Lets start from the top on this

ralman

What is your opinion on the method of bypass

I used on my monoflo system you were previously helping me with. I moved my circulator from the return pipe to the supply pipe pumping away from the PONPC. I added a bypass pipe above the circulator from the supply to the return. I am having trouble dialing in the bypass and the split loop return.

ralman

Not at all.

A very good explanation of why you feel the floor loop will be okay with 180* temps. My understanding is; a circulator before the bypass is a system bypass, which protects the boiler from flue gas condensation and raises the system supply average temp. A circulator after the bypass pipe is a boiler bypass, it protects the boiler from flue gas condensation and lowers the system average water temp. Your drawing has the circulator after the bypass. I am not debating either method. I am trying to gain an understanding of the two bypass methods and their uses because I chose one of the methods. Jamie states, and you agree, that you are restricting the mass of cold water returning to the boiler. I then think that must mean the cold mass is bypassing the boiler and going back to the system, lowering the system average temp. Why choose this method as opposed to placing the bypass after the circulator? My goal is to learn as much as I can as I am trying to improve the performance of my system.

Ken_40

What made you install a bypass on a MF system?

The very restrictive nature of MF systems essentially makes the dT across the boiler very high anyhow.

Close the bypass altogether! See what happens over a 20 minute period. It will typically allow the boiler water temp to rise above 140 with ease.

Remember, the aleady high resistance to flow has your circulator working in the "higher head" range, which diminished the GPM flow-rate! By encouraging this GPM loss, you create wild dT's across the system (not necessarily the boiler) - and will result in unaccapetable system circuit dT's!

The circulator has "known" and predictable GPM rates at defined resistance(s). By opening a boiler bypass, you reduce the GPM's allowed to go through the two circuits.

This will create the very condition you wanted to avoid from jump street.

Questions?

Ken_40

The simplest way I can explain.

The circulator puts out gallons of flow. If you divert that energy as with a boiler bypass, the GPM's stay the same but anything that diverts the flow, also diverts the circulator's ability to make water go where required. You do not heat a structure by heating the boiler.

Mono-flo systems are not high mass, long run-time type systems. No bypass is required. Anything that diverts a gallon of water from entering the distribution/emitter side, reduces BTU transfer. The ONLY reason to bypass any non-P/S design is to protect the boiler from condensing, or protect radiant tubing and the medium it is connected to from excessive temperatures. You don't have a radiant system! The system is probably designed to run at an average water temperaure, on a design day (coldest day of season) at 180F. HWBB, whether mono-flo, zoned, circuited or series loop, are typically designed for a dT of 20F max. By installing a bypass, you divert the circualtors GPM capacity and dT designs to a greater dT, thereby compromising the end-of-run emitters to a lesser water temp that required.

Make sense yet?

ralman

Because...

I read that the bypass would protect the boiler and raise the system average water temp. The material I have read states that a system bypass is recommended for large content water systems such as converted gravity systems OR systems with excessive radiation. How do I define that? I have 17 gallons of water in my boiler and 67 gallons of water in my system pipes and emitters. I felt that if I added it and it did not work I could just close the ball valve and I would just lose on the cost of materials. My hopes were to increase system average water temperature. So far, my experiment seems to raise the average water temp. However, with the bypass open, some of the downfeed emitters will not get any flow through them.

ralman

Yes, and this is what I am experiencing.

With the boiler bypass partially open, I have no flow in one downfeed emitter. I have varied the degree of that opening and still no flow in that emitter. With it fully closed, flow is established in that emitter. I felt the bypass should be closed based on this results of this trial and error. I wanted to know your opininion in case I am not piping it correctly or not adjusting it correctly. I jumped into this thread trying to compare what you were doing with that system with what I am doing on mine. Currently, this is not my only problem. Since moving my circulator, I have not been able to establish flow in another downfeed emitter. I get no air when I bleed it. It is the first emitter to supply off of the main pipe. A 19' fin tube. Otherwise, the comfort level in the home compared to last year is absolutely FANTASTIC. Thanks for helping me.

ralman

A comparison of what I have clocked so far.

With the bypass partially open, outdoor temp 37* at night. Total circulator run time is 50 minutes. Burner run time is 30 minutes. It takes 16 minutes for the boiler to reach high limit of 170*. The boiler gage started at roughly 160* and never dipped below 150*. The return pipe temp started at 80*.


With the bypass fully closed, outdoor temp is 46*, daytime, sun is shining brightly. Total circulator run time is 35 minutes. Burner run time is 30 minutes. It takes 26 minutes to reach high limit of 170*. The boiler gage started at roughly 170* and never dipped below 140*. The return pipe temp started at 74*.

