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Bleeding Baseboard MonoFlow system

seth1066
seth1066 Member Posts: 21
edited January 2020 in THE MAIN WALL
I believe the bleeders are required to be installed on the top of a created slope of a baseboard radiator pipe. This is an old house (1860) and one of the foundation stone walls deteriorated (now fixed), causing a lot of settlement. The rads were always hot until we just recently replaced the boiler. Now several of them don't heat up, but the bleeders spit water. I'm thinking that slope has changed and air is still at the very top.

Will this work for a "reverse" purge: replace the bleeders with small valves that have a way to attach a clear tubing. Run the tubing into a 5 gallon bucket, open the valve until air, if any is evacuated. Additionally, I wonder if turning the reducer to street pressure until the bucket fills would help.

Monoflow T's, feeds and returns are hot. A separate non-monoflow zone has purged fine and those rads are all hot.
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Comments

  • STEVEusaPA
    STEVEusaPA Member Posts: 5,115
    You basically need the water very hot, and keep the pressure up around 25 (high enough to not pop the relief valve).
    Remember, it worked before.
    Did you happen to change the circulator?
    steve
  • Add a tablespoon or two of Dawn liquid dishwashing detergent to the boiler water, crank the pressure up to 25 psi like Steve said and let the system run awhile. The soap will break the water's surface tension allowing the air and water to mix and the high pressure will further reduce the size of the air bubbles, making them easier to move around.
    Often wrong, never in doubt.
    SuperTech
  • seth1066
    seth1066 Member Posts: 21

    You basically need the water very hot, and keep the pressure up around 25 (high enough to not pop the relief valve).
    Remember, it worked before.
    Did you happen to change the circulator?

    Thanks, Steve. Moved in in 2014, plenty of heat.
    2016 the house started resettling due to the wall, even though the slope might have changed, didn't exist anymore or went negative, the heat didn't change because no air came in and no bleeding was needed.

    2019, 3 months ago, new boiler, circulator and damping style back flow tank. Now there's air in that zone that won't bleed out.

  • seth1066
    seth1066 Member Posts: 21
    edited January 2020

    Add a tablespoon or two of Dawn liquid dishwashing detergent to the boiler water, crank the pressure up to 25 psi like Steve said and let the system run awhile. The soap will break the water's surface tension allowing the air and water to mix and the high pressure will further reduce the size of the air bubbles, making them easier to move around.

    Thanks, Alan. I'll give it a try. I'm thinking though the feed is going straight through to the return and not into the radiators at all; no heat in them, but feed an return are both hot and about the same temp.
  • If that doesn't work, find someone with a pipe freezing kit and freeze the common piping between the tees. Flush and repeat on the next radiator.
    Often wrong, never in doubt.
  • seth1066
    seth1066 Member Posts: 21
    edited August 29
    Facing another season of using electric heaters to supplement this system.

    After trying suggested troubleshooting, I bled the system again via purge valves several times, got the baseboard units bled by the bleeder valves. Purged it again with an auxiliary pump supplied by a 5 gallon bucket capturing the return flow. Never saw the first bubble. Baseboards hardly get warm.

    Finally, I backtracked-- sequence of events: The new furnace was an exact duplicate of the old one. The only difference was the circulator pump. The original pump was (physically) 3 times the size of the TACO that came with the new furnace, a TACO 007e2f2.

    I'm thinking that the TACO would work fine on a non-MonoFlo system, but not enough on this one with 9 mono T's.

    I don't have the old pump or the specs, does anyone have a ball park idea on pump capacity that would work on a 47'6" of 1 3/4 + 80' of 3/4 + about 80' of baseboards; 9 mono T's and around 10 elbows? Also, there is a zone with two standard radiators on the same pump without monoflo (those get to about 180 degrees). Or is this enough data for me to plug into a calculator?
    mattmia2
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 9,394
    Picture this.

    Monoflow tees have restriction in them to make them work properly.

    Regular fittings do not.

    If you were a drop of water where would you go?

    Through the monoflow tees or through the other zone with regular fittings and little restriction


    If you can post a sketch and provide how many feet of baseboard on each zone we can come up with what pump(s) to use. Need a list of pipe lengths and fittings for each zone as well.

    Or you can guess at it and still have problems.

    Your probably going to need a total of 2 pumps. Maybe the one you have can be reused for one zone

    And their is no baseboard that is 1 3/4"

    Proof of the problem is that the zone with 2 radiators heats well
  • seth1066
    seth1066 Member Posts: 21
    edited August 29
    What I wrote: "47'6" of 1 3/4 + 80' of 3/4 + about 80' of baseboards." That's 80' of 3/4" baseboard supply/return and 80' of baseboard units, I'm guessing those are also 3/4" max.

