What Temp PEX Pipe

BigFoot · Post by **BigFoot** » Wed. Jan. 30, 2013 8:14 pm

Adding a airhandler in the garage ,139,000 BTU olny 18"X23" ,it will be zone2 on my AA130 .Looking at PEX 3/4 it add it to my supplied PEX 3/4 ,i think the PEX supply is good to 220F and all I can find to add says 200F will this be good ? Irun at 180F in boiler , and my run is 85 FT , says 1/2 degree loss?

Wiz · Post by **Wiz** » Wed. Jan. 30, 2013 9:04 pm

I would use black iron pipe then put insulation around it. Friend is using pex and his issue is sagging, he just added more hangers. Not sure what temp it's rated

Yanche · Post by **Yanche** » Wed. Jan. 30, 2013 11:43 pm

I too would use schedule 40 steel pipe or copper.

The PEX temperature specs taken from several manufacturer's data sheets:

PEX-AL-PEX Manufactured to ASTM F-1281 is 200 deg F at 100 psi for http://www.alliedpipesystems.com/ brand.

Vanguard COMPAX-L Brand PAX-AL-PAX. Design temperature and pressure ratings for COMPAX-L is 200 psi @ 73°F and 125 psi @ 180°F.

IF YOU USE PEX BE SURE YOU GET THE SPEC SHEET AND UNDERSTAND EVERY TECHNICAL DETAIL ON IT. BE AS NIT PICKING AS A "AEROSPACE ENGINEER"

AGAIN USE ... Schedule 40 steel or copper!

Freddy · Post by **Freddy** » Thu. Jan. 31, 2013 6:20 am

You may ask your boiler to run at 180, but a coal boiler can easily go far above that. I added tempering valves so my pex never sees above 180.

RAYJAY · Post by **RAYJAY** » Thu. Jan. 31, 2013 7:48 am

Freddy wrote:You may ask your boiler to run at 180, but a coal boiler can easily go far above that. I added tempering valves so my pex never sees above 180.

freddy how do you add the tempering valves on a hot water system never heard of it

jeff

Dennis · Post by **Dennis** » Thu. Jan. 31, 2013 8:08 am

RAYJAY wrote:
Freddy wrote:You may ask your boiler to run at 180, but a coal boiler can easily go far above that. I added tempering valves so my pex never sees above 180.
freddy how do you add the tempering valves on a hot water system never heard of it

jeff

Freddy,Can you also answer where the cool/cold water comes from when the boiler water is hotter then the Pex temp limits

Dennis · Post by **Dennis** » Thu. Jan. 31, 2013 8:13 am

Yanche wrote:The PEX temperature specs taken from several manufacturer's data sheets:

Yanche wrote:PEX-AL-PEX Manufactured to ASTM F-1281 is 200 deg F at 100 psi

So what if your water temp is higher that the specs,but you have 15 psi, would that meean you could have higher or lower temps than the specs allow before meltdown
It's very hard to keep a hand feed boiler at a specific temp with crazy weather conditions and having 100 lbs of glowing coal with no thermostat calling for heat just idiling

Edit:I will be needing 130' run of PAP 1- 1/4" in burried conduit

plumb-r · Post by **plumb-r** » Thu. Jan. 31, 2013 8:29 am

Pex or even aluma-pex is a bad idea put a little money and labor into it and make it steel or copper. It will serve you better, with less problems.

Post by **Rob R.** » Thu. Jan. 31, 2013 8:57 am

85' total or each way?

If it was 85' total, I'd just pipe it in black iron and be done with it. 170'....I'd consider pex and a mixing valve.

Dennis · Post by **Dennis** » Thu. Jan. 31, 2013 9:03 am

Rob R. wrote:85' total or each way?

If it was 85' total, I'd just pipe it in black iron and be done with it. 170'....I'd consider pex and a mixing valve.

130', 1 way burried approx 3' deep ?,under basement floor,under house footer,under concrete slab,under walk out deck,all dug by hand,then across the back yard crossing under 9 burried pvc and drainage pipes then under garage footer and done backhoe and hand

plumber · Post by **plumber** » Thu. Jan. 31, 2013 9:27 am

RAYJAY wrote:
Freddy wrote:You may ask your boiler to run at 180, but a coal boiler can easily go far above that. I added tempering valves so my pex never sees above 180.
freddy how do you add the tempering valves on a hot water system never heard of it

jeff

You can use a three way or four way mixing valve.
A three way valve mixes the hot supply water with the cooler return water to recycle it back to the system.
A four way valve does the same, but returns the excess back to the boiler accomplishing the same as a boiler bypass.
They can be thermostatic or electronically actuated.

Yanche · Post by **Yanche** » Thu. Jan. 31, 2013 11:47 am

Dennis wrote:
Rob R. wrote:85' total or each way?

If it was 85' total, I'd just pipe it in black iron and be done with it. 170'....I'd consider pex and a mixing valve.
130', 1 way burried approx 3' deep ?,under basement floor,under house footer,under concrete slab,under walk out deck,all dug by hand,then across the back yard crossing under 9 burried pvc and drainage pipes then under garage footer and done backhoe and hand

Wow. All the more reason in my opinion to use a very durable piping material like steel pipe. Be sure to do a water flow analysis to be sure you can move the BTU's needed. Use real engineering analysis not just cook books. All that pipe or tubing plus insulation will be expensive and you don't want to oversize it, needlessly. Any chance you could put it in a chase so that it could be repaired without having to dig it all up again? I wouldn't want to re-do that job.