Ken_40

Regarding the down-fed emitter...

If mono-flo, it must have two MF tees, not one.

Did we discuss this already?

The desire of hot water to rise is alien to a downfeed array, overcoming gravity takes twice as much "venturi action."

Is there 1 or 2 MF tees on the doen-fed emitter?

Ken_40

Implying that you...

have validated the best performance with no bypassage at all?

That makes sense to me, and is empiracal data that the boiler is not in an extended period of below 140 water temp zone of temperature range.

Leave the bypass closed. All water going through the boiler, none through the bypass.

That is what you are saying, n'cest pa?

Ken_40

Perhasp you would trust...

the ultimate authority I refer to, I=B=R, as derived from ASHRAE state:

[Source: Page 68, 1996 I=B=R installation guide 200]

1) in a floor radiant system, "An AVERAGE water temp of 120 is the basis of the designs."

2) NOTE: "No attempt has been made in this guide to evaluate the effect of heat outputof floor panels from the various types of floor covering......" When floor coverings are installed, it may be possible to obtain the required panel output, BY INCREASING THE BOILER WATER TEMPERATURE." (emphasis added).

3) Of some note, I=B=R does NOT set a high limit as to water temperatures in these apps. If a guy has a 1" foam underlayment and a 2" carpet on top, I can easily see why. If I can see that, why can't you?

Since getting a 120 degree average water temp with a system dT of 20F is the design basis, boiler outlet temperature is already at 130F. And this is for bare concrete!

If ASHRAE and I=B=R says its okay to raise the temperature to meet the covering's R-value, why would we have any concerns, especially in light of what 35+ years of intense slab radiant experince has taught us?

Stick with the Legionella hype. It is your true forte without question.

Ken_40

You must have

Sun Rads for emitters? normal convectors would never have that much water content.

Regardless of what's there. Closing the bypass allows full flow throgh the boiler and more importantly, THE ENTIRE SYSTEM, while opening the bypass, reduces flow - without the boiler running for more than five minutes at below 140?

Sounds like a home run to moi, mon ami!

Dave Yates (GrandPAH)_1

You need to check your meds!

If you're designing for that type of floor covering, you need a check up from the neck up as you will have been derelict in your duties as a radiant comfort specialist, if you are one. Must be one **** of a burden being right all of the time. Evidently, it's not a burden for you to ride roughshod over so many folks as I've witnessed you doing quite frequently here of late.

The Wall is yours to do with as you wish. I’m moving on. And, the next time you feel compelled to send out pornographic pictures, leave me off of your e-mail list.


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ralman

Yes, we have.

We have had some discussion relating to sizing the circulator, and how monoflo systems work. All of my emitters have 2 monoflo tees, regardless of length, or location. I think there is a problem with the way the monoflo loop is split, as others here have commented. The first three emitters that supply on the right side of the loop are returning on the left side of the loop. I have 155' of Burnham baseray and 32' of fin tube.

ralman

I want a new piping system.

ralman

I think a new piping system is in order.

I attached a diagram of what I currently have. When I moved the Taco 007 circulator, I replaced it with a Grundfos 15-58 3 speed. I am running it on speed 2 right now because with speed 3, I can hear water flowing through the pipes. Because I can hear the sound of water moving I think maybe speed 2 has enough flow. How much velocity noise is too much?

Delta Tee: It only takes 1 minute to raise the return pipe temp on the short side of the loop 20*. After that it levels off and takes awhile to raise sustantially higher than that. A factor of cool return water maybe. The long side I haven't clocked yet. My DT is wide at the beginning of the thermostat call for heat. The DT comes under 20 usually after 30 minutes of burner run time.

I am not getting any air from the baseboard vents since the second heat call last saturday, I feel the air is eliminated.

Boiler pressure. I had tried every combination of adjusting the 2 returns to try and establish flow in the downfeed emitter. Nothing worked. As an experiment, I raised the fill PSI to 16 and the expansion tank PSI to 16. The heat call brings my boiler PSI to about 24 PSI. I was able to establish flow in that emitter by closing the long loop return and opening the short loop return. This does not work at the 12 PSI fill pressure. I can not leave it set this way as there will be no flow on the long loop side. It is puzzling as to why it worked before but not now. It was very difficult to establish flow in that same emitter last year after I drained the system for repairs. I attached the diagram.

[Deleted User]

In the interest of further education...

I have prepared a drawing showing two systems with two similar variations in bypass flow rates.

I have listed the EWT (entering water temps), AWT (average water temps) and DT (differential temperature across the appliance).

In case 1 and 2 the EWT is higher than in cases 3 and 4.

In case 3 and 4, the AWT is higher than in case 1 and 2.

