Pressure drop, zero flow in baseboard question

Ken_40

You asked, "Does that indicate an 11 GPM flow in the trunk main"? The answer is no. The question rather is, "Since I have calculated my total heat loss to be ~100MBTU's, ideally, shouldn't I have ~10 GPM passing through my system to have a 20 degree dT across the boiler supply and return connections"? The answer of course is yes; you need ~10GPM's of circulation through both/all circuits to get the desired 20 degree dT.

Remember, the presumption we have is that you know the downward pointing/feeding MF tees, must be on BOTH the supply and return!

The reason for that is because: the more bouyant warm water does not want to drop "naturally" down-hill. Conversely, the upfed MF take-offs NATURALLY INDUCE FLOW, since warm water is more bouyant - and will rise without much influence at all anyhow! (like cold and warm air, cool and warm water play the same game: cool water sinks; warm water rises.

I will try and find my mono-flo chart and post it in a few minutes...

ralman

Flow question

I have a downfeed CI 8' baseboard which does not get any flow through it due to the supply and return monoflo T's being spaced 4 inches apart. The main is 1.25" and risers are .75". The CIBB is on the basement floor and the main is 8' above it under the first floor joist. This appears to be original design about 50 years old. To make matters worse there is about 26' of .75" piping for the risers. I wonder if it ever worked? The boiler, Circulator, expansion tank, and near boiler piping are definitely not original. All CIBB in the circuit are connected to the main with two 1.25" X .75" iron monoflo T's. There is a total of six monoflo T's located within a 46" run of 1.25" pipe where the 8' CIBB supply and return connect which I suspect may not be the best way to be piped. I am considering piping this CIBB in series with another CIBB located upstream. I have 2 different CIBB to choose from, an upfeed 4' CIBB and a downfeed 10' CIBB. This would reduce the number of T's on the 46" run by two and eliminate the short spacing between T's for the 8' CIBB. The 10' and 8' in series will put monoflo T's about 14 feet apart and will be the easiest to do. The 4' and 8' in series will put monoflo T's about 18' apart. I am guessing either way will work but I don't know how to mathematically verify it. What's your opinion?

Ken_40

Down feed mono-flo's

Require TWO MF tees, not just one!

If they are both MF style, the problem could be the minimal spacing - but I doubt it.

Please take a look and tell us if it has 2 MF tees or 1 MF and one "common" type tee.

Brad White_118

And...

the red rings between the tees. I had a zone piped backwards when I bought my house. The woman I bought the house from never could heat that back room..

Contrary to what you may have been told, piping circuits backwards does AC a room

ralman

Monoflo T's

I have 5 downfeed CIBB and 11 upfeed CIBB with a total of 32 monoflo T's. A properly oriented, 1.25" X .75" supply and return Monoflo T is used for every CIBB regardless of emitter length, riser length or upfeed/downfeed location. From what I have read, normally a return monoflo T is all that is necessary. Downfeed emitters and emitters with long risers, or emitters with high resistance require a supply and return Monoflo T. I am not sure if CIBB is considered high resistance, the example I read cited fan coils. I am not sure if the original designer/installer chose two for every CIBB just to be on the safe side or if a CIBB actually requires two Monoflo T's. If two are not required for the upfeed CIBB, would it be worthwhile to remove 11 upfeed supply monoflo T's?

ralman

Monoflo T's

50 year old iron Bell & Gossett, 1.25" X .75" monoflo T's, there are no red rings on these babies. There is a metal data plate riveted to each one that states whether it is supply or return and an arrow that indicates flow direction for the main branch. The supply monoflo has a rivet head on the side opposite of the data plate, the returns do not. All data plates are still legible and I have verified that all are installed properly. I had removed the baseboard with no flow and used the garden hose to push water through the baseboard and risers, they are clear of any restrictions, I used a flashlight to check inside of each monoflo T and they seem okay. I did all this before reading Dan's diverter tee explanation posted under the homeowners link. Is Burnham Baseray CIBB considered high resistance? Do you think it would be okay to run two CIBB in series off of a supply and return monoflo T?

Brad White_128

That is a lot of Monoflow Tees in series

CIBB I would say is medium resistance, being roughly the same as pipe but perhaps rougher. Cast iron standing radiation would be in my "low resistance" category and fan coils (depending on coil circuiting) in my "high resistance" category.

The two MF tees for downflow rule comes from countering the buoyancy of warm water; the high resistance is self explanatory as you well grasp, Ross.

