Help/Advice requested, undoing some iffy "modernizations" of a 1920s water radiator system.
Hi everyone, I'm new to the forum but was thrilled to discover it, as reading through past threads has already answered a lot of questions I've pondered.
I am a landlord with several multifamily houses built in the early 1900s. The one I need some advice on right now is a circa 1920 house, with original cast iron hot water radiators (designated by the orange squares on the diagram, and numbered in order of the flow path). They have balancing valves on the outflow from each radiator. Copper pipes were stolen out of house in early 2000s, and when new boiler was installed and piping re-done, the plumber configured it as a series loop. Heat has always been iffy, and even in Spring/Fall the latter radiators get, at best, lukewarm. The radiators still have short sections of ½" copper on either end that the thieves left, but new plumbing that was added is 5/8" PEX A with expansion fittings. The ½" copper and balancing valves suggest to me that this system originally was either a 1 pipe Fluidflow system, or a 2 pipe system, but I have no way of knowing for sure. There are 90 degree elbows at the junction of each PEX to copper transition, but the PEX is just flexed to make most turns, so there are few other couplings.
Boiler (Circa 2008) is a New Yorker AP-490U-BT4 with a net IBR rating of 77 MBH (Designated with the red B star on the diagram)
Circulator is a Taco 007-F5
This system is only responsible for heating the 1st floor apartment. There is an identical system for the 2nd floor apartment, which has suffered very similar problems.
Right now I have 2 related quandaries:
- The 1st floor is behaving particularly badly, with the heat barely warming radiator 4 or 5 (of 10) on the attached diagram. I measured the flow in a rudimentary way, by closing off the return to the boiler, and hooking a garden hose to the return line, and seeing how long it took to fill a 5gal bucket. It took about 12min, so we're getting less than .5gal per minute through the system. In comparison, the 2nd floor only took 5min to fill the bucket, so over double the flow despite the head (although from my understanding, even 1gal is still insufficient for proper function). Obviously, given that that 1st floor is so much worse than the 2nd floor, I need to troubleshoot where the flow is restricted, or if the (possibly already undersized) circulator is crapping out on me. Any suggestions on how to troubleshoot that aspect are very welcome. The radiators all have little bleeder valves (I think people on here are calling them coin valves).
- Secondly, since this configuration for both floors has been mediocre in the best of circumstances, if my handyman and I are going to be getting elbow deep into things, I was inclined to swap this to either a 1-pipe Fluidflow or 2-pipe system, to allow individual regulation of the rooms, and to prevent a restriction (like if a piece of rust busts free from inside a radiator or something) from taking the whole circuit out. Before discovering this forum, I had found that Fluidflow Tees are not so widely available anymore, but I had found some brass ones that would allow me to run a 3/4" PEX main loop, and then use the existing 1/2" copper for the branches. From what I've been reading in other threads though, 3/4" PEX may be insufficient and/or my Taco 007 circulator may also not be up to the task. Basically, I would love to know, from anyone who understands the math of this stuff, what I would need to swap in to get this thing to actually work properly. As I understand it, there are a few elements that might be at play. There's A. More powerful circulator. B. Bigger diameter pipe. and C. Either Monoflow or 2 pipe swap, to allow individual regulation of rooms, the ability to bypass restrictions, and faster delivery of water to the latter radiators in the loop. I am unsure if Monoflow or 2-pipe would be better in this setting, so would love advice on that, given that I'd be redoing it from partial scratch. I have a soft spot in my heart for Monoflow as I have a different house with a early 1900s Monoflow system that has always worked fantastically, but it has a 1.5" black steel main loop, and maybe 5/8" Steel branches.
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I'm attaching an approximate diagram of the house, as well as a pic of the boiler and one of the plumbing entering/exiting a radiator, however I'd be happy to post any more detailed pics that would be helpful. I'm also attaching a pic of the steel Monoflo brand tees at the house that works great (not the one I'm inquiring about), just because I love the vintage labels on them and I thought you all might have an appreciation for them too.
