Piping for New Steam Boiler

Noah_1 · February 6

@delcrossv I added an updated image after closer inspection. At number 4 a dry return is not connected (dotted orange line) to wet. It appears a radiator was eliminated above (but we will be adding it back in) hence disconnect in the dry return there. I will add a vent as you suggested and drop it back into the wet return…that would be the highest return at 73 inches. Any suggestion on size vent? As for that isolated room (between yellow walls) there is another main looping and dropping into the wet return. Hard to connect two sections you proposed due to cinder barriers and staircase. Have included more details including the proposed blocks to lift boiler off ground around 3.5 inches. Let me know your thoughts please.

delcrossv · February 6

Hi @Noah_1 are there any crossover traps between the far ends of the mains and the dry returns? I see what looks like where they're tied together at the short return (?). The main and the short dry return need to drop into the wet return separately so there's a water seal between them.

Seems like you have reverse pitch on the left side return. That drip in the corner needs to go back in or repitch that return towards the boiler.

I think you'll have to run this at under 1psi to get water into the boiler.

Noah_1 · February 6

Thank you for the feedback @delcrossv. Yes, we will be dropping that unconnected dry return into the wet below in the corner. But you had mentioned that we could not add a differential loop if needed. By the boiler (under under main vent) assuming we raise boiler on the 3.5 in blocks the dimension there would be 40.5, on the 1.75 inch block around 42.25 and without blocking around 44in. (Note: measures were taken on the drop and not to location of the vent base). But I thought the furthest wet return is critical to operation which would be the 73 in return in left corner by number 4. Hence, why it is vital to connect it back in. That would give us dimension of 45.5 with 3.5 blocking, 47.25 at 1.75 in blocking, and 49 in with no blocking. There are no crossover traps that I can see. The only traps I see are those at end of radiators. There are two places where mains (steam lines) drop into wet returns (circled green). That is in attached image. I was thinking I would run system at 1.5 fine. I’m not apposed to 1psi. It shouldn’t need much to pump that steam out.

delcrossv · February 6

You're better off not having to use a pumping trap. ($$$$$) A vaporstat is ALOT cheaper.

You need some way to get air out of your mains. When the system went in in the coal fired days, you could get away with venting air through the rads as the boiler was steaming all day.

Now you have to either:

Vent the mains into the dry returns with crossover traps; or

Put vents on the mains at the drips into the wet returns.

Also, can you respond to the situation at the bottom of your drawing where it looks like the main is connected directly to the short dry return? That won't work.

Noah_1 · February 7

@delcrossv I was going to terminate the connection where the two dry returns that meet at the only main vent (right of boiler). I would add another vent on left of boiler and drop that dry return separately below the Hartford (i.e 2 main vents near boiler on either side). I was also going to add a vent and reconnect dry return in section 4 (currently disconnected) and drop that into the wet. I will also only use the 1.75 inch blocks as a start instead of the 3.5 blocks so I lose less of the B dimension. As for your question I circled in green where the mains connect right back into the wet return. Can you circle where you mean? Are those the areas you mean? More details in attached image.

delcrossv · February 7

@Noah_1 Here you go. The curious connection is in the red circle.

As you're doing all this pipework, make sure you flush the wet return.

Noah_1 · February 7

@delcrossv those notes were helpful. Thank you! So you are suggesting two vents on those two mains and two vents on the dry return as I drew on the schematic (right and left of boiler) for a total of 4 total vents? Why not add the one vent you suggested (next to the number 4 on the schematic) closer to the end of the supply main…that would be around where you circled the unknown spot. That loop you circled sends a supply pipe to final radiators and then loops down to attach to the wet return. I have included a photo. Should that final vent be in that area just before it loops down?

delcrossv · February 7

@Noah_1 ok, that spot is fine. From your diagram it looked like your main was connected directly to the dry return.

I do not think you need a vent at the corner with the disconnected drip as the other end is vented.