Any chance of splitting the loop? 32 tees in series seems excessive to me. Figure if the 1-1/4" main can handle between 10 and 12 GPM, divide that by 32, is not a lot of flow to each emitter. And the pressure drops in the main are cumulative.

ralman

The loop is split.

POORLY, in my opinion. The balancing is not going well. Attached is my layout diagram. Mostly everything is to the right of the split.

Brad White_128

The 19' Fin and 18' CI

are served across both circuits, Ross. How do those heat? I cannot see any differential there to speak of. Curious. I realize the diagram has no scale but is very handy.

Also the 24' CI has the same issue and probably an excess of flow being direct-coupled supply to return. Another thought.

ralman

Terrible!

The whole system flow is terrible. I have 2 Welsbach(very old, not in the best of condition) balancing valves at the end of the returns before they tie back together. It has been very difficult to adjust. I completely opened them when I moved in not knowing the purpose they serve. Micro turns of the these balancing valves will completely stop the flow in the 19' fin tube and generally cause problems elsewhere with flow. I nearly have the valve on the left loop completely closed. The 10' CIBB that returns just before the radiator on the right loop works the best in the house. I think it short circuits the right side of the loop. Fuel bills are a killer and I can't blame all of it on building construction. Do you think I could use B&G thermoflo 1" balancing valves on the 1.25" pipe returns to replace the Welsbach valves?

Brad White_128

B&G Thermoflow

I use B&G Thermoflows as flow meters moreso than balancing valves, Ross. For balancing, I would use Macon Controls Wye-Pattern types or the equivalent by Tour and Andersson, Armstrong or Victaulic. Four full turns open to closed beats a 90-degree twist on the B&G or any ball valve for that matter. The Macon balancing valve has a full TEN turns which is why I like them best.

Now, a balancing valve -of any type- is not going to correct your piping by a longshot. The one that heats best may benefit in terms of preventing it from becoming a bypass for the rest of the system; that is one place that will benefit most.

Your radiation in three cases according to your diagram is fed across two supply lines so aside from the main pipe differential there is very little reason to get flow across there. You simply have to give each a reason to divert flow. I would pipe these correctly, each off of the same main.

Jim Pompetti

monoflow

I've seen monoflow tees packed with mud in old systems .

ralman

Clueless.

I am not sure exactly what remedy would be best. I frequently use the search feature here for previous posts to research things I am trying to learn about. I have read your recommendations for the macon valves and you even recommended them to me in a post before. I did some research at their website. The two issues that prevent me from trying them:
1. The website states valves are selected by GPM flow of the circuit not the pipe size of the circuit. I can't figure out what my flow is, and more importantly, I feel my flow is most likely way under what it should be.
2. The testing device to connect to the valve is cost prohibitive at several thousand dollars( maybe I am not looking at the right tester). More importantly, I lack the know how to properly use such a tester.
My other option was globe valves, but it really wouldn't be any more accurate than the method I have been using with the Welsbach valves. It would be an improvement because I feel the Welsbach valves are wearing out and going to start leaking.
I ran across the B&G thermoflo, from reading the literature I thought I could visually see the GPM flow and balance easier with the adjusting screws.

ralman

My piping quandary

I could remove the 1.5" supply from the regular tee location on the diagram and install it after the 24' CIBB supply monoflo T. This would properly divide the supply and return monoflo T's so that they all supply and return on the same side of the split. I could possibly throttle down the flow with the baseboard angle valve for the two CIBB's that supply at the beginning of the loop and return close to the ends of the loop.
Are there any better options? I am thinking of two other options but I don't know if either is better.
1. Remove the left side of the loop and put those baseboards on two separate series loop circuits, one for the main floor common areas and one for the basement. Keep the bedrooms and bathrooms on the monoflo circuit which goes to the right.
2. Remove all the monoflo piping and repipe with a home run system using Pex-AL-Pex. It seems this option would give me the most BTU output from the emitters and would reduce the cold return water problem I have with the current setup. Maybe even get my fuel usage down to an acceptable level.

Brad White_118

You don't really need

the meter normally used with the valves, Ross. I am suggesting that you use temperature and effectiveness as your guide. Pipe size is not necessarily indicative of flow; you can map out approximate flow rates by the radiation and use those numbers. Necking down to balancing valve size is done all the time. Globe valves will work also but with the Macon type valves you can still get a gauge reading and approximate the flow rate from there.