Here is the one of the different house, with the Monoflo black steel setup that works great. There's not getting that installation orientation wrong, and they really don't make em' like the used to!
Comments
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Monoflos are kind of tricky to get set up right — although they work fine when they are. In your situation, I'd suggest repiping the first floor (and maybe the second, if you can get at it) as a reverse return system. That will give you control over the heat from each radiator without too much additional piping — and much more even, and more easily balanced, heat.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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You can’t pipe cast iron radiators in a series loop and expect proper performance. Each successive radiator will be substantially cooler and under perform.
Series loops only work with fin tube baseboards and even then there are limits and each following baseboard has to be properly oversized to accommodate the decreasing water temperature.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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I hate to see a homes heating system butchered like this. This home was probably heated with one hand fed coal boiler and it either had a bottom fed or overhead gravity hot water heating method.
You have thermal mass in the radiators but not enough hot water. At the time the coal fed boiler in the basement would have created enough hot water heat and thermal mass for the entire 2 story home.
I would want to know if there are orifice discs in the first floor and second floor radiators that have never been removed before you go any further.
To increase your thermal mass you need hot water storage. You could increase your thermal mass by adding two fully insulated rectangular 490 gallon hot water storage tanks from New Horizons by using one tank for each floor. You could use these tanks for a single bottom fed gravity hot water system for both living spaces as buffer tanks on the return side of each boiler. The 980+ gallons of water returning to the boilers would be warmer requiring less energy to reheat it.
My thoughts anyway.
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Thanks for the suggestion, I really appreciate it. That does sound like a pretty solid bet. A couple questions in relation to that plan:
1. Do you know if 3/4" PEX would be sufficient for the main distribution loop on a 2 pipe reverse return system? I was unsure if Monoflow or 2-pipe is more demanding in that regard, as Monoflow has more obstructions in the tees, but has less total feet of pipe.
2. Do you have any idea of if my existing Taco 007 Circulator would be up to the task of the 2-pipe reverse return?
3. I've been trying to educate myself on the pros and cons of Direct Return vs. Reverse Return on 2-pipe systems. I found this quote in a guide on hydronic heat system design:
"The designer should attempt to select all terminal units with nearly-equal pressure drops if a reverse-return arrangement is to be used. If the above considerations cannot be met, the primary advantage of a reverse-return piping arrangement will be lost, and the use of a lower-cost direct-return system would be more practical."
"If terminal units have widely varying pressure drops or if throttling-type valves are used to control flow rates, it is generally advisable to use a direct return piping arrangement."
Given that I am looking to continue to use my existing cast iron radiators, I don't have any control over the pressure drops, and would be balancing the radiators heat output using valves on the outflow from each one, which is a sort of throttling valve I think, then do you think Reverse Return is still advantageous for me over Direct Return?
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I do still think reverse return is better. Those existing radiators have almost no pressure drop at all — it's just the various elbows and valves. The amount of additional pipe isn't really all that much!
Pipe size depends on flow rate — which in turn depends on the BTUh which you are trying to push through it. 3/4 inch may take up to about 40,000 BTUh.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England1 -
Yeah, I agree fully regarding the series loop/radiator combo! I didn't know jack about this stuff when I bought this house, and was working in a day job out of state, so I just trusted the plumber who my parents had used for years to do me right. He told me he thought the heat "should balance out fine", and when the first Winter hit, and it didn't, and I'd realized how it was a series loop, I called him up. I had the other house with the Fluidflow that worked great, and I asked him why he hadn't done it using that or a 2 pipe, to better distribute the heat. He actually told me "No one does it like that any more, the fittings cost way too much". Now, after struggling with it for the past 15yrs, I've actually looked up the fittings and see it would have cost me an extra $100-200, on a system that cost somewhere around $10k! So for 1-2% extra cost, I could have avoided 15 years of hassles, tenant complaints, freeze issues, etc…!😡
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Don't feel too bad. I don't know anyone who hasn't made a few errors from time to time. Now you can go back and set things right!
