Insulating steam condensation returns

Brad White_201

Insulating the return piping retards the absorption of carbon dioxide into solution with the condensate. When this happens, carbonic acid can form and erode the piping, starting with the invert surfaces.

Glenn_17

Insulating steam condensation returns

I just finished insulating (with Knauf 1" fiberglass) all the main steam lines and risers up to the floors and to the vents at the ends. I insulated the returns about 4-6 foot back from the floors. That now leaves me with a lot of exposed return lines in an unfinished, mostly poured concrete floor, basement.

Is there any reason, other than the basement gets too hot, to insulate the returns further towards the boiler?

Thanks, Glenn

JJ_4

Not to disagree.....

...but my wet return, about 36 ft of it, has never been insulated since install in 1923. I just had it replaced this year as it started leaking. I won't insulate this new one because it provides just enough heat to keep the basement (one room, 22x36, finished) very comfortable all winter. I'll let the next, and maybe next, owner replace the return in 2093.

Brad White_200

Not to disagree either

Fair point, JJ. It is not an absolute. Yes, I have seen ancient piping in decent shape, but also new piping in rough shape. Different variables at work I am sure, the amount of fresh feed water being another.

Commercially and institutionally we specify Schedule 80 carbon steel for condensate for this reason. Our premise for insulating is primarily for personnel protection, so the CO2/Carbonic Acid issue never really comes up.

But a fair point nonetheless, you made!

Glenn_17

Old house too

Thanks Brad and JJ. This piping is also a very early 1900's install and when the boiler was replaced in 97, the piping was in good shape even though the asbestos had been mostly falling off (floor area is damp in summer) for at least 10 years since the house was purchased by my Dad.

Thanks again, Glenn