Taco 00 Circulator.. thoughts?

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Old 11-08-11, 05:39 PM
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Thumbs up Taco Delta-T 00 Circulator.. thoughts?

Heya Trooper, ltns. I haven't been around much since bb went dark.

I see xiph is also here, how ya been?

Biasi is running awesome since I got the Riello dialed in. Clean, nozzle and filter once a year.. works fantastic.

New project is two Buderus G115WS' in a stage and rotate config. Two CI zones, two radiant zones (two different temps) and indirect DHW.

Piping is p/s with the boilers as secondary.

Thinking about installing a Taco delta-T circ.

Wondering if it would be better as the primary pump or running two of them as the secondary circs to the boilers.

Thoughts on the delta-T? I was originally looking at a setpoint circ but will be running Tekmar controls with outdoor reset, which seems like it would be counteractive.

Wondering if anybody has done something similar.

Tim
 

Last edited by ItsTim; 11-08-11 at 05:56 PM. Reason: clarify title
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Old 11-08-11, 06:08 PM
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Hey Tim! Good to seeya again!

I'm gonna let Xiphias jump in on this one first... he is the 'guru of pumps' as far as I'm concerned... I think he's gonna steer you to maybe the 'Alpha', or a Wilo... but let's see.

ALPHA2 | Grundfos
 
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Old 11-09-11, 04:24 AM
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Delta-T.. or Delta-P? That is the question.

Good to be back!

I believe the Alpha is a Delta-P (and I'm a Grundfos fanboy), but I can't wrap my head around the whole "constant head" philosophy.

I know:
  • I want a minimum boiler return temperature of 130d
  • the Tekmar is going to regulate the water temperature
  • head will vary; there is DHW priority ([email protected] for the SuperStor)

Tim
 
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Old 11-09-11, 07:55 AM
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Hello Tim,
Jumping in here.

How will the temperatures to the cast and radiant be controlled?
Injection pump, thermostatic mixing valve, Tekmar controlled mixing valve, or etc.?
Are there multiple zones in the two temperature groups?

Which Tekmar controller is under consideration?

Many, not all, Tekmar controllers only target supply temperatures.
Tekmar's that can contol an injection pump or mixing valve can also control return temperatures.

How are you planning to control the return temperatures?

IMO the best way to maximize heat extraction from the boilers would be a delta T pump for each one.
If the "bumblebee" is ever released operating costs would be low also.

With the exception of the injection pump(s) if used:
ECM type delta P pumps would likely be very good on the rest of the system, and have low operating costs.


Peter
 
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Old 11-09-11, 10:20 AM
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System config

Heya Peter,

The Tekmar 274 controller I chose will only do the supply temp.

Two CI zones are both simple thermostat-relay-circulator setups.

The two radiant zones are via Tekmar 3-way mixing valves. Right now it is just the valves, which will be manually set. Plans are to add the valve motors and additional controls when money permits. I know this adds a bit of uncertainty to the low temp zones, but theoretically the outdoor reset on the boiler supply should translate to the mix temp. These low temp zones also have separate thermostat-relay-circulator setups.

Total of 4 zones (plus indirect dhw == 5 zones), no zone valves.

Thanks again.

Tim
 
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Old 11-09-11, 01:15 PM
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Hello Tim,
Tough one.
Have you considered the Tekmar 423?
A bit less $$ to start and it can handle the add on controls, later on.

I'm guessing there is no need to change the existing zone pumps.

I'm not fully clear on how the piping arrangement will be.
Will the primay loop have a circulator, or will the zone pumps do all the work.

I still don't think the Delta P pumps are the right item for the boiler pumps.

I'm sure Mr. "Xiph" will have much more to offer.
Haven't seen him around for a few days.
Maybe he's gone out swordfish fishing?

Peter
 
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Old 11-09-11, 03:45 PM
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Tn4..

I did look at the 423, but it is more money because you need the wiring center in addition. I won't dispute it is slick, especially when adding zones.

I am not an "eggs in one basket" guy. I have 3 Wirsbo (Tekmar) controls in my own house. If one fails I still have heat (worst case I have to jump out the boiler to an aquastat).

The separate units appeal to me. The 274 does have a TN4 port, which is why I opted for it over [the other one, I forget the model number]

Piping diag:
 
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Old 11-09-11, 06:48 PM
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Interesting problem. Some thoughts.

