How to fix this mono flow rad? (FIXED)

EdTheHeaterMan

You could try a Taco 006 or 007. They are small and you could put a vented box over it to hide it if needed. https://www.supplyhouse.com/Taco-007-F5-007-Cast-Iron-Circulator-1-25-HP-1983000-p

mattmia2

i think i know what your problem is but it is complicated to explain. basically it is taking the least resistance on your split loop of your split loop so there isn't enough flow to heat the difficult radiators. you need balancing valves in the split loops

EdTheHeaterMan

mattmia2 said:

i think i know what your problem is but it is complicated to explain. basically it is taking the least resistance on your split loop of your split loop so there isn't enough flow to heat the difficult radiators. you need balancing valves in the split loops

Simple explanation: Heated water will take the path of least resistance. The radiator is not the path of least resistance.

There are a couple of reasons why the radiator is not the path of least resistance. One of the reasons is that the hotter water is lighter and will tend to rise in the pipe and radiator system. Since that radiator is lower in the system than all the other radiators, gravity is working against the flow DOWN to the radiator.

Another reason is the restriction and venturi effect created by the monoflo tee, that is designed to create a path of less resistance thru the radiator is not enough to move that heated water DOWN to the low radiator. Most monoflo or venturi tee manufacturers know this is a problem and recommend that you install 2 venturi tees whenever you have a radiator that is lower than the main pipe.

Big Ed_4

A mono flow system uses a single supply pipe , it runs on high water volume and low resistance . The Venturi adds a pressure drop to help feed the radiator , The gravity of the hot water is also helping . One Venturi is normally enough if the risers are up feed . With a down feed(like yours) you use two Venturi to add more pressure drop , because now it is fighting gravity .

Still scratching my head .... 70 years , now it is a problem

mattmia2

Big Ed_4 said:

A mono flow system uses a single supply pipe , it runs on high water volume and low resistance . The Venturi adds a pressure drop to help feed the radiator , The gravity of the hot water is also helping . One Venturi is normally enough if the risers are up feed . With a down feed(like yours) you use two Venturi to add more pressure drop , because now it is fighting gravity .

Still scratching my head .... 70 years , now it is a problem

i suspect it wasn't a problem until the circulators were changed with the boiler. i'll draw a sketch of how i think he described the loops on another thread. i think adding more tees will encourage more flow in the other half of the split loop with one circulator unless there are balancing valves or a circulator with more velocity added.

mattmia2

@sixplex is this how your loops, the boiler, and the circulators are arranged? ignore the exact number of emitters, just look at the general topology:

EdTheHeaterMan

I wonder if this question was ever answered...

sixplex said:

Never worked, 70 y/0. 1 monoflo tee, Tees are only 16 inches apart (narrower than the rad), rad is slightly below the main

Easiest fix?

Current thoughts

1) Just remove the rad connect the ends together
2) Add second Monoflow tee
3) Put in a smaller rads, this one has 14 sections, much wider than 16 inches


What do you guys think? Local contractors don't get monoflo, i basically have to tell them what to do.

Never worked, 70 y/0 for 70 years?
Never worked, 70 y/0 since the new boiler was installed but it worked before that?
Never worked, 70 y/0 since I repiped to pumpin g away? (see this discussion: https://forum.heatinghelp.com/discussion/193072/biting-the-bullet-to-repipe-this-boiler-to-pump-away#)

EdTheHeaterMan

Also: what is the status of your other problems? Curious about your repipe to pumping away, solving the temperature difference in the 6 apartments, did you ever get the basement radiators drained?
https://www.supplyhouse.com/Taco-007-F5-007-Cast-Iron-Circulator-1-25-HP-1983000-p
https://www.supplyhouse.com/Dahl-221DH-01-04-CC-1-2-Female-Solder-or-1-2-MIP-x-Male-Hose-Angle-Hose-Boiler-Drain-Valve-w-Cap-Chain

sixplex

mattmia2 said:

@sixplex is this how your loops, the boiler, and the circulators are arranged? ignore the exact number of emitters, just look at the general topology:

almost! what you labelled zone 1 and zone 2 are actually subzones of my zones (left and right side of the buiding)

the zones are basically your diagram superimposed.

zone1 basement ( all rads before the main)
zone 2 (2-3) floors, all rads (except for the one in this thread) above the main

not sure if that makes sense, not easy to explain

sixplex

rental building (nobody cared enough to fix the issue), builder screwed up 70 years ago, maybe the rad was lukewarm initially if the pump was a lot stronger

i agree and that it needs a second monoflo tee. that's some major surgery money wise it seems

sixplex

EdTheHeaterMan said:

