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clasact 09-28-2008 07:14 AM

what kind of pipe to use
 
I am going to make a new driveway and I want to put some kind of radiant heat through it( wife is to small and I work to much to get out a shovel snow all winter).The pipe will be hooked to a small boiler and it must be able to withstand alot of weight.I park my semi in the drive when I am home so it will be buried in 4-6 inches of concrete with a crushed stone base.What I need to know is what kind of pipe will hold up best for this,I was thinking pex since I have so much but I am not sure it will withstand the weight and suggestions Thanks




This could be in the wrong section but I thought plumbers would know best

Termite 09-28-2008 09:27 AM

Radiant heat/snowmelt systems are normally done with PEX.

By the way, if you're parking a semi on it, you'd better pour that driveway at least 6" thick. I wouldn't consider 4"!

yesitsconcrete 09-28-2008 09:35 AM

'mite might even be a little optimistic on his suggestions,,, static ( parked ) loads weigh MUCH more than dynamic ( rolling ),,, at the least, we'd use 8" 4,000psi w/air for the rig's parking area & the pathway leading to it,,, perhaps even steed reinforced under the tractor,,, pay close attn to the base thickness & compaction, too.

clasact 09-28-2008 09:55 AM

the driveway company suggested driven in 3/4 inch re-bar every 2 ft then 2 layers of reinforced mess on top of a 12 inch base of limestone mixed with limestone dust.They said that the dust once wetted would act as another level of support the the 6in of concrete with a drain in the center but they had no ideal what pipe to use since they had not done anything like this before.I am a little limited to the companies I can use since most want to put down asphalt.I just wasn't sure weather pex would hold up in this application or if their was some kind of reinforced piping for this Thanks

yesitsconcrete 09-28-2008 11:12 AM

vertical rebar's useless in this application imn-s-hfo - columns & pillars, yes, flatwork/bdge, no.

welded wire mesh has 2 functions - 1, gives conc strength while its in tension ( green curing ); & 2, holds the broken pcs in place after cured cracking,,, as i recall, limestone's not high on compressible strength but i'll bow to dick's knowledge on this - if its used locally for hvy-duty pvmts, probably ok,,, ck w/dot to see what they spec for road base mtl,,, stonedust & fines hold aggregate in place - moisture's good to aid compaction.

why a drain ??? pex's fine & very suitable to this application,,, btw, municipal wtr's temp's usually 68f,,, just circulating ambient wtr thru the pipes saves on heating it.

clasact 09-28-2008 12:15 PM

the drain is so when melting the heavy snow loads ( last year 72inches total) it wont just run to the yard or even worse toward the house.Also in the summer washing the car or using the acid on my big truck it wont run into the wifes flowers
temp around here drop below zero at least 30 day each year in the winter really sucks cant wait to move back down south

thank you both for confirming my use of pex just hope I can get to it before winter sets in this year its coming fast

yesitsconcrete 09-28-2008 12:23 PM

got it,,, the apron stores have drain boxes w/cutouts to fit 4" ads flex pvc,,, wtf's acid for ??? on the tractor ??? can't think of anything other'n battery,,, any acid on the conc = T R O U B L E ! ! !

clasact 09-28-2008 12:47 PM

use acid to clean the chrome it cuts the grease and road film make everything shine. I was told by the local truck wash that a sealer on the concrete will help with the effects of the acid

yesitsconcrete 09-29-2008 07:58 AM

understand use but sealer's not permanent nor will it protect against muriatic ( hydrochloric ) acid,,, perhaps the truck wash'd guarantee it but i wouldn't,,, have the burn in front of my garage on new conc to prove my point :furious: my sealer's better'n what you could buy, too !

IF you run water to further dilute dripping acid, that'd probably be ok BUT flush it OFF the conc - DON'T let it sit ! ! !

Marvin Gardens 09-30-2008 10:26 PM

If you use pex with any ferrous components then use barrier pex. It keeps oxygen from being absorbed into the system which regular pix will allow.

