Snowmelting questions

Bob Murray

My fellow wetheads...

I am about to install my very first snowmelting system. I have a couple questions if you don't mind.
I will be heating an area approx. 1600 sq. ft. (40 x 40). 140 deg supply temp, 8"c-c, 8-300" loops 5/8" pex.

This will be going under asphalt. I was told to put a layer of sand 2-3", then bfb bubble insulation, 6" flat wire mesh, tubing, another 2-3" of sand, then asphalt (with cold water flowing through tubing during and 8 hours after pour).

Questions:
Is the sand a good enough base just under the asphalt? I was thinking of stone dust as the top layer. It would pack real nice for the asphalt.
Is stone dust OK packed around pex? Is it fine enough to not do any damage to the tubing during expansion and contraction?

Is their another preffered way to do this? Please don't tell me concrete. The job WILL be asphalt.

Thanks for any input.

Bob Murray
Yankee P+H
Tuftonboro, NH

Mark Eatherton1

Sorry about the screw up.

ME

Mark Eatherton1

Check this out Bob...

I found it with a Google search using the words 'asphalt snowmelt'. There are others there too.

Make sure you get ALL the water out of the tubes prior to inducing rubbing alcohol. Did I say rubbing alcohol???

NEVAH MIND... I must have been thinking geo-thermal...


http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,4137,00.html


ME

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Troy_3

bob

I'm sure some will disagree with me and it does depend on the agrigate in the asphalt but I have done this without sand to protect the tube. We put down 6" x 6" flay wire mesh tied the tubes to the mesh and the hot asphalt was wheel barrowed and hand tamped over the tubes. We did run cold water through the tubes during the asphalt placement. However we did a little experiment with a piece of tube in the wheel barrow. We put hot asphalt 6" over the tube with no water and the oxygen barrier was not even degraded. I would still feel safer with cold water flowing. Anyway I wouldn't deminish the heat transfer rate and add this extra step of imbedding the tube in sand. I can tell you we did this job last fall and in Buffalo NY we received 3' of snow in a day and this baby melted like a champ. I swear it melted faster than the concrete jobs we've done. We used 3/4" tube on 300' loops. Good luck. That's just my experience.

Mike Kraft

Troy,Stupid ? here

While circulating the cold H2O do you leave the draw off open on the returns of the loops?

cheese

Bob Murray

Thanks for your responses guys...All information recieved so far has helped alot and is very valuable. Anyone else care to put their 2 cents in?

Bob

Troy_3

cheese

> While circulating the cold H2O do you leave the

> draw off open on the returns of the

> loops?

>

> cheese



I
'm not sure what you mean. We did let the water run freely out of the return header if that is the question. The supply was fed with a garden hose and had continuous cold water feeding it during the pour. My point was even without cold water in the tube during our little test the tube did not distort.

Canuck

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