Hot water not flowing DOWN to radiator (anymore)

ScubaSteve65

My mystery. I have an <em>overhead</em> 1" loop servicing 4 Runtal panel radiators. Each radiator has 2 venturi tees 1x1x1/2 directing flow to bottom of panel. Each panel has 2 angle stop valves. Worked perfectly like i designed it. They heat up in very quickly. I install the 4th panel (which is no. 2 in the plan) and now no.4 no longer gets hot. I went so far as to completely shut all three panels and still no heat. As I'm bleeding no4 it does get hot (really hot). I close the bleed valve, radiator spends the heat and get cold again and the water keeps passing it by overhead. I go back to my original settings and close off the no2 (the last panel installed) open 1, 3, and 4 (the cold one) and it doesn't get hot like it used too. What gives?

I can't imagine there is an air block. i bled about 3 gallons of water out of a panel that holds maybe 2. And it gets hot while bleeding! I even alternated bleeding with one or the other of the angle stops closed and like it should one side of the panel get hotter before the other.

I'm at a total loss on this one.

Charlie from wmass

How far apart are the tees?

is there a way to purge the main line of air? And of course, do you have a photo to share?

ScubaSteve65

venturi'sabout 18" apart

working on it right now. bleeding more water out of panel radiator no4. it was working fine. there is an air scoop above the expansion tank if that's what you mean???. As I bleed the panel I first had both angle stop open. then the left. then the right. as i stated earlier the of the panel that the stop is open on get hotter faster. when i open both the right side (side with bleeder at top) get hotter faster. all this makes sense. I just don't get whyall of a sudden the darn thing doesn't get hot anymore. even with the other panels closed off or partially closed.

Colud there still be an air lock in the panel even though i'm bleeding it with the result panel getting hotter?

ScubaSteve65

Follow up

Had the bleeder valve wide open. Drained approximately two gallons of water. Got the panel roaring hot. First the left side, then the right side. Now I have both stops open. Closed off two of panels upstream. The radiator is simply spending the heat and water not rushing through it. This used to work great. Even used a cheap laser thermometer to balance out the panels by adjusting the stop valves on each. Never had a problem. It would appear that water moves through it when I open the bleeder. I can reach up and feel the venturis and they are hot as hell.

The panel is 18" wide by 72" tall with 6 flat tubes about 2.75" wide each. The panel is fed by 1/2" with a bottom right angle stop.

icesailor

down in the dumps(depressed):

It is very tricky getting water to flow down. I think there is something on B&G's web site on piping them down. I think that if you get one set of tees too close to another set, you can cause all kinds of turbulence and stop the workings. Whatever your problem, it has to do with the location of some tees in repationship to "other" tees.

Ironman

Tees

Your Tees may be too close together - They should be at least as far apart as the width of their rad and have orifices on both sides, facing each other. Also, adding too many diverter Tees can increase the head in the loop where your current circ. may not be sufficient. You may need a larger circ.



Please post some pics.

JStar

Thoughts.

If this is a new problem, it's worth checking the pump. The impeller may be damaged. Hot water will still get to the higher radiators by gravity, but will never go to a lower radiator.

icesailor

Mono-flow info:

Check out this link to B&G:

http://www.bellgossett.com/Press/BG-monoflo.asp

Notice the part about upfed and down fed. Also, the temperature of the water. I think if you read this and take a very careful look at the tee location, you may find your problem. It may be that you have a tee from one radiator located between the tees for another. Whenever I install Monoflows, I am very careful  to never install anything between the drops to a down-fed radiator. And I think that a high head, high volume circulator can have an adverse effect on a mono-flow down loop.

They are wonderful when they work and a head scratcher when they don't.

And I was never told about using a crossover on disconnected tees. I always wondered about it but never saw a system with a problem. On down fed, it may be a problem.