In case 3 and 4, the DT is extremely high, and could cause a severe amount of differential stress across certain cast iron and steel boiler designs, resulting in early casting failure. Even with low mass boilers, the lower flow rates would be dangerous from the stand point of steam flash generation, and is not recommended by most newer low mass appliance manufacturers.

Note that the overall fluid differential temperature is the same, which is 20 degrees F, resulting in identical discharge temperatures from all 4 cases of 120 degrees F, excpet when limiting boiler discharge temperatures to 180 degrees F as in case 4.

The math behind this comes from Siggys book Modern Hydronic Heating. Stated simply, it is flow in GPM times temperature if degrees F, which gives you a FTU (flow temp unit). Crunch the numbers if you wish to verify the net out comes.

The 200 degree F discharge on case 4 is for illustrative purposes only. If the boilers high limit were set for 180 degrees F, then the supply water temperature to the load would actually be 116 degrees F, backing up my suggestion that this is typically done to limit the temperature to the panel, and not done to protect the boiler from long term condensation production due to extremely low entering water temperatures.

While it may appear that case 3 and 4 do have a higher average block temperature than case 1 and 2, the lowest portions of the cast iron sections are still being exposed to a greater potential for condensate production than would case 1 and 2. And yes, case 1 and 2 are also still in a condensate production mode under this scenario, but to a lesser degree than 3 and 4, and they will obviously get completely out of condensing mode faster than cases 3 and 4 due to the simple fact that their EWT is being raised higher than case 3 and 4.

Next, I will generate a graphic showing what the ESBE THermic valve would be doing under this same scenario, but enough work for the night. Gotta go spend time with the wife.

ME

ralman

Thank you, Mark Eatherton.

I show up here everyday for an education. I do not do this for a living, so my interests are what pertains to my heating system and how I can improve it.

Jamie_5

yes, but...

As an amateur, I am only asking for my own edification. I am not trying to be difficult.

What are the bases for the assumptions that the floor needs 120F water and has a 20F drop across the circuits? If the floor circuits need hotter water and/or the system temperature drop is lower, the average water temperature across the boiler block is also higher, no? For example, if we maintain the assumption that there is a 20 degree drop across the radiant panels but also assume that the mixed supply temp is 140F, allow 4 GPM to flow through the boiler, and bypass 6 GPM, there's a 50F rise in the 4GPM across the boiler to 170F and an AWT across the block of 145F. I don't know, but it may well be that cast iron boilers, with the amount of thermal mass and conductivity they have, would deal with those conditions well.

I guess at this point one needs to have actual experience with the building and boiler type in question, and I don't. I think the ESBE valve approach is probably safer in that it doesn't depend on having the right combination of system water temperatures to make it work. But given that the algebra appears to demonstrate that Ken's approach *can* work, I take Ken at his word that he has experience with these systems and that his approach *does* work.

[Deleted User]

Lots of assumptions...

In our business. Supply temp is dictated by resistance value of floor finishes, back losses of radiant panel, tube type and centers of application.

In a typical high mass cementitious application, per the Radiant Panel Association, 140 degrees F is the max recommended supply tmeprature.

20 degrees differential is the standard differential used by most equipment manufacturers. In reality (and the field) the differential is usually half that amount, but that still doesn't matter in the grand scheme of things. It is what it is, and the heat source just has to deal with it. THe critical point is that if a natural gas appliance see an entering water temperature below 135 degrees F or there abouts, it WILL condense, and if it isn't made to resist the corrosive tendencies of the condensate, it will suffer an early death.

Flow through the boiler is a matter of design and timing. If the system has numerous zone valves (which our first poster didn't have) then the flow rate through the system and boiler is all over the place. You have the tools now to simulate whatever scenario you want and see what the net results will be. Only problem being, the fixed valve bypasses can not respond to changes in flow variables. The ESBE Thermic can.

I'm not out to prove Ken right or wrong. Ken is always right in Kens' mind:-) I'm demonstrating what the different piping schemes do for the appliance. It's your customer and your system, you do what you feel is good. YOU have to stand behind the warranty, not ME, or Ken.

Personally, I haven't specced a conventional atmospheric boiler in so long, I can't remember where the last one was installed. I use mod cons wherever, and don't worry about the production of condensation. In fact, I invite condensation production. I'm just responding to a thread where non condensing equipment was in use, and condensate production a real possibility, and in my opinion, mis-direction being given...

Mine is not to wonder why, mine is but to clairify or die:-)

ME

Ken_40

It is a shame

the RPA, and apparently all its members is only focussed on plastic and synthetic tubing, which is precisely why your somewhat-correct bias against higher than 140F water supply temps is so mis-leading.