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Yeah man, I hear ya on the butchering! You are correct that the house originally had a single boiler. Not sure what the original 1920s fuel source was, but when I bought it it had an oil boiler, that was certainly 50+ years old, but not sure if it was 90yrs old. I also saw signs of earlier old tanks, so it was on at least it's 2nd tank.
Wow, that suggestion about the hot water tanks is blowing my mind. I have never even heard of that, but I can see how it could be uniquely helpful in certain circumstances. I see you are talking about using one for each boiler, but you also mentioned "You could use these tanks for a single bottom fed gravity hot water system for both living spaces as buffer tanks on the return side of each boiler." Sorry if it's a dumb question, but I'm unfamiliar with this concept. Would that intermingle the fuel consumption for the 2 living spaces? I want to be sure to keep the utilities separate. Also, would that hot water tank setup be useful even with an electric circulator, or just if we converted it to a gravity fed system? The 2nd floor has the same 1/2" copper running from the basement up to each radiator, and from what I'm reading Gravity systems need large pipes, so not sure if that would work without a pretty major retrofit.
Regarding the orifice discs, I was unfamiliar with them, but just looked them up. Seems that they were/are used to balance flow to different radiators, and I can certainly see how having them in place could mess with a lot of retrofit configurations that differ from the original. Is it likely that they would have used them if the radiators also have balancing valves on the return branch, or would the valves have negated the need and offered more adjustability? I am attaching a pic of the valve in case that's helpful.
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Wow, thanks for the fast reply! That makes sense about the pressure drop (or lack therof) in the radiators. Regarding the 3/4 inch, am I correct in thinking that you're saying around 40k BTUh is the maximum amount of heat that can realistically flow through it? The boiler is 77 MBH (which I think is the same as BTUh?) but I'm not sure how many BTUh are actually required for this apartment and climate (USDA zone 6…looking at 9deg F tonight and 2deg F tomorrow night). I wouldn't want to substantially undersize the piping and end up having to re-do it again, but if 40k BTUh is reasonable then it would make it a little easier as my handyman and I are already geared up to work with up to 3/4" PEX, but not bigger than that. Having said that, given that the guy who installed this system cheaping out is what got me into this situation, I'm happy to invest in the extra gear to work with the bigger stuff if needed to really do it right.
P.S. Any idea on the applicability of that Taco 007 circulator?
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You really have to start from scratch to get a system that will work. 1/2" copper was common for the branch pipes in a Monoflow system but Monoflow radiation is not in series. You can't run the rasd in series with pex and expect them to heat.
What @Ironman said is correct.
do a room x room heat loss
select radiation (you already have that)
determine system supply temp
calculate pipe size and flow rate
calculate feet of head and select circulator
It's hard to reengineer a system that is screwed up. Best bet is start from scratch, follow all the steps and then you will know what you can keep and save.
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Yeah, I'm happy to do what it takes to get it working right, short of replacing the boiler, and I agree fully about a series loop being a terrible retrofit! So you think that the 1/2" copper is indicative of it being Monoflow originally, or do you think it could have been some other configuration?
Regarding the calculations you mentioned to determine the required specs, forgive my ignorance, but is there some sort of online calculator that a layman like myself can use for that? I know things like the room dimensions, level of insulation in walls and windows (poor!), climate zone (6), boiler supply temp (170f)), etc…but am not sure of how to put it all together. I was hoping that it would be clear cut enough that one of you geniuses could tell me what specs this'll need to work properly off the cuff, but that's probably overly optimistic, as I know the correct answer is often "it depends".
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You can run series on cast iron but with some caveats. I have to fixed this type of setup before and it does works, mostly.
What you need is pretty large water flow rate to limit the delta T in the loop. You need to pipe the boiler as primary secondary and run outdoor rest to control the rad loop. This avoids the issue with some of the rads never getting any heat if the boiler cycles are short. Without a bypass around each rad, you won't have control though, less an issue if the original rads were sized for each room properly.
You are definitely not doing this with 5/8 pex though on such a big loop. Think like 1" pex.
Since a fix means re-piping the whole thing, at that point might as well replumb the whole setup with a simple home run to each rad to a manifold by the boiler. This is about the same work and now you can control exactly how much flow each rad gets and the rad pipes can now be all 1/2" pex.