ScubaSteve65

Placement of venturi's

Thanks thus far. (working on getting pics). Yes the tees the correct width apart. about 18" which is same width as panel radiator. Here' a catch - All four sets of venturis were installed in the proper direction already. I just got around to hanging the last panel (2nd in set of 4) and turning on the stop valves to feed it. There should have been more head pressure without the radiator being connected, yes? So if  no.4 got appropriately hot before installing the last panel one would think that shutting off the recently installed panel might set things right again. But it didn't. I currently have a taco007 feeding only 4 panels. No. 1, (new no. 2), 3 get hot, damn hot. Not no.4, but it used to. No.4 gets hot when I'm bleeding it but as soon as I stop bleed.ing it goes cold

ScubaSteve65

no luck (yet)

This is killing me. I bled 5 gallons. Panel was scalding hot! Closed the bleeder and the darn thing started cooling off. Now it's back to room temp.

Does anyone know how water flows through a Runtal flat panel? I have six 72" tall x 2.75" wide flat tubes(?) tack welded to perforated hanging brackets and a 1" square tube across the top and bottom. The angle stop valves screw into the square tube across the bottom. The bleeder is tapped to the right side end  of the upper square tube.

Does it go Up / Down / Up / Down / Up / Down  ??? Maybe it's clogged???

Or is there an opening at the top and bottom of 6 tubes where they're welded to the 1" square tube?

icesailor

Down,

Maybe not always.

The spacing of the tees apart in relationship to a panel is important. But if a tee from another panel is too close to a set from another panel, it may cause problems. You are dealing with pressures, plus and minus and strange things may happen.

There was a thread here back there there was a tee like I have never seen before which was a forerunner of modern venturi tees. And it wasn't working. A suggestion was that it was being pumped too fast and the water was bypassing the tee. It had the by-pass piped. The first time I have ever seen that. In piping up, you only need one venturi tee. On the return side. On a downfeed, you need two. You MUST have the grooves on the fittings facing each other. But "I" think that if the next tee in line is too close to the last tee, the turbulence could cause a problem.

And Taco tees work differently.

LarryC

Verify it is not the RADIATOR

Steve,

 

If it is possible, can you swap a functional radiator with the non functional one?  If everything else is right, then the only possible answer is the radiator.

 

Larry  (not a heating professional)

Charlie from wmass

it may be the pump

photos of the piping are needed. The resistance through those radiators may require further spacing of the tees. If stuck install a valve between the tees and see if throttling it helps. Also the air may be on the return not the feed line for the radiator.

ScubaSteve65

will atttempt to remove panel?

I attached a pic of the type of valve. It's a Myson product. You take off the cap an insert a large screwdriver to close it off/cut the flow back. I will have to first construct some sort of trough and lay a tarp in it or sacrifice some sort of plastic underbed storage box - when I open that union the water is going to start flowing (after I close the valve of course). Not sure how much water the panel holds - not too many gallons I suppose.

Strange thing is - that was the first panel installed and tested. All the venturis and angle stops were in place around the various rooms, so I installed two more - worked great. I install the fourth one - whoa! no heat in this panel. I adjust the flow to the others upstream, still nothing. Shut the 4th one off as if it was never installed, still nothing. Bleed it and it's hot as hell. Shut the bleeder and I've got nothing. Well, it's cold out, and a blizzard warning in effect for NY -  but who's test their heating system in the August?

LarryC

__guru trick__ a LITTLE bit of dishsoap

Steve,

 

One of the heating gurus on this site mentioned using a bit of dishsoap to get the last bit of air out of a hydronic system.  I believe he depressurized his system, unscrewed the relief valve and put some soap in the open port.  Reassembled, repressurized, and the air bubble came out quickly.

 

I am not a heating proffesional so take this advice for what it is worth.

 

Good Luck.

icesailor

It's not air:

It's not the air. If you bleed enough water out of a radiator that the radiator gets hot, it isn't air. It is flow. Seen that before.

Post pictures of the radiators and how they are piped. Pictures of the tees that feed the radiators, their location and flow direction.

ScubaSteve65

psuedo pipe illustration

ok. i have no graphics programs except some primitive thing called Paint. I hope this works!

