Striping?

Rodney Summers

This was on the website of an online vendor advocating stapling (2) PEX lines in between the the floor joists. Essentially wedging each PEX tubing against the top of each floor joist where it meets the sub-floor. NO PLATES. The insultation recommended under the tubing is an aluminum layer type: "Reflectix® is a 5/16" thick, seven layer, reflective insulation which is available in rolls of various widths and lengths".

I am not trying to diminish this approach, but is this propaganda or in fact better than the extruded plate? Has anyone here used AIM's approach/product? Did striping occur with the older/thinner plates vs. the new thicker versions? Does it still accur or is it a function of running water which is TOO HOT?

"Why use AIM's Under-floor vs. heat transfer plates? Some other companies try to sell you something called heat transfer plates. Heat transfer plates are mounted directly to the subfloor, these plates have channels through them to hold tubing in place. The tubing carries hot water through the plate and dispenses it through the floor. If you staple the tubing directly to the subfloor you can get what is called "Striping." Striping is when you see dark lines through your hardwood or tile floors. This occurs because the tubing with hot water heats up the section of your floor directly above to a temperature that is TOO HOT causing your floor to produce stripes."

hr

Lots of info available

to compare the various methods. Try these links, or the RPA/ Ashrae funded research.

First off do an accurate heatloss calc and system design. this will tell you how many BTUs per foot and the temperatures needed to provide that through your floor coverings.

There are instances where suspended tube will, and does, work. Crunch the numbers to determine. I'm not sure any pex manufacture wants to see pex or PAP fastened tightly to the subfloor? The tube needs to be able to move as it expands. Fasteners will rub if the tube is held too tightly.

Plates increase the heat transfer ability, allow lower water temperatures, and increase the recovery time.

Go with the extruded plates, as they hold the tube tightly to prevent noise issues.

This infared pic shows the output differences between suspended, staple up rubber, plates and Warmboard.

Hard to argue with the numbers AND the pictures, as to which method moves the heat from the tube to the floor, or wall, panel best.

The striping has a lot to do with the covering over the tube. More layers of wood, backer board, carpet, etc, will cause the heat to spread across the panel area more evenly. Again transfer plates help with the spread, compared to bare tube.

Keep the fluid temperatures below 150 to stay in the guidelines of the plywood and sheetrock manufactures recomendations. They like to see extended temperatures at 140 or below. Stay away from systems that drive the wood temperatures above this number to prevent damage to the manufactured wood products.

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,80254,00.html

hot rod

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Rodney Summers

Thanks

Thanks Hot Rod, confirmation is what I was looking for. Next question, how then do I assess who has the most 'efficient' extruded plates? I know of Wirsbo & Watts extruded Style. Are there others worth looking at? If so what brands? .....And do they all produce the approximately same output/effect if extrusion thickness is about the same?

I am planning on using Pex Multicore(aluminum core) for this retrofit install b/c less of expansion issues and noise. However, does the aluminum core PEX transfer heat more efficiently than regular PEX?

hr

As far as I know

the only extruded aluminum plates are the original Radiant Engineering, and the RTI which is now the Wirsbo one.

Hard to find anyone more anal than Dale. When it comes to heat transfer plate design that is He has plenty of experience with the design and use, and continues to look for that extra few %. Mainly in the design and grip of the tube channel. This is where the critical design point is. If the tube falls out or is not held tightly problems arise. Plenty of us have been their. For me silicone and heat transfer plates do not belong in the same sentence

Radiant Engineering has built a ThinFin to compete with the other thiner extrusions. A bit narrower and a tad thinner extrusion, but still the tight tube channel. I believe the ThinFin is also available through Watts Radiant, SlantFin, Roth, maybe a few others. Shop for the product closest to you as shipping get expensive. For new construction I really like the 8 foot long lengths. It covers a lot of floor and allows nice straight installations.

I would highly reccomend an air palm nailer if you have a lot of tube to plate. It is so much faster and really drives the tube deep into the channel. Get the best ear plugs money can buy!

I'm convinced the PAP is the best match for transfer plates. It sure seems that aluminum layer should offer a tad bit better transfer than plain pex??

I have been very happy with the Wirsbo MultiCor PAP in the extruded aluminum plates. The od of that tube seems to be very consistent, although RE's plates are better able to handle some tube tolerance issue, should they arise.

We just finished a large "fin" job with 12" on center joist spacing. We used 3/8" Wirsbo HePex with extruded plates. It seems to be the most flexible tube when tight turns are required. Especially in 90 degree heat, very pliable!

hot rod

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Rodney Summers

WOW Thanks

Exactly the kind of answer I was looking for! Didn't know 80% of what you shared........but now I do. Thanks!