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Double Backcheck w/ Atmospheric Vent???

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  • Double Backcheck w/ Atmospheric Vent???

    I just had the 5th failure of a Caleffi 573 double backcheck with service of less than 1 year. Is anybody else seeing a trend? We switched to them for use with mod/cons to boost the pressure set above 12 psi...which is standard to a Watts 911 our favorite. That being said, I would rather have a boiler flaking out for the psi balance than have a leaking check.
    Last edited by Kevin Jones; 06-18-2010, 03:07 PM.

  • #2
    Re: Double Backcheck w/ Atmospheric Vent???

    new systems have been getting the Caleffi backflow preventers...

    I really like their reducing valve/backflow combo

    I have only changed out 2.... One was a freezeup, the other would probably been fine, but was asked to change it out as it was dripping (while doing it's job)

    I still keep the Watts on the truck, but usually only use them as a replacement.

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    • #3
      Re: Double Backcheck w/ Atmospheric Vent???

      Thanks Radar. I'm with you I like the Caleffi PRV section of the combo. We had some issues with the mod/cons going to soft lockout with the watts 911 combo. Now I am having the Caleffi 573 failing to frequently and some are leaking on the first day of service. I really don't feel like buying the Caleffi PRV seperately and adding the Watts 9D to make a set...but it looks like it may end up going down that way if this continues.

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      • #4
        Re: Double Backcheck w/ Atmospheric Vent???

        I went to a ModCon class once, but never worked on any in the field.

        Natural gas is only run is a very small portion of the area I serve.

        How can a makeup valve cause a lockout?

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        • #5
          Re: Double Backcheck w/ Atmospheric Vent???

          Originally posted by radar_40 View Post
          I went to a ModCon class once, but never worked on any in the field.

          Natural gas is only run is a very small portion of the area I serve.

          How can a makeup valve cause a lockout?
          Most mod/cons have a pressure switch that requires a minimum of 10 psi to operate. So with the Watts 911 you have a pressure of 10-12psi. If a particular PRV hovers out at 10psi then the mod/con may continue to slip in and out of soft lock due to a 1psi pressure difference.

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          • #6
            Re: Double Backcheck w/ Atmospheric Vent???

            i've never used the Watt's ones... I have removed a few I think.

            For new one's I typically install the Caleffi or Taco

            B&G were really popular here in the past, there's still alot of them around.

            Are the Watt's not adjustable?

            Not to state the obvious, as i'm sure you've thought of just bumping the pressure a little.

            I'm concerned about the Caleffi issure you've brought up, as the only makeup valve/backflow combo that in is sold here is the Caleffi.

            I only install about 15 a year, so I guess the total time lost by not using the combo unit is minimal.

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            • #7
              Re: Double Backcheck w/ Atmospheric Vent???

              Watts are adjustable but not by much. Any brand is mass produced and has acceptable tollerances. With that being +/- 2psi on both the manual supply and +/- 1psi on the elctronic sensor...we now have a problem Houston at a +/- 3psi. When 12 is the highest supply and 10 is the minimum demand.

              When this occurs is within 3 days of a new system stretching its legs
              Yes I do set the expansion tank up to 16 psi and set the water by bumping upto 18 psi. Air left in a radiant system as little pockets will begin to escape and that air is not being replaced by a feeder at 12. The pressure in the system drops. Pressure sensor kicks in and failure Mad customer.

              This happened enough times to change brands when installing mod/cons.

              One thing you need to keep in mind is that I do not do new construction. So most of the systems I deal with see much more inlet supply pressure changes and that may also be a factor.

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