Monoflo system help / flow from both tees..?

WirePro_joe

What I have: Monoflow system, black iron main loop 1", old convector radiators piped 1/2" copper w/ small bleeders.

What I did: Disconnected hallway convector to relocate to opposite wall (in order to take down
existing wall) and relocated main loop pipe (offset over 12" to go behind new basement wall I built).

So as the name suggest, I am not a plumber I am an electrician. I've done some basic plumbing over the years and some in (vocational) high school. I understand the basics of monoflo systems thanks to sites like this. Here's the issue. Instead of reusing the old convector, I bought and installed a Myson Contractor Series radiator. They say it will work well on a monoflo system. The bottom of the radiator has a twin entry bypass valve shown here:



I have a regular tee on the supply side of the main loop and a monoflo on the return side in 1 1/4" copper. 1/2" pex to the new rad. I can't get any flow through the new myson rad. All the other rad's in the house were bled and work great still.

On the supply side of the twin entry valve, if I close the return side and open the supply side, water will come out of the bleeder and the rad will get hot. If I close the supply side and open the return side, hot water will come out of the bleeder as well. It seems like I have hot water coming from both sides. How is this possible?

The twin entry bypass valve does have a bypass adjustment in the center of it. Doesn't seem to do anything.



The picture above shows the new mono tees. As you look at it, water is flowing from right to left. The tee on the right is regular and the tee on the left is the mono.

I also replaced the tees (reg & mono) on the next rad down stream (existing convector stayed) and it works great. Can't understand what's wrong? Any thoughts?

GW

that's a pain! are you positive the top valve is open? at the top of the rad? You're getting zero heat?

Is it possible you have an air bubble in one of those two lines in the basement? I learned the hard way many years ago- just b/c there is water doesn't mean there isn't air. Wow that was a painful lesson.

You may have piped the rad backwards, which really should not affect flow---only when the trv starts to close on the flow. Typically the supply is the one towards the center of the rad, and the return is the other, at least on the rads i install.

I would look at the pex lines and see if there's a hump somewhere--this set up doesn't have a power purge 9as i call them anyway), and a stupid bubble can hang you up

Ironman

How long are the pipes feeding the new rad?

Panel rad's have flow setters that are somewhat restrictive compared to a wide open pipe in a baseboard or even a convector. When they show that you can pipe them monoflo, that assumes that all the rad's are panel rad's, not a mixture with others that are less restrictive.

I believe that due to your pipe length and the difference in radiators, that your not getting flow because that loop is more restrictive. Water takes the path of least resistance - just like electricity.

Ironman

You don't use the bypass AND monoflo Tees. It's either or, but not both. See the drawing attached.




It MAY work if you get rid of the bypass valve, install another monoflo Tee at the supply AND shorten the run outs. No guarantee though.

GW

ahh yes, we don't use those valves

HVACNUT

On the Monoflo systems by me, Monoflo tee's are used on the supply and return branches for all convectors.
I don't think I've ever seen one that wasn't piped that way.

WirePro_joe

HVACNUT said:

On the Monoflo systems by me, Monoflo tee's are used on the supply and return branches for all convectors.

I don't think I've ever seen one that wasn't piped that way.

Most of my research told me to put a single mono tee just on the return to create a resistance which will force the water through the supply regular tee. That's how most of the houses were done that I've see.

WirePro_joe

Ironman said:

You don't use the bypass AND monoflo Tees. It's either or, but not both. See the drawing attached.




It MAY work if you get rid of the bypass valve, install another monoflo Tee at the supply AND shorten the run outs. No guarantee though.

Thanks for the diagram, it may come in handy. I installed both the monoflo tee and the twin entry bypass because the manufacturer told me I needed both. Guess I need to call them up on Monday and see what they say.

WirePro_joe

GW said:

that's a pain! are you positive the top valve is open? at the top of the rad? You're getting zero heat?

Is it possible you have an air bubble in one of those two lines in the basement? I learned the hard way many years ago- just b/c there is water doesn't mean there isn't air. Wow that was a painful lesson.

You may have piped the rad backwards, which really should not affect flow---only when the trv starts to close on the flow. Typically the supply is the one towards the center of the rad, and the return is the other, at least on the rads i install.

I would look at the pex lines and see if there's a hump somewhere--this set up doesn't have a power purge 9as i call them anyway), and a stupid bubble can hang you up

If by "top valve" you mean the little bleeder valve, then yes. I bled the rad until I was blue in the face. Got strictly water from the little bleeder valve on the rad. According to the paper work that came with the rad, the supply on the twin entry is on the left (which leads up to a thermostatic valve) and the return is on the right. It's piped correctly unless the paper work is wrong. The only way I can get hot water to come out of the bleeder valve is to close the return on the twin entry and leave the supply open. I can also do the opposite and close the supply, leave the return open and I'll also get hot water from the bleeder. I don't get it.