I would pipe the boilers like whichever one of these is closest to what you want:
Multiple_boiler Installation

In your diagram, the 2nd boiler is not piped, and that has a lot to do with everything else, like pumping. And the indirect doesn't need to be on closely-spaced tees if you pipe it off the connections to the loop.

For boiler loop pump, you could do something like an Alpha (love mine, and suggest some kind of ECM pump anywhere you have a pump...). Not sure if you could/should do a dT pump on the boiler loop, particularly in a staged set up.
 
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Old 11-09-11, 07:13 PM
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Hi Tim,
I think i understand the drawing.
Kinda hard to see.

It doesn't seem like the wiring center is needed unless tN4 thermostats are used.
And. If they are used, the wiring center is needed anyway.


262 is the other control.


Peter
 
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Old 11-09-11, 07:35 PM
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And the indirect doesn't need to be on closely-spaced tees if you pipe it off the connections to the loop.
Not sure I get ya Xiphias? You mean in parallel with the boiler(s) ?

I'm wondering why run three pumps on an indirect call when you could run just one?
 
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Old 11-10-11, 03:49 AM
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I thought the same thing. However the superstor draws way too many BTUs to be piped otherwise.

I had the same scenario on my Biasi; yes you can pipe the return from the superstor direct into the boiler return and turn off the system pump on DHW call.

However, you are dumping return water that could have a large delta-t direct into the boiler with no way to regulate it.

I looked at the diagrams linked, they are one way to do it, but I have to say I like my diagram better There are diagrams out that match what I am doing. The downside is 3 pumps running for any call. The upside is fine regulation of return water temps.

EDIT: link to Siegenthaler article here.

Tim
 

Last edited by ItsTim; 11-10-11 at 04:00 AM. Reason: add link
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Old 11-10-11, 06:13 AM
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Originally Posted by ItsTim View Post
However, you are dumping return water that could have a large delta-t direct into the boiler with no way to regulate it.

Hello Tim.
I looked at the diagram on my big PC and monitor and can see it a little bit better.
However, it's beyond my limited understanding how the return temperatures are going to be controlled. .... ???

Peter
 
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Old 11-10-11, 03:19 PM
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Originally Posted by PeterNH View Post
Hello Tim.
I looked at the diagram on my big PC and monitor and can see it a little bit better.
However, it's beyond my limited understanding how the return temperatures are going to be controlled. .... ???

Peter
Sorry the image isn't bigger, it was really designed to be plotted. If you hold the "control" key and roll your mouse scroll wheel you can make it bigger.

The question of regulating return water temp is really the crux of this thread.

Return temp can be regulated in a few ways (I think): 1) delta-t on the system pump or 2) delta-t on the boiler pumps 3) setpoint in items 1 & 2

I don't think delta-p would work, but again I don't really grasp the whole pressure thing; I see how it is useful in a zone valve setup, but it's uses beyond that are foreign to me.

For example, delta-p on the system loop. Let's say the each zone has 5ft. of head. But then DHW priority kicks in, and now I need 10ft of head. Seems to me it would not work?

The Tekmar is not going to protect the boiler from cold return water temps. It will never try to maintain a temp below boiler min, but beyond that it will just fire the boiler trying to get the supply temp above boiler min.
 
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Old 11-10-11, 07:41 PM
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I totally hate the idea of tying multiple boilers in with their own set of closely spaced tees for a few reasons. If these would be mod/cons it would make absolutely no sense.
1. You are pre-heating the water from the first boiler going to the second boiler.
2. Reduces the efficiency of the second boiler.
3. You have better control of boilers with one attachment points.
The multiple boiler with their own primary tees has lost much popularity since the late nineties.
 
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Old 11-11-11, 04:18 AM
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Originally Posted by rbeck View Post
I totally hate the idea of tying multiple boilers in with their own set of closely spaced tees for a few reasons. If these would be mod/cons it would make absolutely no sense.
1. You are pre-heating the water from the first boiler going to the second boiler.
2. Reduces the efficiency of the second boiler.
3. You have better control of boilers with one attachment points.
The multiple boiler with their own primary tees has lost much popularity since the late nineties.
Agreed on #1. I've redesigned to go with figure 4 from the Sig article. I've also redesigned the indirect DHW so the primary circ doesn't have to run.

