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Hydronic hiccups

raging_rapids
raging_rapids Member Posts: 1
edited March 2021 in THE MAIN WALL
I’ll try to keep it short...

The beginning:
I had a circulating pump replaced last November and 3 days later we started hearing what we describe as a waterfall going through all the upper 2 zones of our two story home. 

Equipment:
- It is a gas boiler and HWT. 5 zones and baseboard heaters through 4500 sqft
- new Grundfos UPS26-99FC which was just replacing the noisy one (like for like model)

Tries and fixes:
- after system is purged and re-pressurized the noise goes away for approx 2-3 days. 
- had 4 auto vents installed thinking air would escape, doesn’t help
- have had the expansion tank re-pressurized but still comes back after a few days. 
- tried all three speeds on new pump to account for air bubbles forming. 

Observations:
- when heat kicks in the upstairs zones you immediately hear the water rushing around to all the baseboard heaters. I can follow the sounds through the living area. 
- lasts for about 1-2min and then ends with what I would consider a slight water hammer at the furthest point from the boiler (ensuite bathroom)
- The pressure does drop slightly but not more than a few PSI on boiler. 
- Boiler is in basement, there is no issue with heat as it is getting water to the baseboard heaters in 2 zones in basement as well as 1 zone on main floor. 

I have full confidence in our plumbing contractor but I feel even he is stumped. (If your watching, this is only a cry for help)

Conclusion:
Prior to the circulating pump being installed we’ve never in the 6 years of owning this 20 year old home have we had this issue. The reason why we had the pump installed was to eliminate the noise it was creating and resonating through the pipes. Is there a chance there’s an issue with the new pump? It’s the only thing that has changed. We’ve been assured the boiler is in good working condition and is regularly maintained by our plumber. 

Your suggestions will be greatly appreciated.
Alan Welch

Comments

  • HomerJSmith
    HomerJSmith Member Posts: 2,426
    edited March 2021
    Are you saying that the old pump was making the noise and that's why the old pump was replaced and now the new pump is making the noise too?

    "The reason why we had the pump installed was to eliminate the noise it was creating and resonating through the pipes."???

    The second floor is probably the longest run in the house. Pic of your boiler sys would help. I am especially interested in the expansion tank and its connection to the sys. What does the boiler gauge say is the pressure and temp when it is running and when it is cold?
  • Danny Scully
    Danny Scully Member Posts: 1,416
    If your losing pressure and air continues to appear, it sounds like you have a leak. Additional evidence of this points to it being the upper floors. The leak could be so minimal that you’re not noticing it visually. I would pursue that route. 
  • Robert_25
    Robert_25 Member Posts: 527
    Sounds to me like your circulator is oversized, and there is still air in the system.

    I think it would be worthwhile to do a little math and see if you really need a 26-99.
    HomerJSmith
  • Derheatmeister
    Derheatmeister Member Posts: 1,524
    Sounds like a Leak /oxygen ingress somehow ..Pictures of the mechanical room would help.
  • raging_rapids
    raging_rapids Member Posts: 1
    HomerJ: the old pumps impeller was worn and could hear it through the pipes. Hence its replacement. The new noise is the sound of rushing water as it passes through the radiators. 

    Robert: the pump was the same model and brand that it was replacing and never had this issue until the new one was installed. 

    Those who say it’s leak: pardon my ignorance. But when you say leak, does that mean, somewhere in my house, water is dripping through the walls? Wouldn’t I see signs somewhere? How do you find it without ripping out the drywall?

    thank you to all who have replied, the boiler room photos I have are attached. I cannot take photos of recent pressure gauge as my basement is tenanted. 


  • Dave H_2
    Dave H_2 Member Posts: 550
    A circulator shouldn't "wear out" in five years. These have a lifespan of at least 18 years. I am going on a limb to say it is oversized, and the motor shouldn't point upwards. For a long life, the motor should always be on the horizontal plane.

    There is Math to be performed to find the correct size.