WirePro_joe

The new rad is located about 8 feet from the tees. It's basically the same distance and set up that was originally there except for the new rad and the tees being a couple of feet further down the main loop.

thanks guys for the quick responses!

WirePro_joe

Should I just ditch this fancy Rad and install a fintube baseboard instead?

Ironman

What was the output rating for the convector that you removed? Whatever type of rad you choose to replace it needs to have similar output.

I'd try what I suggested first. 2 diverter Tees will give twice the resistance to diverting water to the rad. It's commonly done for higher resistance emitters or ones below the main.

Also make sure the flow setter on the rad is open completely.

Also close off the bypass.

Harvey Ramer

I think you may have installed the monoflow tee backwards.

Nevermind, I reread your post and it is oriented correctly for the flow direction you described.

Any idea how many gpm are going through the main?

JUGHNE

If you had some sort of throttling valve on the existing convectors you could close them part way down as a test. Then if new heater worked it is perhaps a pressure drop problem. Your old convectors are an easy path for water and the new is not.

If the entire house was the same radiators it might work.
Maybe the 2nd monoflow tee will do the trick. I would try the throttling experiment first. Maybe no tools needed.

Ironman

WirePro_joe said:

Ironman said:

You don't use the bypass AND monoflo Tees. It's either or, but not both. See the drawing attached.




It MAY work if you get rid of the bypass valve, install another monoflo Tee at the supply AND shorten the run outs. No guarantee though.

Thanks for the diagram, it may come in handy. I installed both the monoflo tee and the twin entry bypass because the manufacturer told me I needed both. Guess I need to call them up on Monday and see what they say.

Whoever told you that needs to take a closer look at the diagram.

JUGHNE

Harvey Ramer said:

I think you may have installed the monoflow tee backwards.

With an old "Mono-Flo" tee in my hands it says: "Install with grove between risers" The groove end has the full size of pipe...the other end has the reduced venturi opening with the branch coming in above it. I have to think about these to get them right. Never installed any, only took them out on a tear out.
I might have what he needs on my desk, 1 1/4" x 3/4" mono flow tee.

Danny Scully

A few suggestions. First off, use (2) monoflow tees and point them at each other. Second, make sure the tees are spaced as far as the width of the radiator. Third, install a ball valve between the tees. You can throttle the valve if all else fails.

Ironman

Using the ball valve,as Danny said, will also make it easier to purge air from the rad. Just close it when purging.

EBEBRATT-Ed

Turn the heat on. See if the diverter valve is getting hot which could be where your water is bypassing. The above posters are correct. Use monoflow tees or diverter valve....not both.

WirePro_joe

Thanks for all the replies everyone!

Here's what I tried today: Removed the twin entry bypass valve and brought the pex directly into the new Rad.

Here's what changed: the return side/pex on the new Rad got hot (Rad got barely luke warm), the supply side/pex stayed coldish. The next Rad down the line after the new Myson (an original convector) has zero flow now, wont get hot. It's supply is hot, return is cold, no air coming out of the bleeder. It was working great while the twin entry bypass valve was installed.

So frustrating. I will Myson tomorrow to see if they have any ideas. I also might try a ball valve in between the tee and mono tee.

Everything I've read on monflo systems says to only use two mono tees if your Rad is below the main loop. Everything else says to use a single mono tee on the return side and a regular tee on the supply. That's how the rest of the house is piped also.

Danny Scully

@WirePro_joe, you came here for advice from professionals and we're giving it to you. If you go through the trouble of adding a valve, install another monoflow tee. The idea is to increase the pressure difference and the additional monoflow tee does that. Again, point them at each other.

WirePro_joe

> @Danny Scully said:
> @WirePro_joe, you came here for advice from professionals and we're giving it to you. If you go through the trouble of adding a valve, install another monoflow tee. The idea is to increase the pressure difference and the additional monoflow tee does that. Again, point them at each other.

You make a good point. When you say point them at each other, do you mean like this?:

https://goo.gl/images/HgZ17Z

Danny Scully

That's correct @WirePro_joe. Basically, what ever direction the monoflow tee you already put on is going, install the new monoflow tee the opposite way.

Ironman

WirePro_joe said:

Thanks for all the replies everyone!

Here's what I tried today: Removed the twin entry bypass valve and brought the pex directly into the new Rad.

Here's what changed: the return side/pex on the new Rad got hot (Rad got barely luke warm), the supply side/pex stayed coldish. The next Rad down the line after the new Myson (an original convector) has zero flow now, wont get hot. It's supply is hot, return is cold, no air coming out of the bleeder. It was working great while the twin entry bypass valve was installed.

