Snow melt

Moses

Thanks ME, and Mad Dog.

We installed yesterday the Insul-Tarp. It has 5 layers, the 1st. layer is a sheet of plastic on one side and aluminum foil on the other side, then a layer of bubble-rap,then 2, layers of quilted material, and then another sheet of plastic with aluminum foil on other side. It cuts very easily, and just have to duct-tape the ends together.

Moses

Moses

Snow Melt

I am doing now my first snow-melt job. The supply house recommended that I use Insul-Tarp for insulation under the slab. It is only 1/2" thick, but the "R" value is equal to 2". Any info on it will be greatly appreciated.

Constantin

Do a quick search on Insultarp

You'll find plenty of entries on the Wall. My understanding is that it's little better than a thermal break, certainly not R10 in that application like some would suggest.

Mark Eatherton1

Moishe!!

Good to see your words. We use 1" of XPS foam insulation R5 for sure.

Dow Foamular 250 is good for 25 PSI pressures which is good enough for a 6" slab with loaded tractor trailer rigs running over the top of it.

ME



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Moses

Snow Melt

Thanks ME.

We installed the Insul-Tarp yesterday. It has 5 layers, 1st.
layer is a sheet of plastic on one side and aluminum foil on the other side, then comes a layer of bubble-rap, then 2, layers of quilted fabric, then another sheet of plastic on one side and aluminum foil on the other side, all combined is only 1/2", when compressed.

Mad Dog

Moses. Listen to Mark....he designed my big

snowmelt job last summer and it worked great. We actually used 2" thick polystyrene boards and 1" for the edge insulation. Worked out great. feel free to email me if you need any pointers. Mad Dog

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mad Dog

Yep...I've used it on radiant slab jobs, but

Mark isn't crazy about it because it has no determinable "R" Value. I didn't want to take a chance with snowmelt. Who designed it for you Moses? Mad Dog

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Moses

Snow Melt

Donald Rathe from Rathe Associates, from here on the Island

Mark Eatherton1

RAKE!!

I hope your cement guy was careful with that rake. I've heard of more than one job where they weren't and punctured the tube, only to cover it up and hope the leak would "go away"...

Looks good Moses.

The insul tarp is 2 times better than nothing at all (R2 or there abouts)

ME

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Moses

Snow-Melt

Thank,s for your concern. I was there and I made sure that they are very careful when they applied the cement.

I am going to install a boiler only for the snow-melt. I would like to install a wall-hung, direct vent type. Which boiler would be ideal for this project? Total Sq. Ft. is 350. We installed,about 400'of 3/4" pex-tubing on 9" center, with Tekmar D-091 Sensor socket, any info would be greatly appreciated.

Thank, Moses

hr

Moses

shop for a condensing boiler for tht application. They love those temperatures and are a bit more fuel friendly when heating the great outdoors.

I have used InsulTarp on quite a few jobs now. Can't put exact numbers on it, but my "backyard" tests and studies show it very close in performance to 1" foam. I still prefer foam for perimeter and edge insulation.

I noticed also, sidewalks and driveways melt very quickly when the sun comes out, without the boiler running on insulated slabs! Proof enough that the insulation under snowmelt is worth the time and expense.

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

marc

underslab insulation

we have found out if you insulate under slab. during frost times with a quick over night freeze, no precipitation, that the slab will freeze / frost. meanwhile the slab sensor is just sitting there waiting for something to fall from above. we currently recommend no insulation underslab. when you are talking 120-200 btu/ ft. to maintain the slab above freezing insulation just adds more money to an already expensive luxury item. (most of the time) marc.

Moses

Snow-Melt

> shop for a condensing boiler for tht application.

> They love those temperatures and are a bit more

> fuel friendly when heating the great

> outdoors.

>

> I have used InsulTarp on quite a few

> jobs now. Can't put exact numbers on it, but my

> "backyard" tests and studies show it very close

> in performance to 1" foam. I still prefer foam

> for perimeter and edge insulation.

>

> I noticed

> also, sidewalks and driveways melt very quickly

> when the sun comes out, without the boiler

> running on insulated slabs! Proof enough that

> the insulation under snowmelt is worth the time

> and expense.