The RPA was initially an invention of those who make tubing that would not fare well if subjected to 180F. That is the ONLY reason they continue to preach the 140F max caveat.

Those of us doing radiant, long before the makers of plastic and rubber tubing were imported from europe, and thinly veiled manufacturer's brotherhood-only marketing claims of how superior their radiant systems were, created the RPA of old. It was initially a marketing entity, with little engineering involved, other than "euro-based" design parameters. Some chose to adopt these desgns, despite already working and almost 40-years of American success in the field.

Now that they lay claim, despite ASHRAE and I=B=R having done all the real, initial and groundbreaking engineering with materials used over 50 years ago, not based on some "brotherhood" of euro manufactuer's you now so willingly embrace. All the basic engineering was done before you and I were born. Not by some "club" of those wishing to hustle product, but by ASHRAE and I=B=R, back in the 50's

Were this a modern radiant system, I would defer to your expertise, especially now that the RPA is no longer a marketing arm of large plastic and rubber manufacturing salesmen.

I applaud the RPA for throwing out the manufacturer's of the "also-ran" euro makers. But to throw away the 50+ year old basis of all the radiant design/engineering out the window, simply because you are unaware of older and more appropos designs is dead wrong.

It was stated the system was steel and Levittown-like in nature. How many Levittown, steel tube systems have you personally worked on Mark? Other than condemning a few, and given your exuberant youth, you probably have never even seen a steel tubed, no underslab insulated, Levittown style radiant system in your life!

One of the things that always enamored me of your talent was that you are a mentor; a teacher; and, a damn good one.

I would suggest my age, knowledge and experience with this form of radiant is the one that will work. I also suspect your caveat of radiant output using a high limit water-in-slab temp of 140 in (presuming a 20dT and return water of 120 is inappropriate in this particular application.

I also suggest average water temp of 130F will leave the client with a cold house now, and become totally unworkable as winter nears. Should they remove all carpeting and underlayment, install thin vinyl tile, or ceramics, the homeowner will experience a cold Levittown style home at 130F average slab water temps.

If you choose to embrace 1990's know-how on a 1950's radiant Levittown style radiant system, and dismiss my solution as "wrong," without deferring to the very basis of the original designs, you now seem to dismiss as an somehow "irelevant" (the basis of which is applying 1990's plastic and rubber-based radiant tube technology to a 1950's steel and copper-based design), I think we do a dis-service.

Can it be made it any clearer?

Perhaps Dan, WHO LIVES IN A LEVITTOWN STYLE HOME, could jump in and tell us how those old, brown, asbestos and rubber-based "marbelized" tiles worked out(;-o) What the original radiant floor water temps were set at AFTER everyone put the underlayment foam down and wall-to-wall. As well as how the bathroom floor was so warm, your feet almost sizzled while "on the throne" where no carpet ever laid, and how boilers with simple piping, EXACTLY LIKE the schematic I drew out, were used for all these style slab homes, typically were steel, not c.i., and lasted 30+ years?

No harm in trying the 140 limit I suppose. At worst, the contractor involved in the re-pipe will be dismissed and sued for claiming to know what he was doing, when he in fact didn't, and someone who has a clue, will yet again take the homeowner's money, and do it the right way, once and for all...

Dan Foley

RPA

The world according to Ken! Curious where you got your mis-information regarding the RPA? -DF

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DanHolohan

Ken,

you're trying my patience with the name-calling.

Ken_40

I apologize!

M.E. is many things, but a "shill" for anything, or anybody is NOT what I meant to imply. Mark is a stand up guy. His dedication to this biz is unquestionable.

Again, my inference is un-called for and was just retracted/edited out.

Mia culpa.

ScottMP

Hey Ken

How about an apology to David Yates ?

I think your "exuberance" over flowed on to him also and he does NOT deserve it. Dave's knowledge, talent and selfless promotion of the plumbing trade does not deserve the Venom you threw his way.

Scott



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DanHolohan

Yes,

that would also be very appropriate.

I've been on the road all week, flying and teaching, and getting in late. I haven't had a chance to spend much time on the Wall. It's a shame that after all these years we still have to keep having the same conversation about mutual respect. It's not like we don't know each other.

I shouldn't have to go through this every time I'm on the road.

What's it gonna take to make it stop?

ralman

More education please.

