Virginia Polytech Comparison of Radiant Systems

jb9

Hello,

I am sure most of the pro's here have seen this study... just curious to know if folks here feel it contains useful information (or is it inherently flawed due to the collaboration with one of the manufacturers).

https://theses.lib.vt.edu/theses/available/etd-01182006-011730/unrestricted/Performance_Test_Protocol_for_Radiant_Floor_Heating.pdf

Thanks in advance.

Rich_49

Let me ask you ? Do you think Universities and their scientists have no integrity or do you suppose they will say whatever whoever is paying them wishes ?

Let's get right down to what your question really is .

Ironman

The study was done by an engineering STUDENT and overseen by the department. He did a mockup with each type of floor listed and measured the results. Do you think he was paid off to rig the results? Do you think the student would risk throwing away his education and future for whatever alleged momentary gain that could be offered?
Knowing most of the types of floor systems tested, I can vouch for the accuracy.
My brother is a Tech alumnus and their engineering dept is highly respected.

jb9

It wasn't my intention to question the integrity of a University or its faculty, I was just curious if folks knew of the study and if the measuring device/instrumentation was a good standard by which one could compare a house installation.

Ironman

jb9 said:

It wasn't my intention to question the integrity of a University or its faculty, I was just curious if folks knew of the study and if the measuring device/instrumentation was a good standard by which one could compare a house installation.

jb9 said:

Hello,

I am sure most of the pro's here have seen this study... just curious to know if folks here feel it contains useful information (or is it inherently flawed due to the collaboration with one of the manufacturers

I glad it wasn't your intention, but the wording leaves that impression.

Tinman

I do not doubt the validity or the accuracy of the study one bit. But you have to admit that it's reasonable for the OP to pose the question. A major manufacturer collaborates on a study in which that manufacturer comes out on top.
If this were a Law & Order episode, the judge (REHAU) would have to recuse himself from the case (study).

Ironman

Could it be that Rehau already knew that their product had the highest output of btus per square foot and was simply looking for an independent source to confirm it.

Stephen, I don't follow your analogy: Rehau was not the judge in this case, the testing and results were. Facts speak for themselves. Naturally, they would want to publish them in their manual.

Tinman

Bob - I agree that Rehau already knew that they had the highest output.

Yes, I guess the analogy is confusing and probably a poor one. My intent was not to say that Rehau was the judge, but rather that the study would have come across as more objective had their name not been associated with the study itself.

Fred

While there is certainly no reason to question any of the party's integrety, it does leave the "Perception" of a Conflict of Interest that probably could have been avoided but it is what it is, at this point. The data apprears valid. Rehau could probably have gotten more milage out of it had they not been so directly involved, but then the study may not have occurred. "Perception" to many is "Reality".

margsuarez

hmm. Haven't had a chance to read the whole report carefully, but I am curious since I put Warmboard-R in my house and have been happy with it.

I agree with the OP that it is interesting that the study was funded by Rehau. The study seems to be an earnest attempt to define a testing methodology to compare the different products/methods of radiant heating.

p. 80 mentions "commercial agreements with REHAU" - in the interest of transparency it would have been good to include the text of these agreements.

pp. 51-53 show the surface temp distributions of Raupanel and Warmboard. My conclusion is that for the same supply temperature Warmboard is able to maintain a higher surface temperature, even at 12" O.C. For some reason there is no infrared photograph shown for Warmboard (or a few other methods). A picture is worth a thousand words...

The graph on p. 51 shows that at 100*F supply temp Raupanel (6" on center with R13 insulation) surface temp is between
73.3* and 74.9*.

The graph on p. 52 shows that at 100*F supply temp Raupanel (8" on center with R13 insulation) surface temp is between 72.2 and 75.1*F.

The graph on p. 53 shows that 100*F supply temp Warmboard (12" on center with R13 insulation) is between 73.8 and 77.1.

Not sure why the measured delta T would be lower then with Warmboard, even though surface area is higher. Tubing diameter and spacing is different, but flow rate was the same across the different methods - perhaps this is the reason?

It would have been interesting to see a measure of how the panels retain/transfer heat between calls.

marg