>

> hot rod

>

> _A

> HREF="http://www.heatinghelp.com/getListed.cfm?id=

> 144&Step=30"_To Learn More About This

> Professional, Click Here to Visit Their Ad in

> "Find A Professional"_/A_

Mad Dog

Wow! that could get expensive

Mad Dog

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mark Eatherton1

Obviously...

marc's not paying the gas bills for the system...

I design every system I do as if I WILL be paying the gas bills.

ME

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

DaveGateway

Moses

A modulating, condensing boiler is certainly the way to go. I've used Peeless Pinnacle (Munchkin w/out Vision which you don't need in this application) Dial a temp and with p/s piping you're in business. Stainless handles the glycol better IMO.
With the 091 and 090 sensor are you using the Tekmar 661? Awesome control. Since it looks like a single fam residential I wouldn't idle the slab. Being that small and it should pick up OK from cold.
Some of my earlier, residential small snowmelts I just gave the HO a switch on the wall to operate. If they wanted more auto control I would add it later. The only addition was a timer for shut off in case they forgot. When the weatherman says it's gonna snow...turn on the system. KISS!

Did you need permission from the city to do this work under THEIR sidewalk? I've been asked but never carried THAT liability to fruition. In Chicago they have a program where you pay half and the city pays half for sidewalk rework IF NEEDED. I see the neighbors opted out of snow melt but that would require another boiler.....!!!! Been there and backed out. Tom

marc

so what is the payback

cmon, mark you are going to tell me it is worth the extra 52 cents / ft just for materials to insulate under the slab.snowmelt is done either for luxury or need. 90 % is luxury. if you use tekmar controls and proper tube spacing the response time is very fast. with insulation you gain faster response.. how much.. what do you have to input for btu / ft to melt. how do you solve the frost on the surface when there is no precipitation. idle ? that uses more fuel. snow melt is NOT EFFICIENT, it is either luxury or a neccessity. do you melt snow at your house???

marc

actual r value

what is the true r value of insultarp under a slab, does anyone have any written documentation on this. people call all the time saying it is just as good as 2 in . foam. what psi is rated for. show me the money????? if someone can produce docs. on the true tested rvalue of insultarp we would use it. our state says minimum r-10 underslab. so is insultarp an r-10 i ask you??

Mad Dog

Trust me, you will \"pay\" if the homeowner ever catches

on that he has no slab insulation. Even the richest folks who go for snowmelt complain about the bills the first year - even with insulation!!!!!! I know it will work without it, but it is not a good practice. Mad Dog

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Kal Row

i am thinking \"rinnai\" outdoor tankless

may be a good fit for this - design to be mounted outside the house - and while they have built in freeze protection for reg DHW application - you need to ask them what if any antifreeze thay can handle

http://www.rinnai.us/

Mark Eatherton1

We have a saying in the snowmelt biz...

If you need to know how much it costs to operate, you probably can't afford it...

I know of no formal "studies" however, I have spoken to ski area operators who have told me that the areas WITH insulation got up to melting temperature in HALF the time that the insulation-LESS systems did. The slabs were equally loaded at 150 btuH/sq ft / hour.

What part of the country are you located in? I've NEVER had a complaint on any of the systems I've done complaining about frost.

I'm also confused about your statement that your state requires 2" insulation below the slab, then you state that you don't use insulation? What state are you working in?

I don't recommend idling non critical slabs. It's a waste of energy. I do recommend, and will supply the HO with two 12 hour twist timers. One is to anticipate a fast moving heavy dumping snow storm. "Warm the oven before you throw in the bread". Snowmelt systems work PROACTIVELY much better than they do reactively...

The other twist timer is to delay the start of the system. If there's a fast moving Spring snowstorm that doesn't warrant firing up the snowmelt system, they can give the DELAY timer a twist and avoid an unnecessary waste of energy.

If they're not there, the system will take care of itself.

We've even got the abitlity to telephone ahead and fire up the system before they get there to make sure that the driveway is clear.

As to whether I have one in my home, no. I don't have money to burn, and I need the exercise:-)

If I DID have a snowmelt system, you can bet your bottom dollar it would be connected to a bank of solar collectors!