(Flow gpm) x (temp) + (Flow gpm) x (temp) / flow GPM = new temp. Correct? Now , How do I calculate the temperature rise across the boiler. For example, I have 170* at the beginning of a heat call, 80* returning. Using scenario 1, 14 GPM flow with 4 GPM bypassed. I come up with 105* mixed returning to the boiler. How do I calculate my new supply temp? Firing rate is 105,000 BTUH DOE heating capacity, 17 Gallon boiler. Does it really matter? I interpret Your graphic calculation exercise in scenario 1 to indicate that a system bypass will be beneficial to my system. This is how I piped mine when I changed the circulator location. I may have to keep the bypass closed based on Ken's advice that I am not in danger of flue gas condensation and my own observation of flow being stopped for the downfeed emitter. Does the triple aquastat protect the boiler from low return temps, if working correctly it should turn the circulator off at 10* minus the low setting? Could you comment on the ESBE device as it applies to my situation. If I understand correctly, at some point the temp would cause the device to have no bypass, which would allow flow in that downfeed emitter. At other times the temps would cause a bypass which would either reduce or stop flow in that emitter.

Ken_40

Don't press it!

Dave Yates suggested I sent him pornography. If a picture of Hillary Clinton's face along with a few other "butts" is pornographic, mia culpa, once again. But, it was done privately, not here!

He had nothing constructive to add to this thread, other than to blow smoke up Mark's post/comment/skirt, suggesting my competence was somehow flawed, and Mark's was the only one worth following. A direct slap in my face.

Would I sit down and have a cold one with Dave? You betcha!
I consider him a peer and wise man. Is he (or I) perfect? **** no. Do we both hit the "send" key a bit prematurely? Sure.

We are all adults, trying to help others. At times we disagree. I don't think Dave needs or wants an apology, nor am I thin-skinned enough to respond to his "author of pornography" slur. We were both in the "heat of the moment" moment. He took a cheap shot. I was not gong to respond, until the above post showed up from Scott and Dan.

Have neither of you anything better to do, this beautiful day?

Let's knock off the innuendo and stupid stuff and just help people fix their heating systems. That is, after all, why we're all here, or is it?

Dave Yates (GrandPAH)_1

I'll press it

Vaginal pictures in graphic detail showing up unsolicited in my e-mail do indeed constitute pornography and I stand pat by my earlier post. Had some warning come along with the e-mail as to its content, I could have deleted it or opened it under more discrete circumstances. I am hardly a prude, but that was way the **** out of line.

I now take my second leave of absense from The Wall and will not be returning to follow the posts you've left that are stinking up the place. The slapping around I've witnessed here was handed out by you and you alone. I'm leaving for a spell because I have reached the end of my patience and anything further I would have to say would be - at best - uncivil.

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DanHolohan

\"Stupid stuff\"

Yes, that's exactly what I'm asking you to knock off. That, and the bullying.

Think you can do that?

[Deleted User]

Wow, lost of questions here...

Let's take them one at a time.

Yes, your intrepetation of the flow X temps calculations are correct.

As for the delta T across the boiler, take the net output of the boiler, and divided by 8.33, then divide by 60, then divide by the flow rate in GPM and then add that answer to the EWT and you will have the new discharge temeprature from the heat source, which would also then be the new merging temperature where they bypass blends into the return water temperatures. The boiler is the major influencer on this whole process. other than the actual load of btu's being delivered to the load. Assuming a starting temperature of 170 degrees is OK, except that in a high mass system, it will drop like a rock, hence looking at it from teh return side is going to provide a more accurate real time scenario.

The over all delta T of the boiler in relation to the system is dependent upon the flow rate though the system over all. The standard rule of thumb is to assume a 20 degree differential, which equates to a 1 gpm flow rate per 10,000 net btu output, but it doesn't have to be. If you have a multi zoned system with flow controls (zone valves), it is entirely possible that you will have less than 1 GPM per 10K output, so your delta T across the boiler will be significantly more. A word of caution to those people reading this from the outside. Some boilers are more critical as it pertains to flow than others. Some high mass steel/cast iron boilers can be fired with NO flow through them, and some low mass boilers must have an EXACT minimum flow rate in order to avoid flashing to steam. I'm assuming in this case an older high mass boiler, which is not sensitive to flow thru boiler issues, and in that case, if you halve the flow through the boiler, the DT will double.

Yours, for example, at 105,000 net output, flowing at 10.5 GPM would produce a 20 degree DT assuming 100% flow through the boiler. If you cut this flow back to say 5.25 GPM, the DT would jump to 40 degrees F, and if you doubled the flow rate to 21 GPM, the DT would drop to 10 degrees F.

All of this assumes a steady state load, which in theory only occurs at design condition. If you have no load to speak of then the DT is a big variable. I have personally only seen a few systems that I actually witnessed a 20 degree DT on, and they were both being commissioned during extremely cold conditions, with a very cold house to begin with. Under normal operating conditons, the DT will be significantly less, unless your system is coming out of a deep set back cold start condition.