Not sure what is meant by "primary tees".

Thanks again for everybody's help. Many eyes help avoid problems.

EDIT: proposed redesign HERE (larger, hopefully easier to see)
 

Last edited by ItsTim; 11-11-11 at 04:34 AM.
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Old 11-11-11, 04:44 PM
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Tim, what's that box on the lower right of the loop, next to the superstor?

I'm a little confused as to why you are using the extra set of tees?

Why not just one big loop with the heating zones teed off of that?

Something about this isn't clicking with me... but it might just be a defective synapse.
 
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Old 11-11-11, 04:53 PM
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I might have partially answered my own question...

because there would be flow through both boilers all the time.

Is that the answer?

Here's what I was thinking, but I do see the problem with the boiler flow...

 

Last edited by NJT; 11-11-11 at 05:09 PM.
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Old 11-11-11, 05:13 PM
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Originally Posted by NJ Trooper View Post
Tim, what's that box on the lower right of the loop, next to the superstor?
LWCO, low water cut off


I'm a little confused as to why
you are using the extra set of tees?
I believe, it is an attempt to control the boiler return temperatures.
However, i don't see how it could work.
It's especially bad because the vast majority, not all, of Tekmar controls terribly ignore the problem.




Peter
 
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Old 11-11-11, 05:19 PM
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Originally Posted by NJ Trooper View Post
I might have partially answered my own question...

because there would be flow through both boilers all the time.

Is that the answer?
The box is a LWCO.. left over from an earlier design (it is now located on the boiler loop)

You are correct, you don't want water flowing through the boiler if it isn't firing.

The setup allows you to regulate flow through the boilers without having to worry about the system pump affecting flow.
 
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Old 11-11-11, 05:19 PM
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Originally Posted by NJ Trooper View Post
I might have partially answered my own question...

because there would be flow through both boilers all the time.

Is that the answer?

Here's what I was thinking, but I do see the problem with the boiler flow...
Not quite it Mr NJ Trooper.
He is going to use a staging control.

I see something like your neat drawing, but with flow checks and a pump for each boiler.
No primary pump.
Boiler protection is non existant, so i think it's not it.

Either some sort of injection pump setup with the correct control is needed for boiler protection.
Or.
Some set-up involving Taco iValves or Taco Set Point pumps for a on demand bypass.

But then there is a budget problem$$

Peter
 
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Old 11-11-11, 05:27 PM
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Originally Posted by PeterNH View Post
It's especially bad because the vast majority, not all, of Tekmar controls terribly ignore the problem.




Peter
I agree, which is what prompted the question regarding the 00 delta-t pumps.

Set up as it is now, the system pump can run (all hyoptheticals) at 15gpm with a 40 degree delta. Like you said, the Tekmar doesn't care, it is just going to keep firing boilers trying to reach that setpoint. The boilers are sized correctly, so it will hit that setpoint. Eventually.

With NJ's diagram, the boilers could be receiving <130 degree water for a long period of time. There is also no way to optimize flow through the boilers.

With the split system in layout 2, the boilers can have flow regulated through them individually by the circulator. The system pump can be running at 15gpm, but if the boiler pump is putting out 5gpm, the additional flow from the system circ will just be flowing between the closely spaced tees.

At least, I think so.
 
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Old 11-11-11, 05:42 PM
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Originally Posted by PeterNH View Post
I see something like your neat drawing, but with flow checks and a pump for each boiler.
No primary pump.
Boiler protection is non existant, so i think it's not it.

Either some sort of injection pump setup with the correct control is needed for boiler protection.
Or.
Some set-up involving Taco iValves or Taco Set Point pumps for a on demand bypass.

But then there is a budget problem$$

Peter
I believe the protection in layout 2 is the separation of loops. The flow through the boiler loop will be the sum of the boiler circulators and would not change with the number of zones firing (or the huge dhw flow). Basically it's using that boiler loop as the bypass instead of the typical tee between supply and return.

One idea might be to use a setpoint circ at each boiler, set it for 130 and have speed increase as temperature increases.

Or, use a delta-t set for 20 degrees.

I've never used either type, so maybe one of you can give me some insight.
 