ME

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mark Eatherton1

To my knowledge...

there are no standards for evaluating the total R value of insulation below a slab, hence people throwing about wild R values for reflective foils, concrete tarps etc.

I'm not even sure if the XPS insulation we use is guaranteed to retain the R value it's listed as having when under 4 to 6" of concrete. My gut tells me that the R value of XPS if a lot better than tarp combinations or reflective surfaces. In order for reflective surfaces to perform, there are numerous criteria that must be met, and if one of them is not met, the net reflective capacity is nil.

As it pertains to spectral reflectivity, a reflective surface using aluminum must be 99% pure aluminum, should have a uniformly smooth surface, and should have a 1" dead air gap on either side of the reflective surface. None of the bubble foil bubble insulations I'm aware of meet ANY of those requirements.

Then how do they work? In my estimation, they have a net R value of around 1. Thats 100 times better than R-0... In other words, SOME r value is better than NO r value at all.

I have tested all different types of bubble insulation under laboratory conditions in bays with suspended heat tubing, and the R value was slightly above R 1. They claim that its not the R value that causes it to work, but that it is its' spectral reflective capacity that causes it to work. Bottom line, the bays with it installed still underperformed significantly compared to the bays with "real" insulation.

I know HR is doing some back yard testing of insulation below snowmelt. Maybe he can shed some light upon the subject.

I will admit this. I wrapped a 2,000 gallon DHW storage tank with 1" poly butylene, and then wrapped the tank with B/F/B insulation, and it lowered the temperature of the boiler room by 20 degrees. So, I believe it has its applications, but its not under slabs. Save the aluminum for making beer cans!!!!

ME




To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Kal Row

\"a bank of solar collectors! \"

and a "septic tank" sized storage tank - then it's perfect

just as long as you are using your hybrid electric vehicle to transport all that anti-freeze

we deny the fossil fuel people every cent we can, even if we are billionaires

marc

the evergreen state

the 2 in. min. is inside, i was just trying to get a honest answer on bubble / tarp insulation compared to rigid. the frost happens because you have isolated the slab from warm mother earth. marc

Kal Row

warm mother earth ????

You are obviously not a lutefisk eating Lutheran from lake woebegone - so you dont know what cold really is ;;)

RB_2

To Insulate or Not To Insulate....

Some info to fuel the mind....enjoy.

Will provide some additional graphics and commentary time permitting...

RB_2

Steady State vs Transient

Reality vs Theory...this is one example - Seattle....its the storm characterisitcs which throws a SIM for a loop (pun intended)...storm prediction is for a power greater than anyone I know! So we design for steady state. The Percentile is what we design for...its an odds game...if the client wants performance for 99% of all storm conditions its a different calculation than say a client who accepts 75% performance...illustrates the benifits of idling a slab for sensitive areas...

RB_2

and last but not least...

The above graphics and text below pulled with permission from a research project which can be purchsed from ASHRAE...would like to share more but we need your dollars to keep funding this stuff...If you want to purchase copies ...I think non-member prices are $30.

cut and paste this link....

http://resourcecenter.ashrae.org/store/ashrae/newstore.cgi?itemid=8231&view=item&categoryid=176&categoryparent=176&page=1&loginid=871729



anyways...if your brain is like mine some of this stuff goes in and rattles around and makes my face do wierd contortions...but never mind the mumbo jumbo...just take what makes sense to you and if you have questions let me know...





"The 99% steady-state non-exceedance loads are not closely correlated to the performance of the system under transient conditions with back losses. In other words, the heat flux required to maintain the pavement snow-free for the number
of hours with steady-state loads less than the 99% non-exceedance loads, may be anywhere from 1 to 5 times as high as the 99% non-exceedance load."

· "Many of the fluxes exceed, by significant margins, a level that is feasible to obtain in practice. The very high fluxes required indicate that, in many situations, it is
impractical to meet the design goal of maintaining a free area ratio of one at the same statistical level assumed in the steady-state analysis without idling the system. Based on the recommendations of the PMSC, we did not consider idling, as it is never or almost never utilized today."
(RB Note: Most of my collegues disagree with this statement. I have a SIM system (insulated) and use idle/on)


· "More than any other factor, the results are most sensitive to the storm itself. Storms that start off with relatively low loads, perhaps even ceasing to snow for a
few hours, then increasing in intensity, will have much lower ratios (of heat flux required under transient conditions with back losses to the 99% non-exceedance
load) than storms that start off with high loads."