Also: what is the status of your other problems? Curious about your repipe to pumping away, solving the temperature difference in the 6 apartments, did you ever get the basement radiators drained?
https://www.supplyhouse.com/Taco-007-F5-007-Cast-Iron-Circulator-1-25-HP-1983000-p
https://www.supplyhouse.com/Dahl-221DH-01-04-CC-1-2-Female-Solder-or-1-2-MIP-x-Male-Hose-Angle-Hose-Boiler-Drain-Valve-w-Cap-Chain

i'll post an update in the other thread, i feel this a separate issue
i own a spare 007 it would be far from ideal putting it there.

sixplex

Does anyone even sell bell and gossett monoflo tees anymore?
I need a 1-1/4 by 3/4. Going to run by the plumber the idea of reping.


Plan B, whenever i fully repipe the boilroom room. Maybe i'll just run
pex to the problematic rad, seems cleaner than putting a 007 and 110v on the rad.

109A_5

sixplex said:

Neighbour has an identical building her rad (same as mine) is piped differently (bottom supply possible other differences) and works great. I'm thinking at this point they piped it wrong 70 years ago, or used a monster pump. Makes no sense for me to have a much stronger pump for this one rad if the other 35 rads work fine

If she will let you just accurately document her version of that radiator and if possible also verify the Monoflo fittings, maybe she has two and you only have one. And to make some folks happy maybe see what circulator her system actually has too. Her system is proof it can work. Make yours like Hers.

sixplex

She has the same rad connected bottom to bottom, which is already better than mine because the tees are spaced at least the width of the rad, mine aren't. Can't see her tee though, they're inside a wall.

She has 2 wilo pumps at medium, they might be hooked up in series though (1 zone), was there a while back, can't tell from the pics

HomerJSmith

Take an IR photo of the supply piping.
Well, the IR photo says, you donna hava no flow. Why? Blockage in the radiator, supply and return inverted, monoflow tee installed backward, monoflow tee plugged?
Just spit-balling here, having the supply to the radiator at the top, I would think that one is fighting the second law of thermodynamics. Hot water rises, moving hot water down to cold water is moving the hot water in the direction contrary to its natural tendency to rise. Do we have a mis-piping problem here? I mean can the Pacific ocean conveyor currents be wrong?

mattmia2

If the way i drew is schematically how your system is piped, with tees feeding other tees and 2 branches on one circulator your answer is there. It doesn't matter for this where physically the pipes are, just that they are arranged how i drew it with the cascaded center of the loop feeds.

sixplex

So.... the problem rad has a REGULAR supply tee, and a monoflow return tee pointing backwards. Bell and gossett specifies 2 monoflow tees must be used for any rad below the main. Which is the main problem.

There is another rad, piped almost identically, it has monoflow on supply and return, pointing in the direction of the flow and works fine.

Questions.

1. The rads PAST this non functional rad were always cooler, it is because the non functioning rad significantly restrict the flow?

2. Is it ok to replace the regular supply tee with a monoflow one pointing in the direction of the flow and keep the return tee, which is pointed backwards ? What is the downside of keeping the return tee that is pointing backwards?

3. Anyone know where i can buy a 1-1/4 by 3/4 cast iron monoflo tee? Nobody sells them.

mattmia2

If the venturi is on the outlet of the return tee it will restrict the flow of the loop. It relies on the flow through the branch to get full flow in the loop. If the branch is before the venturi then the flow in the radiator isn't bypassing the venturi but is limited to what can pass through the venturi.

EBEBRATT-Ed

You can use monoflow tees on the return only , on the supply only or on the supply and return. But the orientation needs to be correct.


Looking at a tee used on the supply the tee will scoop the water into the radiation branch pipe. A tee used on the return will partially block the flow in the main at the inlet to the return tee.

@sixplex you may have to use copper venturi tees with adapters.

You could also use 2 regular tees on the supply and return and put a balancing return between the two tees.

sixplex

Sourced a 1-1/4 by 1/2, bell and gosset.

Does it make sense getting a machine shop enlarging a 1/2 outlet into a 3/4 ? 

mattmia2

If you want to tinker just use 2 plain tees and a balancing valve in the main between the 2 so you can adjust the diverted flow like @EBEBRATT-Ed suggested.

EdTheHeaterMan

sixplex said:

Sourced a 1-1/4 by 1/2, bell and gosset.

Does it make sense getting a machine shop enlarging a 1/2 outlet into a 3/4 ? 

NO that does not make sense. the inside of a 1-1/4" x 3/4" is different than the inside of a 1-1/4" x 1/2" Monoflo® tee. so you will not get the proper pressure drop across the modified part.

