Main to radiator pipe distance

SMRTK

What is the approach for determining the appropriate distance from a main to a single pipe radiator. I am going to redo the near boiler piping and all of the pipes in my basement and hope to clean up the mess that has been cobbled together over the years.

I have lived in this single family home for a little over two years now and it is my first time with steam heat. I have a relatively new boiler (Utica installed in 2019) although it unfortunately looks much older. My near boiler piping is, interesting, and the mains and dry return equally as interesting.

I have really enjoyed this forum and the main site as I have been researching my heating system. Thank you all for that and for any insight you may be able to offer to my question. Many more to come I imagine

David

SMRTK

I should have reviewed better prior to posting. The question I have is whether or not there is a max distance from main to single pipe radiator?

ethicalpaul

Some houses are three stories with the boiler in the basement. Some buildings are dozens of stories. I don't think you should worry about it. The thing to worry about is the pitch/slope of the piping.

Jamie Hall

Not that I know of, and there is no particular theoretical reason for a limit.

However, that said — the pitch and linearity of the pipe become critical. The pipe must have at least the correct pitch, and just as important it must be really truly straight. No sags. No humps. Too many hangers is much better than too few!

And second, insulate that runout. Once the pipe is hot with steam, not so much of a potential problem, but while it is heating up it is generating a good deal of condensate, and the steam rushing out to fill the radiator will pick that up and slam it against any bends with remarkable force. And noise. So insulate it. Insulate vertical risers, too, if you can.

ethicalpaul

And second, insulate that runout. Once the pipe is hot with steam, not so much of a potential problem, but while it is heating up it is generating a good deal of condensate, and the steam rushing out to fill the radiator will pick that up and slam it against any bends with remarkable force.

If you can insulate them, fine, but don't worry that much about it. I respectfully believe that Jamie's concern above is unfounded. The pipe's condensation generation is a rounding error compared to the condensation generated by the radiator itself as it warms up. There's really not that much rushing occurring. The steam filling the radiator is limited by the radiator vent. The steam will not pass a cold runout to get to the radiator…the steam will condense in the cold pipe, slowly warming the pipe as it goes. It's very gentle.

I keep editing this response as I think of reasons not to worry. Here's another one. Insulation doesn't prevent a runout from getting cold, it only slows it. In the shoulder seasons, you will be repeatedly heating cold runout pipes (insulated or not). This does not cause banging so why would it cause banging on an uninsulated pipe?

What's not gentle is when steam comes into contact with cold water from a sag, as I indicated, and he described more fully.

SMRTK

Thank you. Currently the main runs from the boiler make no sense, at least to me (near boiler picture below). I would like to clean them up and hopefully be more efficient with their performance and placement. In doing so some of the runouts may be longer which is why I asked the question. I will mind the pitch and insulation as noted. I am going to map the system as it exists today and then layout what I would like to do when I re-pipe. I will share once I have completed that task.

The picture below shows the near boiler piping. Main A goes out from between the risers and returns back on itself. Main B goes out and returns to the other side. The path around the house for B and the various changes in pipe diameter are confusing. There is only one main vent and it is on B as seen in the picture.

While pipe A makes no sense to me (if there is some reason for returning on itself please let me know), pipe B is truly my nemesis. I have lost count how many times I have forgotten that it is there, that we have a short ceiling and that I am taller. It really hurts. I want efficiency first but if I can eliminate head injury in the process I would consider that a huge success.

SMRTK

ethicalpaul

Definitely insulate pipe B to protect your head at least! 😅

I don't see A "returning on itself".

What it looks like from here is that both of your B pipes are returns (yes, nontypical but still), and your A pipes are two different mains that lead to those returns. But it's hard to tell from that photo, I'd have to be there to know for sure. You are probably in North Jersey or maybe Philly. Don't work with that installer any more, they are not worthy.

When I say "return" above, I just mean the end of each main where it returns to the boiler. So I think two of your directional arrows are wrong. Don't draw those arrows on the pipes in case the steam gets confused 😉

SMRTK

I am outside of Detroit in Holly, MI. The house is an 1890 Victorian with lots of fun projects in store for me. I am not being sarcastic, I actually like working on old houses and learning new things.

I went down to re-inspect and you are correct, both pipe B's are returns. A is the main starting off the header and then splitting before heading out. I am not sure how I arrived at my original observation, probably the head injuries.

ethicalpaul

OK excellent that you got that cleared up! Welcome to the forum, fellow Michigander (I spent the first 45 years of my life there). I will tell you that repiping it isn't going to change the performance in any notable way unless you are currently experiencing surging! (as indicated by a sudden drop in water level in the boiler—the water in that case is going up into the mains)

Are you currently experiencing problems that you want to fix? Personally I'd look first to the main venting to see how it's doing. The one I can see in the picture looks pretty ancient and crusty and may be failed.

