Piping and slow heating

Fizz

Attached are pics of supply piping to slow side of daughter's system. 2 risers off header, but slow side supply pipe is reduced from 11/2" off header to 11/4", then enlarged back to 11/2" after a 3' run at reduced size. Other than water hammer, can this be possible reason for slower steam flow?

Danny Scully

Potentially, but we need to know a little more. First thing to note, pipe reductions can NOT me made on the horizontal of a steam main. This, however, looks like it's increasing on a radiator runout, which causes the same problem. Is that in fact what we're seeing? Is this a steam main or a radiator runout? If it's a runout, how big is the radiator and how long is the runout?

Jamie Hall

It's a good thing steam doesn't mind going around corners...

The additional question I would ask -- besides @Danny Scully 's -- is what, if anything, is the venting like on the slow side?

Fizz

It's a main with 4 attached rads. It's single pipe system, to your question Jamie venting on slow side is much better. If you go to prior discussion on Oil Heating section which I posted on 3/28/17, entitled Single Pipe Issues much was discussed, but this issue of reduced piping was not.

Jamie Hall

Hmm... well, I would expect condensate to lay in the pipe where it expands back to inch and a half. I would not expect the reduction and subsequent expansion to be that much of a factor -- although it surely doesn't help (saturated steam has a way of condensing when it is expanded, rather than slowing down as air might -- strange stuff. Which is fine in a radiator, but not such a good idea in a main). Either the expansion effect or the pooled condensate, however, could cause the steam to take an inordinate amount of time to get past that point. It might be of some interest to stand there when the system is starting up, and see just how fast the steam does move in the pipe in that area (since it is not insulated, that will be easy to do! Then insulate it...). Can you replace that reduced section with inch and a half? Or at the very least make the change with eccentric reducers, the former being preferable?

Fizz

Yes Jamie. Already got one estimate, waiting on another.

MilanD

Reason for slow steam can be wet steam or poor venting.

Is your near boiler piping on spec?

What is your main vent like and how long are mains? You may need better venting and balancing of the 2 mains.

If your reduced section does not hammer, although not ideal, I wouldn't worry about it. You can have 5" main and not a difference if venting is inadequate.

Out of curiosity, what's your connected EDR on that main?

Fizz

Nbp, probably not. See pics and prior discussion on Oil Heating section posted 3/28/17.Front(slow)main is 28', rear main 22'. Both originally had Gorton#1's, swith-out slow main to #2, with no improvement. Connedted EDR is 129 on slow side and 100 on other. Boiler is WM SGO-3, with .85 nozzle. Rated sf of edr is 356, which is oversized somewhat.

MilanD

I'm having trouble finding your orig earlier post.

Is your system hammering at all?

Couple of thing I noticed and note, my thought process is to optimize what's there without having to repipe.

Nbp: If you are over 24" from water line to header, or more, you should be fine. That nbp seems ok as they go without using dropped header, and it looks like 2"? Others should chime in on its sizing.

1-1/2" main on a parallel flow and 128 EDR attached should also work fine. It's borderline, but should work. 3' reduced to 1-1/4 section should not affect it too much. It may restrict the flow some, but it'll be offset with slight pressure increase in that 3" section. However, avg. delta P from boiler to end of main should not be too great to be problematic.

Having an oversized boiler, however, also doesn't help as it probably builds pressure quite quickly. While it's getting to that pressure it may be sucking some water out of the boiler collapsing the steam. But that also depends. Am I understanding this correctly: one branch heats fine and the other is slow?

Now, jow high is your op pressure and do you cycle on steam pressure?

High pressure actually can slow down steam and, counter common sense, operate the system with an oversized boiler better than on lower pressure, although it wastes fuel building and sustaining that pressure. Regardless, you still need exceptionally good venting to at least allow steam to reach end of mains at that higher pressure (before burners shut off on pressure). Smaller vents create greater backpressure, thus get the air out of the way as quickly as you can and pressure will stay lower longer.

This means one of Gorton #1 or #2 vents might not be enough to vent those mains quickly enough before pressure builds. Reach out to Barn and Jones and get one "big mouth" vent to the end of that slow main. Should be available here in the store too or Amazon.

Once you swap it, see how the system heats. This new vent should help nudge the steam to a path of least resistance - theorethocally, to your currently slow main. If still not fast enough, add an antler and add the old Gorton to the big mouth to give it a bit more capacity. And so on. I am curious if you ever fired up the system without the vent to see how quickly that slow main would vent without a vent? That would give you a good measuring base-point.

You may also need to add a few extra vents on the risers to your slow rads, as well as slow down rads (and/or) reduce venting on your currently fast-heating main. As the boiler is oversized, I would try to not reduce any venting but work with increasing it to the current slow side.

To add venting to rad risers involves adding a few fittings before the radiator. For this, I like maid-o-mists that come with a variety of orifices and use the largest one on the longest riser, etc. On rads too, as well as Hoffman 1a to help dial in the balancing.

Lastly, it could be the picture, but water in the boiler sight glass looks quite dirty. You may benefit from cleaning and skimming the boiler, then some water treatment like steamaster tablets (not liquid), or 8-way (this one is liquid), both by rectorseal.

If it were me, I'd try venting capacity increase first. The more venting the better. Then, seeing if the boiler could be downfired some, then clean water and add the mentioned chemicals. If these don't help, then piping redo might have to be next step, if not replacing the boiler to match EDR. Also, remove any insulation to help increase the pickup.