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Old 11-11-11, 06:13 PM
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Originally Posted by ItsTim View Post
I believe the protection in layout 2 is the separation of loops. The flow through the boiler loop will be the sum of the boiler circulators and would not change with the number of zones firing (or the huge dhw flow). Basically it's using that boiler loop as the bypass instead of the typical tee between supply and return.
.
IMO it would not work that way.
The 4 zone pumpos turn on all at once. A ton of icy cold water will flow thru the return of the primary loop. This icy cold water will get pulled into the boiler loop(s), thus chilling out the boilers.
I see nothing that will stop this from happening.


Delta T pumps on the boilers will maintain the delta T but will have no way to stop the delta from being as cold 100<>80 or lower/higher. They will just maintain the delta, as is their purpose.

Set point on the boiler - i can't see how this would limit the cold return also. It might slow down enough so that water coming in at 80 degrees might leave at 130, but that's not a desired state of affairs as far as the boilers go.


Set point on the primary pump - that slow down to a crawl on a cold return - maybe, but of all the drawing of applications i've looked at, i've never seen one used this way.

Peter
 
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Old 11-11-11, 06:30 PM
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Yeah, I know that drawing was wrong as soon as I sketched it out, but I threw it out for discussion anyway...

the boilers could be receiving <130 degree water for a long period of time.
You said two zones of cast iron... so yeah, there might be some cool return time there.

If it were all fin tube I wouldn't even worry about boiler protection.

I'm thinking that I would move the indirect to before the CSTs...

I really don't think you need to worry about boiler protection with an indirect.
 
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Old 11-11-11, 06:35 PM
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I believe the protection in layout 2 is the separation of loops. The flow through the boiler loop will be the sum of the boiler circulators and would not change with the number of zones firing (or the huge dhw flow). Basically it's using that boiler loop as the bypass instead of the typical tee between supply and return.
Depends on how much flow is in each loop. If the system side is flowing more than the boiler side, then there will be no 'mixing' at the tees of the hot boiler supply and cool return from the system. I think this is the point that Peter is trying to make:

The 4 zone pumpos turn on all at once. A ton of icy cold water will flow thru the return of the primary loop. This icy cold water will get pulled into the boiler loop(s), thus chilling out the boilers.
(or the huge dhw flow)
DHW will be priority? non?
 
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Old 11-11-11, 07:02 PM
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Neat idea with the pressure gauges fore and aft of the wye strainer...
 
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Old 11-12-11, 04:19 AM
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Originally Posted by NJ Trooper View Post
Depends on how much flow is in each loop. If the system side is flowing more than the boiler side, then there will be no 'mixing' at the tees of the hot boiler supply and cool return from the system. I think this is the point that Peter is trying to make:





DHW will be priority? non?
I see what you're saying, and hadn't thought of it that way. However, the flow through the boiler is regulated by the circulator at each boiler.

So, let's say the water returns at 110 degrees. If the circulator at the boiler keeps the flow at (hypothetical) 5gpm versus the 15gpm of the system circulator, the boiler will maintain temperature, stack temp will remain above condensing.

The issue of shock remains. However, it is the same issue with all of the designs. I think the only way to address it is with some of the solutions Peter suggested, no matter what the piping loos like.

With the boiler being sized properly, this really shouldn't be an issue, as there should be sufficient btus to keep the primary loop toasty. Condensing at startup due to prolonged periods of cold return water keeping the boiler stack temp down is definitely an issue.

Sounds like a setpoint circ at the boiler could be an option.

EDIT: Peter I agree with the Delta-T; I don't think it's suited for this application. Setpoint would take the guesswork out of the flow of the boiler circulators.
 
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Old 11-12-11, 04:25 AM
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Originally Posted by NJ Trooper View Post
Neat idea with the pressure gauges fore and aft of the wye strainer...
Thanks, I am looking to install THIS to let me know when the strainer should be cleaned.

It comes in different graduations, I think 7.5psi difference should be time to clean?
 
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Old 11-12-11, 08:32 AM
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Hello Tim,
I found a few drawing that might help.
Kinda busy today, so i'll try and get them posted as soon as possible.

Peter
 
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Old 11-12-11, 02:53 PM
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These are very simplified, but illustrate why you can't really rely on P/S for boiler protection.

This one with the system loop flowing more than the boiler loop.



This one the reverse.