Ken_40

Ross,

You cannot "fix" the problem through guessing, suggestions and witchcraft. Those of us in this biz have tables and design parameter data that you may not have. The math is simple. If we know the heat load of each room in the house, we have tables that tell us what size the mono-flo trunk line must be to handle the load of the entire house. If the better design suggests we divide the entire distribution system ointo two (or more) "circuits," we know how and where to do so - based on engineering tables.

Factors we must know to make any system work are: 1. The length of the circuit(s) involved. 2. The resistence to flow of each aspect of the circuit(s) including fitings and particularly the MF tees themselves, which typically add 12' of equivelant trunk length a piece. 3. How many feet of emmitter we need to match the load of each room. 4. The resistence to flow of the selected emitter (in your case, c.i.b.b.) which, by the way, is VERY low in restrictive aspect. 5. Knowing one through four, allows us to select the proper circulator to assure the dT (temperature change) we want - typically 20 degrees F.

By simply changinbg your circulator to the "required" head and GPM model the data suggests, you can make your system sing and dance.

You obsession with the two balancing cocks is for naught. The correct "rough setting" could be done by simply making sure the most restrictive circuit is set wide open: the, remaining cock could be closed so the observed temperature of the returns "feel" as close as your hand can tell them apart tempature-wise. When first starting the system up in fall, wait until each pipe becomes too hot to keep your hand on (~120F), and use that "moment" to determine how much you need to close the short run circuit/cock to have them become equal to your feel/touch.

This is NOT some form of "inferior" design or less efficient heating system design. The beauty of MF designs is the individual control over each room's temperature one can derive. Even if there is no "control valves" on each c.i.b.b., there are ways to micro adjust output to ideal setting. First, you need to get the heat load data by room.

Do you have that data yet?

Uni R_2

3 Speed Circ

I've never found the math for calculating the total head loss on Monoflo circuits to be simple. I can't even think of any software packages that can do it properly. Yet, adequate flow is absolutely essential for Monoflo systems or the flow will not get diverted into some of the circuits.

If it were me, I would be seriously tempted to engage in "witchcraft" and get a small 3 speed circ as a starting point, and see how your home heats on the "Hi" setting. That 007 may not be performing as well as it did when new and changing out a circ is pretty cheap.

Okay... so maybe I prefer experimentation to applied logic.

ralman

Thanks ken, for your help.

I have calculated my heat loss by room with the slant fin program available through a link from this site. I have a 100,847 BTU heat loss for the entire home. Does that indicate an 11 GPM flow in the trunk main? I have no training for this so I probably have mistakes. My monoflo system is 50 years old and probably has design flaws. I know for a fact the near boiler piping is incorrect and there are issues with the split loop, and the locations emitters were tied into the main. Filling, air removal, Balancing, GPM flow, and high fuel usage are all concerns. As to balancing, I thought it worked the way you mentioned in your reply to me, when I set the longest loop(right side) fully open it causes a zero flow condition on the left loop in the 19' fin BB in the basement. I really had a tough time getting both valves set to where I could get flow in all baseboards at the same time. I feel my monoflo system can be made better with my previously suggested piping changes for the split.

Ken_40

OK. Here's the chart

The attached, is the engineering table needed to tell how many feet of head various combinations of resistance will create, based on length of each circuit, HWBB, pipe diameters, etc.

The table will also tell us the circulator dynamics required to give us the desired 20 degree dT.

Read the fine print (if you can see it) carefully.

BTW, the chart suggests you could have one circuit up to 300+ feet long (including MF fittings with equivelant resistance of 12' a pop) with 1.25" "trunk" and 3/4" branches - with a load of almost 20,000 BTU's on each tee!

Your circ. may be toasted (impellor worn to tiny percentage of original diameter).

ralman

I'm sorry Ken.

I sincerely appreciate your time and trouble you have spent to help me. I do not understand how to use this chart.

Unknown

any downfeed radiators

For any down feed radiators, must have both mono flo tees and same distance apart as the baseboard radaitors... If its a 8 ft radaitor, then the distance between the tees are at least 8 ft, standing radatiors, I try to get them apart further or after the next 90* el to have more flo into radiators... Did a major re pipings at at private school because the mono flo were too close together and several other compaines kept replacing the "defective" rad valves. I walked in and saw the improper installation in new addtion done by forced air company. Told them to do it in right way or the kids will be cold... Got brushed off til the heating season start and was busy for awhile... Forced air company? No longer in business..