I would not bother with any monoflow, this is not worth the effort to get it right.
@leonz Not seeing how a buffer tank could help the situation here, care to expand.
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@Kaos, thanks for the info man! If I understand correctly, you are talking about 2 possible solutions:
In the first one you mention, I'd "need to pipe the boiler as primary secondary and run outdoor rest to control the rad loop." If I understand how primary secondary systems work correctly, that often would either require additional circulators for each room/radiator. Besides the fact that I'm watching the budget, I have to admit that, all else being equal, I have a bias toward passive systems rather than active ones. From your description though, it sort of sounds like you are talking about still running the radiators in series, just with 1 extra circulator to boost the secondary (radiator) loop flow. That would certainly give more flow (especially combined with a 1" pipe), but if heat could be individually balanced on a room by room basis using passive balancing valves and a 2-pipe reverse return system, I'm having trouble seeing the benefit of adding one or more extra circulators. Is there a big benefit that I'm missing?
Regarding the second solution, I know newly built houses tend to use manifolds with home runs to each radiator, and I am open to doing that, I just hadn't considered it as I'd assumed it would require the replacement/addition of a lot more equipment. Given the ease of running PEX, and the inexpense of 1/2" PEX, it might be pretty comparable to doing a 1" 2-pipe reverse return system in terms of time and expense. You mentioned the manifold being "simple" and I love the sound of that. Given the bias I mentioned earlier toward passive systems, it seems that this could still work if I installed TRVs on each radiator. Again, compared to a 2-pipe reverse return (or direct return) system, how do you think the 2 would compare?
Thank you for your insights and knowledge!
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The valve in the picture you were so kind to provide is a shut off valve not a balancing valve.
Mr. Holohan talks extensively about gravity hot water heating systems in his excellent book "CLASSIC HYDRONICS". Please order a copy of this book as well as a copy of his excellent book HOW COME which describes early hot water heating systems as well in great detail; they are worth every penny and you suppoort the author and his family when buying them through the Heating Help bookstore page here on the forum.
These excellent paperback books will come from the heating help bookstore and not from a middleman like amazon or a chain bookstore.
The book CLASSIC HYDRONICS comes in a wire bound form that allows you to open to a specific page and fold the book under itself and set it down while you are looking at your plumbing or installing new piping to create the correct piping layout for a gravity hot water system.
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You could have two separate bottom fed gravity hot water systems with buffer tanks to store more cool return water connected to each boiler sump and you would use less fuel because the boiler would use less oil to heat the water that is already warmer.
Having two buffer tanks would and could provide you with fuel savings if one or two boilers are used as the buffer tanks would heat the water to 170+ degrees and if the 2 systems were converted back to a single gravity hot water system the boiler would be operating and reheating the 980 plus gallons of water for the entire heating plant meaning all 20 radiators.
If the entire future system had a combined total of 1,200+- gallons of water including the new properly sized piping your boiler would be consuming the same amount of fuel per hour and per day to heat both units using one boiler and you would split the cost adding it to the rent. If supplemental heat is needed the tenants could use electric heaters as long as the homes wiring can handle the load OR you raise the water temperature of the single boiler and the boiler would just run longer-depending strictly on the system temperature.
The more thermal mass(water storage) you have the greater amount of heat that can be created and continue to provide your individual tennant with slow even heat.
If time allows you can have the living spaces improved by having more insulation installed as well as new wooden windows and doors and the fuel savings will of course increase costing you less money and saving your tennant money.
Increased thermal mass allows for more warm return water to come back to the buffer tank(s) to be reheated using less fuel for each tennant.
If this 2 story home did not have an attic the bottom fed gravity hot water system used the radiators as expansion tanks with an air charge left in the radiators to add pressure to the system to create flow and the first floor radiators had restrictor discs in them.
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A coal stoker boiler could be used to heat both living spaces and make domestic hot water very economically using stoker coal from Pennsylvania, Montana or Wyoming.
You are welcome to contact me via a PM if you would like to learn more.
