monoflow tee from basement to second floor: get rid of monoflow tee

iexpl · February 26

Hi, I have a monoflow tee system from basement to the 2nd floor apartment with gas boiler, and forced hotwater baseboard heating.

There are 5 side loops of the main piping, that goes to 2nd floor living room, bathroom, kitchen, bedroom1, and bedroom2 separately. And 2 little loops that heat up two small registers in the front and back of the house to heat up the first floor hallway.

The boiler is not able to heat up the 2nd floor apartment evenly. After each bleeding, it will be ok for a while. But eventually, the certain rooms will stay consistently under heated due to water can not be forced up there. I have bleeded the system multiple times with only temporary result of even heating.

My question: can I get rid of the monoflow tee, and just run the piping from basement go up to the second floor to living room heat register in one end, go down from the other end of the same heat register, and go back up again to the heat register for the bathroom, and go down from the other end of the bathroom register, then go up again to the heat register for the kitchen, and go down from the other end of the kitchen register, and so on....

My goal is to get the even heating. Is this design feasible? What would be the problem of this design? Any other designs to use to get rid of the monoflow tee so that I can achieve even heating?

Thanks for any pointers!

Regards

Eve

EdTheHeaterMan · February 26

I would think about making it a series loop if that is easy. I don't mean that you should connect all the runs to the individual in the basement. This is only if you can connect the baseboard end of one room to the next room through the wall or by dropping under the second floor and coming right up in the next room.

Although in some cases connecting the pipes in the basement may work, I just don't want you to have 100+ feet of extra pipe from the basement to the second floor 5 extra times, because that will increase the Head required for the pump to overcome. You may need a bigger pump with that long run of ¾” pipe.

iexpl · February 26

A series loop? does it mean to connect a living room exit end pipe to the bath room enterance end of the pipe? If so, the only probably is the Head required for the pump to overcome? Good to know.

Currently, there is 1" pipe in the basement, and 3/4" pipe running up to the second floor. I am thinking of using two separate loop. One loop for all the rooms in the front of the house, and second loop for all the rooms in the back of the house. If it an old house, adding a new piping or to pipe everything in the second floor will be difficult. So, the only way to run these pipes is to go down to the basement and go back up again. So, a lot of up to the 2nd floor, down to the basement, then up to the 2nd floor again type of thing. What type of pipe does it require?

Also, what type of professional should I contact? I am not sure this is a plumber's job or a some more specialty trade.

EdTheHeaterMan · February 26

It may be easier than you think. PEX tubing with O² Barrier is easy to slide from one place to another. Call a company that advertises "Plumbing and Heating" for a better chance at getting a Hydronics pro.

But if you can’t run the pipes all on the second floor, then ½ “ risers will be insufficient for a series loop. You need at least ¾” risers for a series loop. And you do not want to do that in the basement. So the second best design is a home run system to the boiler room from each radiator. As far as zoning, I would not separate the front and back, I would separate the first from the second floor. Place the thermostat for the second floor in a bedroom, not the second floor hallway. The first floor heat will rise up the steps and cause the thermostat to have a false reading of the space the radiators are located in.

Can you draw a basic floor plan of your home and post the picture of it here. The actual dimensions are not important, Just the baseboard radiator locations on the walls. For both the first floor and the second floor. There may be an easy way to keep the MonoFlo on the second floor and the series on the first floor to solve the problem.

Ironman · February 26

Are you getting any air when you bleed the baseboards?

What’s the pressure on the boiler gauge when the system is cold?

How about posting some pics of the boiler and its near piping from a few feet away?

Big Ed_4 · February 26

A Mono Flow is a nice system , it was designed being a even distribution system using a single supply pipe .. Baseboard retrofitted to a radiator/convector riser maybe your problem .

EdTheHeaterMan · February 26

Big Ed_4 said:
A Mono Flow is a nice system , it was designed being a even distribution system using a single supply pipe .. Baseboard retrofitted to a radiator/convector riser maybe your problem .