Ken_40

OK

Let's start here:

In a former post you mentioned 23 MF tees and 132' of trunk at 1.25". Typical fittings array and the infamous plug-cock(s).

Winging it, I come up with ~410' of pipe and fitting-related length equivelants.

This suggestst a minimum head resistance to flow equal to ~16' coupled with a 10-GPM flow rate. I don't have either the B&G or Taco performance curves in front of me but you seem to understand the X/Y thing; perhaps your selections are correct.

Whether or not the amount of HWBB, be it c.i or fin-tube will be adequately provided for is a whole 'nother kettle of fish. But, we must assume a few things to get the circulator/trunk relationships correct and see if they are feasible as we look at the baseboards and their "issues."

If all the MF tees are 1.25 X 3/4", it appears you could deliver close to 20,000 to each baseboard based on that data. If your HWBB can produce 500 BTU's/l.f., to keep ~20 degree dT you could run 40' of baseboard before falling off the chart. Other factors are at play here. but the math is relevant.

Still there?

ralman

Yes I am.

I usually can check this website mornings and very late evenings. If I understand correctly, there is 16 feet of head for this part of the circuit. The Taco 007-f5 I currently have installed is only rated for a maximum of 11 feet. There is some flow in both loops, the long loop we are discussing does get hot. This is dependent on how long the thermostat calls for heat and the circulator operates. This does not occur on an average 30* outside temperature day. I can't explain how there is flow when the head is higher than the pump capability, except that maybe some flow is short circuited by the baseboard that supplies at the beginning of the loop and returns very close to the end, which is the hottest baseboard in the home. But it is as I have felt all along. I have the wrong circulator. Also, your calculation for the 40' of baseboard. I currently have 166' of baseboard supplied from that side of the loop. Only 95 feet of baseboard return on that side of the loop. Do I split the same loop more or do I start with an entirely new loop?

Ken_40

OK

Remember, the head and GPM ratings relative to the restriction is for a 20 degree dT! That is NOT to say you will have no flow if you exceed the circs. ratings. You will simply not get a 20 degree dT; perhaps a 30 instead!

Whether you put in a bigger circ. or split the load - thereby reducing the developed length is a coin toss. Sounds like either would do the trick.

My main fear is the old "a little learning can be a bad thing" adage. You would not see the nuances a pro would in making this decision. "Pumping away" is more critical in a MF system than any other. If the circ. is on the return, I'd suggest you opt for a new properly sized circ. AND re-pipe it to "pump away." This, frequently requires a lot more than simply changing the circs. location. Draining the system will introduce air in all radiation; a factor not to be taken lightly. I presume all the bleeders are old and suspect?

Remember how hard it is for us to diagnose the problem(s), find solutions and explain them all to you, an admitted novice...? I urge you to re-think doing this yourself - unless you truly have a handle on this all...

This could the land-mine to end all land-mines lad. We can help, but the fact hat we cannot see what you do, is a basic flaw in what we're trying to do.

Keep going?

ralman

yes please, I still need more help.

Another thought I have that isn't clear to me. If I remove the supply monoflo T on all the upfeed CIBB, there will be a reduction in the resistance of the circuit. Is it worth the effort? My circulator is on the return, 24" above the boiler drain valve that goes into the boiler. The make up water prv is teed into the line 24" above the circulator with no backflow preventer. The expansion tank is properly sized but overpressurized if I calculated that correctly. It is on the supply pipe 34" above the boiler connected to the backside(boiler side) of the Taco 222 flochek valve. It is 24" below the highest point of the circuit. I do not have a boiler bypass, or any other means of boiler protection, but I do have a cold return water problem. I have 18' of 1.5" supply main pipe leading to the tee that splits the flow into two 1.25" circuits. The 1.25" returns come together in the boiler room with a wye, then a street elbow and 42" of 1.5" pipe, then reduced back to 1.25". I have been visiting this site daily for a year, reading and occasionally asking questions. I purchased 3 books on hydronic heating. You mentioned in a previous post that I seem obsessed. Brad White implied the same several months ago. I am worried, I think I may have 10 days or less before I will need to turn the boiler on. My system does not work well at all, I will have to fix it because in 6 visits from heating companies all have stated there is nothing wrong with my system. However, not one has recommended moving my circulator to the supply pipe, pumping away from the PONPC. I currently have a plan to move the circulator to the supply, pumping away from the PONPC. When I drain the boiler down, I am wondering what other improvements I can make in a reasonable amount of time within my capabilities. Recently, I have been posting some questions in an effort to ensure I do this correctly and only if it is going to have a benefit. This thread started because I read in a book that I could put two emitters on the same branch circuit off the monoflo T's. I posted here to learn from others who are experienced. There are a few more locations on the circuit I could do this to as well which would reduce the total number of monoflo T's even further. If there is a benefit, I could make that change while I have the boiler drained down for moving the circulator. My goal was to gain an 8' CIBB that previously did not work, and reduce the number of monoflo T's by two, resulting in less main circuit restriction which coupled with a different size circulator properly installed could be a benefit to a system that works poorly. I have learned from starting this thread that I have other circuit design troubles. I have been thinking I should repipe, Either pex or copper, I would prefer the pex, as I have calculated the materials to be less expensive and easier to work with and quicker to install under my time constraints. I can't find anyone locally who can identify the problems, I am not exactly the best candidate to make changes, but so far I have been able to identify the problems and make minor repairs with a positive outcome. Last year, 2nd week of October, I removed 13 unused Monoflo T's that had been capped off by previous owners, on the advice of some very nice people on this website. It made a huge difference, it eliminated all the gurgling noises and increased flow. Some of the monoflo T's had a 6" nipple with a cap, some had several feet of the branch circuit still attached with a cap. While I had the boiler drained down for that, I put a brand new Taco coin vent in every CIBB, and a Taco hyvent 400 in the boiler tapping that was plugged. Your caution about the potential for air problems is noted, appreciated, and I am hoping the changes I am going to make are going to prevent or at least minimize those issues.