About me;
I eliminated my oil heating system because my former oil company suburban propain let me run out of fuel 4 times too many and I have used my coal stoker boiler to heat my very old home since 2015.
My keystoker coal stoker is simple to maintain and easy to clean and provides me with plenty of domestic hot water that is temperature regulated using a mixing valve.
Sadly, I lack a buffer tank to store more hot water as this old one room schoolhouse is poorly insulated.
Leon
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Another option is to split the long loop into two shorter loops
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
A buffer or storage tank creates additional thermal mass to deliver more heat to the living space and return a greater amount of already warm water to be reheated using less fuel to bring it up to temperature.
Thermal mass is money in the heat savings bank. The more money you have in thermal mass savings bank the more heat that you can create with less energy used.
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I should have been clearer. You can make a series loop work, but not worth the effort. Even when done better it still has issues, so if you are spending time/money to replumb, do it properly.
In your case, do a nice home run setup from each rad to a central manifold. You don't need TRVs on the rads as you can balance the flow by adjusting at the manifold. Doesn't hurt to add the TRVs, but not worth the cost.
Your mid efficiency boiler most likely will not like a direct to load setup with high mass radiators. I would check the manufacturer's instruction but you will most likely need a bypass loop or primary secondary piping to avoid condensation.
A bypass (could be simple pipe or better one with a thermostatic valve) does not need extra pump or controls. A primary/secondary setup does.
A buffer tank does not reduce your heat load as it has no way of creating heat. If your building needs 50kBtu to maintain 70f, you boiler needs to put out that heat, no way around it. The only thing it can do is average out temperature to avoid excessive cycling. Reducing cycling does reduce fuel use a bit, so sometimes a bit of a buffer is a good thing.
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Thanks for the suggestion and diagram. Am I correct in thinking that if I were to split my current single series loop output into 2, I would be getting half the flow rate on each of the smaller series loops? If my issue is that I'm not getting heat past halfway around my current circuit, would splitting the circuit into 2, but halving the flow rate not result in the same issue at the latter radiators in each of the series loops (i.e. the water takes so dang long to get there that it has lost all its heat)?
Even still, I could see splitting things up into 2 loops being helpful just in terms of layout, so if I ended up doing a 2-pipe reverse return setup, having 2 separate loops of that seems like it could aid the layout while the bypasses on each radiator would allow the water to get to each of the radiators in the series faster.
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The job of the orifice discs was to prevent all the hot water made by the boiler to be pushed into the first floor radiators as the hot water would want to go there first since it is lazy and there is nothing stopping it from going there first and the second floor radiators would not receive enough hot water to heat the radiators and the cooler water would also drop to the basement faster.
An overhead hot water heating system would be created using a single hot water riser to the top floor and then a top floor header pipe in the ceiling would come off an elbow at one end or a double elbow in the center of the building and feed the hot water to the radiators using Tees feeding a line in the ceiling going to a specific radiator and that radiator was piped top to bottom and then the water exiting the top floor radiator dropped to the lower floor(s) and then to the basement where it dropped top the cool water return header that ran around the basement and then dropped to the boiler sump.
If I remember Mr. Holohans writing correctly the plumber piped the risers in such a way that there were two hot water risers coming off both sides of the boiler which would allow the hot water to reach the radiators faster in a bottom fed system where an overhead system used a single large diameter riser and fed hot water to the radiators using a double elbow feeding a header pipe buried in insulation in the attic feeding hot water to all the radiators on the second floor first and then the warm water from the third or second floor radiators would drop from the bottom of those radiators to the radiator below it and then to the basement where the cooler water header pipes would carry it back to the boiler sump.
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Split into two loops… split into individual loops with home runs… split into individual loops with reverse return… (home run and reverse return are hydraulically equivalent)…
Really doesn't matter; the more individual loops you have and the fewer radiators you have on each loop, the better balanced the system will be inherently — and thus the easier it will be to get it "just right".