TRVs do not work with MonoFlo® tee systems. it says so in this book called Zoning Made Easy
on page 22

iexpl · February 26

| TRVs do not work with MonoFlo® tee systems. it says so in this book called Zoning Made Easy
What is the TRV? I am a newbie homeowner and does not understand the terms. Just ordered the book "Classic Hydronics" .

|But if you can’t run the pipes all on the second floor, then ½ “ risers will be insufficient for a series loop. |You need at least ¾” risers for a series loop. And you do not want to do that in the basement. So the |second best design is a home run system to the boiler room from each radiator. As far as zoning, I would | not separate the front and back, I would separate the first from the second floor. Place the thermostat for | the second floor in a bedroom, not the second floor hallway. The first floor heat will rise up the steps and | cause the thermostat to have a false reading of the space the radiators are located in.
Actually, I corrected the original post. The risers are 3/4" , and mainloop is 1" pipe. This is only 1 zone in the 2nd floor. Thermostat is in the second floor. And the thermostat reading never get to the set temperature of 68. So, the boiler constantly kicked in.

This is a 2 family house with the 2nd floor unit with doors closed. So the heat rises from the stairs does not always go directly to the location where the thermostat is.

I am not at t he house so I do not know the pressure reading when the system is cold. But this winter, it used 33% more gas than last winter and the boiler was constantly kicked on.

Another thing, the old honeywell analog thermostat: what is the margin of error for the thermostat?

Big Ed_4 · February 26

Sure you can use TRV's on panels if you also use the optional manufators diverters...

EdTheHeaterMan · February 26

TRV is a Thermostatic Radiator Valve. @Big Ed_4 mentioned them in his post before he edited out TRVs while I was responding to his post. (I hate when that happens).

I think I have a clear picture of your situation.
You are responsible for the heat from a boiler that is located in a basement that is connected to the radiators that only heat your apartment.
The radiators are connected to a monoflo one pipe system that for some reason is not balanced.
There may or may not be air getting into some of your radiators.
You want to pay for the necessary repipe that will solve the problem.

I have an idea of what to do. In order to remove the monoflo tees from the one pipe design, you will need to add a second pipe. That will be the best answer at the lowest cost if done right. While the system is drained of water for that work, you will want to redesign the near boiler piping for eliminating the air from the system. Since your system has monoflo tees it may also be designed with the circulator pump on the return pipe. That is an invitation for air to enter your system and possibly cause a waterlogged expansion tank. You want to eliminate that problem at the same time.

The plumber that does this work will need to understand the principals in this book Pumping Away and know how to build a reverse return for that second pipe you will need to eliminate the Monoflo Tees

EdTheHeaterMan · February 26

Here is the diagram for the three different systems I talked about.

You have the middle one with the diverter tee. If you want to eliminate the diverter tee then you will want to have a 2 pipe design. like this.

I tried to match that diagram to your description of the system you have with 2 radiators on the lower hall/entrance and the rest of the radiators on the second floor. The second pipe is indicated in Blue and all the diverter tees must be removed from the existing pipe (that your plumber will probably use as the supply pipe.

iexpl · February 26

@EdTheHeaterMan , Thanks for the detailed drawing. And yes, you are right on. That is very informative. I will get the book: Pumping Away and figure out how to build a reverse return for that second pipe to eliminate the Monoflo Tees.

I hope this is the best solution. Any drawback with this solution?

MikeL_2 · February 26

Using a monoflow tee on the supply & the return may help the second floor radiators.

EdTheHeaterMan · February 26

iexpl said:
@EdTheHeaterMan , Thanks for the detailed drawing. And yes, you are right on. That is very informative. I will get the book: Pumping Away and figure out how to build a reverse return for that second pipe to eliminate the Monoflo Tees.

I hope this is the best solution. Any drawback with this solution?

The only drawback that I might see in this system is the difference in the resistance to the flow of water through a long baseboard, radiator compared to a short baseboard radiator. The longer radiator may have more resistance, therefore less flow. That may cause an imbalance in the heating of each room. In order to resolve that, balancing valves on each loop would be a good idea. That way you can throttle down on radiators that get too hot in order to induce flow into the radiators that do not get hot enough.

iexpl · February 27

|The only drawback that I might see in this system is the difference in the resistance to |the flow of water through a long baseboard, radiator compared to a short baseboard |radiator.

hmm... This brings back to the original problem: monoflow caused uneven heat issue in different rooms. What happens if I run two hot water pipes for the supply loop to force hot water directly to the long pipe for the bedrooms instead of sharing a single supply pipe to each room on the second floor.