The whole loop is maybe 125 feet long. Each Panel (RAD) is piped from above with venturis the exact width of the panel. The ventursi face the SAME direction as suggested by much homework. They are 1x1x1/2 venturi tees. The 1/2" drop is approximately 7 feet to the bottom of the Panel. Only when I introduced the panel in the bathroom did the last panel not heat up. As I stated earlier that panel just need to be hung, unions tightened and angle stops open. But even with that bathroom panel shut (or the other two shut) I still get no flow (except when bleeding to that last panel.

There are two more zones not illustrated. One is indirect fired DHW and the other is a separate line and pump for upstairs. I can pull those ice cubes from the zone controller, shut the ball valve to them, whatever, to make sure they are not robbing some flow rate in a weird way.

This panel is not that old (1 season) and it used to heat up. I never had a problem with the venturi placement before.

I am so darn confused by this.???????

Mike Kusiak_2

Increase pump head?

Have you tried increasing the pump head by switching the 007 to something like an 008? By adding an additional pair of monoflo fittings to the existing system, you may have decreased the flow to the point where it cannot maintain sufficient velocity to force water down to the last rad.



Anytime I have had problems with uneven heating in a monoflo system, increasing the pump head has always worked for me, especially when downfeeding.

ScubaSteve65

increased pressure

I'm not a plumber (as if that's not obvious) so I might ask some obviously dumb questions. Can I overdue the pressure? is the eight better than just throwing in a 010? If it's overkilll can I throttle back via a ball valve? or am I asking for trouble? I have a swing gate that rattles like crazy (another recent post) so perhaps I splurge for a Taco010 or 8 or 9 IFC and get rid of the gate and increase pressure killing two birds at once

Anyone know how these Runtal panels are constructed? When I alternate bleeding the either the left or right side angle stop valve I notice that the two center flat tubes(?) of the 6 that make up the vertical panel don't get hot like the sides.The top does but that could just be heat migrating across the metal as opposed to water flowing on the interior.

Mark Eatherton

You said...

"The ventursi face the SAME direction as suggested by much homework. They are 1x1x1/2 venturi tees. The 1/2" drop is approximately 7 feet to the bottom of the Panel. "



First off, if the convector/emitter is above the main, you normally only use one venturi tee, and it is usually located on the emiitters return to the main. Coldest (relatively) densest water.



If you are using a high pressure drop emitter, like a fan coil unit, you MUST have the inlet tee facing UP stream, and the return tee, connected to the emitters return connection, facing DOWN stream. The same rule applies to any emitter that is below the main.



Venturi tees don't really work well at low flow rates, and each tee represents a fairly health pressure drop. I'm thinking you need a pump with more guppies per minute, and subsequently more head pressure in order to over come the drop occurring in the loop. I'd also suggest you check the positioning of the tees, because if they are in fact facing in the same direction, they will counteract each other. -10 plus 10 = ZERO.



The fact that it worked before may have been a fluke.



Don't get too frustrated. It's not rocket science, but if things are NOT set up right, it won't work as designed. Fall back, re-group and double check that everything is set up right. Try lowering the water temperature, and raising the pressure as well. Once purged, you can raise the temperature, and lower the pressure.



Go back to Icesailors link to the B&G web site regarding MonoFlow tees. There are some VERY useful tips there.



Let us know when you get it figured out.



ME

ScubaSteve65

radiation below the main

http://www.comfort-calc.net/monoflo_system.html



Check out this link. (about half way down - monoflow radiation below the main). It's not what I used originally. The one that I finally referenced in my decision to face them the same direction was more "science" based for lack of a better word, or maybe more professionally worded.

I'll check back after I dig out of the snow here in NY.

The other monoflows are installed the same way as well. I'm going to check the Taco site regarding pumps and pressure. I sort of remember them having specific details - unless of course anyone out there knows what pump I should try? I believe a friend has a recently removed but fully functional 0010 and was hoping that would do the trick, but again, I don't want more problems.Thanks everybody so far. Time to start moving snow..

icesailor

Tees:

Maybe you are misunderstanding the part about "tees facing the same way". They don't. If they are B&G tees, there should be a groove cut in the tee next to the outlet. These are the parts that must face each other. If you use two tees, you MUST have these grooves faceing each other on the drop to the circuit. That way, it doesn't matter which way the flow is. If you use only one tee, you better have the flow direction correct.