As has been mentioned, home run does have the advantage of all the balancing controls being in one place. I'm not really keen on two grounds — one trivial, one not. The one not trivial is that is uses a lot more pipe to do the job. Granted, smaller pipe — but a lot more of it, particularly if the house is at all spread out or multi-story. The trivial one is related: I've never cared for the look of or the visual complexity of the resulting array of manifolds and valves in the control compartment, if you can call it that. I've seen piping arrays in a nice four bedroom house which made the piping in the engine room of USS New Jersey look simple… why?
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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whoever "repaired" it didn't understand hydronics.
- the boilers are almost certainly way oversized.
- you need about 1.25" pipe minimum for enough flow to carry the output of those boilers.
- .5" can carry about 1 gpm and about 10,000 btu/hr.
the fix is to repipe it with a supply and return main that is about 1.25" or home run each radiator to a manifold.
if you were to mix the water down to a low temp so the radiators didn't output much and do that on outdoor reset and use constant circulation you could maybe get the series loop to work but that wasn't what the person that did this was going for, they were just clueless. you would have to keep the boiler at a high temp and have mixing controls to make low temp in the system. if someone closes or partially closes a radiator valve anywhere the loop the flow goes away. it will only work if you heat loss is around 10,000 btu/hr per floor. I absolutely don't recommend trying to get this to work in a rental unit. it could possibly work in your own home if you do the math and that works out. with high temp water the forst 2 or 3 radiators are going to dump all the heat and you get much cooler water to the rest. this option is more academic than a viable solution. the solution is a repipe with supply and return mains or home runs.
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@Jamie Hall Thank you for juxtaposing the various options discussed above! As you saw, when I'd first inquired, I was leaning towards swapping my series loop for either a 1-pipe Fluidflow, or a 2-pipe setup. Given that no-one here seems to be advocating for a new Fluidflow installation, and you made a strong case for 2-pipe reverse return, I was leaning towards that option.
Plus, I have the aforementioned bias toward passive low tech systems vs. adding additional powered circulators for secondary loops, which some of these primary/secondary diagrams I'm seeing involve.
After @hot_rod mentioned splitting it into 2 series loops, I started thinking of the layout, and for some reason the idea of 2 loops sounds appealing, although I'd still want to do the 2-pipe reverse return on each of them for the individual radiator/room control. If Jamie is saying that there's no harm in doing 2 loops vs. 1 (and potentially even a benefit), I'm now thinking about splitting my current output into a loop that runs from the #1 through #5 radiators on the diagram in my original post, and then a 2nd loop that runs backwards from the #10 to the #6 radiators. Both would be reverse return, and with the flow split between 2 loops, it seems like 3/4" PEX may be sufficient as I could run up to 4gpm through each loop, which is comparable in capacity to the 1" loop @Kaos had suggested for a single loop system, and it fits with @Jamie Hall's point about 3/4" PEX maxxing out at about 40k BTUh, so 2 individual 3/4" loops could handle my Max boiler output of 77 MBH. I'm looking to make it work well, but also get it done quickly, as I have cranky tenants and our temps have been in the single digits the last few nights, so getting it to 80% of optimal is good enough for all of our needs.
In my own living space, I can see how a manifold/home run system that I can fine tune for my preferences could be a great setup, but I rent mostly to student tenants from the local universities, so in this case I'd prefer to have a setup where they can regulate each radiator individually from their living space. That way, they're not needing to go to the basement to try to adjust the heat delivery for their loop, and if one roommate wants it to be 80f in their room and another likes to optimize their sleep with a 60f room, they can self manage with the valves on each radiator (which has not been possible with the current series loop system).
3 questions for y'all:
- Does the above 2 loop 3/4inch 2-pipe per loop reverse return system seem like a "80% of optimal" solution to you?
- Should I remove the super small/tight elbow following the flowcheck in the upper right of the following pic when I set up the new system? It seems unnecessarily restrictive. My inclination would be to place the 3/4" wye or tee to split into the 2 loops right after the flowcheck to avoid the bottleneck, and then just flex the PEX to head off in the proper direction, and avoid unnecessary restrictions.