· "After the storm, the results are most sensitive to the spacing. The farther apart the tubes, the more difficult it is to maintain a completely snow-free surface. Also, as
the tubes are placed deeper, the effect of spacing is less important."


· "The required design heat fluxes under transient conditions with back losses are almost completely insensitive to the soil conductivity and whether or not
insulation has been installed. Insulation is, however, useful for reducing back losses, particularly as the snow event increases in time."

Thats it for now folks...

Mark Eatherton1

So....

It would appear to me that depth of tubing has more to do with thermal performance than does insulation. In other words, if you want to spend more money on a high tech chair system that keeps the tube closer to the surface, you can skip the back side insulation. But in the real world, the one without chairs, it appears that insulation cuts the load by around 20 % for a comparitive example.

Is that your impression RB. The charts are really subject to a lot of (mis) interpretation, its really hard to say. Thanks for your input, valid as usual and always welcome.

ME

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

RB_2

The report can clear up the interpretations that I'm sure will come from the post but its fair enough to say that a significant amount energy can be consumed in heating the ground below and to the edges. Sometimes as much as 50% of the load can be in back losses particularly if the tubes are towards the bottom of the slab - but hey its just money!

There are trade off's between tubes up towards the surface vs. down low. Tubes located low in the slab have greater temperature consistency at the surface. Tube located higher the slab have less surface temperature consistency and can lead to striping. (similar to RFH)

The researchers also discuss several storm scenarios (example posted) and their influences on SIM loads and performances.

Right or wrong I like to think of heating up mass as if it were a swimming pool…what does it cost on start up…what would it cost to operate under setback if were used all the time…what if was used intermittently…what if it had a pool blanket vs not having a blanket…if our intention is to use the pool regardless of weather or usage then its maintained at steady state conditions…if we use it infrequently and can wait a few hours for it to heat up then we can idle it at a lower temperature…if we rarely use it and can wait a few days then we would shut it off. As you said, in critical areas idling make sense…I agree. My system was built up by taking the grade down to undisturbed soil, leveled and compacted, 2” Dow Blue Board, ½” tubes at 9” o.c. buried in 8” of compactable road gravel with 2” sand under the pavers. Because of the large mass and loads in Calgary we idle/on the system with a 30 °F ÄT controller and setpoints between 90°F and 140°F. The switch from low to high is based with a precip sensor. Startup times to idle temp is about 24 hours and is activated when the temp drops below 36 °F. This can be disabled manually – which we do in the spring and fall.

Here’s a photo of a lovely project which could use some snowmelt…anyone disagree? Gotta love surveyors and land developers.

Dave Stroman

All I can do is laugh!

Dave in Denver

ScottMP

As we say in Baston

Oh MY GAWD.....

What are they Tarded or somthin.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

ScottMP

By the way RB

What are your thoughts on not insulating under a slab for a construction shed that will mantain temps and at "times" have heavy equipment being brought in for service.

Thanks

SM

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mark Eatherton1

Are you near the Ocean?

I've personally never heard of this phenomenom of hoar frost on an insulated pad, but I've NOT seen everything there is to see.

Is the RH and dew point typically high in your area?

Have you tried continuous pumping without thermal input for idle when approaching dew point?

Curious Colorado minds want to know...