In the end, question is what the size of your budget is. If the system doesn't hammer, and if one of 2 mains heats well, if op pressure is 1-2psi range, get better venting to the slow main, to nudge the steam in its direction.

Best of luck!

Steamhead

Venting speed is only part of the picture here. The other part is how much steam a given pipe can deliver under the ounce pressures in a steam system. That 1-1/4" pipe is much more of a bottleneck than it looks.

Enlarge the pipe to 1-1/2".

KC_Jones

What size is that header? To my eye it looks like the same size as the 1 1/2" main coming off of it. Can you please confirm header OD is 2 3/8" indicating 2" pipe? I've been staring at those pics and the header and main look like the same size to me.

Steamhead

Looks to me like a 2-inch header, pipe to steam main reduced to 1-1/4" then increased to 1-1/2".

If that SGO is 3 or 4 sections, W-M says you can get away with a 2" header. Me, I'd go 2-1/2", the full size of the steam outlet.

KC_Jones

Fizz said:

Attached are pics of supply piping to slow side of daughter's system. 2 risers off header, but slow side supply pipe is reduced from 11/2" off header to 11/4", then enlarged back to 11/2" after a 3' run at reduced size. Other than water hammer, can this be possible reason for slower steam flow?

My comment is based on the OP's description. Stating 1 1/2" at the header. I think it's important to the OP's question to clarify this detail.

Fizz

Will be going-up house today to measure header. I think it's 2", not sure. Also, I ran system without vent in place on slow side with no difference. I switched-out a #1 for a #2 still no change. Rads have larger vents than other side, also. Insulation had been removed in cellar piping by prior owner. Water runs clean on blow-down, but during summer months no blow-down, though boiler runs for hot water supply.

MilanD

Then, it must be as @Steamhead said, that 1-1/4 reduction really kills the flow. And the other main heats
OK?

Fizz

Here's deal, confirmed header is 2", risers 2" to a 2" supply main on back circuit, which heats fine, but 11/2" then reduced to 11/4 then back to 11/2" on slow side. I will get it repiped to11/2" .
Thanks to all!

Jamie Hall

MilanD said:

Then, it must be as @Steamhead said, that 1-1/4 reduction really kills the flow. And the other main heats

OK?

It can do that. Saturated steam is a very strange stuff in some ways -- and one of the ways is that when it goes through a venturi (or anything that looks like a venturi, such as this section of pipe or a reduced port valve) when it expands going out, instead of happily slowing down and having a pressure increase, as that infamous fellow Bernoulli found (and which is true of water or subsonic air, for instance)... it condenses. Not all of it, and the fraction that condenses is a function of just how much expansion takes place, but some of it. And I wouldn't be too surprised if that was at least part of the problem here.

It's also why reduced port valves are a no-no on saturated steam lines...

MilanD

Jamie Hall said:

MilanD said:

Then, it must be as @Steamhead said, that 1-1/4 reduction really kills the flow. And the other main heats

OK?

It can do that. Saturated steam is a very strange stuff in some ways -- and one of the ways is that when it goes through a venturi (or anything that looks like a venturi, such as this section of pipe or a reduced port valve) when it expands going out, instead of happily slowing down and having a pressure increase, as that infamous fellow Bernoulli found (and which is true of water or subsonic air, for instance)... it condenses. Not all of it, and the fraction that condenses is a function of just how much expansion takes place, but some of it. And I wouldn't be too surprised if that was at least part of the problem here.

It's also why reduced port valves are a no-no on saturated steam lines...

The more you know... I really didn't think 3 ft of 1-1/4" pipe would make such a huge difference. I was thinking that fluid is a fluid is a fluid, kind of like how nat. gas piping has to be certain diameter in order to carry enough btus to the appliance but a small narrower section around the gas meter usually does not have an effect on the total volume, as that section creates a slight increase in pressure for that short section, but overall avg. pressure stays the same (like 3 oz or so) and thus, so does the volume of gas it can carry. Now I know this is not so for steam. Quite informative exchange - thanks @Jamie Hall and @Steamhead !

gerry gill

Fizz said:

It's a main with 4 attached rads. It's single pipe system, to your question Jamie venting on slow side is much better. If you go to prior discussion on Oil Heating section which I posted on 3/28/17, entitled Single Pipe Issues much was discussed, but this issue of reduced piping was not.

Can't be a main pipe at that size. And as others noted the reducers...i know it is...but it can't..

Fizz

So what's the answer?

Steamhead

gerry gill said:

Can't be a main pipe at that size. And as others noted the reducers...i know it is...but it can't..

Depends on the load. If this is a small house and the main is carrying less than 140 square feet EDR or so, 1-1/2" will work fine. There are probably a couple thousand rowhouses in Baltimore with 1-1/2" steam mains that run perfectly. We've actually replaced or rerouted some.

Fizz

There's 126 attached sf of EDR to this main and 96 on other, Steamhead. Yes the house is small. So you are in agreement with solution to replace 11/4" pipe with 11/2"?

Steamhead

Yes. 1-1/2" is all you need there. But no less.

Fizz

That's great news! Thanks to all.
Fizz

Fizz

Update: repairs done today; replace 11/4" with 11/2" by piping 2" to 11/2", also replace leaking pipe. will have pics tom. Test run was good no leak, and slow side was much better. Thanks to all.