So frustrating. I will Myson tomorrow to see if they have any ideas. I also might try a ball valve in between the tee and mono tee.

Everything I've read on monflo systems says to only use two mono tees if your Rad is below the main loop. Everything else says to use a single mono tee on the return side and a regular tee on the supply. That's how the rest of the house is piped also.

You've probably got air in the other rad. It can sometimes be extremely difficult to bleed air from a monoflo system. Adding the valve between the Tees causes all the flow to go through the rad when purging with the valve closed.

Again, think like water: what is the easiest path to take?

GW

Can you take a pic of the top end of the rad, opposite the bleeder? There're no valve there?

GW

It seems like you piped the supply and the return backwards. Shouldn't matter much unless you're using a trv

WirePro_joe

> @GW said:
> It seems like you piped the supply and the return backwards. Shouldn't matter much unless you're using a trv

They were piped according to the directions. If it's backwards then the paper work is wrong. There is a thermostatic valve on the top right side opposite the bleeder.

Ironman

WirePro_joe said:

> @GW said:

> It seems like you piped the supply and the return backwards. Shouldn't matter much unless you're using a trv



They were piped according to the directions. If it's backwards then the paper work is wrong. There is a thermostatic valve on the top right side opposite the bleeder.

Jus to be clear: the inner connection on the rad is the supply and the outer is the return. Your pic of the monoflo Tee would lead us to believe that you piped the return to the inner connection on the rad.

Also: make sure that the flow setter under the TRV is set to fully open.

WirePro_joe

Does anyone think a standard fintube baseboard would work better in this case? If I can keep the main loop and branch piping the way it is (one mono and one regular tee) and just use a piece of baseboard I'd be content. Then I can throw this myson in the trash (or actually maybe try to sell it on Craigslist).

Ironman

Again, you need to have something with the same output as what you took out.

Asking if anyone thinks it will work without knowing that is like asking how long a piece of rope is or how high a hill is.

j a_2

Good thing it's your own house, and your able to do it yourself...Customers get a weeee bit upset when s##t don't work correctly...Hope you figure it out, myself, i would not have chosen to go with that style radiator on the single pipe system you have...A seperate zone,then yes it would be fine....

GW

idk, the rads we have worked with, the supply is on the outer (1" in from the edge of the rad) and the return is the inner (3" in from the edge of the rad). But that's not your main issue here.

If there's any droop in the 1/2" lines you'll get a small air pocket, no flow. If your other rad/convector/baseboard isn't heating up, and it did before, and the other units are heating up, sure looks like air in the line. NOTE, not air in the rad, air in one of the the lines leading to the rad.

If you're still scratching your head, take out the TRV and the valve assembly.

Look for a droop in the 1/2 lines

GW

Remove the Myson??---it looks so nice, if you have the energy i would try to get it to flow.

You're sure the main circ is moving good hot water? the main heats up fast? Sure would be a stinker if you have a circ issue disguising itself as a rad issue.

Ironman

GW said:

idk, the rads we have worked with, the supply is on the outer (1" in from the edge of the rad) and the return is the inner (3" in from the edge of the rad).

@GW
That may be true with the brand you've been using, but every brand I've used (including Myson) has the supply on the inside:

GW

sons a gun my minor case of dyslexia is kicking in!

Supply is 3" in and return is 1" in.

Good grief

On Sept 23rd my brain was working:
You may have piped the rad backwards, which really should not affect flow---only when the trv starts to close on the flow. Typically the supply is the one towards the center of the rad, and the return is the other, at least on the rads i install.

WirePro_joe

UPDATE: so I added a second monoflo tee (one on the supply side of main loop) and a ball valve in between the two monoflo tees to help with purging. I still have the twin entry bypass valve at the rad but it's completely closed and not bypassing any water. I did remove it at one point to see if anything changed but no luck.

Rad is getting warm but not hot. The return (1/2 pex with one coupling) is barely getting luke warm. The supply (1/2 pex with no couplings) is hot. If I close the ball valve and force all the water in the main loop through the rad it will get hot and both supply and return lines will get hot however the next convector down the line gets no flow. I tried the ball valve at 25%, 50%, and 75% closed trying to maybe find a sweet spot to create some better flow into the rad but still cuts down the flow too much in the main loop effecting the next convector.

Any other thoughts or ideas?

Will a fin tube baseboard be easier for the water to flow through? I'm getting sick and tired of this myson rad.

I called myson they told me it was air bound and I need to "purge, purge, purge".

WirePro_joe

Here's a shot of the piping

Ironman

The flow setter on the Myson; did you set it to the fully open position?

Ironman

Also: what make and model circulator do you have on it?

Danny Scully

The wall does have its limits @WirePro_joe. Sorry my/our suggestions haven’t solved the issue. Where are you located?