As far as having a tee in the wrong direction here is an illustration of what you should do when using 2 diverter tees on one radiator.
. It can be confusing to know where the red stripe goes based on the arrow on the tee. For the most part it is easiest to remember that the red stripe on the tee is closer to the other pipe on the radiator. If using 2 tees then the red stripes are facing each other. Or to be more clear, the red stripe is connected to the same pipe nipple.
Take a look at these illustrations in the attached files

sixplex

mattmia2 said:

If you want to tinker just use 2 plain tees and a balancing valve in the main between the 2 so you can adjust the diverted flow like @EBEBRATT-Ed suggested.

thanks! didn't fully understand what he meant.

sixplex

every other hvac guy ive spoken just says to put it a stonger pump, "it must've worked originally" they say.

will a pump with a high enough head fix this??

to me that makes no sense, water will still take the easiest path, which is along the main and not through the rad.

ScottSecor

I probably missed it, what is the make and model of the current circulator pump? Please show us a photo of YOUR boiler and near boiler piping.

mattmia2

sixplex said:

every other hvac guy ive spoken just says to put it a stonger pump, "it must've worked originally" they say.

will a pump with a high enough head fix this??

to me that makes no sense, water will still take the easiest path, which is along the main and not through the rad.

the loop is fed with one circulator in the middle with 2 returns form that center point right?

it is probably balancing of the 2 halves of the loop, especially if that tee is in backward one side of the loop is going to get much more of the flow unless you have balancing valves on each side of the loop

sixplex

ScottSecor said:

I probably missed it, what is the make and model of the current circulator pump? Please show us a photo of YOUR boiler and near boiler piping.

- Taco 0015e3 (007 equivalent at medium) (008 at high) at high, max head is 18ft and the problem rad still doesn't work
- 2" supply pipe and with split return pipe, 2 pipes 1-1/4 each.
- boiler boiler 225 input 180,000 btu output
- 95% of the rads are baseboard cast iron, which needs very low GPM as far as i understand

sixplex

mattmia2 said:

sixplex said:

the loop is fed with one circulator in the middle with 2 returns form that center point right?

correct! each return is mostly balanced in terms of head and BTU load, they also have gate valves for some degree of control

return with the bad rad does UNDERHEAT a bit and the other returns OVERHEATS

mattmia2

sixplex said:

mattmia2 said:

sixplex said:

the loop is fed with one circulator in the middle with 2 returns form that center point right?

correct! each return is mostly balanced in terms of head and BTU load, they also have gate valves for some degree of control

return with the bad rad does UNDERHEAT a bit and the other returns OVERHEATS

gate valves are for on/off only, the gate will be damaged over time if they are partially closed (are you sure they aren't globe valves?)

sixplex

what i don't understand is.

bad rad which has 0 flow, cuts the flow in the main by 25%-75%.

if i were to put in a balancing valve between the 2 existing tees of the bad rad, further INCREASING restriction along the main but diverting some flow to the BAD rad.

would the flow in the main past the bad rad INCREASE afterwards??
this is super counter intuitive to me

sixplex

mattmia2 said:

sixplex said:

mattmia2 said:

sixplex said:

the loop is fed with one circulator in the middle with 2 returns form that center point right?

correct! each return is mostly balanced in terms of head and BTU load, they also have gate valves for some degree of control

return with the bad rad does UNDERHEAT a bit and the other returns OVERHEATS

gate valves are for on/off only, the gate will be damaged over time if they are partially closed (are you sure they aren't globe valves?)

i think so

mattmia2

yeah looks like a gate valve.

You would have to replace the monoflow tee with a regular tee if you go with the balencign valve on the min in between, essentialy the valve does the same thing as the venturi on the monoflow tee.(use a globe or ball valve for balancing, a globe valve allows for better control but is more restrictive)

Might be easier to use a combination of iron and propress copper or propex pex to replace it rather than trying to fit all iron pipe in there.

I'm not recommending this but it is a thought that popped in my head, you could cut the pipe in to the monoflow tee and use a hole saw to cut out the venturi in the tee then put a new section of pipe with a balancing valve between the 2 fittings.

EdTheHeaterMan

mattmia2 said:

yeah looks like a gate valve.

You would have to replace the monoflow tee with a regular tee if you go with the balencign valve on the min in between, essentialy the valve does the same thing as the venturi on the monoflow tee.(use a globe or ball valve for balancing, a globe valve allows for better control but is more restrictive)

Might be easier to use a combination of iron and propress copper or propex pex to replace it rather than trying to fit all iron pipe in there.

I'm not recommending this but it is a thought that popped in my head, you could cut the pipe in to the monoflow tee and use a hole saw to cut out the venturi in the tee then put a new section of pipe with a balancing valve between the 2 fittings.

