Same size steam heating supply and return lines?

djthx

<span style="font-size:12pt">As luck will have it, I was able to get a nice, used Smith GB 4L-S-INT replacement steam boiler for my home .  I'm installing all new around the boiler piping, and planned to put a 3" dropped header off the 2" riser, leading to a 1 1/2" equalizer.  However, after contacting the manufacturer, a rep stated that </span>

<span><span style="color:#000080">........boiler piping indicates a 2” piping size across the board for this unit (this includes riser, header, equalizer, hartford loop, and even for the return line.)</span></span>

From what I understood, in steam heat piping, the returns should be smaller.  Furthermore, the wet return lines (the ones I didn't plan on replacing) are 1".  Is it heard of to use 2" all around?  May I still add a 3" (or 2 1/2") dropped header?  If I go with the 2" return (from the boiler), where should I make the transition to the 1" return lines?

Another question, the manual indicates a cold water fill.  Doesn't this pose a thermal shock risk whenever the hot boiler is cold water fed?  Is there anything wrong with hot water fill? 

Thanks. 

nicholas bonham-carter

cold water fill?

no one here seems comfortable with hot water fill, and when we have water supply problems to a fixture, it always seems to be the hot side liming up, but not the cold side so much.

pipe the water feed well into the returns, so the cold fill water is mixed well with hot returning condensate, and you should be alright.

as far as return diameter goes, generally the mfg. has the final word on pipe layout and sizes. one benefit of the smaller dia. vertical wet-return would be less water volume leaving the boiler as pressure rises, and pushes water up into the returns. however, at the bottom of the wet returns, i would always like a greater dia. pipe which would be less likely to plug up. some systems have a sort of drip leg installed with a full-port ball valve, at 1 end, and a hose connection at the other, for flushing out.--nbc

Charlie from wmass

I find the smith diagram works

The piping diagram works fine for their boilers. a drop header is for limited head room to get the height on your risers above the water line.

Jamie Hall

a cold water fill

would only cause problems if you added a lot of water at once to a hot boiler.  However, if you are proposing to do that, seems to me that you might have other problems... boom!