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Questions on a new install design

04090
04090 Member Posts: 142
I inadvertently cut/pasted into this post and the original content is lost, so some of the comments below may not make sense anymore.  Thanks to help on this board, the system was reconfigured a bit to work better.  Still have two concerns which I'll ask here:



1)  The boiler seems to be on as long as the thermostat calls for heat.  In the 92 hours it's run, it's done 1219 cycles (one evey 4.5 minutes).  The differential is set to 20.  When the boiler reaches it's desired temperature of, say, 160, the thermometer at the supply elbow reads 10 degrees cooler at 150 and the Delta t is 20 making the return water 130 so the boiler quickly starts up again as the signal to start the cycle again happens at 140.  Is that typical?

  



2)  The manual calls for 12psi.   The pressure is at 20psi cold, 25 hot.  This might be why it's high...  the expansion tank is on a dead end horizontal stub before the air vent, perhaps air locked and the sides are cool to the touch. The pressure regulator is on the return side.  The instruction manual shows the pressure regulator feeding fresh water into the area of the expansion tank, and the expansion tank is under the air vent.  If the plumbing was done by the book, would the pressure be lower and should it be redone that way?

  

Is any of this worthy of concern?  Or should we just enjoy it and chalk up worries to the learning curve of new technology?

 

Thanks again. 

Comments

  • CMadatMe
    CMadatMe Member Posts: 3,086
    In a Nutshell

    First off let me compliment you on the nice craftsmenship. Secondly please read this article and then share with us the anwser to your own question.



    http://www.pmmag.com/Articles/Column/BNP_GUID_9-5-2006_A_10000000000000657694
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • 04090
    04090 Member Posts: 142
    response

    Well, OK it looks most like Figure 2 except the air eliminator is on the other end of the system.  Figure 2 is described as less commonly used and benefiting by having the expansion tank remain on the cooler side and describes properly working hydraulical pressures.



    That's an interesting article.



    So all's well? 
  • Henry
    Henry Member Posts: 995
    Circulators

    I don't like the way the circulators are connected. Common practice is 5 dimensions of straight pump before and 3 after. We have standardised 5 and 5 on all are smaller installs. On the large pumps, we use suction guides.
  • Ironman
    Ironman Member Posts: 6,868
    Missing the Point

    The point of no pressure change (PONPC) that is. By having the circs on the return and the expansion tank on the supply, you're pumping toward the PONPC; you should be "pumping away" from the PONPC. In other words, the circs should be on the supply, downstream from the expansion tank.



    Nice workmanship.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • 04090
    04090 Member Posts: 142
    edited November 2011
    Changes

    The installer agreed to move the pumps from the return to the supply side, insistent that it made no difference in a system this size.



    Does it matter as much on a small system as a large one?
  • Ironman
    Ironman Member Posts: 6,868
    Does it Make a Difference?

    As I said earlier, the workmanship is excellent and I believe from that your installer takes pride in his work and wants to do the job right. However, he may be like a lot of good pro's who are not as up to date on hydronic design and theory as they could be.



    For years, American boiler manufacturers shipped their boilers with the circ. mounted on the return. They did this not because it was hydronically correct, but because the shipping department found that it made packaging easier. The engineering department knew better, but cutting $$$ prevailed. Since the boilers came with the circ. on the return, the tradesmen assumed that was where it should go, not realizing the shipping department made that call to keep packaging as small as possible. Hence, the error continues to perpetuate itself.



    It appears that your installer could have just as easily mounted the circs. on the supply as the return. He probably chose the return because that's the way he normally does it based on what I stated above. I'm sure he thought that was the correct way to do it until you challenged it based on the info you got here. His response may have been more of a knee jerk reaction (human nature), but it shows well for him that he's willing to re-do the circs to the supply.



    Would it hurt anything to leave them on the return? Maybe not. There are tens of thousands of boilers with them like that. But it certainly makes the circs. work harder, uses more current, makes cavitation more likely, as well as the other issues that Siggy pointed out in his article.



    Does it only matter on larger systems? Since your installer made that claim, it would be up to him to substantiate it.



    As a side note, let me make a helpful suggestion: since he's willing to change the circs. at his cost, which is substantial, why not get him Siggy's book on "Modern Hydronic Systems" as a "thank you" gift. He'll be a better technician from it and you'll get even better service as will everyone else who uses him. It's available from this site:



    http://www.heatinghelp.com/categories/Hot-Water-Heating-Books/26/1
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • 04090
    04090 Member Posts: 142
    edited December 2011
    Moving forward

    The pumps were relocated from the return to the supply, but it's still not plumbed according to Burnham manual. There are no valves before the circulators, the are no flow checks on the return lines, and there a few missing unions and a purge valve, the cold water supply is connected to the return instead of the expansion tank.  Henry posts the circulators may be too close together. Is any of that critical?