I don't understand why that existing Monoflo® tee needs to be removed. As it is existing and does not create sufficient pressure drop to make the heated water detour to the radiator, what harm is there in leaving it there? To solve that problem, MORE pressure drop or more restriction is required. How does removing some of that restriction help? There is no benefit to that extra work and after all that work is completed, that restriction is gone ...so to compensate, one would need to crank the balancing valve a half a turn more to add the restriction lost by all the unnecessary work.

If adding a valve will solve the problem, just add the valve and adjust accordingly.

mattmia2

EdTheHeaterMan said:

mattmia2 said:

yeah looks like a gate valve.

You would have to replace the monoflow tee with a regular tee if you go with the balencign valve on the min in between, essentialy the valve does the same thing as the venturi on the monoflow tee.(use a globe or ball valve for balancing, a globe valve allows for better control but is more restrictive)

Might be easier to use a combination of iron and propress copper or propex pex to replace it rather than trying to fit all iron pipe in there.

I'm not recommending this but it is a thought that popped in my head, you could cut the pipe in to the monoflow tee and use a hole saw to cut out the venturi in the tee then put a new section of pipe with a balancing valve between the 2 fittings.

I don't understand why that existing Monoflo® tee needs to be removed. As it is existing and does not create sufficient pressure drop to make the heated water detour to the radiator, what harm is there in leaving it there? To solve that problem, MORE pressure drop or more restriction is required. How does removing some of that restriction help? There is no benefit to that extra work and after all that work is completed, that restriction is gone ...so to compensate, one would need to crank the balancing valve a half a turn more to add the restriction lost by all the unnecessary work.

If adding a valve will solve the problem, just add the valve and adjust accordingly.

Rotate the tee in your diagram above 180 degrees and think about where the water doesn't go when you do that and tell me why it needs to go.

That is if the return tee is in fact backwards.

sixplex

EdTheHeaterMan said:

sixplex said:

Sourced a 1-1/4 by 1/2, bell and gosset.

Does it make sense getting a machine shop enlarging a 1/2 outlet into a 3/4 ? 

NO that does not make sense. the inside of a 1-1/4" x 3/4" is different than the inside of a 1-1/4" x 1/2" Monoflo® tee. so you will not get the proper pressure drop across the modified part.

As far as having a tee in the wrong direction here is an illustration of what you should do when using 2 diverter tees on one radiator.
. It can be confusing to know where the red stripe goes based on the arrow on the tee. For the most part it is easiest to remember that the red stripe on the tee is closer to the other pipe on the radiator. If using 2 tees then the red stripes are facing each other. Or to be more clear, the red stripe is connected to the same pipe nipple.
Take a look at these illustrations in the attached files

My monoflo tees are ARMSTRONG, no red ring. Return is pointed against the flow.

If i replace the regular supply tee, with one where the red ring is is closer to the return tee,
is that all it takes to fix this?

if i use a 1-1/4 by 1/2 tee, instead of 1-1/4 by 3/4 would it work ?

sixplex

which way is the cone on my monoflo tee?


if my cone is oriented the way the lower cone on the picture below is, considering the supply tee is a regular tee, of course it doesnt work

EBEBRATT-Ed

Agree.

hot_rod

Could you get a 1-1/4 X 3/4 Tee and put a restriction washer in it? Or do those diverter tees actually have a cone shape inside?

A flat reducing disc would be not unlike a partially closed gate valve between tees.

sixplex

there are 2 1/8 bleeder vents at the top, screwed into what looks to be a reducer, at least 1/4 i guess.

before i do any major surgery on this rad, thinking of connecting the two outlets at the top together.

would not fix the rad but would possibly affect the rads downstream in a positive way

EdTheHeaterMan

Every reply from @sixplex brings more questions. In this picture there is an Armstrong Monoflo that appears to be installed backwards, if the Red "FLO" arrow is correct. If this is the tee that comes from the return of the problem radiator, then I want to know where the supply for that radiator is connected to the 1-1/4" pipe? Also, this 3/4" branch pipe appears to go up from the 1-1/4" main. So why are there so many comments about the radiator being lower than the main?


Now if the backwards tee is on the problem radiator, then the fix would be to turn that tee around. The easiest fix would be to cut the 1-1/4" pipe on both sides of that tee, then turn that tee 180° tighter, then use 2 Megs Press couplings https://www.supplyhouse.com/Viega-25085-1-1-4-MegaPress-Extended-Coupling-without-Stop You would rent the tool for installing the fittings

The other fix would be to cut the 3/4" pipe and the shorter 1-1/4" pipe and remove the Monoflo® tee and turn it around in the proper orientation. Replace the short pipes with copper or nipples and unions as needed.