# PEX  pipe temperature



## Bullet (Nov 25, 2010)

What type of pex pipe to use  that can handle the heat from a wood boiler ?  I have all copper and black iron in my home . I might be wrong but I didn't think that the pex pipe could handle the  temperature that a wood boiler can put out .


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## bigburner (Nov 25, 2010)

Ya, super heated steam is a little hard on it, tends to melt about 250 + . But for hot water this stuff is the bomb, I have  installed several hundred miles of the stuff with zero issues. lot of the systems that are on here sound like they are below about 180F which is well within the safe operating range of the pipe. My system can run to about 240F, but we use a mix valve installed back wards to limit the water going to pex to 180F. HDPE - comes in many flavors PEX is the one used for hot water,but it's used, for sewers, water mains,gas lines etc. It is the single best product to hit the plumbing world in the last four decades since the introduction of PVC. there where scores of inferior products that came first. A lot of pipe buried in concrete or walls that didn't work as advertised.


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## juddspaintballs (Nov 25, 2010)

Most outdoor wood boilers heat the water to 180 degrees and have a high temperature safety at 190 degrees.  Use regular oxygen barrier PEX rated for 180 degrees.


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## stee6043 (Nov 25, 2010)

My Pex-AL-Pex has seen 210 once or twice and showed no signs of stress...


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## heaterman (Nov 25, 2010)

Actually pex will take some pretty impressive temperatures as long as there is little to no pressure along with it. Throw a piece in a fire and observe how long it takes to start distorting let alone burning.


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## 91LMS (Nov 2, 2011)

so instead of starting a new thread.....

i am ready to hook my radiant floor to my wood boiler with 3/4" pex.....  i want to go with oxygen barrier tubing however i see 3 types available and a wide range of prices.  will regular oxygen barrier pex cut it, is therma pex better?  by the looks pex-al-pex is crazy money compared to the cheaper end of the scale.  why are there 3 grades if they all cover the same temp range and have oxygen barrier in them?


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## bupalos (Nov 2, 2011)

Pex-al-pex is a more robust oxygen protection and it holds the shape you bend it to, which eases installation in certain cases. When I bought mine it wasn't that much premium to the coated stuff.


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## 91LMS (Nov 2, 2011)

also was suggested that i use 1/2" for radiant flooring by one wholesaler i contacted for pricing.  i have seen 3/4" and 7/8" suggested as well.  would 1/2" heat better with no storage as it moves a slower volume of water?


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## Hunderliggur (Nov 3, 2011)

I used 7/8" PEX in my three under wood floor zones.  You need to move BTU's, which are carried by pounds of water.  The large pipe caries more BTU's/foot.  You need to properly size your radiant distribution to get the BTUs into the area you want them as fast as you need them.  You will need a heat loss calculation for each room/zone and then size your distribution from there.

My domestic hot and cold water is all 1/2 pex from the manifold in the basement to the individual fixtures.  1/2" is easy to route.  7/8" PEX for radiant was a little challenging even through web floor trusses but it works very well in my application.  The Radiant Company has some good information and supplies available. http://www.radiantcompany.com/details/joists.shtml  shows my type of installation.


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## 91LMS (Nov 3, 2011)

i have not done a heat loss calculation however i will have my 3/4" advantec with 3/4" oak layed on top of that.  the room has a 12' wall and cathedral ceiling so i am thinking i should go with 7/8" tubing to make sure i can keep up with the heating demands.  quite a learing curve with this stuff, especially with hooking up to a wood boiler.  hoping i can get a handle on determining the actual demands, required flow, etc. of this heating system right off.  seeing how the heating season has already started, lol.

and yes that will be my type of installation.  12" engineered truss 16" on center that will be insulated from the basement.


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## 91LMS (Nov 4, 2011)

also see that 1/2" is much more commonly carried by heating wholesalers.  almost no stock of 7/8" available.  i see some installs that double run of 1/2" for 16 on center.  any thoughts on which would be better?


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