Snowmelt Insulation Test Results (ME)

Christian Egli_2

From the data about the ground temperature rise, we easily see the Insultarp let the most heat go through.

Now, insulation works by stopping heat flow, whether downwards or upwards.

With good insulation, the ground does not interfere with the snow melting job. With little (the Insultarp case) or no insulation then the ground effect can be seen. This ground effect can slow down our snow melting, and it can also help. The ground is a big help, if the ground temperature is above 32F. 32F being our working surface temperature for melting slush.

This early season test was conducted with ground temperature of 40F, well above 32F. For this early season case, the ground effect is a helper not something you'd want to shield yourself from. How much help? Well, the low shielding the Insultarp provided shows how big the benefit was: slab temperature rose well above those of the other test samples. An advantage for melting snow.

How long will ground temperature remain above 32F? That depends where you live and it is related to how deep your footings should go, but if it remains at 40F, then there is no advantage in having insulation. It probably doesn't snow much either!

Follow ups on these test strips will be fascinating to watch as the winter gets colder and I think it gets cold where ME lives. Then the Insultarp should show signs of trouble.

Thanks for keeping us posted. Isn't this fun?

[Deleted User]

The results are in...

We finally got a decent period of snow this last weekend. It allowed me to "peek" at the system while it was melting snow. I retreived the data loggers yesterday, and down loaded the information and converted it to an Xcel spread sheet for graphic analysis.

I must caution everyone that the data as presented is just that, only data. Everyone can make their own judgements based on the information presented, and cases can be made for or against any and all products sampled. It's your money, spend it as you deem fit. Now, for the testing parameters.

All six samples tested were run simultaneously under the exact same operating conditions, except that they were laid out such that they were in the center of the driveway, but were positioned up and down hill from each other. There were 6 samples tested, including bubble foil bubble, 3/4" styrofoam with BFB applied to it, 1" thick XPS Pink Board, Insultarp, The Barrier and 3/4" styrofoam Fan Fold insulation.

The snow storm that hit came on Friday evening, and for the purposes of not wanting to see irrelevant data, I chose the last 36 hours of operation prior to removing the data loggers. The actual amount of data recorded covers about three weeks with a sample being taken once per hour.

The bar chart represents the average delta T between the top of the given insulation and the soil 2" under the insulation.

The line graphs are of the actual sensor temperatures during the 36 hour period. Your intrepetation is just that, YOUR intrepretation.

Questions please...

ME

S Ebels

Basically speaking

The better insulation would show the greater temp difference above vs below. Correct?

Cosmo_3

Awesome

I have been patiently (yeah right) waiting for these test results. Thanks for all the hard work ME. Looks like teh barrier was not even as good as the insultarp. I thought that maybe it would have been the other way around. At any rate looks like nothing can get close to the 2" foam board I currently use. Interesting that the insultarp gets pretty close to R-5..........


Cosmo Valavanis

Dependable P.H.C. Inc.

[Deleted User]

Steve, that is correct...

THe greater the delta T the higher the R value.

ME

[Deleted User]

Cosmo, nothing...

beats good ol' dead air. Not even reflective surfaces :-)

ME

rb_6

Great stuff Mark

It's interesting to observe how all but the XPS applications, saw sub soil temperatures rise above 45 deg F. (downward heat flow)

Also of note is the sub soil difference between the 1" XPS and the 3/4" XPS/BFB combo.

Using 40 deg F as the base line, the nominal 9 deg F rise for the BFB only vs the difference between the 1" XPS and 3/4" XPS/BFB ...about 2 deg F (+/-) 0.5 deg F suggest the BFB has negligible (perhaps “questionable” is a better word) benefit since the variance can be explained by the 1/4" difference in XPS thickness...

Of equal interest is how the insultarp had the highest rise in subsoil temperature...but also the highest temperature above the insulation...I'm not familiar with the product but is the top surface highly conductive or is there other explanations for this results.

The most important information I think these results show is energy going into the earth, shown as a rise in soil temperature is energy not contributing to the objective, which is the process of melting snow.

Dr. Eatherton, I do believe you win the award for useful data for the least cost…those academics have nothing on you.

Weezbo

VAry nice presentation...

Here is the accurate info make up your own minds... i was interested in this as i kind of like new products and just in case i get a wild hair...i now have some siccsors to nip it in the bud:)

bob_50

Thanks Mark

Good Stuff. bob

Unknown

The bad news is;

I just had a whole bunch of this (The Barrier™) insulation delivered to a jobsite for a residential driveway/walkway system we’re gearing up for. Now I’m wondering if I should return it and use XPF pink/blue/green board that we’re use to dealing with but it’s MUCH more difficult to install correctly.

