Pex Tubing

I just bought a DS Stove to tie in with my oil boiler last week. Can I tie the two together using pex tube?

Most pex tubing can handle about 200 degrees F at the pressure typical for a residential boiler...copper or iron pipe would be a much safer bet...and even with rigid pipe you should have the proper controls to keep the temperature in check.

Friend did his with pexs and regrets doing it. What happens with high temps the pexs will sag like a wet noodle. I would use copper or iron pipe then insulate piping.

I am using pex-al-pex for the runs, but I have a tempering valve installed to keep the temps at 180 or below. No sag or other issues. I have an oil boiler and the coal boiler, and tied the two together with copper. If the coal boiler overshoots the temp, you could see 220*+, not a temp I would be comfortable with using pex.

What size line should I tie my two boilers together with? My big problem is that I'm about 40' away from my oil boiler. Running 1 1/2 copper pipe is going to be very expensive.

yamaha wrote:What size line should I tie my two boilers together with? My big problem is that I'm about 40' away from my oil boiler. Running 1 1/2 copper pipe is going to be very expensive.

Black Iron pipe is a good alternative. You didn't say how many gpm you need to move.

The big orange box store has good prices on black pipe and fittings. Imported of course.

make sure it is cross linked pex, for hydronic heating, and not plumbing pex. also expandable wirsbo or uponor with expanding ring is much better for high temp. situations, as the crimp rings can wear through the tube during expansion and contraction. secure it well, it is a cheap and easy alternative. I have installed thousands of feet in high temp conditions with no problems.

I wouldn't use any pex piping. Cross-link pex is only rated at 180°. Even the aluma-pex or fosta-pex is only rated to 200° and only rated to 140° in constant circulating systems. Use a metal pipe copper or steel. Do it rite the first time.

Near boiler metal, then PEX

I am using pex. After taking to the manufacturer I added tempering valves to keep the water at 180 or below. I have seen my Axeman Anderson make water of 240 degrees. I'm sure the Pex wouldn't have liked that at all.

I've decided to go with black iron pipe for my insallation. What works the best? Teflon tape or the liquid teflon to seal the fittings.

yamaha wrote:I've decided to go with black iron pipe for my insallation. What works the best? Teflon tape or the liquid teflon to seal the fittings.

i like the # 5 rector-seal or Blue Block™ Gasket and Pipe Joint Thread Sealant

yamaha wrote:What works the best? Teflon tape or the liquid teflon to seal the fittings.

Teflon tape and then rector seal. That's what I did.

I like the Blue Block also. When messing with gas or boiler stuff that's all I let my guys use. It's pretty gummy, try not to get it on you, you'll look like you got in a fight with a smurf. With black iron with pipe dope if you have a leak a lot of times it will stop when the system is heated up (things expand), if you have teflon on it you either have to redo the joint or tighten it more, either way you have to take everything apart to the joint that is leaking. That's my 2 cents worth after 30 years.

plumb-r wrote:I like the Blue Block also. When messing with gas or boiler stuff that's all I let my guys use. It's pretty gummy, try not to get it on you, you'll look like you got in a fight with a smurf. With black iron with pipe dope if you have a leak a lot of times it will stop when the system is heated up (things expand), if you have teflon on it you either have to redo the joint or tighten it more, either way you have to take everything apart to the joint that is leaking. That's my 2 cents worth after 30 years.

Thats why i will install unions in a couple of places to make breaking the pipe a little easer, and it always works out that i have to change something so can alway do that at the union

jeff