SMRTK

Currently the system works OK on about half of the radiators (9 total). 3 of the 9 receive almost no heat and one seems to receive more heat (this is likely due to being oversized for the space it is in). The balance of the group seem to operate properly. I have a couple of valves that need to be repacked since they leak, these are on the rads that work well and I know not related to the piping. I am going to look at all of the vents, including the main, during this process as well.

Water has gone up into the mains, however not as a result of surging as you describe it. The old water feeder was leaking and I replaced it. Prior to closing on the house the pipes had completely (I believe) filled with water as a result of the faulty feeder and blew out the vents at almost all of the radiators, the most from those radiators that work well. I am thinking that this may indicate that those that do not work well (or almost not at all) may have blockage?

The near boiler piping needs to be redone based on my research and that it is not even close to the near boiler piping required by the boiler manufacturer. And no Hartford loop. I don't think that piping was ever right and they just kept replacing boilers with it.

The distribution piping in the basement appears to be cobbled and added to over the years with pipe they had on hand. There are diameter changes here and there that do not seem to make sense. There is an 8' section for instance that gets much larger for example towards the end of the main that splits off after leaving the header. Maybe there is a reason for pipe diameter changes? I am thinking forced air and pressurized air systems that get smaller farther out. Getting bigger in the middle and then going back to the original diameter has me scratching my head.

Additionally there have been pinhole patches in the past by the previous owners and a couple from me since I bought the house. I feel like those pipes will need to be replaced regardless and depending on the vintage their neighbors may start showing holes too.

I guess my thought is that if I am already down there and have to do near boiler and replace some pipes due to pinholes why not take this opportunity to take a look at the system as a whole (not including the risers in the walls). It's possible I may be going to far, I usually do. I think I will know better after a more thorough review of the system.

I am learning as I go, I may not be using the correct terminology in some cases.

Updated picture below. I changed the arrows so the steam does not get confused :)

EBEBRATT-Ed

Pitch and pipe size for the connected load is all that matters as well as a drip pipe if needed for long runs.

ethicalpaul

don’t worry about the size of a radiator. The radiator’s vent determines how fast it fills with steam.

A massive radiator with a slow vent might as well be a small radiator.

Start simple. Check to see if your main vents are working. Their job is to make steam fill and heat the mains first, before any radiators get steam

EdTheHeaterMan

Of course this is a case of "if it ain't broke, don't fix it" however the near boiler piping is incorrect. as long as you are not having loud banging problems that can often be caused by that bad design, then leave it alone. But this is the design problem I am referring to.

This is correct design

Your system is connected like the lower piping design (WRONG) and and cause you the have wet steam problems.

The system piping must provide dry steam—wet steam causes water hammer, component damage and water level problems. If you are experiencing these problems then you may want to redesign the near boiler piping to match the manufacturers recommendations.

BUT …. if you don't have these problems, "IF IT AIN BROKE, THEN DON'T FIX IT"!!!!!

SMRTK

I think the near boiler piping is a given, regardless of whether or not I tackle the rest of the distribution system. I will take a look at the main vent as well. EDIT: I do have water hammer. It increased later in the season last year even after replacing the leaking feeder valve. This leads me to believe that the near boiler piping may be slowly letting water into the system. I will check it out along with the pitch of the distribution pipes. The house has a significant sag in the middle that I plan on addressing over the winter that may allow for the water to slowly accumulate over time

I hear both of you on the don't fix it if it isn't broken and appreciate the reminder.

ethicalpaul

The house has a significant sag in the middle that I plan on addressing over the winter that may allow for the water to slowly accumulate over time

Just a small observation here…if there is a sag or low area in a main or in a radiator runout, water will not slowly accumulate over time. Water will fill the sag in a single call for heat and will never drain.

You have to picture yourself as a single drop of water in one of your radiators. That single drop of water needs to be able to flow all the way back to the boiler and/or wet return. Otherwise, you may see issues with banging or cold radiators.

This isn't exactly true…radiators hold a little water in them and small amounts of water may be held by things such as bushings or other adapters. These tiny amounts of water may not result in any issues, but I think the "imagine you're a single drop of water" exercise works well as a theoretical ideal to help with visualization.

And I saw this question from you earlier that I missed:

I am thinking that this may indicate that those that do not work well (or almost not at all) may have blockage?

No, almost certainly not. Maybe those radiators didn't spew water because their vents have failed closed, or other reason unrelated to a blockage.

RTW

The original posters question seemed simple enough in beginning, however it has developed into a cluster…. of multiple issues after issues. I am an amateur that uses this site for assistance, but to be honest, at this point I strongly recommend the original poster getting a qualified steam expert (off this site as a consideration) to take an inperson look at things - as I have done as needed. Lastly, in all fairness to site advisers, a single photo vs photo of entire system lacks enough info. for proper solutions or advise. Thus, it leads mostly to speculation back and forth…

Regards,

RTW

RTW

P.S. Original Posters Question:

"I should have reviewed better prior to posting. The question I have is whether or not there is a max distance from main to single pipe radiator?"

Regards,

RTW

ethicalpaul

as often happens. His original question was answered quickly and accurately if I do say so myself