ScottMP

Not only the tees

But a down feed radiation could be packed with mud and debris. This problem might easly befixed by flushing out the offending piece of baseboard. Just a thought.

Scott

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Uni R_2

Pumping away...

Ross if you have to do this on your own with a 10 day window and a family to keep warm, I'd keep it really simple. You have to have enough velocity in a monoflo tee to divert to the branch. If a branch isn't heating either it is obstructed (maybe a shutoff valve you haven't noticed or gunked inside) or there isn't enough flow to create a venturi. A small 3 speed Grundfos is not at all expensive and it will let you choose the minimum speed that will still heat all of your branches.

If you want to pump away, you could also consider for this year just adding an air scoop (or Spirovent or even just a riser with an autovent on top) about 18" before your circulator and also putting the exp tank there. Pumping away doesn't mean that you have to pump away from the boiler, it just means that you have to pump away from the air elimination device and exp tank.

ralman

I am trying to keep it simple.

The Spirovent came UPS last week. I will have to move my make up PRV, expansion tank, and circulator from their current location. The prv relocation is going to be difficult for me. The near boiler repipe for the return piping is going to be difficult. I have not yet made a decision for the replacement balancing valves. I have been considering a Grundfos 15-58, and posted a question comparing it with a Taco 007 on Hydronic pro software about that previously. I also considered a taco 0010. Ken has calculated my resistance higher than the number I came up with when I selected these circulators for comparison. So, I will have to do some more comparison with the charts and other circulators. Like anything else, microbubble resorbers are preferred by some but not everyone. I thought about it for a long time(all year). I went over all the options I could find for air elimination, which is a major problem with my system. I finally decided on the Spirovent because I did not want to be sorry I did not use a microbubble resorber after I start my system when the Circulator relocation is completed. There are no requirements for a minimum straight length of pipe for installation, which will make it easier for me. I felt their could be a chance for improvement, and at least things would not be worse. I am 100% sure the circuit is not obstructed and all the Monoflo T's are installed correctly. Do you have an opinion or personal experience piping two CIBB in series, on the same branch, from a pair of monoflo T's? I would like to try this with my CIBB while I have the system drained down.

Ken_40

Ross,

Ross,

The Spiro-vent may be gross over-kill.

What make and model boiler do you have. You may have stated, but I don't have time to read it all to find out. The best place to catch air (of which I'm positive is PART of your problem) is in the boiler block. Most American brands have an air purger tapping at the top of the block - precisely for that purpose. What make and model do you have?

Uni R_2

Series

Either 2 closer Monoflos or 1 Monoflo with wide spacing from the other tee on the main should result in the same flow for that branch.

The two CIBBs in series will effectively be the same as one CIBB of the combined length, unless you have a ton of pipe and elbows in between, then you'll need to factor it larger accordingly. You could do it with Monoflo's at each end (in this case they would be closer than the total length of radiation - approximately half) or you could just ensure that the space between the first regular tee and the Monoflo is roughly the total length of 2 CIBBs plus any allowances for whatever is in between. It could even be somewhat less than an equivalent length if there are minimal fittings based on my experience.

