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Pressure relief valves?

JackW
JackW Member Posts: 236
in Radiant Heating
The picture below shows two pressure relief valves on the same line, why would you need that?
Thanks,


Comments

  • DZoro
    DZoro Member Posts: 1,048
    You don't. Keep in mind this set up is not perfect, what you do need on those reliefs is a drop pipe to within 6" of the floor. Looks like this designer was more interested in filling up his board with ups and downs of piping. Safety drop piping must not have met his standards for the look he was going for. The gas piping is questionable also, but hard to tell how it is actually done. Glad he found a place for that wrench ;)
    D
    JackW
  • HVACNUT
    HVACNUT Member Posts: 6,421
    That's gotta be a classroom or something. No cold water fill.
  • JackW
    JackW Member Posts: 236
    DZoro I plan on following this plan, if not per say, then pretty close. What would you change?
  • JackW
    JackW Member Posts: 236
    HCVAVNUT what is the valve to the left of the 90 degree elbow going into the return side?
  • HomerJSmith
    HomerJSmith Member Posts: 2,635
    It bothers me to see unnecessary piping and I like to see 10 pipe diameters on the input to a pump and 5 pipe diameters on the output of a pump. But that's just me.
    JackW
  • JUGHNE
    JUGHNE Member Posts: 11,301
    If this is your DIY project, one important thing for the pressure relief valve, you do not want any valve between the boiler and the relief valve. This could isolate the relief valve from the boiler.
    JackW
  • JackW
    JackW Member Posts: 236
    HomerJSmith what would you change?
  • JackW
    JackW Member Posts: 236
    JUGHNE then the first relief valve is where it should be, and no need for the second one.
  • JUGHNE
    JUGHNE Member Posts: 11,301
    IMO yes
    JackW
  • Dale_3
    Dale_3 Member Posts: 58
    Need vs want. Are they possibly different pressures?
    JackW
  • JackW
    JackW Member Posts: 236
    Could be Dale, maybe one a backup just in case.
  • HomerJSmith
    HomerJSmith Member Posts: 2,635
    edited October 2019
    It is a nice looking installation, but I would have done it differently.

    There are too many 90 deg fittings. I would have carried the primary loop straight across and put the pumps to the zones under the primary loop and eliminated the U piping on the outlet to the pumps. I don't see a need for that many gauges. I don't know whether you have concentric venting, which I never do, but I usually put a PVC tee on the air intake with a drain loop of 1/2" vinyl tubing to catch any water that might enter the air intake and drain it out before it can enter the boiler.

    I don't see a need for two pressure relief valves, either. A pressure relief valve should be within 6" of the boiler.

    Zman's suggestion of off-setting the expansion tank will keep any debris from getting into the tank that's pulled out of the air eliminator. Putting isolation valve and a drain valve makes it easier to charge the tank when that needs to be done.
    JackW
  • JackW
    JackW Member Posts: 236
    Thank you Homer for the ideas, any chance you could draw me a diagram? I understand what you are saying, not sure where to go with it.

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