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Help with monoflow system

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Kenny_od
Kenny_od Member Posts: 5
edited March 30 in Radiant Heating
Hello all,

I've been reading as much information as possible on monoflow systems and I'm really here just for confirmation that what I'm thinking is correct. 

Recently had all my basement re- plumbed  with 3/4 pex main. I believe the plumber installed the monoflow tees improperly. Let me just say I don't know how or why but all the baseboard, convectors and toekick heaters get hot. As you can see he has 2 monoflow tees on every convector heading in the direction of the return EXCEPT the living room convector. Those monoflow tees goes the opposite way. 
 
Also, on the toe kick heaters shouldn't the monoflows face each other if it is determined there needs to be additional flow through it? 

All of the heat is above the main. 

Basically what I'm thinking is..
1. Place one monoflow on the return on each convector/toekick and a regular tee on the supply side. 

2. Re orient the living room monoflow the proper way. 

Thanks in advance for any help. I just want to make sure I get this right before I sheetrock the ceiling. 




Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,539
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    Living room tees look wrong to me. Monoflo is supposed to be designed closely ...not just wing it. Normally only one Monoflo tee is used for each piece of radiation but if it works with two and you get enough flow, I guess I wouldn't touch it except for the living room tees are pointed in the wrong direction. It looks like you have Monoflo and baseboard loop mixed.

    Normally only one Monoflo is used for each branch unless the radiation is below the main

    You never point Monoflo tees at each other.

    Except for the living room it should work as is. The double Monoflo's are just causing more flow restriction. If your happy with the heating leave it just change the living room tee orientation.
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,526
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    There’s a red ring on the Monoflo tee. That ring has to be on the inboard side of the riser that goes to the radiator. When you have two Monoflos the rings will both be on the inboard side of each riser, meaning one is going to appear to be backwards. Just look at the rings. B&G put them there to avoid confusion. 
    Retired and loving it.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
    edited March 30
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    I might be wrong, because there is not enough information in your diagram. But if you have more than about 65Ft total baseboard with heating element (number of feet varies based on heat output of your brand of baseboard), or a combination of baseboard and convector the exceeds 40,000 BTUh output into the rooms, you may have a problem heating your home on the coldest day of the year.

    Your boiler has the ability to send 130,000 BTUh into the connected radiators. But the pipe connecting that 130,000 BTUh heater to whatever your radiators can emit, is only ¾”. That ¾” pipe can only move about 40,000 BTUh from the boiler to the radiators. This booklet Zoning Made Easy can tell you why. It it starts on page 4 pages and easy to understand. By the time you get to page 7 you will be an expert on sizing boiler piping. Even if you need to read it more than once to get the gist of what I'm saying.

    There is a little information about Mono-Flo® Tee systems starting on page 22.
    The file below may be easier to zoom in on.

    The top of the diagram is how two tees should be piped, forget the arrows. But you are correct in the way it should be connected, as long as you do not confuse the arrow for the flow direction. It is actually means the flow direction if the Tee is installed on the return side of the radiator. In this older photo of a Monoflo® Tee there are two arrows and you select the flow direction based on the location of the Tee, Supply is to the left and Return is to the right. So if it is on the supply, "Turn It Around"

    The red circle that Dan Holohan is referring to.


    I still believe you need to check how much heat your are going to need when it is very cold! You may have redesigned your piping into a system that may not work, but you will not know about it until it is way too cold the do anything about it.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Kenny_od
    Kenny_od Member Posts: 5
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    I might be wrong, because there is not enough information in your diagram. But if you have more than about 65Ft total baseboard with heating element (number of feet varies based on heat output of your brand of baseboard), or a combination of baseboard and convector the exceeds 40,000 BTUh output into the rooms, you may have a problem heating your home on the coldest day of the year. Your boiler has the ability to send 130,000 BTUh into the connected radiators. But the pipe connecting that 130,000 BTUh heater to whatever your radiators can emit, is only ¾”. That ¾” pipe can only move about 40,000 BTUh from the boiler to the radiators. This booklet Zoning Made Easy can tell you why. It it starts on page 4 pages and easy to understand. By the time you get to page 7 you will be an expert on sizing boiler piping. Even if you need to read it more than once to get the gist of what I'm saying. There is a little information about Mono-Flo® Tee systems starting on page 22. The file below may be easier to zoom in on. The top of the diagram is how two tees should be piped, forget the arrows. But you are correct in the way it should be connected, as long as you do not confuse the arrow for the flow direction. It is actually means the flow direction if the Tee is installed on the return side of the radiator. In this older photo of a Monoflo® Tee there are two arrows and you select the flow direction based on the location of the Tee, Supply is to the left and Return is to the right. So if it is on the supply, "Turn It Around" The red circle that Dan Holohan is referring to. I still believe you need to check how much heat your are going to need when it is very cold! You may have redesigned your piping into a system that may not work, but you will not know about it until it is way too cold the do anything about it.
    Thank you for the insight. Not saying it is correct but seems most people here re-pipe these systems to 3/4 around my area. 

