Cooler bedrooms on monoflo/one-pipe baseboard system

Fus1982

Hello,
I have a onepipe/monoflo boiler system for heat. For the bedroom zone, the thermostat is located in bedroom 3. Now that the weather is cooling and the heat is on daily, I've noticed a difference in temps between the 3 bedrooms. The room with the thermostat is the warmest, the bedroom next to it is about 2 degrees cooler and the last room is 4 degrees cooler. The coolest room is the first room on the inlet side, and the warmest room is at the end of the run on the outlet side. What options do I have to help warm up the other two rooms? Are there valves I can add to lower the flow to the warmest room to allow the cooler ones to catch up?

I did my best explaining the setup in the diagram. The yellow is the supply line and the orange is the return line.

Thanks

EdTheHeaterMan

That diagram does not look like a one pipe monoflo® system. It appears that there are 2 pipes and that it is a direct return system. I will look up my old slides from teaching about this and post them shortly. In order to properly help, we MUST know if you have a monoflo® or not. Your description of the problem sounds reverse to what should happen.

Fus1982

EdTheHeaterMan said:

That diagram does not look like a one pipe monoflo® system. It appears that there are 2 pipes and that it is a direct return system. I will look up my old slides from teaching about this and post them shortly. In order to properly help, we MUST know if you have a monoflo® or not. Your description of the problem sounds reverse to what should happen.

I'm certainly no hvac/plumber, so my terminology could be wrong.. as well as my crappy attempt at a diagram lol.

I have 4 zones, and this one is above a finished garage, so seeing the piping isn't as obvious as the rest of the house. In the next zone over, the basement ceiling is open so it's a lot easier to breakdown. There is a one inch pipe from the boiler that runs around the perimeter of the house and goes back to the boiler. There is a monoflo tee wherever it branches off to a baseboard, and then a regular tee at the return side of the baseboard back to the main feed.
In the diagram i drew here, the main feed pipe is in the middle of the garage (I'm assuming it was just easier when they built the house in the 60's), but I believe is the same set up as the other zones in the house

EdTheHeaterMan

So the diagram you posted has some conflicting information. I would like to first discuss four different designs. The first design is a direct return system that uses 2 pipes from the boiler.
This was used on old gravity or thermosiphon systems. Large pipes with no circulator pumps. Usually with large cast iron radiators. The closest radiator on the supply is also the closest radiator on the return. With gravity flow (Very Slow) and hand fired boilers (Coal) that worked nicely.

When Circulator pumps were added to that system, the closest radiator would over heat and the furthest radiator would not get enough heat because the path of least resistance was the shortest or closest radiator. To counter act that problem, a similar two pipe design was introduced called a Reverse Return
The path from the closest radiator on the supply was the furthest on the return. So this made the path of resistance for all the radiators about the same. The middle radiators were on the middle of both the supply and the return. And the furthest on the supply were the closest on the return. This made a system using a circulator easier to balance the. This was more expensive because there were more pipes involved.

B&G developed a special MonoFlo® Tee that could be placed on a single pipe system that would divert some of the heated water into a branch that lead to the radiators. See the files below for examples of other companies that offered the diverter tee. This reduced the cost of piping a system because there was only one pipe and both the supply and return were connected to that pipe, using that special tee. The center illustration below is a diverter tee or MonoFlo® system


The final system was introduced to reduce the cost even further. The baseboard series loop. By using a copper or steel pipe with some fins attached to introduce more heat transfer surface, and enclosing that pipe in a 6 to 12 inch cover, the convection currents of room air could pick up more heat to transfer into the room. This baseboard heater used the actual pipe as the heating radiators where ever the fins with the covers were placed in the room. The connecting pipe would then be able to go under the floor or behind a wall in order to connect to the next radiator in the loop. That system is the top diagram in the illustration above.

What is confusing about your diagram.
1. The first radiator on the system or loop is the coldest
2. The orange lines indicate a supply and the yellow indicate a return. That is not a one pipe design
3. There are 2 large yellow arrows indicatng a supply and a return whicj looks like a series loop.
4. The Red rectangles would remind me of a baseboard radiator, but you do not indicate if they are cast iron baseboard or copper tube with fins baseboard.

I have made some changes to illustrate my confusion. Can you tell me which diagram is most like your system?
A: the series loop

or B the Direct Return

C None of the above

Robert_25

What type of radiation are you using? Most baseboards have a damper that you can close to reduce the output and help balance the system. Many radiators have a supply valve that an serve the same function.

EdTheHeaterMan

I just read your second comment. You DO have a monoflo system. So my query is two fold. In the basement where you can see the monoflo tees, are there three separate tees for each of those bedrooms? or is there only one monoflo tee the feeds all three?

Second, what radiators do you have? Cast iron or Fin Tube?

Another illustration to follow

EdTheHeaterMan

Is this a possibility?
Also... are all the radiators in the home the same type?

PeteA

great visuals @EdTheHeaterMan
The pictures are awesome and really puts these systems into a better perspective. Like they say a picture is worth a thousand posts (used to be words but we don't talk anymore we just type a lot )

Fus1982

EdTheHeaterMan said:

Is this a possibility?
Also... are all the radiators in the home the same type?

