pex for single pipe radiator return?

[1870monster]

I have a really old single pipe marine style steam boiler system with radiators.(system runs a bit less than 3psi)

I wondered if there was a flexible pex type product I could use that would allow me to move a radiator easily - the only other option will mean welding a new stub on an existing line - and it is in a very awkward place. I could use the current stub - if I could use a flexible pex type product to get around the odd angle I have to deal with....any ideas?

[LazyPup]

Your boiler it technically defined as a “Low Pressure-Unattended-Saturated Steam Boiler” and per ASME (American Society of Mechanical Engineers) standards it may fire at a working pressure not to exceed 15psi.

I am really surprised that you are firing at less then 3psi. Typically they are set to fire at about 5 to 10psi, however if it is satisfying your heating needs at 3psi there is no reason to increase the pressure, however when making repairs we are required to use materials that are rated to handle the temperature at the maximum firing pressure.

At 3psi your firing temperature is 222degF but if you were to increase the pressure to the maximum 15psi the firing temperature would then be 250degF.

PEX tubing will tolerate short-term temperatures up to 200degF but it is rated for a maximum working temperature of 180degF therefore you cannot use PEX for this application.

Copper Pipe & tubing is rated for “Saturated Steam” applications therefore you can use type L roll copper pipe, which can easily be formed to work around your odd angle.

You could also use standard 50/50 tin/lead solder which has a lower melting point than the lead free solder we use for potable water systems.

Question. Are you familiar with the periodic maintenance, which should be performed on saturated live steam boilers?

[1870monster]

How might a replacement Heating system be configured?

first thanks so much for your comprehensive reply. Much appreciated.

I am somewhat familiar with maint - but please - any/all info would be appreciated.

Also - The heating system is at the end of its life and the question is: What is the best way to replace it? How do I ask for a quote? What configuration would work best?

Presently I have two quotes - one simply replaces the existing boiler with a far more efficient one.

The second is a multi-furnace confiuration - since there is no way to "zone" the house - the heat is branched Left/Right from the basement to the third floor - not broken up by floor - the idea of the multi furnace design (which includes computer controlled valves and out door temp/wind sensors) is that it would only burn the fuel we need to achieve the needed heat given the conditions - of course this seems complicated to me - probably difficult to calibrate - but makes a lot more sense then the single thermostat(!) system that controls the hungry monster in the basement now.(and actually this quote was about 10% less)

Any input would be appreciated - the sheeting and tubes in the old boiler are swiss cheese at this point and I am just praying to get through one last season before it dies. If anyone has any ideas Please let me know what additional info you may need.