Both types will allow propylene glycol for freeze protection.

Don't have any connections in the slab. Use one contiguous piece.

I suggest 3/8 inch and keep it close to each other. It is easier to bend and does the job just fine.

Never let pex be in the sunlight for more than 30 days total. It will deteriorate so all of it should be buried or insulated from the sun.

Make a good slab and use rebar. If the slab cracks then more than likely the pex will be broken and your radiant heat project is toast. Some people have put the pex under the slab rather than in the slab for this reason.

YerDugliness 10-01-2008 09:28 PM

Consider this product
 
Quote:

Originally Posted by clasact (Post 161838)
I am going to make a new driveway and I want to put some kind of radiant heat through it( wife is to small and I work to much to get out a shovel snow all winter).The pipe will be hooked to a small boiler and it must be able to withstand alot of weight.I park my semi in the drive when I am home so it will be buried in 4-6 inches of concrete with a crushed stone base.What I need to know is what kind of pipe will hold up best for this,I was thinking pex since I have so much but I am not sure it will withstand the weight and suggestions Thanks

A company called Watts Radiant makes a product intended for just this purpose, it's called Onix. It resembles a 5-ply garden hose and is used for both radiant floor home-heating systems and for driveways like you suggested.

The problem I see with PEX would be that it might be somewhat prone to cracking if encased in concrete that is not of adequate thickness to prevent flexing from the load of that semi-tractor. I wonder if this Onix might be just the product for this project. I saw a photo of this Onix product being doubled back on itself, it looks like it is as flexible as a garden hose and it looked like a 12" piece was more than enough for this, so it can take a pretty severe bend without rupturing, ought to stand a bit of flex from the weight of that semi.

Here's a link to their snow-melting web page:

http://www.wattsradiant.com/homeowner/snowmelting.asp

Hope this helps...

Dugly :cool:

YerDugliness 10-01-2008 09:43 PM

Quote:

Originally Posted by Marvin Gardens (Post 167004)
Make a good slab and use rebar. If the slab cracks then more than likely the pex will be broken and your radiant heat project is toast. Some people have put the pex under the slab rather than in the slab for this reason.

If one were to use this approach, wouldn't it be best to install some sort of radiant barrier under the PEX? Just curious, I've never thought of putting it under the slab....intriguing!

Dugly :cool:

clasact 10-01-2008 10:03 PM

thanks I will check it out and let yall know how it works out

YerDugliness 10-01-2008 10:38 PM

Quote:

Originally Posted by clasact (Post 167467)
thanks I will check it out and let yall know how it works out

You're welcome. If it looks like something you'd like to use, call the 800 number for Watts Radiant and ask to speak with "hydronic support". I spoke with a gentleman named Jonathan, he emailed me all the info he needed to help design the underfloor radiant heat system I'm planning for my vacation home. This is one great service, they offer free system design and I'd suspect they can tell you what concrete thickness and base support you'll need for your project--not sure if they have worked with the weight loads you've mentioned, but I'm sure they will know.....

Dugly :cool:

Marvin Gardens 10-01-2008 10:44 PM

Quote:

Originally Posted by YerDugliness (Post 167460)
If one were to use this approach, wouldn't it be best to install some sort of radiant barrier under the PEX? Just curious, I've never thought of putting it under the slab....intriguing!

Dugly :cool:

I always recommend sand around pex buried in the ground. It prevents voids and voids are insulation and will cut the heat transfer. Once the sand gets warm it will stay warm for a long time. In cement it is in contact with the slab as the concrete cures it gets tighter.

Heating a slab would be slower than if the pex were only 2 inches below the surface. But it would retain the heat longer since the ground is a great thermal mass. This would allow for heating once a week on a regular basis and controlled with a timer rather than having a set up to turn it on when there is snow and off when there isn't either manually or via a moisture sensor and thermostat. Snow and ice wouldn't even form with a constantly warm slab.


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