I’m always looking for better and more versatile products, but I can’t help feeling as if I’ve made an error in judgment. I was a bit concerned by what I’ve been reading here on The Wall WRT under slab insulations lately. I was under the impression that it is "all about K-value" when it comes to subterranean testing of insulation products. The K-value equivalency to R-value math was discussed in a thread a few months ago and is an equivalent R-value of 1.65 for the 3/8" but your graph shows us another story.


I’m always a bit nervous about SIM system performance meeting customers expectations. Who wouldn’t? What to do now is the question?


Wallace Radiant Design

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Wayco Wayne_2

I wouldn't

worry about it Gary. Basically The Barrier is similar 3/8 syrofoam and it's behavior on the charts showed it to behave vary similar to the .5 in fanfold. 1 inch extruded is hard to work with and very brittle. You want better insulation with the Barrier just double it up. What blows my mind is the insultarp. Why higher temperature both below it and above it? (the manufacturers might take this data and say the insultarp turbocharges the availible heat. Ha!) I have to believe there are variables in location and water temps and loop lengths that may have influenced the data. Remember this is not a testing lab, it's someones driveway. Thanks you for doing this Mark. I'm sure you had fun doing it too. WW

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[Deleted User]

Dr Bean...

Thanks for the kudos.

Although this was not a "TEST" , because testing occurs in a strictly controlled environment, this "COMPARISON" does prove out a lot of data when comparing one product application to the other. I think it answers a lot of "what if" based questions. In order for it to be an exact comparison, I would have had to use equal thicknesses of all materials observed. But given that the manufacturers have their given products at their given thicknesses, I feel it is a fair product comparison.

While every effort was made to position and secure our thermal sensing wells such that we'd get an accurate mid tube span temperature, I have no way of know for sure if the light footed (yeah, right like there is such a thing..) concrete guys didn't kick some of the sensors closer to a tube, hence the higher above insulation readings for the Insultarp. And I agree with you, one of the more important things this shows is the amount of energy lost to the dirt below from back losses that most contractors who don't use insulation pooh pooh to the "But heat rises dontcha know" falacy. We ALL compete with these folks on a daily basis.

Here's but one of a gazillion bits of interesting information that was obtained during the sampling.

Thanks again for your brilliant observations.

ME

[Deleted User]

Gary, the good news is...

You ARE insulating the slab.

And in your case, if you've got extremely rough surfaces, then the use of THe Barrier is probably better than using one of the other rigid boards that would crack and fall apart and provide ZERO resistance to downward heat flow.

Each product has its benefits and detractors. None of the products demonstrated are perfect in every way. Some appear to be better than others in THIS application, but I can think of some situations (rocky, virtually impossible to get a smooth surface) where the Barrier is more appropriate than XPS...

Or, in confined space over pours where heighth is an issue.

Cheer up. You learn as you go. Go with what you brought. It's a HECK of a lot better than NOTHING, which is what your competition was going to use....

ME

[Deleted User]

Wayne. the water temps....

are extremely well balanced. This was one of those one way piping runs from an upper manifold down to a lower manifold, piped parallel reverse return with a 4 way reverser in the circuit. I feel pretty confident that all tubes are flowing at nearly the same rate. We also used a 1-1/2 HP sewage lift station pump to fill and purge this system. No whimpy utility pumps on this job...

As previoulsy stated, it is possible that the above insulation sensor was kicked nearer one of the heat delivery conduits, and then again, maybe it IS the nature of insultarp to conduct heat laterally at a substantial rate. That could be perceived as a benefit.

Wish I had access to a FLIR camera and a bucket truck...

ME

Brian (Tankless)

You're a pioneer, Mark, thanks

A truly objective, un-biased side-by-side comparison, thanks.

Insultarp surprised the heck out of me. So as well as being an effective insulation, it's also an excellent vapour barrier in crawl-space applications & attics etc'.

Now, can one of you computer savvy guys tell me how to save this entire thread, including attachments & links to attachments to an (accesible) place on my machine in some way?

I ask for this, because it's an incredible uphill battle down here in the 19th century South, convincing builders & homeowners of the relative benefits of different insulation materials for different applications.