I use a 15-58 on a 1.25" black iron Monoflo system (3/4" branches) with fintube and it has 19 Monoflo fittings. With the flow check on the circ removed, it's fine on speed 2 or 3 but on speed 1 most branches don't pick up any heat from the main.

ralman

Peerless oil fired EC -03 -100

I do have a tapping for air removal on the boiler block and I did put a Taco hyvent 400 there.

ralman

Very good information.

Thank you. Is your main circuit split? What length of main pipe are you working with? Do you have a supply and return monoflo T on your upfeed fin tube or just a return monoflo T?

Ken_40

Ross,

A couple of things, in the order of importance:

1) Re-pipe the boiler so as to "pump-away."

2) Forget about venting air (other than doing each emitter once, after draining and re-filling required to repipe) all together. Only one auto-vent is needed on your system; and it belongs on the boiler! Adding other auto-bleeds may induce air - not eliminate it!

3) Remove all other so-called "automatic vents" other than the one in the boiler top.

4) Replace the "weak" undersized circulator with one having the correct dynamics.

5) Leave those circuit cocks alone and open the highest head one fully - adjusting "balance desired" by using the other one.

6) Add a second MF tee to those emitters that are below the MF trunk - and don't forget to add 12' of "head" for each one you install!

8) THEN - let us know what happens.

Uni R_2

Qs

One circuit with about 100' (maybe a bit more) of main branch. All MFs are returns except for 3 circuits that are under the main where they are obviously on both.

tk_3

Monoflo Tees

rjbphd has the right answer. The pressure difference between the tees is as important as the flow created by the circulator. When the tees are too close together the pressure increase is infront of the supply tee. When your tees are far enough apart the increased pressure will be at the supply tee and overcome the resistance to flow through the radiation. When piping down use two monoflo tees. The supply tee will be installed backwards and the return tee will be installed the proper direction. Never use less than 3/4" pipe when piping down from the main. Never exceed 40K of radiation on this 3/4" pipe.

ralman

This is what makes the system so difficult to repair.

Ken, prior to purchasing the microbubble resorber I had read the installation instructions from the different manufacturers products that I was considering. There is nothing I can find in writing that says I should not use the boiler air elimination tapping and a microbubble resorber and automatic air vents at high points and emitters. The hydronic heating book does not speak of an issue with using all at the same time. I have seen a picture of a boiler installation posted here that has a microbubble resorber in the piping and a hyvent on the boiler. Don't take me wrong, I am not challenging your comments, I am writing to say that I am frustrated by spending so much time researching these components, then at the last minute, concerns are raised that were not covered in the text book or the manufacturers instructions. Did you see in my layout diagram that 3 baseboards supply from the right side of the loop and return on the left side of the loop? Your above recommendations did not address this issue. I am not sure if you did not mention it because you feel it is not an issue or if you did not mention it because you were not aware of it. Do you think crossing the split loop with these three baseboards is a problem?

ralman

Thank you.

From the information you provided our systems are very similar. It seems you are satisfied that yours is operating properly. I am hoping to get mine operating just as well.

Ken_40

Guess what...

The exotic nomenclature of: "micro-bubble resorber" is nothing more than a very expensive air vent. People who make air vents, want to sell them. People who lay claim to wonderous air vents, charge a lot more. On a few rare occassions, unlike yours, they are handy and easy to install. They all work the same, regardless of price or fancy label. They try and capture air and allow it to vent off. If you have the kind of boiler most of us have, they are unnessary and in fact potential leaks and problems that are a waste of time and money.

You and a few others here, especially those who use boilers that do NOT have internal air-ways for capturing entrained air from their systems, must use more and more exotic and expensive devices to overcome the short-comings of boilers that do not have internal water-ways to trap the air where science says it is easiest - and most effective to capture it!

That being, where the water is hottest; and, where the water moves the slowest. The water will never be hotter than in the boiler - nor will it ever be slower!

Air comes out of solution, the hotter the water. It is easiest to "catch," when moving the slowest.

RE: Your diagram... No. I did not see it, but assume at this juncture, it is irrelevant since by far-and-away the problems of not "pumping away" and having vents in places they should not be, is what should be addressed now.

Once the basics are addressed, we can see what may be needed next. I suspect the correct circulator and pumping away will have such a major impact, you can stop teaking and stop wasting money of stuff you don't need.