Help with pipe size

joe7

<span style="font-size:12pt">I’m a new homeowner with little experience with steam heat.  I was hoping that some of the pros on this forum would be kind enough to help me with my question.</span>

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<span style="font-size:12pt">I’m renovating the whole top floor for myself.  My contractor convinced me to exchange the bulky, column cast iron radiators with recessed Surad radiators – to save valuable space.   In preparing the piping for the Sunrads, the plumber reduced the pipes to 1”.   (note: he didn’t reduce any risers. each 1” pipe goes only to a single radiator).   This got me a bit worried, since I noticed that the original pipes were wider.</span>

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<span style="font-size:12pt">He insists that 1” pipes are more than adequate for a single radiator.  (on the top floor, there will be 6 Sunrads ranging between 12 and 14(16) sections, plus 2 smaller sunrads for the bathrooms).</span>

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<span style="font-size:12pt">My system is a 1 pipe steam system.  It’s a 2 story building (plus an unfinished basement).  The mains are 2” (from the boiler until the back of the house is aprox 25’, to front - 50’).   The risers range between 1.25” to 2”.</span>

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<span style="font-size:12pt">Thank’s in advance for your guidance and advice</span>

nicholas bonham-carter

Size matters

If these were piped as 2 pipe radiators, then they might work; but a 1 pipe radiator will need enough room in the pipe for the steam to come in, and the water to exit. Why not run returns from the other end of the radiators back down to the basement floor, and into the wet return.

If you can reinstall the old cast iron radiators, they would work best, as their thermal mass will match the rest of the system, which the sun rads may not. Lower thermal mass rads will need more frequent short shots of steam to keep them warm, while cast iron can have longer, and less frequent cycles.--NBC

BobC

It could work

I assume you are going to insulate everything to death and the length of 1" pipe will be short (I would insulate those pipes if you can). For the largest Sunrads you will be on the edge, a 14 section has about 31.5 EDR rating and a 1" single pipe will supply 28 on a horizontal run so they may not get hot all the way across. If the space is well insulated and that 1" pipe is real short you will probably be ok, some of the more experienced pro's will have a better feel for how this will work than I do.



If those Sunrads had a return pipe on them the 1" pipe would be rated for an EDR of 68.



I have a single small sunrad in a second floor bath that is 1" copper from the main all the way up and aver and it works fine. That radiator only has an EDR of 17.5 but is fed by 20+ feet of 1" pipe and it works well.



Bob

JStar

Rads

Post a list of all the radiators and number of sections, and the lengths of the horizontal run-outs. We can tell you what size pipe they should be.



Maybe you should invest in a steam expert to do the work.

STEAM DOCTOR

Caution

I have seen endless jobs done by general contractors that have involved moving or recessing radiators. The results have not been pretty! Undersized pipes, poor pitch and other knuckleheading. I have made a good bit of money fixing up these problems. Do yourself a favor and get a steam pro involved. It is always cost effective and more pleasant to have it done correctly the first time.

joe7

Joe Starosielec

They are Sunrads, they will run between 12 and 14 sections.  The 1” horizontal run-outs run anywhere between1’ to 6’  Thank you!

BobC

Mind the details

Steam systems are simple but the details matter. Make sure all the piping is properly pitched and insulate it if at all

possible. Any problems you had on the second floor before may be worse after this modification, so look at the entire system nt just the work being done now. The Sunrads will lose the heat faster than the column

radiators did but if the space is well insulated that should not be to

much of a factor.



Take the cautions of the two pro's who posted after me to heart, they have a lot of experience between them. Make sure your installer backs up that work with a performance guarantee, in writing if possible.



Make sure all the piping is properly pitched and insulate it if at all possible. The Sunrads will lose the heat faster than the column radiators did but if the space is well insulated that should not be to much of a factor.



good luck,



Bob

JStar

Rads

1" run-out is only good for an 11 section SunRad. Go with 1-1/4". You MIGHT be okay with 1" pipe in the vertical rise but NOT for the horizontal run-out. In other words...use 1-1/4" the whole way. Also, if you exceed 10 feet or can't pitch it enough on the run-out, go up one size to 1-1/2".