# Pex Pipe or copper?



## 68dodgeramman (Nov 12, 2009)

I got a question for ya, actually a couple, here goes. Can I use Pex pipe instead of copper to go from the boiler in the attached garage to the heat exchanger and side arm in the basement? And if so, does it need to be installed in a relatively straight line like copper does? I mean when I get in to the basement can I just go diagonally to the heat exchanger in the furnace? Also in the garage I plan a hydronic heat unit. The garage is 840 sq. ft. what size heater do I need? Would 60,000 Btu be enough? The garage is attached and well insulated. Thanks again.


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## Tony H (Nov 12, 2009)

you can run pex instead of copper and it should be a fair amount less expensive depending on the size you need . In my install we used copper at both ends and pex for the long haul from the boiler to the furnace and hot water heater. At the hwh furnace end we stopped about 6' from the hwh and used copper from there on 
in that stretch we have the auto fill valve, a back-flow prevention valve, a couple of drain valves  high and low, a bypass using 3 valves so I can run in the summer hot water and bypass the hx in the furnace , sidearm and shutoffs for the 2 lines from the boiler.
As you can see with all the different connections couplings and such it works much better to use copper for these connections and there are a similar set of connections at the boiler where we used copper and even some cast iron to connect a temp pressure gauge, shut offs, connect to overheat zone , air scoop, expansion tank, drain , pump, termovar bypass and who knows what else.

With the running of the pipe I am an old cable systems designer installer , power , telephone , date , video , fiber and the only way I can run cable or piped is straight where all corners are 90's square and secured. We used to get some new guys that would run what we called "cross country" cables and we would make them pull them out and redo it the right way. If I remember correctly with many this was required by code. Take a look at almost any professionally  done  electrical conduit or plumbing pipe and you will see what I mean. With your situation you can run diagonal pipe and it will not cause operational problems but it will be unattractive and could be a code violation I would check with your local plumbing inspector to avoid any future problems


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## Gooserider (Nov 12, 2009)

I would suggest that any "near boiler" plumbing be done w/ copper or iron, not PEX.  I think there may even be code requiring a certain minimum distance in metal before going to PEX...  Reason being that if you have an overheat situation, you will be seriously crowding the point where PEX starts getting soft, and loses it's strength - I've heard of people that tied to the boiler and melted off the connections, which obviously makes a bad situation even worse...

My own personal suggestion is that you are best off to be in metal for the piping between the boiler and storage (assuming the two are close to each other) and PEX from the storage out...

Gooserider


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## stee6043 (Nov 12, 2009)

All of my near boiler piping, including my bypass, are black iron.  I wouldn't go PEX right off the boiler for the reasons mentioned above.  I built a supply and return manifold out of black pipe and ran PEX from there to my water-to-air HX in the furnace.  Works great....


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## Mushroom Man (Nov 12, 2009)

I am still in the midst of plumbing so my opinion can be taken with a grain of salt.

If I had it to do again. I'd go with Black iron for the boiler loop because that won't change in all likelihood. 

I'd use copper for the primary loop because that might change and leaks can be easily remedied. I'd use copper around water to air heat exchanger and sidearm to keep things neat. Big pex has wide turning circles so looks stupid when in place. Looks so stupid that I'll re-do in the basement next summer.

Copper is hard to beat for modifying whereas the other two are somewhat difficult to modify. The great irony of my installation is that I didn't use copper yet.

 I'd use pex for the underground runs or long secondaries. 

At the time I purchased a lot of materials, copper was pricey; still is, but it has come down in price.


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