[time-nuts] OT Euro/US plumbing was 14 tpi UNS die

Joseph M Gwinn gwinn at raytheon.com
Wed Jul 8 00:21:26 UTC 2009


time-nuts-bounces at febo.com wrote on 07/07/2009 05:38:52 PM:

> From:
> 
> bg at lysator.liu.se
> 
> To:
> 
> "Discussion of precise time and frequency measurement" <time-
> nuts at febo.com>
> 
> Date:
> 
> 07/07/2009 05:40 PM
> 
> Subject:
> 
> [time-nuts] OT Euro/US plumbing was  14 tpi UNS die
> 
> Sent by:
> 
> time-nuts-bounces at febo.com
> 
> > bg at lysator.liu.se wrote:
> >> Hi Chuck,
> >>
> >> Been living in Sweden my whole life. And almost exclusivly in houses
> >> heated by circulating hot water through radiators. I have yet to spot 
an
> >> O-ring.
> >>
> >> Where in Sweden did you see this strange system?
> >
> > Hi Bjorn,
> >
> > In the US, hydronic heat comes in a couple of flavors:  The old 
fashioned
> > cast iron radiators, fin/coil baseboard radiators, radiant baseboard, 
or
> > steel radiators/towel warmers imported from the Europe.
> 
> Your description does not enlighten me... there are all sorts 
> of radiators available here.
> 
> > Most of the European systems are geared towards PEX tubing, and
> > compression
> > fittings... and untapered pipe thread with jamb nuts and O-rings.
> 
> PEX tubing has been "certified", but Prisol tubing (ie soft bendable Cu
> with plastic "coating") is much more common here. Cu tube joints are 
made
> with "nut", "support cylinder" and a "squeeze ring".
> 
> > Runtal, Cordivari, Wirsbro and Wesaunard are examples I have run into.
> 
> It is actually Wirsbo... ;-) The others are unknown to me.
> 
> > Do you install and repair systems?  Or just live with them?
> 
> I do minor changes to the house system. And I have accumulated more than
> enough radiator heating seasons to know your "two seasons to 
> leak" quality must be a US craftmanship problem.

The relevant US pipe-thread standards are quite clear - straight threads 
are for mechanical connections only.  For connections that must also 
contain fluids under pressure, one uses taper threads such as the 
ubiquitous NPT.  Over the decades, I have lived in many houses, including 
my current house, with circulating hot water heat and cast iron radiators, 
and I have never had to redo a radiator connection.  I've never had a 
leak, and most of these systems were old when I bought the house. 

If you have straight pipe threads going into radiators, there is an 
installer who should be made to re-do the job.  Maybe he was an 
out-of-work electrician, and used rigid electrical conduit for pipe.

Straight threads and O rings are seen only in hydraulic systems, not 
domestic water or heating systems, and the mating parts have correctly 
designed pockets to hold the O-rings.  And they do not use jam nuts.  One 
screws them together until they bottom.

Joe Gwinn



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