The American hydronician has a tendency to get to tied up in delta T in my experience and estimation. If the system is set up correctly, and flow has been established as being correct to all loads, and the appliance is being as efficient as its supposed to be, comfort will be the end product, regardless of what the system DT is.

The more important things that we have to be aware of and critical of are supply water temps (in the case of human contact with a radiant surface), and the possibility of extended periods of low return water temperatures to appliances that were not designed to see the production of condensation, which is acidic and will eat your boilers lunch. A tripple aquastat is specifically deigned to maintain a higher residual boiler temperature. It was originally designed to provide semi priority to the DHW loads if an immersed coil was being used, but was then adopted as a means of avoiding long term condensation production potentials.

The ESBE is a proportional thermostatic operator. It will only allow those water temperatures that are in excess of required boiler protetion temperatures to be allowed out into the system. Once the system has warmed up, 100% of the boilers production capcity is sent to the load. It only activates during periods of cold start or extremely heavy loading. Lets say for the sake of clarity that your home boiler also does the snowmelt for your drive way. The house is perking along, and the boiler is producing water temps in the 180 degree F range. The ESBE is out of the picture because the return water temperatures are well above the dew point. Suddenly, the snowmelt systems turn on, and the return water temperatures drop like a rock to 50 degrees F. THe ESBY kicks in, bypassing flow around the boiler until the EWT is above its set point. It then opens PROPORTIONALLY, allowing only excess btus to be allowed to escape out into the system. As the system starts warming up, and the return water temps begin warming up from the initial cold start shock, the valve bypasses less and less until it is once again completely off line.

Your assesment of flow through the system and emmitters as influenced by the ESBE are correct. Just remember that is will only be in place during cold start up, not typically at desgin operating conditions.

In your case. the lack of flow to the down feed emmiter sounds more like an air binding issue. If you are 100% certain that that loop has been thoroughly and completely purged, then it is a flow issue. Mono FLow systems are notorious for high pressure drops, especially if the branch circuit is closed off.

I have two diverters/venturis on each branch of my system (home) due to the pressure drops of the heat emmitters (European panel radiators and RFH circuits). I also have a flow meter in the main circuit, and I can see the influence of closed valves and it is REAL significant.

Hopefully I have answered your questions, if not feel free to respond.

ME

ralman

Thank you.

I will have to study this for awhile, but I have a few comments/questions. I appreciate your response.

"Assuming a starting temperature of 170 degrees is OK, except that in a high mass system, it will drop like a rock, hence looking at it from teh return side is going to provide a more accurate real time scenario."

You are correct, this is exactly what happens with my system. It takes 30 minutes of burner cycle to get the delta t under 20. The burner currently cycles about 45 minutes to satisfy the thermostat on a heat call, I have it set for the lowest span setting.



"In your case. the lack of flow to the down feed emmiter sounds more like an air binding issue. If you are 100% certain that that loop has been thoroughly and completely purged, then it is a flow issue. Mono FLow systems are notorious for high pressure drops, especially if the branch circuit is closed off."

I do not get any air when I bleed any of the the emitters in the house. I have 3 emitters that are supplied from the right side of a split loop and return on the left side of the split loop. Comments from the wall have indicated this is a problem. 2 are upfeed baseray and seem to work well. The problem is a downfeed 19' 3/4 fin tube. It has a supply and return monoflo t correctly installed and wider than the emitter. I can't say with 100% certainty that it is not air, but I am not getting air when I bleed it.

"I have two diverters/venturis on each branch of my system (home) due to the pressure drops of the heat emmitters (European panel radiators and RFH circuits). I also have a flow meter in the main circuit, and I can see the influence of closed valves and it is REAL significant."

What are you using for flow meters? I have been researching the B&G thermoflo balancers and discussed it a little bit here. I have trouble with the balancing of my split loop. The temperature method is not working for me. I am interested in using a flow meter for this purpose.

[Deleted User]

Flow meter...

Letro brand.
http://www.kingsolar.com/catalog/mfg/letro/flow3s.html

Some of your terminology doesn't make sense to me, but then you could be stating something using terms that I would term differently. If you can generate some sort of drawing showing mains, branches and loops along with the heat source, heat emitters and circulators I will try and help resolve your issues.

Ain't nothing that can't be fixed!

