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Weird hybrid two-pipe/one-pipe system
Thor Simon
Member Posts: 10
I own an apartment in a 1924 building complex in New York City that consists of about 10 4-story buildings all of which have hot-water heat from a central boiler system at one end of the complex. I believe the system was originally gravity upfeed but has since been converted to use circulators.
In each 4-story building, the system is to all appearances a pretty conventional two-pipe system except for the first floor. The first floor, as far as I can tell, has each radiator plumbed directly into one side of the two-pipe system. There's some argument about whether these radiators were originally plumbed directly into the main line (which seems completely insane) or used a conventional diverter-tee system, but that the "bypass" segments of the main pipe with regard to each radiator plugged up over time (perhaps because of the restriction at each diverter tee). Not all of the piping is visible without tearing into floors/walls in other apartments but enough can be seen to make it clear that the first floor is _some_ type of one-pipe system, indeed, and that it really is connected to one side of the two-pipe system serving the other floors.
In any event, the current status of this odd hybrid one-pipe/two-pipe system is that if any first-floor radiator is turned off, the radiators on the corresponding bits of the two-pipe system lose all heat. So the first floor gets all heat, all the time, or the upper floors get none!
The only logical way to fix this would seem to be to ensure that each first-floor radiator has some kind of bypass, but there's concern about the pressure drop when the radiator valves are closed hopelessly unbalancing the two-pipe system on the upper floors. I've thought of solutions involving full-size bypass pipes and Unique valves or their modern equivalent, but I'm an engineer in another discipline, _not_ a professional plumber, and before I take any of this to the folks who would do the work I want to make sure I have a proposal that makes sense. Is the concern about the restriction from new bypasses on my radiators unbalancing the upstairs system legitimate? If so, what is a reasonable way to work around it? Clearly keeping all my radiators
turned on all the way for eternity is _not_ a good solution for ensuring heat to the upper floors.
Finally, are hybrid one-pipe/two pipe systems like this common? Like I said, I'm no plumber, but I've lived in quite a few places with hydronic heat, including a number of buildings this age in New York and Chicago, and I've sure never seen one before! How are they _supposed_ to work, and did they ever work well?
In each 4-story building, the system is to all appearances a pretty conventional two-pipe system except for the first floor. The first floor, as far as I can tell, has each radiator plumbed directly into one side of the two-pipe system. There's some argument about whether these radiators were originally plumbed directly into the main line (which seems completely insane) or used a conventional diverter-tee system, but that the "bypass" segments of the main pipe with regard to each radiator plugged up over time (perhaps because of the restriction at each diverter tee). Not all of the piping is visible without tearing into floors/walls in other apartments but enough can be seen to make it clear that the first floor is _some_ type of one-pipe system, indeed, and that it really is connected to one side of the two-pipe system serving the other floors.
In any event, the current status of this odd hybrid one-pipe/two-pipe system is that if any first-floor radiator is turned off, the radiators on the corresponding bits of the two-pipe system lose all heat. So the first floor gets all heat, all the time, or the upper floors get none!
The only logical way to fix this would seem to be to ensure that each first-floor radiator has some kind of bypass, but there's concern about the pressure drop when the radiator valves are closed hopelessly unbalancing the two-pipe system on the upper floors. I've thought of solutions involving full-size bypass pipes and Unique valves or their modern equivalent, but I'm an engineer in another discipline, _not_ a professional plumber, and before I take any of this to the folks who would do the work I want to make sure I have a proposal that makes sense. Is the concern about the restriction from new bypasses on my radiators unbalancing the upstairs system legitimate? If so, what is a reasonable way to work around it? Clearly keeping all my radiators
turned on all the way for eternity is _not_ a good solution for ensuring heat to the upper floors.
Finally, are hybrid one-pipe/two pipe systems like this common? Like I said, I'm no plumber, but I've lived in quite a few places with hydronic heat, including a number of buildings this age in New York and Chicago, and I've sure never seen one before! How are they _supposed_ to work, and did they ever work well?
