have it all sealed up in the next couple of weeks. Many thanks!
Sign In or Register to comment.


It looks like you're new here. If you want to get involved, click one of these buttons!