And thinking back on "the old days", there used to be a rule on baseboard about how many feet of baseboard you could run on a 1/2" tee. If more than that, you had to go to 3/4". I know once, I had to TS a basement zone and it was a ****. I learned a lot. It had to do with placement of tees.

Also, if you piped the thng as you show, in MY opinion, if you run the primary and secondary meeting on the run and exiting on the branch could slow down the flow. If you have a balancing valve on the primary side, close it down and see if it helps.

My computer is dying. I'll have to finish this later

icesailor

Flowing tees:

Again, you do not have a correct primary/secondary system. Although you have two loops, for it to work properly, you MUST bring the secondary piping into the primary loop on the same plane and closely spaced tees or within 12" or closer to each other. If you do it as you drew, the two circulators will fight each other and the more powerful, the 010 will overcome the 007 slowing down the secondary circuit. That secondary circuit is supposed to circulate within a close space while the primary is going by. That way, you get your mix. You can't (in my opinion) put a tee on one side of a 90' turn and the other on the other side. I said before, if you can throttle the primary circuit way down, so you still get flow through the primary, you should be able to feel flow through the secondary. Changing circulators is not the correction. The tee placement is. In MY opinion. Maybe I am wrong because I can't see the actual piping, just your drawing. In my opinion, if you did it as the drawing, it might not work and it would be the cause of the final radiator not working.

icesailor

Flow Tees (mono-flow's)

That shows what I said. The grooves must face each other. They used to have a sticker that had arrows on them that showed arrows with flow direction and which way you installed them. And I mentioned the thing about 3/4". It takes flow to make them work. They used to make what they called "Super Tee's" to be used on long runs, long baseboards or down fed.. They used to paint the groove with red paint. As a cost cutting measure, I'm sure that they cut out the paint. For what they charge you for them, they should be polished.

ScubaSteve65

I think I see the light

I had to do some dismantling of the ceiling to see this. Fortunately I can see the supply side tee. It's a Nibco venturi (full tee, not the little insert). Don't see them on their website. Anyway..If I understand you correctly, and I think I do - I need to un-sweat that and turn it around. Even though it has Supply and Return arrows, I need to disregard them and face the return arrow at the on-coming water to create the resistance to push it down.

OK, how about this scenario - is there any chance in hell that the cone tapers down AFTER the 1/2" tee? (or the return side of Nibco Tees?) Logic would say no, but it would be just my luck.This going to be a doozy to work on.Fire extinguisher at the ready!

EricAune

If you bleed it...

To quote Dan, "if you bleed the radiator and no air comes out, its not an air problem!"



The supply tee to the lower radiator has to be "backwards" in order for the proper pressure change that will force water to the lower radiator.

 

The others are right and it sounds like you may have figured it out but check this link out for further info:



http://www.heatinghelp.com/article/11/Hot-Tech-Tips/155/Diverter-Tee-Tips

Charlie from wmass

I was thinking

Back in my very early 20's I did a monoflow to convectors for the heat in a church basement. When I was done with the pressure test and had purged the whole system I went through and checked each unit for heat. They all heated great. I was so pleased as it was the first large job my father had given me free reigns to layout and install. As I was cleaning up and closing up the convectors I looked up at the first unit's tees and noticed the return tee was backwards. every other tee was correct just the one was backwards. To be honest it is still backwards. for what ever reason it worked fine. God looks out for fools and children I guess. I decided if there was an issue I would gladly go back drain it down and spin the tee. That was almost 20 years ago and it never was an issue. I am guessing the others worked before but with this many hooked up the flow was reduced enough for it to stop.

icesailor

Mono-flows:

Charlie,

I find Mono-flow tees to be under the influence of un-natural forces. That they can do things that defy explaination. Perhaps it was the location of the job that saved you. Maybe that will explain it.