Replacing Oversized Rad with smaller - piping question

JeffBrown

Greetings,

The 1 pipe steam rad in my living room is both oversized and in an inconvenient location.  I plan to replace the existing rad (38 EDR) with a smaller one (24 EDR) and at the same time I am going to move the location into a corner.



The existing 38 EDR rad uses a larger supply pipe than the other rads in my house.  I imagine this is because the larger rads need a larger supply pipe.



My question is how do I size the supply pipe for the new, smaller, rad?



My plan is to reuse the existing supply pipe, add a 90deg elbow and extend the supply pipe to the new rad location.  But I am wondering if the existing supply pipe is going to be too large for the new smaller rad?  If it is, can I just reduce the supply pipe size using an eccentric reducer?



I am not certain how to measure the pipe sizes, but the larger pipe that feeds the existing 38 EDR rad measures 6" circumference.  The other smaller rads in my system use supply pipes of 5" circumference.  These smaller rads in my system range between 12-24 EDR



In general, what can happen if you use a supply pipe that is too big or too small?  I imagine it would cause the rad to heat too fast or too slow depending on the specifics



Thanks!



--jeff

KC_Jones

Size vs. slope

I am just a homeowner, but what I have learned here is in your situation over sizing the pipe isn't going to be a problem.  The vent on the rad pretty much dictates how fast it will heat.  If it ends up heating too fast for you put a smaller vent on it and vice versa.  Think of it this way an electrical outlet in your house is rated for 15 or 20 amps, but if you plug in a 1 amp device it doesn't blow up.  The pipe would act similar it is capable of supplying a certain amount of steam that doesn't mean it will force the steam into the rad, the radiator will use what it can based on the vent it has.  Another way to think about it is if you block the vent entirely.  If the air can't get out doesn't matter how big the pipe is the steam isn't coming in.  The bigger issue is slope.  You need to make sure your extension has good slope back to the main to avoid any banging.  It should slope 1" for every 10' of run since this is a counter flow situation.  So basically any none vertical pipe feeding that radiator should have this amount of slope.

Mark N

Moving a Rad

Why is its location inconvenient? They are usually placed under windows where heat loss is the greatest. Did you do a heat loss to determine that the new rad will provide enough heat. A horizontal pipe feeding the new rad is a recipe for disaster if the pitch is not right. I would put a smaller vent in the rad to slow how fast it heats and leave it alone. If this is not done exactly right it will hammer and not heat properly. Post some picture of what you want to do.

Fred

Don't be afraid

Don't be afraid to move that radiator. There are a multitude of reasons why radiators must be moved to accommodate current living requirements. I've had to move 3 of mine, over the years. You look for options to leave them where they are before tackling the job but sometimes it just has to happen. Follow the pitch instructions that KC provided above and you'll be fine. As to reducing the radiator size, make sure you really do need to downsize it. The larger radiator, with a smaller vent will give you many more heating options for that room than a small radiator that's max'ed out.

JeffBrown

Inconvenient because....

The room is narrow and due to the location of the radiator my couch is pushed into the room by about a foot.  Moving the rad into a corner will open up the room and make it more usable.  Yes I know the rad is probably in an ideal location under the windows, but it's in the way of the people trying to live here.



Ultimately, I am going to do this so no point in trying to dissuade me. 



I didn't do a heat calc, however I can tell you that the 38 EDR rad has never heated all the way across.  I have a #4 vent on it because it's in the same room as the thermostat.  I am going to (safely) make the assumption that I could theoretically make due with a rad half the size, but I upped the EDR a bit just in case.



The system is currently pretty perfectly balanced....ive got a giant gorton on the mains and varying size vents on the rads and everything heats quickly and evenly without any untoward noises.



So for the above reasons I am confident I am making the right call



--jeff

Mark N

Rad size

What is the width of the rad? Post a picture. My rads are of the modern thin type only 4 inches wide. Maybe a thin rad in the same place will work.

KC_Jones

Not trying to talk you out of it

But if I am interpreting you correctly you have a window a radiator and your couch in front of that.  If that is correct be aware once you move that rad away from the window, you will notice all the cold coming from that window on the back of your neck when you sit on the couch.  That radiator is providing a nice warm barrier between you and that window increasing your comfort.  Not attempting to talk you out of it just pointing out one thing you may not have thought about.  I do a ton of remodeling in my house so I can relate to moving things around and agree with Fred don't be afraid as long as it's done properly.

JeffBrown

existing radiator type

U S Radiator Co, 2 column, 17 sections, 22" tall (or whatever that size's technical height is)



Sorry I don't have a pic handy...but pretty much this style



http://media-cache-ak0.pinimg.com/236x/c3/13/20/c313205f147341866598184d29e1642a.jpg



I thought about a thinner one like maybe a 3 tube slenderized version but you don't really gain much space if you reuse the existing floor hole....and even if I moved the hold closer to the wall you are still losing wall space



I love my house but one of the things I DONT like is the narrow dimensions of this room....so the solution of moving the rad into a corner and changing from a short-long rad to a tall-narrow rad will gain me some sanity without adding an addition to the room



I also considered in wall 'sun rad' rads under each of the windows.  I can get enough BTU but it involved ripping the wall apart and replacing trim and all that fun stuff....corner rad is much simpler



Had a plumber take a look and he said he'd just use the same size supply pipe (1.25) and not bother to downsize.  he also told me to mind the pitch without my asking

--jeff

JeffBrown

10-4

I thought of the cold emanating via the windows....but remember this rad usually only heats maybe 4 sections before the thermostat is satisfied so removing the rad to another location is not going to make a huge difference in this regard



--jeff

KC_Jones

I have something similar

In my house so I took out a wall and opened up the room...lol.  Not something everyone can do though.  Good luck with your project sounds like you have put a lot of thought into it!

JeffBrown

less walls = more happiness

maybe some day...though in this room 2 walls are exterior, the other one is open to the hall, and the 4th wall is about 50% brick fireplace/chimney...limited options without turning the front porch into living space



maybe next weekend! 

KC_Jones

Porches

Are already outdoor living space!  I was lucky my house had the old 2 parlor set up in the front.  The wall dividing them wasn't load bearing so it eventually came out.  I keep telling my wife "Imagine how boring our home life would be if we didn't have this old house to fix up".  Then all 3 kids start screaming and the chaos begins.  lol

Jamie Hall

To get back

to the original question -- the only thing you have to worry about at all with regard to the piping is to make sure that the pipe is big enough and that it slopes enough.  A bigger pipe doesn't have to slope quite so steeply, so there might be something to be said with staying with a bigger pipe -- but there are a lot of possibilities there.  Anyway, there's no problem with a bigger pipe than is needed (well, within reason!).  Just make sure of the pitch...

New Hampshire DIYer

Radiator location will be fine

I have a big 1850s house with huge double-hung windows--they're 38"x84" or the size of most doors. The windows are original, weather-stripped with metal, and have good-quality combo storms. But they have uninsulated sash weight pockets and certainly prone to some air infiltration. There's no room for a radiator underneath these windows--they start just 10" from the floor. So my radiators were apparently placed years ago wherever they made the most sense from a room or piping layout perspective--they are variously in a corner, on an outside wall, on an inside wall, near a window, across the room from a window....you get the point. My experience is that radiant steam heat seems to be very forgiving of rad placement.

JeffBrown

that is my experience as well

My last apartment was a 1910's 2 family.  Steam rads in each room but none were under or near windows.  Never had an issue with hot/cold areas