ATTENTION STEAM EXPERTS...what size pipe?

hankwylerjr

Hello, I am installing two additional rads which are steam one pipe to my addition. I have an unused T with plug that can be removed easily. The main piping done by the deadman, is in great shape and appears to be 2 inch black pipe. No issues everything runs really well Crown boiler fairly new. My addition has two radiators one that is big and the other small I thin very light maybe made from a different metal than cast. Questions, what size black pipe do i go with off the main? I am think because the run is 33 foot maybe 1 inch? However Ive been told that a 1.25 inch coming off the main then a 1 inch from a T going to each rad? Not sure need this done fairly quick. Have access to pipe cut/thread machine and used to help as a pipe-fitter back in the late 70s. The EDR for the large is about 84 and the small is 18.64. The boiler can handle not 2 but almost 5 extra rads according to plumber who installed (he cannot work anymore as he is seriously disabled from accident) So i can do it just dont want my work to be doubled if the 1 inch doesn't









work. Attached see rad pictures thank you

JUGHNE

The 33' run you speak of, is that the length of new pipe from existing main to new rads?

KC_Jones

It's not how many extra rads it can handle, it's how much EDR. Did you request an over sized boiler?

As for pipe size, my book isn't in front of my, but I know 1" is too small for that much EDR, 1 1/4" I seem to recall is good for ~55 EDR, so you probably need to go to 1 1/2" for that much EDR.

Did you do the heat loss calculations for the rooms you are adding radiation to so they are sized appropriately? That's a fair amount of EDR, you say addition so I'm thinking modern construction insulation windows etc. That amount of EDR in modern construction would probably heat ~1000 sq ft of living space.

JohnNY

That's an 84 sq. ft. EDR radiator requiring an 1-½" supply pipe.

JUGHNE

Do you have a parallel flow main.....high point at the boiler and then main slopes down away to the end into a smaller return pipe?
How large is the plug in the tee of the main that you want to use?

If you run to that new location with out a return pipe then that is counter flow piping. It needs to have a slope back of 1" for every 10' of pipe.

There are 3 factors to calculate EDR:
The height of rad from the floor to the top,
The number of tubes or columns looking from the end of the rad, I can see you have a 5 and a 3.
The number of sections from the front view. (like slices of bread in a loaf).

Come up with that info and someone here can tell you the EDR of each.

EBEBRATT-Ed

Make sure the tee comes off the main at 45 degrees up. Make sure you pitch the pipe upward from the main 1/2"/foot. According to the Burnham Heating Helper you need 2" pipe for anything over 85 EDR especially with a 33 'run. I would use 1" branch for the small radiator and 1 1/2" for the larger one

You realize that 104 edr is 25,000 btu/ hour. Did you do a heat loss of the space? That's the first thing to do. sounds like you radiators could be oversized

JStar

If the run-out is going to be longer than 10ft horizontal, you should increase it by one pipe size. With those EDR ratings, 2" run-out would be minimum to handle both on one run. The vertical risers can be 1" and 1-1/2", but I wouldn't reduce them down smaller than 1-1/2" at any point while they're still horizontal.

JUGHNE

If he extended the main to that area and also added a return for the new area then this has a chance? But if the run out is that 33' he mentioned then pipe oversizing and drastic pitch could be an issue??

Haven't heard from OP for a while, hope we did not scare him off.

hankwylerjr

The new run yes is from the main to the new rads. The boiler can handle the extra EDR in fact I have will still have 200 extra EDR after adding these. I'm sorry I can't answer every one I'm mobile but I think that the plug off the main is 1 1/2 so I'm guessing I need to make the new run that size? Shoot a 1 inch for the small rad and a 1.25 to the large one? The run is above the boiler so a pitch of the pipes that are horizontal is in order. The room is extremely well insulation R38 in most areas new windows everything new and sealed Any other ideas? Thank you

JStar

1-1/2" will be borderline adequate for just the one bigger radiator. You'll likely have trouble getting them both to work that way.

hankwylerjr

@JStar according to @JohnNY 1 1/2 should handle up to 150.i think I'll run 1 1/2 the entire run now 27 feet after I measure it. Worst case I'll replace the bigger one with a smaller one but don't think I'll have a problem

JStar

Check that chart again. It's good for 85 EDR.

JUGHNE

And 8' horizontal maximum?
Is that for a counterflow run out?

JStar

> @JUGHNE said:
> And 8' horizontal maximum?
> Is that for a counterflow run out?

Yep. Parallel flow mains have a different rating chart.

