Pex Tubing??

timberdoodle · Post by **timberdoodle** » Thu. May. 29, 2008 10:30 pm

CAn pex tubing be used for a coal boiler installation? Looking to run from coal boiler to oil fired boiler then to zones and aqua therm hot water tak??

Someone told me pex should not be used as it cannot withstand the heat from a coal fired boiler. I just don't know

Thank you!!

Scottscoaled · Post by **Scottscoaled** » Thu. May. 29, 2008 10:48 pm

Yes, pex can be used. There are many members here who can verify that. As far has the heat from a coal boiler, water from the two boilers should both be the same temp. Unless you are using steam for your method of distribution. I would recommend using the pex with the oxygen barrier. Pex is a great moneysaver. Goodluck.

Scott

timberdoodle · Post by **timberdoodle** » Thu. May. 29, 2008 11:30 pm

Thank you very much sir!!

Scottscoaled · Post by **Scottscoaled** » Thu. May. 29, 2008 11:43 pm

Welcome to the forum. You will find a wealth of heating information here. There isn't many heating questions that can't be answered by this bunch. There are many members who qualify either by schooling or experience, or in some instances both, to reply with correctness. My answer may not be the best but it is the first. Good reading!

Scott

Freddy · Post by **Freddy** » Fri. May. 30, 2008 5:30 am

Pex-al-pex can be used in boiler systems. Do not use domestic water pex. No pex can be within 18 inches of a boiler. Stub away with iron or copper, then adapt to Pex.

Personally, I'd only use pex on a boiler system if going more than 15 or 20 feet.

Yanche · Post by **Yanche** » Fri. May. 30, 2008 11:12 am

Freddy wrote:Pex-al-pex can be used in boiler systems. Do not use domestic water pex. No pex can be within 18 inches of a boiler. Stub away with iron or copper, then adapt to Pex.

Personally, I'd only use pex on a boiler system if going more than 15 or 20 feet.

Just be sure you use PEX-AL-PEX tubing NOT PEX tubing with "oxygen barrier". The PEX tubing is polyethylene manufactured with a process the cross links the molecules that transforms the polyethylene into a thermoset plastic. If the PEX (not PEX-Al-PEX) tubing clams to have an oxygen barrier it has an additional EVOH (ethylene vinyl alcohol) layer for the oxygen diffusion barrier. It's no where near as good a oxygen barrier as the aluminum. Buy the good stuff, ASTM F1281 specs. Also avoid the rubber based tubing.

Freddy · Post by **Freddy** » Fri. May. 30, 2008 11:21 am

Much better explanation. *smile*

coalboy · Post by **coalboy** » Fri. May. 30, 2008 11:38 am

I plan on useing pex when plumbing my coal boiler in a series with my oil boiler. Would 1in diameter be big enough or should I go larger. thanks Coalboy

Bob · Post by **Bob** » Fri. May. 30, 2008 4:47 pm

coalboy wrote:I plan on useing pex when plumbing my coal boiler in a series with my oil boiler. Would 1in diameter be big enough or should I go larger. thanks Coalboy

Pex al pex and regular pex are manufactured to different standards. 1" Pex al pex has approximately the same inside diameter as 1.25' diameter pex.

The (inside) diameter you need is a function of the amount of heat to be transported, the length of the loop, and the design temperature drop. The size of the pump you use can also make a difference.

As a rough rule of thumb for a typical home installation--with perhaps 100,000 BTU per hour net output, and a loop length of less than 300 feet 1" Pex al pex should work fine. If you have doubts about your installation it is worthwile to do a more detailed calculation.

Yanche · Post by **Yanche** » Fri. May. 30, 2008 8:08 pm

My rule of thumb is, for a given boiler the supply and return piping should not be less than one pipe size smaller than the boiler tapping. So 1 inch supply piping would only be appropriate for smaller sized boilers. For an accurate answer you need to calculate the piping resistance and then select a circulator that has the required flow rate at the intersection of the pump curve and the system resistance curve. You can make any pipe size work, if the pump is large enough. A fire engine pump could get a lot of flow through a straw.

Devil505 · Post by **Devil505** » Sat. May. 31, 2008 9:55 am

Looking at PEX tubing to attach outside sink (hot & cold water) & add some sillcocks. Does it require special tools to work with it?

Freddy · Post by **Freddy** » Sat. May. 31, 2008 10:55 am

You'll need a pex crimper to crimp the rings onto the fittings. Factory built ones run about $130 each size. I recently bought one off eBay for $80 delivered that does 1/2" and 3/4" in one tool. The seller makes them on his CNC milling machine. I have yet to use it but it looks like a solid tool built to exacting specs. Do an ebay search for pex crimper & you'll find it.

coalboy · Post by **coalboy** » Sat. May. 31, 2008 1:36 pm

I am going to get a pex crimping tool. But I see there are two diffrent types. The stainless Steel Cinch ring.And the copper ring.Which one is better.

Freddy wrote:You'll need a pex crimper to crimp the rings onto the fittings. Factory built ones run about $130 each size. I recently bought one off eBay for $80 delivered that does 1/2" and 3/4" in one tool. The seller makes them on his CNC milling machine. I have yet to use it but it looks like a solid tool built to exacting specs. Do an ebay search for pex crimper & you'll find it.

Freddy · Post by **Freddy** » Sat. May. 31, 2008 2:18 pm

I guess it's up for debate. Some quotes from a tool website where this question was asked:

(Cinch ring)
"I have a project I am working on where several of these have snaped at the water heater transitions. I am not certain as to the cause of the failures yet but I would probably not recommend them until I figure it out why they are failing."
"They're made of stainless steel which is less prone to vibration than the soft standard brass rings. Also, SS; no problem with corrosion."

(Crimp)" the crimper exposes the entire ring while crimping so you can adjust and make every crimp perfect."

Devil505 · Post by **Devil505** » Sat. May. 31, 2008 2:34 pm

I just bought 100 ft of 1/2" PEX Red tubing for $24.95 at Lowes. I want to run a short line for hot water to a sink & the rest for cold water runs to new sillcocks I will be installing. The red should be fine for both applications, right?