    The electrician left without connecting the post purge because he didn't know how to wire it, said he'd look into it and be back.   With a single zone, the yellow and white wires in the boilers teminal box lead to the circulator and all's well.  With two circulators and a 504EXP, if the boilers leads went to either circulator that circulator would be on regardless of which zone was calling for heat.  How should it be wired with a two zone boiler and a 504EXP?



    Sure wish the contractor simply plumbed it according to the installation manual in the first place.



    Thanks.
  • Henry
    Henry Member Posts: 995
    Circulators etc.

    The spirovent will cause turbulence. The pumps will most probably cavitate with hot water as there is insufficient straight piping before which is most critical plus the turbulance caused by the spirovent. The hotter the water, the more cavitation! The lack of valves before the pumps will make servicing more expensive. We redid a similar install by another shop last year that ended up in court. Our client won after we did the corrections for him.



    The pumps shouild be controlled by relays actuated by the zone thermostats.
  • Ironman
    Ironman Member Posts: 6,868
    Other Issues

    1. You don't need flow checks on the returns, you have them on the supplies above the circs.

    2. Connecting the make up to the return is not an issue as long as someone doesn't manually open the bypass and dump cold water into the boiler when it's hot. Even then, it would take a major slug of cold to shock the boiler.

    3. The Spirovent does cause some turbulence inside itself, but it also reduces the velocity so I don't see this as a major issue. Someone might be able to correct me, though; I'm teachable.

    4. I don't think the installer could have gotten any longer nipples on the inlet or outlet of the circs. unless he shortened the supply riser coming up from the boiler. Then there may not have been enough room to mount the expansion tank. He did have very limitted space to work in.

    5. It would have been nice to have valves on the inlet side of the circs. (you've got them on the outlet side), but that is not a requirement. If you ever have to change a circ., that would be a good time to put isolation flanges on the inlet side of the circs.



    I'm not quite sure about what you're asking regarding the wiring of the circs., but they should be controlled by the Taco panel. I don't see any simple way to make the post purge feature of the boiler signal the panel to hold the pumps on. It could be done with more relays, but may not be worth the trouble or expense. Have the electrician check the I&O manual to see if there's a diagram.



    As I stated previously, your installer's workmanship is excellent and you should be thankful for the job he's done and his willingness to correct the pump location at his own expense. I'd recommend that you maintain a good relationship with him.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • 04090
    04090 Member Posts: 142
    Always one more thing

    The contractor was actually quite pleasant switching it around, and we're talking about future projects.  All's well there.  I appreciate your tying up some loose ends, and can pass along the compliments on excellent workmanship.



    We'll live with the system for awhile and see how it works.  I suspect it'll be fine, but will keep an eye our for cavitation.  Valves on the inlet side of the circulators would have been preferable, but it'll be easy enough for someone to just drain some water through the pressure relief valve which is just downstream.  Hopefully, that won't be necessary for a very long time.



    I'm being told that the pump over run setting (powers the circulators xx minuutes after the call for heat ends to dissipate the heat within the boiler) benefit from the Burnham ODR control only works with a single pump system.  There should be some way to design it such that the circulator that was in use would run a few minutes after the call for heat ends; it's only basic electicrial circuitry.  And it would be good if they'd indicate in the literature that the feature is not available with multiple zones, but so be it.  Are other ODR's designed the same way?



    For those unfamiliar with it, the terminal box within the boiler has leads that power the circulator.  Great with only one circulator, but when there are two circulators that lead is not able to provide post cycle power to the zone that called for heat.  Utilizing the heat stored within the cast iron boiler by circulating the water a tad longer after the thermostat call for heat ends sounds like a good thing to do.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Post purge

    There was a question previously on how to set up post purge with the Taco controller and multiple circulators. It seems that a plug in card is available for the controller to accomplish the function:



    http://flopro.taco-hvac.com/products/PC600%20Series%20PowerPort%20Cards/index.html?category=146



    Here is a link to the whole discussion:



    http://www.heatinghelp.com/forum-thread/138422/Will-an-old-Intelledyne-HW-work-well-with-a-new-Burnham-ESC
  • 04090
    04090 Member Posts: 142
    edited November 2011
    Maybe?

