Multiple hydronic questions


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Old 11-07-08, 05:37 PM
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Multiple hydronic questions

I have a few hydronic questions, and I am hoping that someone could assist me with them. My boiler system was installed in 2004 and I would like to modify the piping arrangement because I think it is incorrect, so I am seeking to find assistance from this group.

This first image is a photo of my existing boiler system as it is at this moment.

Note: Ball valves on supply and return piping were closed temporarily and at this time of writing are open and have remained open from the date on the photo.

Here is a piping schematic of my system, which resembles the actual installation.


Here is the legend for the schematic:


My first concern is the location of the expansion tank and the air separator. Is it ok that it is on the hot water return into the boiler or should it me relocated?

The installation manual for the Weil Mclain GV-6 shows the expansion tank and air separator on the hot water supply to the system circulators when the boilers’ internal circulator is not used for system circulating.
Here is the image from boiler installation manual showing this:


Another concern of mine is the placement of the circulator pump separate from the others. This circulator is for the indirect hot water heater, which is an Amtrol Boliermate, and was plumbed on the boiler hot water return. According to the Amtrol installation manual this seems to be incorrect, shouldn’t it be plumbed to the supply side?
Here is the excerpt from the indirect hot water heater installation manual:


A third concern is my system is not piped using close proximity tees, but the installer did pipe the supply and returns together with elbows and I think this was the installers’ way of taking the place of the close proximity tees (from the photo).

I have read multiple strings and forums, as well as papers by John Siegenthaler, P.E. and tried to understand the reason for placing close proximity tees on a systems supply and return and I am still confused, so any help here would be greatly appreciated. Should I incorporate close proximity tees into my piping, and if so where would be the best place to locate them (from the photo)?

All my zone circulators are Taco 007-IFC. These were installed because they have the built in check valves. I am not so thrilled with them, so I am considering keeping the pumps and installing additional valves, either swing check valves or the B&G Hydrotrol™ Flow Control Valves.

Why is it that check valves are always shown after the discharge of the pump and never shown before the suction intake of the pump? Doesn’t the pump have to pushing against the valve causing friction loss?

I was thinking that I would place a swing check valve on the discharge side of each of the pumps.

On the manifold where the system return lines enter, I was thinking to place a single Hydrotrol™ Flow Control Valve or a Taco Flo-Control valve at the return line. (which one) and would this be effective in preventing overheating and gravity circulation in the all of the zones or would I need to have Flow control valves on all of the return lines?

Should there be a Hydrotrol™ Flow Control Valve, swing check valve or a Taco Flo-Control valve on the return line of the Boilermate?

The system in effect has not failed yet, but I know that it may not be as efficient as it should be, and I would very much like it to be. Any suggestions would be helpful. I will post proposed piping schematics after suggestions from the forum.
 

Last edited by Skyslmt; 11-07-08 at 07:28 PM.
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Old 11-08-08, 05:54 AM
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Some thoughts.

If you want to pipe this primary/secondary with closely-spaced tees, a very simple, clean installation can look like this:

http://www.htproducts.com/literature/lp-185.pdf

If you want to zone with valves, use figure 2A. If circulators, use figure 2C.

Note that is for a modulating/condensing boiler, but the principles are exactly the same.

You can use a number of strategies for the primary/secondary, including simple on/off, mixing valve, or injection mixing. Good tech articles are available here:

tekmar Essays

in the tech essays section.

For mixing valve and injection mixing options, you will need a control. The tekmar 361 would be a fine choice for the latter.

What don't you like about the 007IFCs?

[OK, now I see that this boiler has two internal circs. If they can be used to modulate supply temperatures, then you may not need the whole p/s thing. Get a control like a tekmar 260. Pipe like the GV manual, and go.
 
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Old 11-08-08, 08:39 AM
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Looking at the pic of the system as installed, it makes me wonder if the installer wasn't somewhat 'confused' by the piping diagrams ...

What is the purpose of the loop with the ball valves on the supply and return?

I believe it may have been a misunderstanding ...

I _think_ that all you need to do is remove the two elbows where the supply and return meets the wall and goes left/right, put two tees in at that point, and create your CST point right there. Then get rid of that silly 'loop' ... You could move the exp tank to the supply side... but if it's working, why bother?

I wouldn't be too concerned that the indirect pump is on the other side ... it's working, right?