    I should have been clearer on the 2 radiators, it's not really a separate zone, it's in the same supply and return as the rest of the system, just isn't mono flow. The first set of figures is for the monoflow units. The non-monoflo rads are probably another 35 feet and 6 elbows.

    "Proof of the problem is that the zone with 2 radiators heats well" I agree 100%. Those 2 radiators get hot because that's the path of least resistance i.e. no restrictive monoflo junctions.

    But this has to be considered: the original single pump mounted in the exact same place had every radiator in the house hot. In fact I had a housemate once that would turn on his window a/c because his room (the smallest in the house) got uncomfortably warm.
  • psb75
    psb75 Member Posts: 422
    Save some words and lots of postings by submitting a good plumbing schematic of your system. You'll be amazed at the responses you will get. The verbal descriptions of your system are not clear. We all know what a picture is "worth."
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 9,394
    Just like I posted and @psb75 basically said the same thing.

    We don't have x ray vision. You are there we are not.

    If you want a quick fix buy a bigger pump. It may work and it may not. If you want a sure fix post a sketch of the piping with sizes and baseboard and radiator sizes. and we can do some calculations.

    BTW, cast iron radiators and copper baseboard should not be on the same loop
  • Robert_25
    Robert_25 Member Posts: 325
    seth1066 said:

    Facing another season of using electric heaters to supplement this system.

    After trying suggested troubleshooting, I bled the system again via purge valves several times, got the baseboard units bled by the bleeder valves. Purged it again with an auxiliary pump supplied by a 5 gallon bucket capturing the return flow. Never saw the first bubble. Baseboards hardly get warm.

    Finally, I backtracked-- sequence of events: The new furnace was an exact duplicate of the old one. The only difference was the circulator pump. The original pump was (physically) 3 times the size of the TACO that came with the new furnace, a TACO 007e2f2.

    I'm thinking that the TACO would work fine on a non-MonoFlo system, but not enough on this one with 9 mono T's.

    I don't have the old pump or the specs, does anyone have a ball park idea on pump capacity that would work on a 47'6" of 1 3/4 + 80' of 3/4 + about 80' of baseboards; 9 mono T's and around 10 elbows? Also, there is a zone with two standard radiators on the same pump without monoflo (those get to about 180 degrees). Or is this enough data for me to plug into a calculator?


    Did your old circulator look like this: https://bellgossett.com/pumps-circulators/circulator-pumps/heating-cooling-circulators/series-100/ ?

    A Taco 007 has a different pump curve than those old B&G circulators, but I would not expect it to cause the situation you are describing. Are there balancing valves that allow to control the flow through that zone with the standard radiators vs. the monoflow system? I think it is more likely you have a flow balancing issue than lack of flow from the circulator.

    -Rob

    Dave H_2SuperTech
  • Oilmon
    Oilmon Member Posts: 3
    If you have any valve(s) on the cast iron rad sub-loop, try to restrict there to force flow down the mono-flo portion of the run. That is likely the path of least resistance.
  • seth1066
    seth1066 Member Posts: 21
    edited August 30
    Oilmon- I had tried that last season; the supply to those two radiators are the first tap on the supply line and return just before the rest of the return loop. The results from "off" to various reduced flow settings was the furnace went to its max temp and then shut off and repeated after internal temp drop.

    EBEBRATT-Ed
    and
    psb75

    I'm with you on the diagram. I've read a lot of entries here and I know it's important and I'm working to draw a legible one.

    Thanks to all.
  • seth1066
    seth1066 Member Posts: 21
    edited August 30


  • STEVEusaPA
    STEVEusaPA Member Posts: 5,115
    edited August 30
    What happened to the installer of the new boiler? Sounds like it never worked right after that.
    You need some competent boots on the ground there. Someone that knows what they are doing can solve most problems like this in about 1/2 an hour as opposed to back and forth on this forum for a year and a half.
    Also looks like the problem isn’t helped by not pumping away.
    steve
    mattmia2
  • seth1066
    seth1066 Member Posts: 21
    edited August 30

    What happened to the installer of the new boiler? Sounds like it never worked right after that.
    You need some competent boots on the ground there. Someone that knows what they are doing can solve most problems like this in about 1/2 an hour as opposed to back and forth on this forum for a year and a half.
    Also looks like the problem isn’t helped by not pumping away.

    I'll find out more after I post the system schematic. In the meantime, the only difference is the circulator, which was on the return with the original/identical furnace and (supposedly) on the return because it works better on a monoflo system.