- Will the valves in the following pic, that I'd thought were balancing valves, work to modulate heat to the individual rooms? @leonz informed me that they are actually shutoff valves, and so I'm assuming they don't offer the same level of fidelity as proper balancing valves. These valves will go 1/2 turn, lock to lock, so fine tuning is assuredly a bit more difficult but, assuming that they can be set to intermediate points between open and closed, I am having trouble seeing why they can't be used for modulating the heat delivery to individual rooms with the above spec, 2-pipe 2 loop, system.
Thanks again, everyone, for your contributions. You're really helping me narrow down the myriad options to get to something that will get us not just back in action, but restored to proper function.
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Valves can be used to balance. with the split loop i'd probably do 1.25" copper to the center and 1" copper for each half of the loop. 1" and 3/4" probably can carry more heat than you need but the boiler might cycle more with the smaller piping. if you use pex compare the id to copper, especially in larger sizes you have to use a size or 2 larger to get the same size as copper. 3/4" and 1" fittings are reasonable, 1.25" fittings get expensive in copper so the split loop saves a lot of cost in fittings.
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@mattmia2 Thank you for your input. On your first post, you said "whoever "repaired" it didn't understand hydronics." Yeah, fully agreed, and every winter I get more and more angry at that idiot/slacker (who's name happens to be Tim). He went to tech school, and grew up/inherited the plumbing business from his dad, plus my parents had relied on their plumbing biz for years, so I'd assumed he knew what he was doing, but I never got a good vibe from him when we were talking face to face. I've moved on to doing things myself with a great "old timer" handyman, but have the urge to call Tim up and give him a piece of my mind every time I end up dealing with particularly irksome situations on this system.
Your description of someone messing with a radiator valve and shutting down the whole system rings very true to me, as I've been there and done that. We took the knobs off all the shutoff/balancing valves, to deter that, but that doesn't keep someone from using a wrench on the flats of the stem. It's particularly difficult with student renters, due to the high turnover, different move-in dates of each roommate, and possible language barriers with international students (of which, there are an increasing amount). That is why I was originally looking at a swap to Fluidflow or 2-pipe, as that is how I was assuming the system was originally configured, and restoring the bypasses around each radiator would be very forgiving of a single roommate turning their radiator off (for whatever reason). Basically, idiot proofing is always a consideration for me
Regarding your second post, thank you for the suggestions about specific pipe diameters, and reassurance that I'm not crazy with the 2-pipe split-loop idea. I love the idea of optimizing fuel usage, but as long as my tenants are happy I am less concerned about Short Cycling. so that layout is gaining steam with me.
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if you are up for something “off the wall”?
Ive built a couple different flow reversers
One using a 4 way valve with a damper motor actuator. Every 15 minutes it swaps flow direction. I built two of these for a jobs with a “builders special” single 1000’ radiant loop
The other was on a 500 gallon buffer tank for my wood boiler it would flow bottom to top when heating, pull from top to bottom when discharging. It was basically two circulators bolted together facing each other😗Run one at a time, of course.
It can also be done with a few 3 way zone valves
here is what the 4 way valve piping looks likeBob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream1 -
The only problem with two series loops rather than individual piping is that while you can control each loop individually, you can't control individual radiators within a loop, since what you do to any one of them affects the flow in all of them. You may well be able to live with that.
It's quite true that quarter turn valves are usually pretty miserable at balancing flows, but… with patience they can and do work. They're just a good deal more finicky.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
@PC7060 what do you disagree about? 1' is iffy for 70,000 btu/hr but it is fine for 35,000 btu/hr.
If you split your main in the middle most of your main can be 1", you just need to use 1.25" to the center of the main. Your return mains can be 1" and connect together at the boiler.the load on the first floor is probably under 35,000 btu/hr but really the first step is a heat loss calculation. if the boiler can't get rid of the heat it is producing it will cycle on the aquastat frequently which ideally you would avoid by sizing the piping large enough to get rid of the heat.
1 -
Considering all things involved, it’s probably gonna be best to go with a home run system connected to a good manifold with flow setters.
Make sure that you use O2 barrier pex.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.0
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