Steam minitube - still experimental or proven?

Rekonn

I'm a homeowner with a 2100 sqft house near Boston with single pipe steam heat. It has a spacious walkout basement that I'd like to finish someday. It would be great if I could replace the thick, suspended, headroom robbing steampipes with thin copper tubing that could be run in the basement ceiling along the floor joists.



I've seen posts and videos by Gerry Gill and a few others on steam minitube, and it looks great.

<a href="http://www.youtube.com/watch?v=d6BHXov_BW0">cast iron radiator on steam minitube</a>



But, is it still something experimental that only a few skilled plumbers are putting into their own homes? Is it something that requires a lot of adjustments? Or, when properly installed, would you consider minitube as reliable/robust as regular single pipe?



Would you put something around the 3/8" OD copper tubing to protect it from an errant drywall screw? I'm thinking something like BX for electrical cable.



Would a town home inspector allow it?



Btw, I have a post on the main wall with pics and info on my radiators and boiler if it helps to answer these questions.

gerry gill

Proven,

actually 50 years ago..just came along to late for the steam era, otherwise they would be everywhere..regaining the lost knowledge was more the issue..i consider the design to be absolutely reliable and am already offering it clients.. Looks like i may be doing an addition on an existing steam heated house with a mini tube system.. I wouldn't encase it in anything metal as it might make expansion noise.. as for the city, they really should have no issues with it at all, other than i bet you would know more about it than the inspector..when an inspector doesn't know what they are looking at they tend to want to say no..purely out of ignorance.

Rekonn

excellent

Excellent, I'm seriously considering it. But, It sounds like there isn't another homeowner that has lived with it for years that I could call as a reference. So, there is some risk. Maybe I could ask about a warranty of some kind.



Gotcha on the expansion noise. Does anyone make fiberglass insulation for that size pipe? Smallest I'm seeing so far is 1/2".



I'll definitely let a steam pro explain this and pull whatever permits are needed. I just started reading about this a couple days ago.

Eastman

PERT

Gerry,



I just saw an article that described PERT as fusion weldable plastic.  Have you considered this material for the returns in minitube?  I would think this could have the potential to significantly cut material cost.

Rekonn

max temp for PERT

I see oxygen barrier PEX has a max temp of 200 deg F, what's the max for PERT?

Eastman

PERT

Looks like it's only 200.  That's too bad.  Perhaps something else is out there that could function at the required temps. 

SWEI

Try PP-R

http://www.aquatherm.com/

Rekonn

PP-R

Meh, looks like that only goes up to 180F.

http://www.aquatherm.com/working-pressure

Rod

High Temp Plastic Tubing

Polysulfone tubing will take high heat and can be used for steam. However I'm not sure whether the availability and/or price makes makes it practical.

- Rod

SWEI

PP-R

http://www.aquatherm.com/working-pressure/hydronic-and-industrial-applications

IIRC, at zero pressure it can take 220F.  They will evaluate "other fluids" and have told me that steam condensate should not be a problem.  It would be fantastic for buried returns IMO.

SWEI

Polysulfone

is hard.  Really hard.  Never seen pipe, other than custom molded bits inside equipment.  How do you join the stuff?

Rod

Polysulfone

  The polysulfone tubing I saw was connected with compression fittings. Polysulfone is now being used a lot in fittings. Watts makes polysulfone fittings for pex tubing.  I noticed the Watts made were rated at rated at 180 F. which may be just due to the fact that they're expected to be used with pex tubing and shouldn't normally exceed the pex temp rating. Most polysulfone fitting / tubing uses are rated at 250 F and 200+ PSI.  Where I saw it used was for medical equipment and steam was being used to clean/ sterilize the tubing and equipment.

   Mini Tube wise-  Personally at this point I would stick to copper tubing as both it

and fittings are readily available. I just mentioned the polysulfone as the subject came up about using plastic tubing for steam and polysulfone, due to its high temperature tolerance,  is the only one I know that that might have future potential use in mini tube steam systems.

- Rod 

SWEI

Polysulfone fittings I'm familiar with

just had not seen the pipe.



I would not feel comfortable with Aquatherm above the waterline, even for condensate lines -- just too many ways for steam to make its way into those when something goes wrong.  Below the waterline, I think it has the potential to extend the life of a system.



Once you factor in the labor savings (over any kind of rigid pipe), 3/8" copper tubing looks cheap to me.

Eastman

erosion

Is copper corrosion erosion a concern with this type of steam application?  What about galvanic interaction?



I did see a PPR composite pipe advertised for temps up to 110 C.

gerry gill

sorry for the delay Eastman

yes, there would have to be galvanic action, however its not as much as it appears, due to being mini tube and small mains..the galvanic action relies on cathode (copper) to anode (iron) ratio..its not as much as say when someone pipes an old style system in copper with huge copper pipes. But yes, it does take place..

Rekonn

Polysulfone tubes

I was curious and looked into polysulfone tubes. Couldn't find any for purchase, so I found a plastics company that could make them and got a quote. I googled the specs for 3/8" and 1/2" copper pipe and gave those requirements to them.



They sent me a data sheet on the polysulfone plastic, Deflection Temperature under load, 264 psi (1.8 MPa), Unannealed is 345 deg F.



$11 each

.375'' OD +/-.005 x .250'' ID Ref x .063 Wall Thickness +/-.005 x 120.00'' Lg +.250 /-.000



$19.80 each

.625'' OD +/-.005 x .500'' ID Ref x .063 Wall Thickness +/-.005 x 120.00'' Lg +.250 /-.000



Do those specs look like something that can be used in place of copper pipes/tubing for steam heat?