ME

ralman

Here is my drawing

I have a L shaped 56 year old ranch style home. 1500 SF main floor and 1000 SF heated basement. The drawing describes/shows how the system is laid out but is not to scale. The monoflo T system and baseray look original. The fin tube is likely due to remodeling over the years by previous homeowners. They look like replacements not new additions because the main pipe appears to not have been disturbed. The first 19' fin tube supplied from the long loop (right side) return on the short loop (left side) is the one I am currently having trouble with. It has been stated here that there is a pressure differential problem with this arrangement. The valves at the end of the split loops make a difference in the system flow. If I understand correctly, I should only require a valve on the short loop. I should be able to close this valve and balance my temperatures between the 2 loops. Varying this valve degree of opening affects flow at the last downfeed 10' fin tube on the short loop and the 3' upfeed fin tube on the long loop. Conditions there range from nice and hot to very cold when I vary that valve. The long loop valve which I feel should be unnecessary, will affect the flow in the 19' fin tube. I have been able to get the flow to get down the supply pipe and through about 5' of the fin tube with the long loop valve fully closed. This certainly is a crazy situation I have here and I have been studying my repipe options. I think there is no point in fooling with what I have anymore. I would hate to do a repipe if it wasn't required, but at this point I feel that this system is poorly designed. I wonder if it ever worked properly?

EDIT = I recently changed my circulator and forgot to update the info on my drawing. The new circulator is Grundfos 15-58 3 speed and I am running with medium speed right now. I also noticed the description missing for the 24' CIBB. I fixed those mistakes and reposted the drawing.

[Deleted User]

Oh my....

That one hurts even my head:-)

I'm going to print it, read it, absorb it and I'll get back to you later with either more questions (likely) or possible solutions.

Thanks for your paitence, and by all means, if anyone else feels the urge to chime in, please do so. I don't hold any franchises around here:-)

ME (Out harvesting solar btu's off my roof and sending them where the sun has not shone in over a million years;-) ) Pictures later...

ME

[Deleted User]

Your tang is all toungled up...

Your tees are dotted and your I's are crossed, and your system is improperly piped.

Mono flow tees, venturi tees and scoop tees are all extremely critical to direction of flow. Unless your system was installed by a master of hydronic wizardry, I can see no less than 3 points that would cause me concern.

In order for MF tee systems to work correctly, the emmitter must be placed such that branch flow is parallel to the main flow. THe 19' down feed is connected on the supply main going to the right, and also to the main feeding to the left. Hardly parallel to the main flow.


If you could move the right hand tee to the left hand side of the main, it should start working, however, pay attention to the arrows on the tee's or your efforts may be for naught. You want the inlet tee installed in a forward flow manner, but the return tee should be installed backwards to give the water a place to get back into the main stream flow. Following this same line of thinking, the 18 foot CIBB upfeed should have its supply tee moved to the left of the supply split, and the unnamed upfeed loop located to the left of the boiler needs to either have its return moved to the right hand side of the loop, or its supply moved to the left hand side of the loop.

Theoretically speaking, and this is why I mentioned a hydronic wizard, the system could be made to work, but it would require placing tees such that it would be a critical balancing act to follow. The flow through both returns would need to be perfectly equal in order to guarantee proper branch flow. That doesn't make hydronic sense because you have 2 completely different loads to contend with.

The theory of operation between a Monoflow tee and a venturi tee are somewhat similar, but different enough that they need to be understood. The monoflow tee is really not much more than a restrictive orfice in the main pipe with a side branch right next to it. Depending upon how it is installed, it will either create positive pressure to the branch, or slightly reduced negative pressure in the main where the branch re-enters to give water a path to get back into the main stream, kind of a safe harbor in a wind storm if you will. THe pressure differential created by these two tees presents the branch piping with enough differential to induce flow. The amount of flow is dependent upon numerous variables. Those variables being equivilant pipe length of the branch, whether you are feeding in an up flow or down flow configuration, main flow values and the amount of main piping between the tees.

Venturi tees on the other hand work as a true venturi where the branch stream re-enters the main stream, and as a diverter tee where the brnach stream exits the main stream. A venturi works primarily on the principle that wherever there is an increase in velocity, there is a decrease in pressure. This decrease in pressure, if properly presented to a side branch, will and can produce significant flows through the branch piping. If the side branch is either a high pressure drop device (kick space fan coil units, panel radiators, etc) then you must use both a diverter tee (nothing more really than a venturi tee installed backwards) AND a venturi tee on the return tee back into the main regardles sof wheter it is an up feed or down feed. This is also the case for heat emmiters below the main as Ken previously pointed out to you due to hot waters afinity to rise, and cold waters afinity to sink.

SO, in a nut shell, the branch piping suppply and return fittings SHOULD be connected to the same main branch, not crossed over as yours are. Once this is cleaned up, main flows can be adjusted to balance out the main flows to match the loads being imparted.