With one boiler, can I use two supply pipes (instead of suggested one supply pipe)? The problem is that the cold temps are mostly in bedrooms (two bedroom on one long baseboard pipe. ) I want to solve this problem once for all. Currently, this is a single zone system. Maybe I can add a second zone in order to run a separate loop.

balancing valves requires electricity to run, right? This is for a 5 room, 2bedroom apartment about 800 sqft. Are the balacing valves typically used in this setting?

delcrossv · February 27

balancing valves requires electricity to run, right?

No those are zone valves. Balancing valves are set once and then left alone. No electricity.

bburd · February 27

Ironman said:

Are you getting any air when you bleed the baseboards?

What’s the pressure on the boiler gauge when the system is cold?

How about posting some pics of the boiler and its near piping from a few feet away?

This. Check the simple inexpensive things before redesigning your piping!

iexpl · February 27

@bburd thanks for the advice on checking order. I will check those. I will post pics when I get to the apt next time.

EdTheHeaterMan · February 27

So @iexpl, Is there any air released when you bleed the baseboard?

EdTheHeaterMan · February 27

Can you look at the pressure gauge on the boiler when it is cold and tell us where all the arrows are pointing? If you have a red arrow, that one does not matter but tell us where it is pointed to anyway.

iexpl · February 27

| So @iexpl, Is there any air released when you bleed the baseboard?
Yes, there is very little amount. I don't think that is the major issue. In addition, the system was bleeded 4 times within 2 months in one winter due to uneven heating. Uneven heating occurs a lot and in different rooms of the apt.

After bleeding the system, the plumbing/heating company said they can not guarantee heating evenly due to poor pipe design. They suggested the series loop system, which I can not do given the old house layout.

Ironman · February 27

I’m trying to make sense of the information provided. In your original post, you said the system worked “for a while after each bleeding”. Then you just said that a little air was released after each bleeding, but that you don’t think that’s the issue. Those two statements don’t add up.

The plumbing company that you had out bled it four times, but said that it needed to be repiped. That doesn’t make sense. If it’s only letting out a very small amount of air each time, the why do they keep bleeding it? If the piping is wrong, why didn’t they say that originally and why did they keep bleeding it?

Your problem may be something much simpler than needing to repipe the system, but you seem to have formed an opinion based upon what you’ve been told and haven’t provided the basic information that was requested. I’m not being unkind, I’m trying to help, but a proper diagnosis cannot be made based upon someone’s opinion; facts are needed.

Im not saying that the piping couldn’t be the problem, but we see situations like this regularly and most of the time the problem is in the boiler room.

To repipe would be expensive and invasive, whereas it may be that the solution is something easier.

iexpl · February 27

@Ironman your critical analysis is highly appreciated. the bleeding of 4 times are done by 3 different groups. The actual plumbing company came out to do the 3rd bleeding, and told me some aircans need to be changed in the bathroom (a small run of baseboard) and kitchen was not accessible. At this same first visit from the plumbing company, he told me of the guarantee of even heating due to piping issues.

The first two times, I have a handyman did the bleeding, first from the heat register, second time the whole system is drained from the basement.

The 3rd and 4th bleeding done by the plumbing company drained the whole system from the basement as well. 3rd time it also checks for the bleeding from each heat register (- bathroom and kitchen). I believe the 4th time did the same thing but with all rooms.

After the 3rd bleeding, I asked the tenant to keep the apt at 68 degrees always and do not adjust the thermostat even when the apt is empty for a few days. It is better when not adjusting the thermostat, but rooms still not evenly heated (an annoyance now instead of a no heat emergency). After 4 times bleeding, 2.5 winters gone by and system works to a degree, but does not work well overall. Some rooms gets really cold, and some rooms are very toasty.

The circulator pump on the return pipe as well.

MikeL_2 · February 27

Modern baseboard heat has an adjustable damper that can help with balancing; closed dampers in hot rooms & open in cold rooms.
Also check to see if the cold rooms have a floor covering that reduces the clearance below the front cover of the baseboard. And remove any automatic vents connected to the baseboard. They can let air in when a return pipe mounted circulator comes on.
As I mentioned before, a monoflow tee on the supply & return can help with flow issues, and, we use ball valves with bleeder caps at the branch piping for reliable 2 way purging.
Moving the circulator to " pumping away " would be my next move if the above relatively inexpensive tactics don't help.

