Need to kno everything about Twintube...

The Steam Whisperer (Formerly Boilerpro)

Just came across a twintube system in need of a boiler replacement. It was obviously a very expensive system to install and was piped incorrectly.  There are leaks at the manifold with screw type clamps.  Oxygen Barrier? , expected life ?

hot_rod

Color?

Orange colored TwinTran from Heatway, or the thin walled, black colored EPDM Radiant Roll?



If it has screw clamps it is probably the TwinTran.



Yeah the connections were always a leak problem. A spring tension clamp works better as it maintains tension throughout the hot and cold cycles. At one point a small tube of rubber cement was included to help seal the connection. Stiff automotive constant tension clamps work best.



The Heatway product has been known to harden and crack, but not all of it failed and sometimes only small sections of a 200' loop failed, weird science?



The lack of an adequate O2 barrier is the biggest issue. It will continue to corrode ferrous components, use all stainless, brass, or composites if possible, and a coated expansion tank.



Keep the operating temperature as low as possible to limit O2 ingress.



Do a good power flush with Rhomar or Fernox cleaner.



And don't give, or imply any warranty

The Steam Whisperer (Formerly Boilerpro)

It's orange

I spoke to the Watts rep and he said it is pre- 1990 and the suits are settled.  Are the spring clamps available  ( 5/16 right?)  The system has a cast iron boiler, CI pumps and a mix of cast iron radiators...all on the same main supply loop.  Make take some work to split the CI rads off and maybe install a heat exchanger.

hot_rod

someone should write a book

about the colorful history of that product. I'm not sure how much info you will, or can get from Watts Radiant. Probably no repair parts



I would have guessed 1992 or 93 vintage. If enough tube is exposed it will show a date code.



I managed to "rat hole" a wide variety of tube, fitting, clamps adhesives, and manuals dating back to year one for Heatway. I'll share what I know.



I believe the TwinTran and Entran was called a 1/4" tube. Clamps and fittings changed a lot over the years. I think the first Selftite™clamp for pre 1994 vintage was a 13mm.



The 1994 catalog shows it as a 15mm clamp for Entran 3, 1/4" tube. E-3 may have been a larger OD as the tube evolved, the OD grew, which is why there are so many different clamps listed. The tube changed when Goodyear became the manufacturer, as I recall Dayco was the original manufacturer.



They make a point in all the manuals to use the correct clamp for the different vintages of tube. I'm not sure all the suppliers and installers paid attention to this detail which may have been some of the connection leak issues.



The screw clamps did not work as well as the spring type.



Actually the spring clamp with the adhesive worked well, even in glycol systems. Terrible shelf life for the adhesive was a problem.



It looks and smells a lot like the cement in tire tube repair kits. It was sold as a "industrial adhesive specially formulated to bond Entran to brass fittings" (high temperature) Hose-barb adhesive.



Don't use a typical small stainless hose clamp it will damage the tube, as it "saws" it's way to tightness.



I suspect you could go to a hose shop, or online and find a clamp like this. I took a die grinder to a pair of old vice grips to build a tool for those clamps. They had a habit of "launching" across the room or into your face.



It's a common clamp in the automotive industry, finding the correct size is the key.



My advice if you chose to try and help them out...



Inquire if the system does the job on design days. Make no performance promises.



Build a temporary test fitting and be sure all the loops still flow. They sometimes plug beyond flow, even with high pressure water or air.



Cobble together a clamp and test it to 30psi, at operating temperature.



Isolate with a plate HX or use all non ferrous components, boiler pumps, fittings, expansion, EVERYTHING.



Keep the operating temperature low, maybe a reset control.



Sometimes just removing the old fluid and adding new can put it over the edge. Some suggested flushing the original fluid also flushed the plasticizers that were keeping the tube entact.??



COD, and offer only a "tail light" warranty



Have a plan B ready if the system is not salvage-able, or you don't want your name on it.

The Steam Whisperer (Formerly Boilerpro)

Up and running

However, we can't get the leaks stopped with just cleaning up the barb and hose and a clamp.  The tube is very stiff so I think we will need some type of sealant on the tube.  It sounds like I should try the tire sealant per Hot Rod.  Also I could not find any clamps under 1/2 inch that were heavy duty.  Any suggestions.   Water still flows in the tubing, but at the manifold was about 2/3 closed up.  I am hoping with the tubing now isolated, that the debris will start slowing eroding out and we can clean out the strainers occasionally.   I am afraid of using cleaners...it may loosen up too much debris and plug the tubing.

I have plate heat exchangers, brass pumps, air separators, strainers, relief valves for the radiant floor, a new cast iron boiler with variable speed mixing pump for the main system. 

SWEI

Spring hose clamps

come in quite a range http://www.clipsandfasteners.com/Spring_Action_Hose_Clamps_s/673.htm

hot_rod

get some constant tension hose clamps

they look like this. most auto suppliers have them, O-Reilly Auto in my area does.



They tighten and hold a constant tension better than spring clamps.



If the tube is hard and brittle be very careful, maybe dry everything and use some adhesive as mentioned.



You really should flush it, I know some guys are using this Fernox pump to clean out old non-barrier tube.



Really any pressure type pump, maybe a small 1/2hp fill pump or shallow well type pump. it may need to circulate for a few days.

The Steam Whisperer (Formerly Boilerpro)

H. R. Should I use tire sealant?

Or something like form a gasket.  Should I worry about losing the plasticizers if I flush it with cleaner?

hot_rod

maybe try this

Goo. I have used it on all types of rubber and plastics. Looks and smells like rubber cement, but thicker viscosity. I think you want something that "sets", not a pipe dope or gasket sealer.



How bad (black) is the fluid in the system? if all the zones flow, I'm not sure I would flush the fluid and replace it.



If it flushes out like old motor oil, or a thick heavy sludge, it will probably not exchange heat as designed, and it may plug the HX.



If the tube is getting hard or brittle in places, not much you can do to bring it back.



I remember Heatway trying various chemicals and additives to try and keep the tube from going south. I doubt anything really worked.



The lowest possible operating pressure, of course.

The Steam Whisperer (Formerly Boilerpro)

Water condittion....

It was black, but not thick when we flushed it and after a relatively short period started coming out just about clear. So I guess we'll leave it be.

I remember that glue and will give it a try.  Thanks so much for your help!  I do very little hot water any more ( almost all steam), so I need a little help sometimes!