Down here, Fibreglass batt & blown in cellulose (for the adventurous modern types are still the norm.

Thanks again, Brian.

Gary, you're still ahead of the game. As mark said "at least you did something", way more than your competition would have done. Can you imagine the fuel bills if you'd done it the "cheap" way. Your name & reputation would have been mud, hard to recover from, when word of mouth is everything in your business.

jp_2

orginal post?

I am looking for your orginal post on this, don't want to ask questions that are found in the other post?

interested in the "soil" make up here, gravel sand etc....

thanks

Mike T., Swampeast MO

I'm not familiar with the product but is the top surface highly conductive

It is surrounded (top and bottom) by an aluminum or aluminized layer and aluminum is a very effective conductor...

From their website:

"Insul-Tarp's innovative combination of layers and reflective material enable it to effectively control all three modes of heat transfer -- Conduction, Convection and Radiation. In a heated slab, Radiation is responsible for 93% of the heat traveling downward.

I've never understood how that could be with a slab on earth, but maybe there's something to it...

What seems really strange is how the below slab temp is so much higher than with all of the rest--in fact often higher than the above slab temps in the other products.

Is the below slab sensor in contact with the Insultarp?

It's almost as if the insulatarp is acting like a sort of thermos bottle and actually is reflecting radiant energy back into the slab...

Unknown

jp

Original Thread

Wallace Radiant Design

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jp_2

thanks gary

thanks!

Wally Radjenovic

Test results

Very interesting. Can I have the Excel data emailed to me to see what the average delta T was during the entire test?

Unknown

Well, I think we have to remember that the actual temperatures are not reliable here, because sensor position could be variable in relation to the tubing and you could thus be reading one slab as higher or lower than another even if the same insulation is used.

This means what *is* important.. I think.. is relative temperature changes.

As far as I can see, 1" rigid saw the least under soil change for the most concrete slab change.. by a wide margin. Look at the curves, the soil temperature barely changed while the slab temperature rose. The other methods had a much more direct correlation.

And 1" is half as much as is usually used.

Maybe I'm off base, but all this does is confirm to me that it's not really worth using anything else other than rigid.

ScottMP

Mark

I also want to say thanks for doing this. I am by No Means, in the same classroom as the others here , but I find this Very interesting.

It makes me feel better about insultarp as it does have a high delta T, but the ground temp rise is also interesting.

You've done some great stuff here and its One More reason to hang out on The Wall.

Flying with the Eagles .....

Scott

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Mike T., Swampeast MO

To save a thread:

From the TOPIC menu, right click on the thread title. Choose "save to". Provide YOUR name and file location.

This will save the actual text and "basics" of the thread screen, but it will NOT save the "hotlink" attachments.

Right click on each attachment and give the SAME FILE NAME as displayed and store in the same location as the thread.

The "hot link" to the attachments won't work but at least it will be stored under the same name in the same location.

[Deleted User]

Thanks Mike..

Maybe that explains it. Higly conductive surface provides fin effect. I'm prety sure the sensor below the insulation was NOT in contact with the Insultarp, but the one above it may very well have been on contact with the material.

Maybe an organization like ASHRAE will see this comparison and pop for more detailed studies of each product. They have no axes to grind, or rmembers to alienate, unlike some orgs.

ME

[Deleted User]

No problem Wally...

FYI, the numbers in the vertical bar grap represent the average differential temperature for the 36 hour period.

Thanks for playing.

ME

[Deleted User]

You're right Rob...

This is a product comparison as opposed to a controlled test. I spent about $1200.00 of my own money to determine this comparison. If someone wants to antie up around 1,000 times that, I'd be more than glad to perform actual controlled "tests" on my next project. I'd even go as far as pouring the concrete myself just to make sure it is done properly and evenly. I even have a college that would be glad to offer up a permenent test bed.

Tell you what. I'll sit over here in the corner and hold my breath waiting for someone to post the moneis necessary to do some real in depth (literally) research. I couold get use to a blue tint for my skin color:-) Just call me Papa Smurf!

ME

[Deleted User]

Soil Make up...

Consisted of "road base". Compacted to 95% prior to our disturbing it for sensor locations, then stomped back t oaround 95% compaction prior to cover (tongue firmly planted in cheek in regards to the compaction issue.)

Basically, road base is small crushed aggregate with compactible fines.

ME

Unknown

I really hope that didn't sound like I was trying to slam you or your methodology.. this is great stuff mark!