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Comments
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How are the ground floor radiators connected? Bottom-bottom? Top-bottom on the same side? Top-bottom on opposite sides?
Are the supply/return lines the same size on all individual radiators?0 -
Bottom/bottom on all radiators. Every supply and return line that I can see (as I said, some piping is difficult for me to access) is the same size.
Looking at the piping I have access to (like I said, I can't easily examine all of it) it sure looks like this is in fact a pretty "normal" one-pipe system with diverter tees that happens to be plumbed into one side of the two-pipe system that heats the upper floors.
The complex's super says no, my radiators are plumbed _directly_ into the return side of the two-pipe system. Either way (plugged up correct system or just plain crazy system) it sure is true that if I turn any radiator off, the radiators hooked up to that supply/return on the upper floors go cold.
I don't want to argue with the guy, I want to get a real pro in here to fix it. But I do want to have a good general plan _before_ having anyone do any work, that accounts for any issue anyone's raised (e.g. the "it's plumbed directly into the return line, and adding any bypass might unbalance the two-pipe system") while still solving the basic issue (can't turn off 1st floor heat, ever) _somehow_, at all.
Heck, I'd just like to know if this system is as weird as I think it is. I can't find an example of a hybrid like this in the Q&A on this website or in any of several books I looked at on the subject.0 -
Bottom/bottom on all radiators. Every supply and return line that I can see (as I said, some piping is difficult for me to access) is the same size.
Looking at the piping I have access to (like I said, I can't easily examine all of it) it sure looks like this is in fact a pretty "normal" one-pipe system with diverter tees that happens to be plumbed into one side of the two-pipe system that heats the upper floors.
The complex's super says no, my radiators are plumbed _directly_ into the return side of the two-pipe system. Either way (plugged up correct system or just plain crazy system) it sure is true that if I turn any radiator off, the radiators hooked up to that supply/return on the upper floors go cold.
I don't want to argue with the guy, I want to get a real pro in here to fix it. But I do want to have a good general plan _before_ having anyone do any work, that accounts for any issue anyone's raised (e.g. the "it's plumbed directly into the return line, and adding any bypass might unbalance the two-pipe system") while still solving the basic issue (can't turn off 1st floor heat, ever) _somehow_, at all.
Heck, I'd just like to know if this system is as weird as I think it is. I can't find an example of a hybrid like this in the Q&A on this website or in any of several books I looked at on the subject.0 -
just an idea?
> I own an apartment in a 1924 building complex in
> New York City that consists of about 10 4-story
> buildings all of which have hot-water heat from a
> central boiler system at one end of the complex.
> I believe the system was originally gravity
> upfeed but has since been converted to use
> circulators.
>
> In each 4-story building, the
> system is to all appearances a pretty
> conventional two-pipe system except for the first
> floor. The first floor, as far as I can tell,
> has each radiator plumbed directly into one side
> of the two-pipe system. There's some argument
> about whether these radiators were originally
> plumbed directly into the main line (which seems
> completely insane) or used a conventional
> diverter-tee system, but that the "bypass"
> segments of the main pipe with regard to each
> radiator plugged up over time (perhaps because of
> the restriction at each diverter tee). Not all
> of the piping is visible without tearing into
> floors/walls in other apartments but enough can
> be seen to make it clear that the first floor is
> _some_ type of one-pipe system, indeed, and that
> it really is connected to one side of the
> two-pipe system serving the other floors.
>
> In
> any event, the current status of this odd hybrid
> one-pipe/two-pipe system is that if any
> first-floor radiator is turned off, the radiators
> on the corresponding bits of the two-pipe system
> lose all heat. So the first floor gets all heat,
> all the time, or the upper floors get
> none!