ME

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

RB_2

Hi Scott, I always love this question because I always get this image in my head of Dilbert with fists full of dollars bills trying to decide if he should store the money under the mattress or under a concrete slab. You can see inside his head having a conversation with himself…mattress… slab…mattress…slab ….hmmm…what to do? Sometime when I’m really having fun I imagine this group of proud citizens at a ground breaking ceremony - burying a time capsule, packed full of cash, under the slab – in some kind of holistic prepayment plan to mother earth for the use of the ground as thermal storage. Can you see them there with their shovels and hard hats? Telling each other how important it is we bury the dollars in the dirt. If you have a really good imagination make a movie picture in your head of the city’s chief accountant calculating how much money has to get buried so each heating season mother earth has enough money for 50 or so years worth of rent. Then add a sound track with a conversation between the mayor and the accountant discussing the potential value of the dollars compounded over a 50 year period…they whisper to each other (in fear of upsetting the celebration) it makes more sense to keep the dollars out of the ground but ultimately cave in to the citizens who insist mother earth needs the money more than the city….so the hole gets dug…they pour in the rent cash and then cover it over with a concrete slab. Once the movie is over in my head…I’ll then try to get a feel for how many buildings there are in North America which don’t have insulated slabs and then try to picture how many buildings in the future will be constructed without insulated slabs. What comes to mind - is if I were a bank robber…I’d be thinking there is more money stored in the ground from uninsulated slabs than all the cash in America sitting above ground behind locked doors. If I were a bad guy…I’d be taking some good old Alberta horizontal drilling techniques used in the oil patch and running some lines under the next door neighbors uninsulated heated slab and connecting it to my heat pump.

Putting on my shop designer / building owner hat, if the water table were at least six feet down, the soil of very low conductivity, the building size and footprint configured such that the first 6’ to 8’ could be insulated…then I’d be having a heart to heart with the accountant about comparing return on investment for insulating the interior portion - understanding that the dollars will get spent one way or another. Either up front as a one-time capital cost for insulation…or a long term drain as fuel consumption. If I don’t spend the cash on insulation and can make enough from investing the dollars to pay for the fuel plus a little more – then the accountant gets the money. If he can’t demonstrate a return high enough to pay for fuel then the slab gets insulated.

Does that make ‘cents’ for you?

As far as the heavy equipment...it becomes a heating load...it can be calculated as to how much energy it will consume to heat it...Tim Doran from Wirsbo can help you out with this...he'll need to have a few details about the building and equipment type and weight, plus an elemnt of time...as in 'how long is acceptable to warm it up?'

Scott, I hope this answer your questions...if not - keep asking.

RB

Troy_3

snowmelt insulation

I have also seen this in my area. When the weather is in that 32deg change over period the insulated slabs freeze very quickly. The uninsulated slabs will melt snow for quite a long period from I assume the ground heat. The grass will stack with snow for hours before the slabs start to hold any snow. That is why I have been recommending perimeter insulation down 4' into the ground. The thought being that the ground will store the solar heat gained during sunny periods. Am I way off base? I really would love to have definitive answers to these things.

leo g_13

RB

forget the snowmelt, i'd opt for driveway drying capabilities on those "cliff" dwellers!

leo g

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Kal Row

yeah..

i have been watching this thread get sillier and sillier, we need monty python’s “silly” police – the guy that comes in and brakes up a skit saying, “awh say, braaayk eet ahpp, thhhiss iss juh-sstt tu-eh sill-aaay… tu-eh sill-aaay”

there are so many variable here – with temp, frost line, degree days, moisture in ground, water table – etc – the science is weak, real weak!!!

RB_2

For under $30

You can buy the science and for less than $60 bucks you can buy ALL the science (about 567 pages ) for both steady state and non steady systems...its amazing how much science is available in exchange for cash...even practical information is included...and Kal...a significant chunk supports some of the stuff you mention. As a past SIM designer(over 1,000,000 sf to date), and user ( I have about 1400 sf at my house (see attached picture) - drives and walks)I look at the science as one way to sharpen the practical saw...can honestly say no two projects are the same...location, application, expectations...the three amigo's of SIM design...Anyways...it sounds like you could read and shred the available science...would suggest for $60 bucks you'd have in your library two awesome documents to supplement your current knowledge - take in what sounds good to you and discard the rest as silliness (ie: the mumbo jumbo Ph.D. talk)...once you digest the stuff - I'd really like to hear what you'd have to say...ASHRAE is always funding stuff like this and someone with your's and Marks perspective makes for better "real life" research.

Kal Row

you are such a teese , which book? where's the link

Tim Doran_2

Layout

Serpentine layout for snow melt?? I usually suggest a counterflow layout.

Tim D.