Homemade preheated question

[markr]

I am thinking of making a homemade preheater and a friend of mine suggested that I use the piping for radiant heat flooring instead of copper. It would be a lot cheaper as he has a bunch of it. I would do this but I have a couple questions about it. 1 - Do you think it would conduct heat the same and 2- Do you think it would hold up to the heat. I would hate to go to all the work for nothing. Any input would be greatly appreciated. Thanks

[wiam]

I so not believe it would transfer heat as well as copper.

[325abn]

I was just looking into using PEX as a preheater this past weekend. Once I read the the heat transfer coefficent of copper was about 200 times greater than that of PEX I stopped reading.

I have 1000 feet of 5/8 Pexalpex in my slab and love the heat but as a pre heater I dont think you are gonna beat copper.

[Johnny Yooper]

I'm not a plumber by trade, but I have worked with what is typically referred to as PEX piping: I put PEX in my 2000 sq. ft. slab but I'm not running very hot water through that system, it's less than 130F. PEX is common for plumbing houses now, I'm sure they use it for hot water baseboard heating, which is typically 180F. The underground portion of the feed/return lines from my outdoor boiler to the house are a PEX type material and have been operating non stop since Nov. 2004 (I run year round as I continue to heat my domestic water throughout the summer) and in the coldest winter months I crank the temperature up to 190 - 195F so I know some versions of that piping are rated for it. Nonetheless, I'm not sure what your design entails or how close your piping would be to the heat source, but in this type of application copper is the winner. I just completed an oil tank arch build and made a preheater from 20 ft. of copper tubing wrapped around the stack. If it quits snowing this month maybe I'll get a chance to fire it up! Good Luck!

[jake22si]

Yup, pex will burn if you wrap it around your stack, unless you have another idea of heating it?

[markr]

Thanks for all of the input I was planning to make a hood and put it under it but after all the feedback I think I'll just stick with copper