 
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Old 11-12-11, 04:16 PM
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Originally Posted by NJ Trooper View Post
These are very simplified, but illustrate why you can't really rely on P/S for boiler protection.
Thanks for taking the time to post those.

The first one wherein system flow is greater than boiler flow is what I was looking to do. In your diagram the radiators are not piped secondary, so all water will be returned at a lower temperature. In my diagram the emitters are secondary.

With the emitters piped secondary, if the system pump is at 10gpm and the flow to the emitters in 5gpm, there is 5gpm of hot water that is recirculated through the system loop. In my head it seems like a round-about way of providing some protection.

The way I think it would work is:

-the system pump provides the protection from cold return temps
-the boiler pump protects the boiler from condensing

Of course, I occasionally see pink elephants and flying pigs.

Tim
 
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Old 11-12-11, 05:43 PM
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Originally Posted by ItsTim View Post
With the emitters piped secondary, if the system pump is at 10gpm and the flow to the emitters in 5gpm, there is 5gpm of hot water that is recirculated through the system loop. In my head it seems like a round-about way of providing some protection.

The way I think it would work is:

-the system pump provides the protection from cold return temps
-the boiler pump protects the boiler from condensing

Of course, I occasionally see pink elephants and flying pigs.

Tim
Hello Tim,
Afraid they are flying.
This method is no diferent than plumbing in a fixed bypass.

As far as i can see there are two options:

When using Tekmar controls, if boiler protection is needed, then two Tekmar controls are needed. Gets $$$$ quickly.

The other way would be to use either a Taco variable speed setpoint pump plumbed to provide protection, or a 2,3, or 4 way Taco valve to do the same thing.
From what i understand, the pump method usually costs less.
The Taco would just provide protection and the Tekmar control you want to use would do the outdoor reset and staging.

Please read these two articles, to help understad my scratchings.:


Thermal Curve Balls - Archives - PMEngineer



How Low Can You Go? - Column - Plumbing and Mechanical



Peter
 
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Old 11-12-11, 05:53 PM
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Hello Tim,
Here is another great article on the subject:

Thermal Clutches<br>John Siegenthaler, PE - Column - Plumbing and Mechanical

Peter
 
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Old 11-12-11, 06:41 PM
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Originally Posted by PeterNH View Post
Hello Tim,
Here is another great article on the subject:


Peter
Thanks, Peter. I find "Thermal Curve Balls" as the easiest for me to understand.
 
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Old 11-13-11, 09:48 AM
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I think what I have will work, let me know what you guys see:

Layout

My question is.. what happens when the flow of the zone circulators exceed that of the system circulator.
 
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Old 11-13-11, 09:58 AM
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Tim, how do you know that the boiler pumps will pump 5 GPM?

Are they 50K BTU boilers?
 
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Old 11-13-11, 10:00 AM
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what happens when the flow of the zone circulators exceed that of the system circulator.
Recirculation, just like in the diagrams I posted.
 
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Old 11-13-11, 10:36 AM
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I'm uncomortable with the whole concept... not because I have a better idea, it just doesn't 'feel' right to me...

Does this article change anything? Hydraulic Separator, yes, but P/S tees can be thought of in the same way.

Overkill - The Glitch and The Fix - Radiant and Hydronics
 
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Old 11-13-11, 10:39 AM
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Originally Posted by NJ Trooper View Post
Recirculation, just like in the diagrams I posted.
Re: pump size. Was just for exercise, I took the numbers 10 and 8 from your diagram to create a parallel.

The diagrams you posted are similar, but they differ in that in my setup the emitters are secondary off the primary loop.

However, you are correct. For example, system pump is operating at 1GPM. Zone 1 calls for heat at 5GPM. The return water from zone 1 will flow backwards through the closely spaced tees (opposite the system pumping direction) at a rate of 4GPM. 1GPM of the return flow will continue on to the next set of closely spaced tees.

I find the whole thing pretty interesting. Got the ol' brain cells firing.
 
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Old 11-13-11, 10:43 AM
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Originally Posted by NJ Trooper View Post
I'm uncomortable with the whole concept... not because I have a better idea, it just doesn't 'feel' right to me...
I share the sentiment. Reading that article now..

EDIT: read the article; makes sense. Seems like my diagram will work (eg "overkill"), but the way depicted is a much better solution.
 
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