Where does the short dry return between walls go? Was that previously connected to the dry return in the lower left corner? Has to go somewhere.

Noah_1 · February 7

@delcrossv I did my best to show it, but that too is parallel to the main that loops and did not show well. There are two short dry returns in there. One is to the right of the main loop (see photo) and goes back under the beam and oddly up (unlike all the others which all pitch down). This is the only one that goes up about a foot and connects to the line that is currently disconnected from the drip (it is connected I believe to a second floor radiator). The other is next to the main but when I drew the main it covered it. It is disconnected but is supposed to connect to drip in corner (it too coincides with a radiator which will be reconnected. I have drawn the ends of the returns in white so a bit easier to see. I can connect the two dry returns so the one does not loop down and up and run them to the disconnected drip in one shot??? Please see attached.

delcrossv · February 7

@Noah_1 Ok. Obviously condensate can't run uphill, so yes, you can connect the two short dry returns, but you'll have to drip them from the lowest point into the wet return. If the lower return can pitch down to the corner, you can connect with the other dry return and reinstall the missing drip. Else, you'll have to drip and vent the combined short returns separately. Down and up makes a water seal that will pass condensate but not air. Not what you want.

Make sense?

To reiterate, and i can't emphasize this enough, flush out the wet return loop and provide fittings to be able to flush it in the future. If that long wet return isn't full of crud after a century I'd be shocked.

Noah_1 · February 7

@delcrossv so they can be connected and run in parallel and then connect in one pipe down the line to the drip as long as the pitch is down? (see schematic please)

Is it okay to vent on either side of boiler as previously suggested and will that vent on the left of the boiler suffice for the disconnected drip on the corner given how far it is and the different pitches?
Or will I need to add another vent on the dry return in that corner where adding disconnected dry returns?

delcrossv · February 8

How big and long is that dry return (drip to boiler distance approximately)?

"so they can be connected and run in parallel and then connect in one pipe down the line to the drip as long as the pitch is down?"

Yep. Has to drain to the drip.

Noah_1 · February 8

@delcrossv the run is about 60 feet from the drip to boiler and it is 1.25 pipe connecting to 1.5 right before the Hartford.

delcrossv · February 8

As you're not venting mains through your dry returns, you don't need a ton of venting. As you're splitting the loop I'd think a Gorton #1 on each side would be fine. You're not evacuating the pipe, just the rads. In normal operation they should never close.

If you find the rads are filling more slowly than you'd like, it's easy enough to double them up later.

What are the mains size 3"?

You'll probably want a #2 at the end of each of those.

delcrossv · February 8

On another note, did you measure the EDR of all your rads? Including the ones you're putting back in? With all your drips, you really do not want to oversize the boiler. You may even want to cut back a little on the pickup factor.

Noah_1 · February 8

@delcrossv there are three mains. Main 2.5 inch to 2 to 1.5 at end. Main 2.5 to 2 to 1.5 at end. Main 2 to 1.5 at end. Please see attached. I could do the takeoffs and header at 3.5 instead of the 3 inch dropped header I was planning which would reduce to the current main sizes immediately but I thought that would be overkill. I had wanted all my mains to be at least one size smaller than the header (currently one is and two are only .5 smaller) …but I think the consensus on here was that going more than 3 inches on the dropped header would be overkill.

delcrossv · February 8

@Noah_1 Ok. I'd say #2s on the 2.5" mains and a #1on the 2" main.

Where does the 2" main go( the one in the middle). Is it dripped? What are the dry returns associated with that main?

Noah_1 · February 9

Hi @delcrossv

So the middle main runs to the radiators in the middle. It is currently disconnected but will be reconnected to the radiators above. These radiators’ return lines go back to the long dry return on the right. I was thinking of terminating their connection to it and tapping into the wet return closer to these radiators as indicated by brown star and dashed brown lines. Is this possible?

More importantly, does this middle main need to be vented given how close it is to the boiler?

For reference, please see attached image.