I was just trying to converse about different ways to interpet the data most reliably since there is obviously a lack of "laboratory control" to some degree. I think we can extract useful info from this regardless! I just think in doing so we can't pay attention to specific temperatures and instead we should be looking at the relationships between the temperatures shown. That is, look at the trends and relations, not the specific temps. even if the sensors were off, or in slightly different positions, it seems the relationships between the sensors in each test bed would be fairly constantly read, even if the actual temps don't compare completely apples-to-apples across test beds.

What do you think? I think it looks pretty clear that the soil temp didn't move much under the EPS but there was much greater variation under the other methods. Do you agree? Do you attach the same importance to that as I do or do you think I'm missing something?

Do you have this data in some kind of database format or excel sheet or something? I might like to do some parsing if so.

[Deleted User]

Thaks Scott...

I like flying with all these Eagles as well, and an occasional turkey;-)

ME

ALH_4

Control

Was there a control, with no insulation? Without that, we cannot know what the differential would be with no insulation. Maybe we can take the BFB as the control ;-)

These are very illustrative comparitive results. Thanks Mark, for going to all the trouble to satisfy everyone's curiosity and perform a reality check. With all the wild claims many manufacturers make, it can be difficult to sort out the good products from the not-as-good.

-Andrew

Christian Egli_2

It's all relative, 3 ways, ground, pipes, slush

Of the two sensors I am far more ready to make a judgment based on the data from the below sensor.

This is why:

The pile of energy that gets dumped into the slab disappears only in two ways. It either gets lost by conduction into the slab and the ground or it gets put to use to melt snow. (We are really not interested in heating the slab, we just want to melt snow)

There are convection losses such as in heating the air layer above the slab and the pool of melted snow running off the slab. There are lastly, radiation losses into space (and solar gain). All these we can assume to be identical for the entire driveway, thus, none of the sensors will register a difference.

When we melt snow, it takes energy to effect the transformation while we observe no temperature change in the slush. Slush, unless salted, remains very accurately at 32F, the same way good steam boils at a constant set temperature, no matter how many BTU you are playing with.

The slab itself is water proof, the insulation are waterproof too, so we can assume that nothing of what was going on above the slab - as far as melting snow - was having an effect below the layers. There was no snow to melt underground.

The underground appears only as a heat storage. The more BTU you abandon into it, the higher the ground temperature will go. There is no place for the heat to go, but deeper down and hotter until you reach steady state where the ground and the pipes are just as hot as each other. If you run the system long enough, insulation or not, you will eventually reach this steady state.

But within 36 hours, you can clearly tell the difference between the layers that keep the energy from sinking into the ground. Unequivocally.

What goes on above ground is a different story. If there is no snow to melt, the slab temperature will rise, but with snow and with water run off the temperature will do its own thing. And for as long as there is slush, the slab melting surface temperature will not rise above 32F.

We could argue that since it snowed everywhere the same way, it should make no difference. Right? No?

Well, if the ground acts as an enormous heat sink, it is clear to understand that there will be less energy left for melting purposes. That seems obvious too.

So far there is one big assumption we're all making: that the underground is always acting as a heat sink.

What if the ground is acting as a heat source? In this case there would be more energy for melting purposes and no losses to the worms. How do we know what's going on?

Conduction is all relative.

The ground is all at the same time a heat sink and a heat source depending on the temperature of whatever other thing you're comparing it with and depending how much insulation there is between the two.

Energy migrates by conduction in a solid mass from the hotter area to the cooler.

In the slab, we have the cold melting surface at around 32F, we have the pipes at boiler temperature, we have the ground at 40F in this test at this time of the season.

The pipes are a heat source for the surface and the ground. The surface is a heat sink to the pipes and the ground. And the ground is a heat source to the surface and, all at the same time, a heat sink for the pipes.

We could write some kind of differential equation to solve all this, but, oh dear, it's getting late! What a convenient excuse. But whatever we do, in our minds, let's not just interchange temperature (in F) value for heat (in BTU) value.

Back to the data

The insultarp shows no resistance to heat going downwards, because ground temperature rose so much. This also means the insultarp has no resistance to heat going up, there is no such thing as one way insulation.

The insultarp is a poor insulator.

From the data, the ground at 40F was hotter than the melting surface at 32F. It follows that ground heat migrated upwards into the slab and into the slush. The traces of this heat migration are left in the temperature rise in the slab, and they are the highest for the insultarp case - which followes again, that the insultarp is the poorest insulator in this test.