    The original "back and forth" was specifically and only about bleeding the system; bleeding turned out to not be the problem.
  • mattmia2
    mattmia2 Member Posts: 3,429

    What happened to the installer of the new boiler? Sounds like it never worked right after that.
    You need some competent boots on the ground there. Someone that knows what they are doing can solve most problems like this in about 1/2 an hour as opposed to back and forth on this forum for a year and a half.
    Also looks like the problem isn’t helped by not pumping away.

    That was my thought, why isn't the installer that botched the flow calculations on the new boiler fixing this?
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,115
    I'm thinking a DIY, or side job. Might just be a simple matter of knowing how to, and some tricks, for bleeding a monoflow system. Could even be a leak. If my thinking is correct, the H/O should bring in some help to fix it. It may be simple and inexpensive or it may not, but either way, they'll have heat.
    Bleeding is usually so simple with eyes on the entire system, but trying to do it getting spoon fed info and pictures is a little tiresome.
    steve
    psb75
  • psb75
    psb75 Member Posts: 422
    I'm in agreement with STEVEusaPA. This is taking up a lot of brainpower on this site and space in the digital universe. A schematic posted long ago could have netted some really good results. One and a half YEARS later....no schematic.
  • seth1066
    seth1066 Member Posts: 21
    That was my thought, why isn't the installer that botched the flow calculations on the new boiler fixing this?
    Flow calculations? I know what those are now; the unit came with a circulator, we used it, no one else to blame.

  • seth1066
    seth1066 Member Posts: 21

    I'm thinking a DIY, or side job. Might just be a simple matter of knowing how to, and some tricks, for bleeding a monoflow system. Could even be a leak. If my thinking is correct, the H/O should bring in some help to fix it. It may be simple and inexpensive or it may not, but either way, they'll have heat.
    Bleeding is usually so simple with eyes on the entire system, but trying to do it getting spoon fed info and pictures is a little tiresome.

    One more time, the system has successfully been bled; nothing but water running in it.
  • seth1066
    seth1066 Member Posts: 21
    psb75 said:

    I'm in agreement with STEVEusaPA. This is taking up a lot of brainpower on this site and space in the digital universe. A schematic posted long ago could have netted some really good results. One and a half YEARS later....no schematic.

    "Long ago" the thought was that the system still had air in it. It doesn't. Does a schematic help to accomplish a successful bleed? I think not. Did anyone suggest a I provide a schematic "long ago" to help configure a bleeding procedure? No.
  • mattmia2
    mattmia2 Member Posts: 3,429
    seth1066 said:

    That was my thought, why isn't the installer that botched the flow calculations on the new boiler fixing this?
    Flow calculations? I know what those are now; the unit came with a circulator, we used it, no one else to blame.



    Just because it came with one doesn't mean it was the right one for that application.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,115
    Well OP, sounds like you know more than everyone trying to help you. Good luck.
    steve
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 9,394
    Perfect example of what @DanHolohan always says. "if you bleed it and don't get air it's not an air problem it's a flow problem"


    Fact is you can't mix a monoflow system with a two pipe system unless you have multiple pumps, or balancing valves or zone valves or something unless you put a huge pump on it and get lucky.

    shouldn't mix fin tube and CI on the same zone
    SuperTech
  • seth1066
    seth1066 Member Posts: 21

    Perfect example of what @DanHolohan always says. "if you bleed it and don't get air it's not an air problem it's a flow problem"


    Fact is you can't mix a monoflow system with a two pipe system unless you have multiple pumps, or balancing valves or zone valves or something unless you put a huge pump on it and get lucky.

    shouldn't mix fin tube and CI on the same zone

    From my very vague understanding of fluid dynamics I can agree with you on that. I am witnessing that exact thing, most of the flow is through the unencumbered pathway of the plain old radiators.

    Schematic is coming.
  • seth1066
    seth1066 Member Posts: 21
    mattmia2 said:

    seth1066 said:

    That was my thought, why isn't the installer that botched the flow calculations on the new boiler fixing this?
    Flow calculations? I know what those are now; the unit came with a circulator, we used it, no one else to blame.

    Just because it came with one doesn't mean it was the right one for that application.

    My post from 8/28 that started this part 2 of the thread:

    "Finally, I backtracked-- sequence of events: The new furnace was an exact duplicate of the old one. The only difference was the circulator pump. The original pump was (physically) 3 times the size of the TACO that came with the new furnace, a TACO 007e2f2. I'm thinking that the TACO would work fine on a non-MonoFlo system, but not enough on this one with 9 mono T's."
  • mattmia2
    mattmia2 Member Posts: 3,429
    I don't know enough about how the fluid dynamics in a monoflow system work, but i'm not sure the number of tees has a whole lot to do with it, or at least not as much as being at the higher end of the allowable velocity in the main(which would be affected somewhat by the number of tees).