In addition to the pressure differential created by the branch tees, flow is also induced through the side branches by any additional pressure differentials created within the main piping. I would surmise that the 10'er up feed shown just to the right of the boiler gets SMOKIN' HOT, because it is not only seeing the pressure differential created by its own monoflo tees, but is also seeing the pressure differential created by all of the other monoflo tees between its inlet and oultet, AND the pipes and fittings between its tees. Water should be SCREAMING through that section.

Remember also that water is like my ex prother in law. Wet lazy and stupid. It justs want to get back to the pump for another ride around the block. Hence it ALWAYS follows the path of least resistance, which is NEVER the same path we WANT it to flow, so just like my ex brother in law, WE have to show it the way by creating paths of greater or equal resistance. In my B.I.L.'s case, I showed him the door:-)

I hate being the bearer of bad news, and hopefully, you have a better grasp on your situation and understand the fix. If not, you know where to find help.

Oh yeah, don't forget to purchase a brick for The Wall to help keep the doors here at Heating Help.com swinging. The Holohans will appreciate it I'm sure.

I've attached some pictures and information retreived from The Library to hopefully clear up this issue in your minds eye.

Let us know how things work after you change the piping. Monoflow systems are generally trouble free.

ME

ralman

An excellent explanation that makes things much clearer.

I keep banging my head thinking I am not bleeding all the air out or the circulator is wrong or some thing else and at the same time thinking this thing has never worked correctly in 56 years. The 10' CIBB, you nailed it, screaming hot while everything else in the house is "warm". The fix will be difficult due to the location I need to move the split to is congested with supply and return monoflo T's. Not a lot of room on that area of the main pipe run. I understand that the monoflo T's will have to be oriented to the proper flow direction. This would also require their angle valves and bleeders to be moved is my guess. One more monoflo question I have asked in the past and don't have a grasp on the answer. Can I connect two baseboards and remove two monoflo T's? This would make the changes easier and reduce the resistance in the main, possibly improving flow performance even more. For example, the 10' CIBB and 8' CIBB downfeeds on the right side are in the same room. The 8' CIBB has zero flow, there is 25' of 3/4 pipe, 4 90 degree elbows, and the monoflow T's are 4 inches apart. Not enough pressure difference to move hot water down that distance. I think I could connect the return of the 10' to the supply of the 8', remove those two tees and it should flow. There are two 4' CIBB right there that could be combined also. Thanks for all the education, Mark.

[Deleted User]

I don't see why not...

You should be able to run the 8 and 10 in series without any significant consequences. The 8 footer is not seeing much flow through its branches because it is being "leap frogged" by the 10 footer. The 4 foot up feed is also being leap frogged, but it has gravity working to its advantage, not against it so it is not as noticeable, but its flow IS being negatively affected by the 10 footer running parallel to and around it.

What you have are MF tees that are "nested", creating numerous paths of parallel flow that substantially drop the velocity on the main, thereby seriously handy capping the MF's ability to generate pressure differential necessary to exert flow through the side branches.

If you have some way of choking down the offending "bypass" emmiters that are leap frogging the other branches, you will increase the main flow and get better action through the "leap forgged" convectors.

It has also been my experience that with monoflow systems, there needs to be a manual air vent at the highest point of ALL above main convectors, and all down feed branches should come off the BOTTOM of the main. This will aid in air removal, which can be a major PITA with these system. Especialy in light of the fact that you have so many leap frogged convectors.

One of the alledged benefits of a system like this is the ability to close off individual branches should they become over heated. The disadvantage is, that if you close off the branch piping, the pressure drop of the MF tee jumps to an equivilent developed length factor of around 25 feet of pipe. That can add up to some serious pressure drop in no time flat, requiring a SIGNIFICANTLY larger circulator to overcome the pressure drops. In your case, it would create ALL kinds of craziness and havoc :-(

This would be a PERFECT setting for a variable speed, constant pressure circulator like the Wilo or Grundfos circulators. No branches closed, pumps is idling along. Branch pipes closed by non electric TRV's, pump see drop in pressure and increases speed to maintain required pressure differential.

Just for the heck of it, if you can, choke flow to the 10'er right next to the boiler (upfeed) and see what happens to the other convectors on that branch.

I think you will be mildy suprised :-)

Remember grass hopper, in order to understand water, you must think like my ex brother in law:-) "Hey DUDE, where's the party???"

And thanks for the questions. I assure you that you are not the only one learning from this discussion.

ME

ralman

I tried varying the flow in that hot 10' CIBB last year.

I tried every variation in the degree of opening and closing for the angle valve on that 10' CIBB last year. I thought I could force some flow into the other CIBB past it. It did not seem to make a difference. But I have moved the circulator to pump away from the PONPC this year and my perception is flow in those far baseboards is MUCH better. I will try varying the valve tomorrow and see what happens.