Hap_Hazzard

I assume that's what "riser not dripped" means.

hankwylerjr

@JStar your correct, but because of the work involved, I probably won't run a 2inch I'll have to take a chance see how it works. If it doesn't I'll downsize that rad with an extra I have in storage. Getting older running low on funds after the addition. To be honest, I think it would be OK but I've been wrong before

JUGHNE

Please let us know how this turns out.
We are all interested in a situation where you might have more EDR connected than pipe to feed it.
I have wondered of the situation where a larger EDR rad does not get all the steam needed but still might heat the area well enough.
Good Luck!

Hap_Hazzard

I have a few situations where the EDR is higher than what's shown on that chart. All of my upstairs radiators are on 1" risers, and four of them are > 25 ft.²: two 32 ft.² and two 36 ft.². They all heat perfectly fine, and the only one that ever makes noise is one of the 32s, but it's located in an addition that was added back in the 1960s, and its riser doesn't connect directly to the main. It seems to have been added on to the riser for one of the 36s, and I suspect the runout doesn't have enough pitch. Even so, I only hear it on cold mornings when the hare-brained thermostat has reset itself to its default 10° overnight setback. I'm pretty sure what I'm hearing is differential shock from the runout.

hankwylerjr

@JUGHNE @Hap_Hazzard I think that the chart is not an exact science so thats why Haps system works even though it the way it is. I have an extra 30 EDR with my existing rads and these two new ones for my boilers sq foot . I am assuming that it will work but have to try. Worst case I can remove and replace that monster 24 column rad with a 16 and add a split heat source or space heater etc. Everything is well insulated including all mains and returns and the same thing will be when I add a new 1.5 off my 2 inch with the 27 feet of new pipe. If I was way over the EDR I wouldn't attempt it. But me too, have seen in different systems in the past many more rads and even in some cases thinner piping required and the systems have worked for 40+ years no issues.

Hap_Hazzard

I think the key is that you can get away with a smaller pipe if it's vertical. Anything approaching horizontal is going to allow condensate to accumulate, and the steam velocity is so high in a narrow pipe that it will propagate waves, form water pistons, and bang.

hankwylerjr

@Hap_Hazzard all of my run will be vertical coming off the main except for about 10-12 feet horizontal that will be pitched. Your theory makes sense. I will ensure that this new run is heavily insulated with fiberglass from beginning to end no gaps. Wondering if one of those thermostats for the individual rads will help me with this situation cant think of the name off the to of the head this morning? Ill keep you posted going for supplies this morning. Thanks

KC_Jones

@gerry gill has commented on the pipe sizing situation before. He has said that sometimes systems seem to have been piped with a different set of sizing charts utilizing smaller pipes than normally acceptable. These systems will work fine, but the stipulation is usually that the entire system is following the same rules. Stray from that and it's anyone's guess as to what might happen.

For me, why do all that work to find out it doesn't work properly? That much EDR is essentially a new main, this is what the sizing charts indicate too. I look at my own house with 265 total EDR and I have 2 2" mains to supply that.

I will also reiterate the comments about heat loss, did you do the calculations to know how much heat you actually need? Given the description I will revise my previous statement and say that's enough rad to heat beyond 1000 sq ft of living space. Calculations don't cost money, but can save it.

Hap_Hazzard

If you can make the horizontal run bigger, it will help.

This video illustrates what causes differential shock:

https://youtu.be/JyvoN1hIqRo?t=210
(Skip to 3:30)

hankwylerjr

@Hap_Hazzard I can get about 16 to 18 horizontal if needed

Hap_Hazzard

By the way, @hankwylerjr, did you look up the EDR for your radiators or just estimate? You can download the ratings for the ARCO Cast Iron Radiators from the Heating Help Museum here, if you don't already have it. https://heatinghelp.com/heating-museum/arco-cast-iron-radiators-1959/

Using the above, I get an EDR of 57.6 ft.² for the big radiator on the dolly. (24 sections, 25 in. 5-tube).

Hap_Hazzard

hankwylerjr said:

@Hap_Hazzard I can get about 16 to 18 horizontal if needed

I mean bigger in diameter.

hankwylerjr

@KC_Jones I don't have 1000 Sq I have about half of that for the main room however, if I leave the door open it would also heat the other smaller room about 350 Sq. There is another closet walk in style with louver doors about 200 Sq I'm thinking it might heat as well. The main in my house is 2 inch but the rads are all on 1.5 there are 6 of them fairly large. It may not be by the book, but still think it would work. If not, I'll replace larger rad with a 16 tube I can't do the 2inch because of space between the floors