Big Ed_4 · February 27

Most mono flows also used radiators and convectors and the tees were spaced for the length of the radiation . Adding 15' of baseboard to 36" spaced risers , they might get warm but all the problems show up on the coldest day of the year , when they don't heat up the room . Yes, you can extend the tees to the length of the new radiation if you have access . The system needs a good water flow to work the ventures , a disconnected and capped set of tees will affect the whole system . They can be removed or the risers piped together . The system needs a constant rise to the bleeder to remove air . I am not much for baseboard , its just a cheaper type of radiation that steals wall space .

With your issues without repiping the supply, panel radiators would be what I recommend . I stopped installing baseboard on mono flow convector systems 20-30 years ago because of the issues . Yes, adding ball and purge valves will help to fix the some of the problems . The main reason for installing the radiation is comfort . With panels you will get radiant and convection heat . The panels have optional TRVs valves , each room will have its own control . To add the TRVs on a mono flow you also need to add the optional diverter valves . So when the radiator shuts down the mono flow will bypass through the diverter . The tees are already set for radiators and panels are easier to instal then baseboard . They take up a fraction of wall space will a higher output . They come powder coated so dirt does not stick.

iexpl · March 30

@Big Ed_4 thank you for the suggestion. Never thought of using panel radiators. Good to know.

@EdTheHeaterMan , what do you use to draw these awesome diagrams. I would like to use one such tool to illustrate.

EdTheHeaterMan · March 30

iexpl said:
@EdTheHeaterMan , what do you use to draw these awesome diagrams. I would like to use one such tool to illustrate.

Depends on what system you are on. I believe it is called Paint on Windows computers. I'm on a Mac and it is called Paintbrush.

I can open a screenshot in Paintbrush and make notes or draw diagrams on the image. I can also open a second screenshot and Copy it to the clipboard then open the original screenshot and Paste it the the original.

Very easy to do basic stuff. there are more advanced things that took a while to learn so I could do stuff like this

neilc · March 30

Dan's done it all

iexpl · April 1

|Q: Can you look at the pressure gauge on the boiler when it is cold and tell us where all the arrows are
| pointing? If you have a red arrow, that one does not matter but tell us where it is pointed to anyway.

What is the definition of the boiler is cold? Is it right after thermostat's call of heat finished or do I have to wait the call of heat?

I will be at the apt today and can take more info needed.

Again, my major issue is that main pipe is hot for the loop in the basement, but side loops to the 2nd floor (about 9ft above) is unevenly heated. This is a forced hot water system with no TRVs. Circulator pump at the return. I am looking for suggestions to solve the problem or improve the situation.

Here are some photos of the boiler.

1. expansionTank with Brass Valve Automatic Bleeder Above

2. Circulator Pump with Taco 007 Zone Valve

iexpl · April 1

Cont'd:
3. Heating System fullview

4. Heating System Top View

5. temp/pressure Gauge and Gas Valve

Mustangman · April 1

Knowing the boiler prssure is critical. Piping doesn't matter if you aren't running enough pressure to reach the second floor. The gauge says 20 psi @ 180? Is that correct?
This post got long and TRVs were mentioned. Are you using TRVs? They can't be used on a Mono flo system. Here is why. In your main, you may have we will say, 6 gpm. Then you hit your first mono flow tee. By design, this tee is going to divert 1 gpm up to your radiatiion take 1 gpm out of the main so between the tees, you have 5 gpm. The theory is, once you hit that return side tee... you will be back to 6 gpm and off to the next tee. If you have a TRV that is closed, you are basically dead heading the mono flow tee against the TRV, and preventing that 1 gpm to get back to your 6 gpm main. There would also be turbulance at the diverter tee which will hinder flow. Imagine the mess if you had 3 TRVs off. You would never balance it. I don't know if this is what you have going on or not.
Good Luck

iexpl · April 1

@Mustangman no TRV involved. Just some aircans at the end of the baseboard.
Yes,system is set 20 psi @180

SuperTech · April 1

I think PSI is on the inside of the gauge, if so then you are only around 10. There's your problem. Get the pressure in the expansion tank and boiler to 15 and that should help a lot.

Mustangman · April 1

PSI is on top in Blue @ 20 psi. Temperature is in red 180 degrees. 20 is a tiny bit high but the boiler is on limit at 180 so it shouldn't climb anywhere close to to 30lb to trip a relief.