The other barriers show marked resistance. They kept ground heat at bay and prevented it from rising to the surface and help in the snow melting battle. For these, the slab temperature increase was mostly caused by the piped in heat.

At this time of the year, a test patch with no insulation at all would have acted like the insultarp and shown even better snow melting results.

This could be an argument for the no-insulation people. And it is if you live in an area where ground temperature remains high throughout the season. (Where it probably doesn't even snow.)

This test was done in the early season, I am anxious to see how things progress. I predict as the ground temperature falls during the season, the insultarp will show much lower slab temperature and reduced snow melting capability.

One more comment

The light footed concrete pouring may have moved the sensors nearer to the pipe.

The pipe is what gets hot and cold at a moment's notice. If the sensor was real near a pipe it would show rapid ramping up and down, whereas, if it were further away, the sensor temperature curve would show up much smoother.

That's how I would interpret the differences in jitteryness between all the graphs. Nothing you can't just smooth out over the hours with the stroke of a pencil.

Thanks for sharing the data. I loved your night re-radiation box too.

Wayco Wayne_2

Mark

like Rob I hope I didnt sound critical. I guess I was just trying in my clumsy way to make sense of the readings. If I had the money I'd buy you the camera and boom truck, and be right next to you looking at the pics. WW

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[Deleted User]

NO offense taken...

and I agree, the trend really shows more than the bar graph portrays. It's just hard to graph a differential to give a good "picture" of each product compared to the other.

This is research, and it is subject to criticism. I'm not offended.

I'll send you the data.

ME

[Deleted User]

Raw Digital Data

For Wally and anyone else interested, here (attached) is the raw data. Bear in mind that during the period of time that this information was recoreded, that the system was being tested and commissioned on the fire side of things, so some anomlaies in operation may be seen. If memory serves me correctly, there were also a couple of small snow storms that may have caused the system to start, and there was also one misfire due to improperly configured controls. The last 36 hours of the test is the best example of a natural start, with uninterrupted data.

Unfortunately, my agreement with the new owner was that I'd only collect data during construction, prior to his taking possesion. He takes possesion this Friday, so this is the only data that will be harvested from this installation. I've already pulled the recorders.

Enjoy!

ME

[Deleted User]

Andrew...

No, unfortunatley there wasn't a control patch sans insulation. I couldn't take a chance on having a slick spot on this very hilly terrain with curves.

Maybe some day I'll have one in an area with less hills and curves that we can then do a double blind test on:-)

BTW, my copmment about people using letters instead of names was not directed to you or anyone else here who is legitimately using a real e-mail address. It was pointed directly at people who intentionally hide their real identity. Like you, my name is so long that I use my initials to save time. SOme people have mistaken it for me being a mechanical (or would that be maniacal) engineer. I am not, and have never held myself out as being one. I'm just a wild and crazy hot water plumber, roaming the hill and dales of Colorado, trying to help edumucate the masses and keep people comfy and safe on their steep, curvy driveways...

Say hey to your bosses and see what they think of this data. Dales always good for a few comments:-)

ME

[Deleted User]

Christian....

you make some very valid points. I like your open way of thinking. Keep it up.

ME

physics

Control

I can't seem to find a reference to a control. There should be sensors monitoring delta T with the slab directly in contact with the base.

[Deleted User]

Phisiques...

This was a comparison of off shelf insulation components, not insulated versus non insulated. Sorry. Maybe next job.

ME

Constantin

Thanks for sharing!

Mark,

All that data collection is real community service and a treat to sift through. Many, many thanks again for taking it upon yourself to do some down and dirty testing of manufacturer claims and affirming the trends reported by others.

Knowing nothing more than the info of this thread, I also interpret the lower subsoil temperature of the XPS system as one where most of the heat is being directed "up". I imagine that the maximum ΔT's that can be achieved between the sub-soil and the top of the base are finite (conductivity of all the stuff in between being what it is), so the temperature of the sub-soil hence indicates how much of the energy is going down vs. going up.

Based on what I see, the XPS is the clear winner. However, as you correctly point out, any insulation is better than nothing.

Mark Hunt

The Insul-tarp


numbers suprised me.

Thanks for posting this Mark.

Looks like you have some frigid weather heading your way?

Mark H

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hr

Seems like edge insulation

of an exposed edge snowmelt slab would be the bigger loss to insulate against?

I've yet to see a good detail for that, however.

Thanks for the data and willingness to question

hot rod

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