    The Burnham manual reads:   post purge... continues pump operation after a call for heat has ended, sending excess heat from the boiler into the priority zone. Ensure system piping and zone panel settings allow water flow to the priority zone after the call for heat ends.



    The Taco PC600 manual reads:  The solid-state Taco Post Purge Plug-In Card maintains power to the circulator once the priority zone is satisfied.



    There is no priority zone in the setup we have.  Both devices above would power a designated circulator (our choice, zone 1 or zone 2 depending on how it's wired) regardless of which thermostat zone is calling for heat.  In other words, if zone 2 is calling for heat and the designated priority zone is zone 1, the pump for zone 1 would be running all the time heat is called for in zone 2, and when satisfied then zone 1 would run it's post-purge cycle. 



    There really isn't a priority zone, so the card wouldn't function right in this circumstance.  Please correct me if I'm misunderstanding the function of a priority zone.



    I'm thinking a common relay, receiving a signal from the 504, properly wired could power itself from the boiler connection and maintain the power until the boiler told it to shut off, and that run time would include the post purge.  But that's also messing with the electronics which carry a manufacturer and installers warranty, so I'd hesitate to do that until they expired.
  • Mike Kusiak_2
    Mike Kusiak_2 Member Posts: 604
    Priority zone

    The SR-504 exp designates zone 4 as its priority zone. When set for priority, activating this zone will inhibit operation of the other 3 zones until the priority zone is satisfied and its call for heat ends. This comes in handy for something like an indirect water heater which may require higher temperature water than the heating zones. Putting the indirect on zone 4 will prevent the heating circulators from operating until the indirect is satisfied. If the post purge card is installed, the boiler would then dump its residual heat into the indirect before responding to any call for heat from the heating zones.



    If the priority feature is not enabled, then zone 4 acts independently, the same as the other three zones. I believe the post purge card is only associated with zone 4, so the post purge can only be used with the circulator connected to it. Whatever circulator connected to the zone 4 output can post purge, the others cannot. It would make sense to connect the largest zone to the zone 4 output, so the residual heat will not cause excessive overshoot in room temperature.



    At least that's how I understand it. Perhaps Chris can correct me if I am wrong and explain more fully as he has extensive experience in using the post purge card.
  • AFred
    AFred Member Posts: 81
    Post purge

    I think you might be overthinking it, the post purge feature is a wast of time in my opinion. You don't have standby loss like you would with a natural draft boiler.

    Turn your t-stat up and enjoy!

    2 cents

    -Andrew

    PS: damn nice install!
  • 04090
    04090 Member Posts: 142
    edited December 2011
    OK, I'm learning....

    We've enjoyed the benefits of a deep night setback and a monster boiler to recover from it without any problem.  The heat came on at 6AM, and the place was toasty at 7AM.  But the new boiler, with the ODR limiting the temperature and boosting it every 20 minutes as needed, struggles to catch up to satisfy the thermostat.  Would it be a good idea to set up a dedicated thermostat which would essentially only tell the ODR, via it's aquastat connection at teminals 3 and 4, to run at it's maximum setting of 180 between 6AM and 7AM?  Or should we run the heat at a higher level overnight... or in a nutshell what's the most efficient way of running this?



    Added:  Am making progress on this.  Seeking a happy medium between the thermostat's feature of learning when to start the system after a setback (instead of using a set time) and having less of a night setback.  Although it seems less of a night setback, as suggested here, will prevail.
  • 04090
    04090 Member Posts: 142
    edited December 2011
    To be expected?

    Some concerns about a new system...  should these be addressed or forgotten about? 

    1)  The boiler seems to be on as long as the thermostat calls for heat.  In the 92 hours it's run, it's done 1219 cycles (one evey 4.5 minutes).  The differential is set to 20.  When the boiler reaches it's desired temperature of, say, 160, the thermometer at the supply elbow reads 10 degrees cooler at 150 and the Delta t is 20 making the return water 130 so the boiler quickly starts up again as the signal to start the cycle again happens at 140.  Is that typical?

      



    2)  The manual calls for 12psi.   The pressure is at 20psi cold, 25 hot.  This might be why it's high...  the expansion tank is on a dead end horizontal stub before the air vent, perhaps air locked and the sides are cool to the touch. The pressure regulator is on the return side.  The instruction manual shows the pressure regulator feeding fresh water into the area of the expansion tank, and the expansion tank is under the air vent.  If the plumbing was done by the book, would the pressure be lower and should it be redone that way?

      

    Is any of this worthy of concern?  Or should we just enjoy it and chalk up worries to the learning curve of new technology?

     

    Thanks again. 
This discussion has been closed.