Wow, thank you so much for the information.. you've truly gone above and beyond here, and taught me some things. So, after further investigating with the info you provided me, this diagram appears to be closest to what my set up is. And yes, the cooler rooms are closer to the return side, I was wrong. Just to confirm, I've attached a photo of my boiler system. If the left side is the inlet side and the right is the return, then you are correct.



My house is a ranch style with 4 zones, including one in the basement. The basement and is all fin tube, my living area is all cast iron, and the other 2 zones on the are a mix of cast iron and fin tube. Basically, only the 4 bedrooms have fin tube (there is a 4th bedroom on the opposite side of the house, not part of the issue at hand). With the issue i'm having, there are also two bathrooms with cast iron that are the first two on the inlet side, then it hits the 3 bedrooms. So it does make sense that the last room in the zone is a little cooler.

And to answer the other question, each baseboard has it's own tee and monoflo, and this is the case throughout the entire house, except for the basement zone which is a series system based off your photos

EBEBRATT-Ed

If the piping is over a garage that is a hard ceiling how does anyone know how it is connected??

I think that @EdTheHeaterMan suggestion of a Monoflo zone off the main loop is certainly a possibility.

Fus1982

EBEBRATT-Ed said:

If the piping is over a garage that is a hard ceiling how does anyone know how it is connected??

I think that @EdTheHeaterMan suggestion of a Monoflo zone off the main loop is certainly a possibility.

The main feeder pipe and tee's are below the sheetrock, then the pipe elbows up to above the sheetrock and disappears. I think I was able to figure out the path after looking at it enough times

bburd

The key point here is that the room with the thermostat is the warmest room in the zone. To balance the system you need to reduce the heat output in that room, so the zone will call for heat longer before the thermostat is satisfied.

Most baseboards have a damper in the top that can be closed to reduce airflow. If you have these, try this in the warmest room.

If not, there is a very effective and easy trick: wrap some of the fin tube in the hottest room with aluminum foil so air cannot pass through it. Perhaps 25 or 30% of the length to start, then see how you do. You may need to do this with the next warmest room as well, to get enough heat to the coldest room.

EdTheHeaterMan

this comment concerns me.

and the other 2 zones on the are a mix of cast iron and fin tube.

having different emitters on one thermostat never works properly. Cast iron is slow to heat and slow to cool off, so it will take longer for that radiator to warm up that room. if that is the thermostat room then the baseboard rooms may over heat for a short time, then when the thermostat is satisfied, that room will be slow to cool off, to call for heat again, leaving the baseboard heated rooms colder more often than not.

If you also have convectors and cast iron baseboard on the same thermostat, then you may never get an even heat in that zone.

Erin Holohan Haskell

@Fus1982, I've merged your duplicate posts into one here to prevent confusion.

EdTheHeaterMan

I might suggest that you have one MonoFlo® zone with all the same radiators. The other 3 zones may not be. The basement is a series loop with fin-tube baseboard. The problem zone is all fin tube baseboard hopefully. I can suggest that you close the damper on the room with the thermostat. That will cause the other two rooms to get warmer. This diagram shows the baseboard with full output

By closing the damper and reducing the amount of air flow thru the baseboard convector fins the amount of heat in that room will be reduced. This is a trial and error process. You mau close them off too much and have the opposite problem. so tru to close half the radiators in that room to see if that is enough. It will take two days for you to see the difference, do changing the damper position will not make the room get colder instantly

Fus1982

EdTheHeaterMan said:

I might suggest that you have one MonoFlo® zone with all the same radiators. The other 3 zones may not be. The basement is a series loop with fin-tube baseboard. The problem zone is all fin tube baseboard hopefully. I can suggest that you close the damper on the room with the thermostat. That will cause the other two rooms to get warmer. This diagram shows the baseboard with full output

By closing the damper and reducing the amount of air flow thru the baseboard convector fins the amount of heat in that room will be reduced. This is a trial and error process. You mau close them off too much and have the opposite problem. so tru to close half the radiators in that room to see if that is enough. It will take two days for you to see the difference, do changing the damper position will not make the room get colder instantly

The mixed heaters have been there since i bought the house 10 years ago, and even possibly original to the house. Maybe they just didn't know better back in the 60's. The zone in question does have two cast iron recessed radiators in the bathrooms, one being the master bath which is also the room that gets the warmest and has the thermostat.

I appreciate all your help and the helpful diagrams. I already closed the dampers on the warmest room tonight, I will check the temps of the other bedrooms the next couple of mornings and see if that helps balance the temps. If that doesn't work, is there any harm in trying the other guy's suggestion.. covering some of the fins with aluminum foil? You seem to have a ton of knowledge and I would love your take on it.

Thanks again!

EdTheHeaterMan

Fus1982 said:

I appreciate all your help and the helpful diagrams. I already closed the dampers on the warmest room tonight, I will check the temps of the other bedrooms the next couple of mornings and see if that helps balance the temps. If that doesn't work, is there any harm in trying the other guy's suggestion.. covering some of the fins with aluminum foil? You seem to have a ton of knowledge and I would love your take on it.
Thanks again!

That will do the same thing. If you have cast iron baseboard, you and block the bottom opening to reduce air flow thru the radiator. If you have a room that is too hot, and you can block the heat emitter's air flow, then that heat emitter will release less heat. A piece of sheet metal laying across a convector type radiator will do the same thing. Slow the air down = slow the heat down.