    NY weather doesn't cooperate very well. I was hoping for a cold day or 2 after this was done but of course it was a very mild winter. 
  • Danny Scully
    Danny Scully Member Posts: 1,425
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    Where in NY are you located @Kenny_od?
  • Kenny_od
    Kenny_od Member Posts: 5
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    Where in NY are you located @Kenny_od?
    Massapequa, long Island. 
  • Danny Scully
    Danny Scully Member Posts: 1,425
    edited March 31
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    We’d love to help out! 

  • Kenny_od
    Kenny_od Member Posts: 5
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    We’d love to help out! 

    Appreciate it, but I'm capable of fixing it myself once I get the layout info I'm looking for 
    Danny Scully
  • hot_rod
    hot_rod Member Posts: 22,157
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    Have you looked at the pressure drop through a tee like that? A single 3/4 monoflo is about equal to 70' of tube.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,844
    edited April 1
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    Kenny_od said:


    Thank you for the insight. Not saying it is correct but seems most people here re-pipe these systems to 3/4 around my area. 

    NY weather doesn't cooperate very well. I was hoping for a cold day or 2 after this was done but of course it was a very mild winter. 

    You should be able to make the layout yourself, however I might make 3 different loops. One loop with Monoflo® tees and the other with a about 1/2 of your baseboard, the third with the other 1/2 of your baseboard. You may be able to use just one 3/4" series loop if you have less than 60ft total baseboard element in the home. Since PEX is so easy to install is should be a breeze. You will need the Oxygen Barrier Tubing for this project. Here is a plan that I might use.



    The Orange 3/4" pipe will extend the Convector heaters back to the boiler.
    The Red 3/4" pipe will finish the Baseboard Series Loop.
    The Gray pipe indicates common piping that is 1" diameter
    Your original pencil lines stay "as is". (no need to waste that stuff)

    As long as the total amount of fin elements in the baseboards do not exceed ~65 feet, then 3/4" tubing will be sufficient for this project.

    If you have more than 65 feet or element, then you will split the baseboard loop somewhere in the middle, and feed (or return shown in blue) them with a common 1" pipe, back to the boiler. as shown here.

    By using the rule of thumb charts for pip sizing in Zoning Made Easy you can see what size pipe will carry the amount of BTU capacity needed to feed the radiator loops

    If you need more that 80,000 BTU capacity for all the radiators, then you MUST use 1-1/4" common pipe. If all you need is less than 80,000 BTU but more than 40,000 BTU then 1" piping is the common pipe size. Once you split off to a loop or zone that is less than 40,000 BTU then you can safely use 3/4" tubing.

    Hope this helps.




    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Kenny_od
    Kenny_od Member Posts: 5
    edited April 1
    Options
    Thank you for the insight. Not saying it is correct but seems most people here re-pipe these systems to 3/4 around my area. 

    NY weather doesn't cooperate very well. I was hoping for a cold day or 2 after this was done but of course it was a very mild winter. 
    You should be able to make the layout yourself, however I might make 3 different loops. One loop with Monoflo® tees and the other with a about 1/2 of your baseboard, the third with the other 1/2 of your baseboard. You may be able to use just one 3/4" series loop if you have less than 60ft total baseboard element in the home. Since PEX is so easy to install is should be a breeze. You will need the Oxygen Barrier Tubing for this project. Here is a plan that I might use. The Orange 3/4" pipe will extend the Convector heaters back to the boiler. The Red 3/4" pipe will finish the Baseboard Series Loop. The Gray pipe indicates common piping that is 1" diameter Your original pencil lines stay "as is". (no need to waste that stuff) As long as the total amount of fin elements in the baseboards do not exceed ~65 feet, then 3/4" tubing will be sufficient for this project. If you have more than 65 feet or element, then you will split the baseboard loop somewhere in the middle, and feed (or return shown in blue) them with a common 1" pipe, back to the boiler. as shown here. By using the rule of thumb charts for pip sizing in Zoning Made Easy you can see what size pipe will carry the amount of BTU capacity needed to feed the radiator loops If you need more that 80,000 BTU capacity for all the radiators, then you MUST use 1-1/4" common pipe. If all you need is less than 80,000 BTU but more than 40,000 BTU then 1" piping is the common pipe size. Once you split off to a loop or zone that is less than 40,000 BTU then you can safely use 3/4" tubing. Hope this helps.
    Wow, thanks for the diagram. I definitely do not have more than 65 feet of baseboard. 

    So just a few questions. 

    Essential the pipe I currently have with monoflows and the new baseboard series would both be fed off the same circulator from the common pipe? 

    The pipe coming off my circulator is 3/4 copper which then transitions to 3/4 pex. Can I just branch off the copper with 1 inch PEX for the common pipe? 

    And then I just tee the return from the convectors in with the baseboard on the return to the boiler?