I'd also like to know why you don't like the IFC's ?

Why such a humongous expansion tank ? If that's only three zones of 3/4" fin tube... you could get by with a 30 size instead of that 90 that's on there !
 
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Old 11-08-08, 08:53 AM
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tried to understand the reason for placing close proximity tees on a systems supply and return and I am still confused
CSTs provide a method of hydraulically isolating two separate flows.

You can maintain two different flow rates, and two different temperatures in two separate, but inter-connected 'loop' of pipe.

Let's say you want to do ODR with a conventional boiler, you can control the flow and temperature in the SYSTEM differently than on the BOILER, and INJECT just the heat you need across a 'bridge'.

With your boiler, the flow in the boiler would be controlled by the internal circulator... and the flow in the system would be controlled by the zone circs. The HOT boiler supply would be mixed with the system water at the point of the CSTs ... The second circ in your boiler is a pumped bypass that protects the boiler from cool return water.

I didn't look real close at the install manual, but doesn't W-M have an ODR control that is a plug and play for that boiler ? or is that control 'standard' equipment ?
 
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Old 11-08-08, 08:22 PM
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Nevermind that stuff I said above. It's wrong. I read through the GV manual....

This boiler's got a lot going on. Variable speed system circ and a pumped bypass. You'd think that would cover everything, but it was surprising to see they want closely-spaced tees, additional bypasses, and other stuff depending on application. Yeesh.

This is the manual I read. That it?

http://www.weil-mclain.com/downloads...ilermanual.pdf

I would pipe this like figure 14a or 14b. Use a tekmar 360 and a motorized tekmar mixing valve where the GV manual notes "10."

Pipe the indirect off the supply/return before the closely-spaced tees.

Follow the application guide for the tekmar 360 that matches how you want the system to work with the GV.

http://tekmarcontrols.com/literature/acrobat/a360.pdf
 
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Old 11-10-08, 11:43 AM
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I appreciate the comments NJ Trooper and Xiphias.

The reason for the two ball valves at the supply and return where it is looped together is because this was originally isolated and capped for a future unit heater. After I told the installer that the system needed to have the tees installed per the install manual, I believe that the installer thought that connecting these together would be sufficient.

When you say ODR, is this outdoor reset? Do not believe that Weil Mclain has this built in.

I think I grasp the purpose of the close proximity tees now more so. Actually it reinforces what I already assumed.

I am not quite sure as far as the indirect pump is concerned. According to the manual it should be located on the supply side, which to me makes sense that the pump isnít pulling water through the coils, and I assume that the pump with IFC controls any cycling water from entering the zone, when domestic water is not being called for. So, as it is on the return side, the Amtrol is overheating and I get the ER2, which according to the manual is because the CP is not installed on the supply.

The reason for the large expansion tank is that I plan on doing an addition to the house and I may add an additional floor. So, I thought it might be worthwhile to have the expandable system.

As far as the IFCís, I am not convinced that they do what their supposed to do. When the pump isnít on, flows are getting through the CP and heating the zones. So, I think I would be better off with additional check valves. As far as what checks to install, I would like some input there.

Will post a new schematic after receiving comments on check valves. Again I appreciate the thoughts.
 
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Old 11-10-08, 02:28 PM
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Put the indirect circulator on the supply side.

I have two 007IFCs and they do not allow any flow past them when not running. Just FWIW.

Use spring checks if you are going to ditch the IFCs.

B&G makes a 'checktrol' that is in a flange. Taco makes 'flo-chek's that are a separate unit. Both work.
 
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Old 11-10-08, 04:08 PM
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I agree to move the pump to the supply side, but somehow I just don't believe that the pump being on the other side is the cause of the ER2 ...

What _might_ be happening is that the internal boiler circulator is causing the flow in the indirect. And, if it is, it will do the same thing with the pump on either supply or return. When that boiler circ is running, I believe it could very easily pump right through the indirect ...

I didn't notice if the WM manual showed any recommended indirect piping, did it ?

I think the first thing to do is remove those two elbows, and connect together there, with tees ... leave those valves on the 'coat rack' closed. Then, evaluate ... don't change the indirect just yet, you may not need to ...

Once the CSTs are in place, you could probably pipe the indirect off the SUPPLY line from the boiler to the CSTs with another set of CSTs ...

Yes, ODR = OutDoor Reset
 
 

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