    I hope that helps
    Dave H
    HomerJSmithkcopp
  • raging_rapids
    raging_rapids Member Posts: 1
    Thanks, you’re right. This is the second time in 10 years it has been replaced as I’ve been told. Unfortunately I inherited someone else’s faulty design. 

    But it still begs the question, why is there air getting in. 
  • HomerJSmith
    HomerJSmith Member Posts: 2,426
    edited March 2021
    What part of the impeller on the old pump was bad? If the impeller was chewed away at the outer edges, that would indicate cavitation. If the pump was mounted as shown in your pic and mentioned by Dave H_2, the upper bearing could run dry. That pump should be mounted in a horizontal position. You could unscrew that silver plug on the rear of the motor until you see water coming out. That plug is where the rear bearing is which is lubricated by the water.

    We normally want at least 10 pipe diameters of straight pipe before the intake into the pump. That's 10-12", and I like 5 pipe diameters on the output of the pump before a change in direction. Coming from a 90 deg fitting so close to the intake of the pump may create cavitation. Cavitation can be noisy.

    The fixed speed pump that powerful is not the best choice for a sys with zone valves unless there is a differential bypass valve installed. A better choice, I would think, is an ECM pump which would reduce its speed as the zone valves close, one by one.

    What do you mean "AutoVents" installed, on the base board? Coin vents? Why I was interested in the expansion tank was whether you were pumping into the expansion tank. Pumping into the expansion tank could create negative pressure at the top of that run which could pull air into the sys.

    That auto vent in the 90 deg fitting before the intake in to the pump could be pulling air into the sys. You might want to close it off and see if that helps. If you want to vent the boiler a coin vent would be a better choice in that location that you can close off. If that is a replacement for an air scoop or a micro scrubber, that ain't gonna work. You need to remove the air from the sys, so you need something that is designed to do that. I didn't see that in your pics. You may need something like below:

    https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Caleffi-546116A-Brochure.pdf

    Your pic are too close, how about pics from further away.





  • raging_rapids
    raging_rapids Member Posts: 1
    Yes I was lead to believe cavitation was the issue but was also told the bearing was warn after inspection. 

    The auto vents were installed on the 90’s on 4 of my upper radiators. They were installed to release any air but if hasn’t helped.

    re: pics. I don’t have 24/7 access to the boiler without asking our tenants. I will see if I have older ones. 

    I don’t believe we are pumping into the expansion tank. Again, for 20 years the system ran fine as is prior to this new pump installed. 
  • HomerJSmith
    HomerJSmith Member Posts: 2,426
    edited March 2021
    Change the pump position to horizontal position. Install a mico scubber and replace that auto vent on the intake to the pump with a coin vent that you can close off or plug the 90.

    What is the auto vents model that you installed on the 4 baseboards?

    Hydronic folks would never install a pump in that position. It's something a plumber would do. I'm not disrespecting plumbers as there are many good ones, but I have seen this so many times.
  • Derheatmeister
    Derheatmeister Member Posts: 1,524
    edited March 2021

    Thanks, you’re right. This is the second time in 10 years it has been replaced as I’ve been told. Unfortunately I inherited someone else’s faulty design. 


    But it still begs the question, why is there air getting in. 
    As others have mentioned the Circulator should be rotated to have the shaft in the horizontal position...This system looks to be a Mess/Collaboration of some "Handyman's" work.
    External corrosion on Piping indicates leaks in the past/Present? Birdsnest wiring,Power outlets on top of the boiler with the Wire close to the exhaust,Wires not restrained,Code violations everywhere..
    I know it is not your Circus.... but you own it now..

    I understand that the system worked fine until the circ was changed, hard to tell from the pictures because they hurt my eyes.
    I am just going to throw this out there...
    Can it be that the direction that is circulator was installed in was reversed during the change out?
    Pumping into the boiler vs. away ?
    This would change all of the fluid dynamics and can cause air to be Sucked into the system.
    The arrow on the "PUMP" Volute may help decipher in which direction it is Pumping..
    We have seen this issue many times. Mistakes happen.
    Respectfully submitted.
    Hope this helps. :#