>
> The only logical way to fix this would
> seem to be to ensure that each first-floor
> radiator has some kind of bypass, but there's
> concern about the pressure drop when the radiator
> valves are closed hopelessly unbalancing the
> two-pipe system on the upper floors. I've
> thought of solutions involving full-size bypass
> pipes and Unique valves or their modern
> equivalent, but I'm an engineer in another
> discipline, _not_ a professional plumber, and
> before I take any of this to the folks who would
> do the work I want to make sure I have a proposal
> that makes sense. Is the concern about the
> restriction from new bypasses on my radiators
> unbalancing the upstairs system legitimate? If
> so, what is a reasonable way to work around it?
> Clearly keeping all my radiators turned on all
> the way for eternity is _not_ a good solution for
> ensuring heat to the upper floors.
>
> Finally,
> are hybrid one-pipe/two pipe systems like this
> common? Like I said, I'm no plumber, but I've
> lived in quite a few places with hydronic heat,
> including a number of buildings this age in New
> York and Chicago, and I've sure never seen one
> before! How are they _supposed_ to work, and did
> they ever work well?
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just an idea?
why not take the first floor radiators and put them on its own zone with a new circulator set up. and keep the other floors as is?
jim f.0 -
It would be a lot of work, I think. There are actually seven separate supply/return pairs from basement to 4th floor; one radiator in each floor is on each (save the 1st-floor ones, which are "one pipe" on only one side of each pair!). So that'd mean disconnecting all the first floor radiators from the side of each two-pipe setup and then doing a lot of lateral pipe runs to connect them together into a new zone, wouldn't it? Plus, if there really is no bypass at all around the first-floor radiators, they'd still need it added, would they not, or the new problem would be that turning off a single radiator on the first floor would turn them all off?
Or am I missing something? Given my lack of background that seems entirely likely.0 -
I've certainly never read nor seen such but others here have WAY more experience.
Was asking about the method and size of connections thinking it might have been a steam system converted to water long ago but that doesn't sound likely at all.
If the ground floor rads are indeed piped off of the return alone of three stacked rads each piped two-pipe they should be receiving water significantly lower in temperature than the rest.
My only guess for the logic involved would be that the ground floor radiator valves act as a crude "master control" with the assumption that if adjusted for reasonable comfort those above (likely identical rads and spaces?) would be at least as warm. Wild guess I know, but in a strange way it seems to make some sense.0 -
To get even stranger
IF my previous post is the way AND the reason it was piped this way you MIGHT be able to do something really strange.
If you installed thermostatic radiator valves on the FIRST FLOOR RADIATORS ALONE and set their lower limit stop at some reasonable temperature you just might wind up IMPROVING on the original "master valve" logic.
REALLY weird I know but you could quite easily experiment with just one TRV on one radiator to see the effect.
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You say there is a basement. If there IS a bypass around the first floor rads you should be able to see such in the basement. If the piping for the first floor rads comes through the floor you'll be able to see if any bypass line was originally installed. If you just see a pipe going up to a rad and another coming down out of the rad and nothing in between I'd guess that there is no bypass line.0 -
Possible way to confirm that theory of operation
This question had me staring at the ceiling when I should have been sleeping so that's why I'm writing so late--had to come to my office so I could get it out so I could get some sleep.
With a number of buildings served by a single centralized boiler that "master control" theory keeps making more and more sense.
If correct I would say there is a very good chance that the 2nd and 3rd floor radiators (even in identical spaces) will be a bit smaller. The 4th floor rads may well be the same size or even a bit larger than the ground floor because of the added heat loss through the roof (I'm guessing it's flat).
Again, IF this is the case I would sincerely try one TRV on one of the ground floor rads. This may well wind up increasing comfort and reducing fuel use for all at minimal cost. There won't be much in the way of individual adjustability, but if my ideas of radiation and proportional control are at all valid you won't really need much in the way of adjustability for exceptional comfort.0 -
The TRV's a clever idea. I'm going to suggest it to the super as a "temporary fix" -- he'll like it because it's on my rads, which are in my apartment, so I can have the work done without involving him beyond shutting off the heat for a few hours.