    If I understand your system correctly the non-monoflow section is in series with the monoflow loop and I suspect that is more of a restriction than the combination of the monoflow main and tees and branch piping especially since it will be limited to common baseboard radiator sizes. the old circulator may have been able to develop relatively high head and flow so it could push enough flow through that restriction to make the monoflow tees induce branch flow. It is possible that the simple solution may be to add a bypass to the series section with a globe or ball balancing valve on it to relieve some of that restriction and somewhat balance the monoflow and series sections.


    I think someone posted a document on designing monoflow systems a couple years ago.
  • seth1066
    seth1066 Member Posts: 21
    mattmia2 said:

    I don't know enough about how the fluid dynamics in a monoflow system work, but i'm not sure the number of tees has a whole lot to do with it, or at least not as much as being at the higher end of the allowable velocity in the main(which would be affected somewhat by the number of tees).

    If I understand your system correctly the non-monoflow section is in series with the monoflow loop and I suspect that is more of a restriction than the combination of the monoflow main and tees and branch piping especially since it will be limited to common baseboard radiator sizes. the old circulator may have been able to develop relatively high head and flow so it could push enough flow through that restriction to make the monoflow tees induce branch flow. It is possible that the simple solution may be to add a bypass to the series section with a globe or ball balancing valve on it to relieve some of that restriction and somewhat balance the monoflow and series sections.


    I think someone posted a document on designing monoflow systems a couple years ago.

    If I remember, I read somewhere that a one (two?) monoflow T(s) is equivalent to 30 feet of pipe. As far as the pump, look at it this way, if I had installed the old circulator I wouldn't have this problem.
  • psb75
    psb75 Member Posts: 422
    Sure. Let's keep considering more possibilities. Why not? They're endless.
  • seth1066
    seth1066 Member Posts: 21
    edited August 31
    psb75 said:

    Sure. Let's keep considering more possibilities. Why not? They're endless.

    What part of my previous post:

    "psb75 I'm with you on the diagram. I've read a lot of entries here and I know it's important and I'm working to draw a legible one."

    don't you understand?
  • Robert_25
    Robert_25 Member Posts: 325
    edited August 31
    Your diagram does not have to be complex.  Here is my 2 minute guess at it (don't mind the orientation of the radiators).  If your system looks like this, most of the flow generated by the circulator will bypass your monoflow loop.  The difference in circulator may have something to do with this, but I would look for a valve in the *other loop" that can be used to throttle the flow.  If you find a valve there, it likely got closed and fully opened during your boiler swap.


  • psb75
    psb75 Member Posts: 422
    ....and people are resorting to guessing. Robert_25 is right though. A simple hand-done line drawing would 'speak volumes.' Can you see that people are interested in helping?
  • seth1066
    seth1066 Member Posts: 21
    edited September 1
    Robert, thanks, that is right on the money. I put two X's where the valves are, X1 for the 2 radiator loop and X2 for the return line. Above each valve is a valve/outlet for purging. The first baseboard is an oddball about 4 feet in length with a mono inlet and standard T for the outlet.






  • Robert_25
    Robert_25 Member Posts: 325
    Make sure the valve marked by X2 is fully open, and close X1. Turn the heat on and let the circulator run for a few minutes to see if your monoflow loop gets hot. If it does, slowly open the X1 valve until the "other loop" gets hot also. At that point you should have a balanced system. You can verify by letting everything cool off, and then turning the heat on - both loops should get hot.
    Alan (California Radiant) Forbes
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,115
    Looks like your circ is pumping the wrong way based on the monoflow tees.
    steve
    mattmia2
  • mattmia2
    mattmia2 Member Posts: 3,429

    Looks like your circ is pumping the wrong way based on the monoflow tees.

    Which way is the arrow on the tees? i assume that is one of those packaged boilers that comes with the ciruclator in the wrong place so the flow is in to the circulator than out to the boiler. If the circulator is on the outlet after the expansion tank and the air elimination then the air elimination works better.
  • seth1066
    seth1066 Member Posts: 21
    The Tees point toward the return flow. The circulator is on the return line pushing into the boiler.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,115
    edited September 1
    Usually when it’s one monoflow tee it’s on the return. Water wants to short circuit thru the non monoflow loop.
    But @Robert_25 gave you right info for simple balancing.
    Where’s the expansion tank and what type?
    steve
  • GW
    GW Member Posts: 4,186
    I skimmed though the posts- if you’re still jammed, hit me. Making water flow is high on my things to get done list 
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]