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PEX tubing embeded in asphalt driveway

The most common driveway paving material around seems to be asphalt. Why is that? Poured concrete paving can't compete?. Actually, I don't know why we see so much of it. All I know is it's a damn poor conductor of heat and a poor choice for melting off driveway snowfall. Hovever, that's the specified drive I'm working on.

I am aware of the dangers of pouring hot asphalt over embeded PEX tubing circuits. This is a major concern of mine as I have never used this type of cover before.

I have been instructed that running cold water through the circuits while the asphalt is being laid down will prevent any damage to the PEX tubing. However, it seems to me that blacktop is WAY TOO HOT. Even with cold water running through it, covered with a layer of sand. Isn't that stuff in excess of 300 deg.F. when they put it on? Then the steamroller comes along and ....... oh boy! ...... I just might have a heart attack when I see & feel what's comming out the return side of the manifold. Guys, could I be seeing some steam?

Any "real world" experience or tips from you snow melting Wallies would be of great interest to me before I get my Wethead feet wet on this one.

Thanks. (GW)


  • John MacGregor_2
    John MacGregor_2 Member Posts: 32
    Asphalt & snowmelt

    Gary, After slipping and falling on my driveway at our main shop entrance three times, and having lost two local people to slip and falls on ice up here, I decided to put snowmelt in. The asphalt people would not consider paving on it so we had to go with concrete. I've noticed since then that while my boiler is chugging away burning up gas, most of the 14,000 sq ft of blacktop has already melted. I have since added black dye to the concrete twice, but the blacktop still seems to melt faster. Your concern about melting the PEX may be well founded but the answer may be to run water thru it while the asphalt is laid down. That question probably can best be answered by your manufacturer.
  • pjb
    pjb Member Posts: 1
    pex & hottop

    The hot top people told me they will not warranty their driveway with a snowmelt system.

  • snowmelt


    In tests done by friends in Michigan, even having the coldest asphalt put down (yes you can order the temperature) AND wasting thousands of gallons of cold water, the pex was still melted 1/2 way through or better on some areas.

    Use concrete, pave over it is you muct... just like the PA Turnpike :-)

  • Radiant Wizard
    Radiant Wizard Member Posts: 159

    After the installation of the tubing, cover with a compactable soil/sand bed (typically 3 inches) prior to the pour. Your idea about running the water is a very good one. You must maintain atleast 60 lbs for your pressure test for atleast 24 hours and you must maintain atleast 60lbs during the pour. If you don't use a soil/sand bed the temp of the asphalt poured directly over the tubing must not exceed 240 degrees.
  • Wow, that's leaving money on the table and walking away

    Here's some info...


  • GAverill_2
    GAverill_2 Member Posts: 20
    Snow melt installation in asphalt

    We have supplied a few jobs that are set in asphalt, though the majority in our area are concrete.
    We do have a contractor who puts snow melt systems in tennis/basketball courts, and our vendor Infloor provides the following information on these:
    ' A maximum asphalt temperature of 270F is required. The contractor should have workmanship, tools and instruments required to install the asphalt successfully below this temperature. The addittion of small amounts of certain petroleum products to the asphalt prior to installation is said to be common practice at comparatively low asphalt temperatures. Tubes should be pressurized prior to the asphalt pour, and cold tap water should be flushing through the tubes to a drain during the pour, maintaining a static pressure between 15-40 psi (achieved by regulating a valve near the drain). The water flow through the tubes may need to be increased during the pour to ensure that a maximum water outlet temperature of 140F is maintained. Continue flushing water through the tubes until the asphalt is below 140F.' I remember watching the first tennis court we supplied go in, fearing the worst. It yet works fine, but it did take a lot of water for many, many days to accomplish this.
  • roger provencher_2
    roger provencher_2 Member Posts: 2

    we did our 3500 sq ft driveway 5 years ago following the directions from Rehau pex manufacturers, embedding the pex in stone dust as well as all of their other directions and have been happy with the results.we had no problems with the install. did not run water or anything else in the system as the asphalt was put down. just had 100# of air pressure and had no leaks. the system works great.
  • Asphalt eating PEX

    I've often heard that "PEX and asphalt do not mix since they are both petroleum products and the asphalt will break down and eat the PEX tubing over time." Anybody else heard of this?

    I wonder if there is a specific type of PEX (A/B/orC) that may be better suited for asphalt pours? It appears that some tubing manufacturers do not reccomend asphalt at all.

    I'm a bit sceptical of a 2-3in. layer of sand or stone dust as it may act as an insulator.

    Any thoughts?


  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,490
    Here's the

    original thread. Thanks.
    Retired and loving it.
This discussion has been closed.