EdTheHeaterMan · April 1

Mustangman said:
PSI is on top in Blue @ 20 psi. Temperature is in red 180 degrees. 20 is a tiny bit high but the boiler is on limit at 180 so it shouldn't climb anywhere close to to 30lb to trip a relief.

Actually pressure is on top in Feet @ about 20 feet or about 9 in PSI.

Are any radiators higher than 16 feet above the gauge? If yes, then if the gauge is off by 10% you may not have enough static pressure to get the water in those higher radiators.

iexpl · April 1

@EdTheHeaterMan and @Mustangman thanks for looking at it so closely. I will check tonight to get a better photo.

Also, here is a photo on the pipes and monoflo Tee:

Mustangman · April 1

Is't the formula : elevation of boiler, say 2'. to the bottom elevation of radiation on the 2nd floor is, say its 25 minus the 2' so the difference is 23' x .433= 9.95. add 4 psi for a buffer. The .433 is the static weight of water.

LRCCBJ · April 1

Mustangman said:
Is't the formula : elevation of boiler, say 2'. to the bottom elevation of radiation on the 2nd floor is, say its 25 minus the 2' so the difference is 23' x .433= 9.95. add 4 psi for a buffer. The .433 is the static weight of water.

Correct. You'd need 14 psi for that arrangement. He doesn't have it.

EdTheHeaterMan · April 1

Here is a visual of the weight of water and how it relates to pressure.
Starting on the left you see a container that has a 28 square inch bottom. It has one pound of 70°F water in it. The hight of the water is 1". For reference one gallon of 70° water weighs about 8.33 pounds.

In the center of the illustration there is a container that has a one square in bottom measurement and it is at least 28" tall. When we place the 28 cubic inches of water in the second container, it will fill it to a height of 28". It is still one pound of water, and it is in a square inch container. So a gauge at the bottom will register one pound pressure or "1 PSI"

On the left side of the illustration there is a house with radiators and some vertical pipes which illustrate that you need more pressure to lift the water to get to the top of the pipe. The first pipe has 1 PSI so the water is only 28” high (or 2.333’ high). The second pipe has 6 PSI on the gauge so the water is about 14 feet high. The third pipe has 12 PSI so the water is near the top ar 28’ high

Looking at the radiator on the second floor of the house, the second floor radiator can not be filled with only 6 PSI water pressure in the boiler.

Each home is different and the top radiator in your home may be only 12 feet above the boiler gauge, So 6 PSI may work in your home. Since most US residential homes are 2 stories with a basement, the 12 PSI Standard was adopted because that works for almost everyone. You may need to make changes based on you actual conditions. But I would use 12 PSI as a minimum even if you are in a one story home. That pressure helps keep the air out. Also remember when you get to the top of the water column in an open system, the top water pressure is zero. The pressure at the top of a closed system should be somewhat more that zero but it will be lower than the pressure at the bottom. That is because the water actually weighs something.

And none of this has anything to do with circulator pump head. That is a story for another day.

EdTheHeaterMan · April 1

From looking at your gauge, it is possible that you could solve the problem with adding water pressure to the system.

A couple of Questions:
Do you believe that the baseboard radiators were the original radiators when the system was installed?

Do you see any evidence that the original radiators were 36” wide x 24” tall convectors that were replaced by baseboards?

Was the system balanced at any time during the time you were there?

If yes, when did it change?

iexpl · April 3

The front hallway still uses a cast iron heat radiator is 27" long x 25" high x 6" wide . The rest the system are all baseboard heating.

Baseboard length in various rooms are as follows:
Kitchen : 10' 8"
Bathroom: 2'
living room 12'8"
mid + back bedroom: 8' + 8'6"=16'6"
front bedroom is L shaped. One section is 10'6", another section is 8'. 2 sections are connected.

main pipe is 1" in diameter, and riser pipes are 3/4" (or 1/2", I need to double check).
Distance from the main pipe to the 2nd floor baseboard: 12'2"
From the bottom of the boiler to the main pipe: ~6'1"
So, the total distance from the bottom of the boiler to the baseboard on the second floor is: 18'3"

I am working on the schematics of the main pipe loop in the basement. Here are the floor plan layout with baseboard length marked:

monoflow tee from basement to second floor: get rid of monoflow tee

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