I'm not 100% sure if it will work, though, because these buildings are on top of a cliff and the 1st floor apts are the only ones shielded from the wind on one side. But I suppose we'll see.
Looking up at the rads from the basement _I_ sure think I see a bypass line around them. The super says no, and I don't really want to annoy the man by arguing about it. It's the typical sticky NYC situation where you own your home but you don't own the space its fundamental services like heat, water, etc. are delivered through.
Same result either way, though -- if the TRV thing doesn't work, I can't see any solution except to add _working_ bypass. I just hope that can be done, if necessary, without creating chaos on the floors above...0 -
The TRV's a clever idea. I'm going to suggest it to the super as a "temporary fix" -- he'll like it because it's on my rads, which are in my apartment, so I can have the work done without involving him beyond shutting off the heat for a few hours.
I'm not 100% sure if it will work, though, because these buildings are on top of a cliff and the 1st floor apts are the only ones shielded from the wind on one side. But I suppose we'll see.
Looking up at the rads from the basement _I_ sure think I see a bypass line around them. The super says no, and I don't really want to annoy the man by arguing about it. It's the typical sticky NYC situation where you own your home but you don't own the space its fundamental services like heat, water, etc. are delivered through.
Same result either way, though -- if the TRV thing doesn't work, I can't see any solution except to add _working_ bypass. I just hope that can be done, if necessary, without creating chaos on the floors above...
Thanks for staying up thinking about this, Mike!0 -
Just try one first!
And let it operate through some changing weather conditions to make certain those above don't complain about not enough heat.
The only way I see it working is IF the ground floor rad valves were ORIGINALLY intended to control those above.
Has anyone out there seen a system controlled this way (not the TRVs)?0 -
Oh, man. You've gotta love New York City. The complex's management refuses to shut off the heat for the installation of a TRV, because they're afraid of being fined if the temperature in one of the apartments up above ever falls below the city-mandated 65F and, of course, there's some possiblity a TRV might let that happen.
Evidently there are no automatic fines for _overheating_. Of course I could just shut my radiator valves and force the issue but I'm just not that much of a jerk. Feh. Gotta find some way to work _with_ these guys.0 -
So much for that idea. Sorry.
Are your ground floor radiators tapped quite large--like the same size as the supply riser to the rest of the radiators?
Maybe someone else has seen a similar system and will have input.0 -
Some of the building's still got the original 1924 risers, which are 3". There, the radiators are _not_ tapped the same size; they use 1". Coincidentally, that's the one piece of pipe I can't see -- the part where the 1" and 3" meet -- but I have a _lot_ of trouble believing there's no bypass there.
Some of the 3" risers have been replaced with 1" at some point in the past (I assume they did it when they added the circulators). That's the section where it sure as heck looks to me like I can _see_ a bypass, but the super claims no (and access to that part of the building requires his consent, so suffice to say he's not really interested in _helping_ me follow the tangle of piping). They sure made a mess when they replaced those risers, that much I can say. Maybe they really _did_ plumb it with no bypass at that point.
Very frustrating. At least now I know why it's so hard to get anyone to cooperate: even if I'm willing to pay to get it dealt with for the 1st floor, if anything goes wrong up above they risk automatic fines. Hard to believe anyone would install this crazy system in the first place. They get pretty hostile if I even suggest that I'm willing to pay their preferred pro to look at it and recommend a solution...0 -
One other question. The core of their concerns about adding any bypass seems to be the potential to create additional backpressure (compared to having the 1st floor rads on full-blast all the time) and reduce flow on the floors above. A friend who does industrial plumbing sketched a valve that looks _just_ like the picture of a Unique valve in Dan's Q&A and said that it would allow the bypass to be full size pipe with no additional restriction. Of course he also basically said "ask someone who knows more about home heating, I don't even know if they make these valves for pipe that small". The basic idea seems like it could work. What do you think?0
This discussion has been closed.
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