Main sizes:

Main 1- 52 ft (terminal pipe diameter 1.5in )

Main 2- 22 ft (terminal end at 1.5in negligible run)

Main 3 - 48 ft (terminal pipe diameter 1.5in)

delcrossv · February 9

All mains need vents or crossovers. Even the "short " one.

I'd leave the dry returns from those rads as presently configured. No need to reinvent the wheel.

Does that short main have a drip at the far end or is it pitched back towards the boiler?

Noah_1 · February 9

@delcrossv I don’t see a drip for it , can one add it and install #1 vent and drop it back at nearby wet return? Seems like one can pitch it either way with connection by boiler removed. Another option would be to get counterflow on the pipe but I would rather keep the system mains all pitched away from the boiler rather than flow and counterflow setup.

delcrossv · February 9

You can do either:

Pitch it away from the boiler and drip and vent it at the far end like the other mains; or
Run it counterflow with the vent at the far end and the drip at the boiler end right before it drops down to the header. Note: counterflow is about double the pitch as parallel flow. (1"/10' minimum)

Just depends on how easy it is to do. Reversing pitch can be problematic depending on what's attached downstream. With no far end drip, I'm guessing that main is counterflow. Dripped and pitched correctly, they work fine.

delcrossv · February 9

Fyi, this'll work.

Noah_1 · February 9

@delcrossv thank you for all the insight and great pointers!!!
The pitch (1/20) on flow will definitely be easier given the limitations in space near boiler. So will go with original plan. Gorton 2 on larger mains and #1 on smaller with drip into wet.
For the second post, I was going to post regarding that because I had concerns when I came across a photo online with a similar loop (although it seems here they did the return this way because of the overhead beam). I did not want the system to act up if merged with the other dry. What are your thoughts on this loop???

delcrossv · February 9

As you don't have vents on your rads, that drawing doesn't apply. That's a 2 pipe air vent system, which you don't have.

Radiator traps control air and condensate into your dry returns. They all need to function for your system to work.

The reason that drop kinda worked on yours was that the application of steam with a coal fire was slow enough that condensation in the drop to the wet loop gave enough of a partial vacuum to pull some steam into that rad.

I doubt it ever heated well.

You REALLY do not want a rad drip loop on your "conventional" 2 pipe system. Rad returns need a straight shot to a vented dry return with consistent pitch to the drip.

Your wet return should be the only loop seal.

Noah_1 · February 9

@delcrossv thank you for that explanation. And your 100% right, it never heated much and in fact the steam would not make it past the first rib. Now I know why! I will connect with the other dry return into the wet as we previously discussed. I will draw a plan based on our discussion to make sure I did not miss anything important…but I believe without your pointers and insight I would be guessing with some of the connections…so thank you very much!!!

delcrossv · February 10

You're very welcome. Glad to help.😁

Post a pic of a typical rad. Please show the valve and rad trap.

RTW · February 10

Greetings:

BY delcrossv: "To reiterate, and i can't emphasize this enough, flush out the wet return loop and provide fittings to be able to flush it in the future. If that long wet return isn't full of crud after a century I'd be shocked."

My Experience

Good advice by "delcrossv " and something I did on a short, wet return that ran below the concrete Infront of a bilco door. In my case I removed the old pipe and configured the wet return with new malleable piping and valve etc. as a replacement that allowed it to be flushed. My local plumbing shop made it up to my specifications.

All the best,

RTW

Noah_1 · February 11

@delcrossv will do. Configuring the header and thought someone would address my riser lateral runs (horizontal lengths) before they drop into the header. Just wondering if it’s okay to have them in that configuration given the space limitations? Haven’t found anything definitive on this. Most systems run in parallel with equal lateral lengths before dropping into the header.

delcrossv · February 11

@Noah_1 Not sure what you're referring to here. See below. Note, the takeoffs work better coming off at a 45 degree-ish angle before going up to the mains.

If you're talking about the mains going off left and right, that's not an issue.

Noah_1 · February 11

@delcrossv I was referring to the risers’ lateral runs marked in green. They will be of significantly different lengths before they drop into the header. As for the takeoffs, I was going to do the first two in 45 and the last vertical and you suggested 45 for all.

delcrossv · February 11

@Noah_1 The variance in lengths of the two supplies into the common header is of no consequence as long as they come into the header together. You're good.

Noah_1 · February 11

@delcrossv thank you for confirming it’s okay. Btw attached is typical rad.

delcrossv · February 11

https://forum.heatinghelp.com/discussion/comment/1842052#Comment_1842052

Oh dear! You have no traps! 😲

What does it say on the side of your supply valve?

Any markings on the elbow on the condensate side?

We'll have to take this step by step. There'll either be an orifice plate on the supply side or the valve is a regulating one.

You'll REALLY need a vaporstat now. You have a Vapor system. Upside is you won't have to worry much about your B dimension at the pressures this operates at.

Noah_1 · February 11

@delcrossv i thought it was at the bottom inside the last elbow for return. Here is a closer shot . Will need to add them if there are none, which I was going to do anyways given the age. Should I add on supply side or return side and which valves would you recommend? Also pressurtrol not vaporstat. Was going to run on lowest setting.

delcrossv · February 11

If the supply valves work, I wouldn't mess with them. It will be a considerable expense to get trap bodies for all your rads and you'll have to find a new body that will fit where the elbows are now. I strongly recommend a vaporstat- you can get a mercury switched one off ebay for a pretty reasonable price.

Any writing on the valves and elbows?

Noah_1 · February 12

@delcrossv i would take out the ones in which radiators did not heat after lowering the pressure. I couldn’t make out anything on the valves. I guess the only way to find out is to open one up and see if a valve is in the orifice.

delcrossv · February 12

With those radiator elbows on the condensate side, orifices are pretty much guaranteed as the original regulating valves look to have been replaced. If you're curious, you can open the union on the supply side valve to see if there's an orifice plate.

In any event, there's really no reason to add traps to each radiator, ($$$) when the system will heat fine provided the pressure is kept low.

At the correct pressure range, the orifices will only pass enough steam for the rad to completely condense it before the steam can get to the elbow. Sweet spot is when 80% or so of the rad gets "steam hot" at max output. If the pressure is too high, the dry returns fill with steam, the vents close and the system stops heating. Hence the vaporstat recommendation. 🙂

Looks like a Kriebel system. Any idea when the place was built?

Lastly, what's up with non heating rads, aside from the one that drained into the loop seal?

delcrossv · February 12

@Noah_1 really good intro article on orifice plates.

https://tunstall-inc.com/macon-controls/steam-radiator-inlet-orifice-plates/

Noah_1 · February 12

@delcrossv
Built around 1920.

Aside from that one radiator, they were just were just disconnected (perhaps when floors were done) and we will reconnect.

I think you’re right about the type of system given the design…however, there is no vapor-vacuum controller near the boiler. Also the return side of the radiators may have bafflers on the elbows.
From an operational perspective does this change what we previously discussed in terms of the piping and venting on mains and dry returns?

delcrossv · February 12

@Noah_1 No, you're replacing the vacuum controller with vents. Basement pipes should be as we discussed.

The system should work fine if:

The inputs on the rads are metered so you get full condensation and

The pressure is low enough so that can happen without losing your water seals

For the rads that were disconnected, were any orifice plates found? Do you see a check plate (baffler) in the return elbows?

Important:

Is the new boiler already bought? Reason I'm asking is the effective EDR for this system is only 80% of the measured EDR (due to the metering and full condensation requirement). You may also consider dropping the usual 33% pickup factor to 10-15%

Here's a table of orifice sizes I found here that specs sizes by EDR and pressure if you have to replace them.

napier oz (1) Oriface plates.pdf

I don't think the table has the 20% EDR reduction built in.

Piping for New Steam Boiler

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