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Looking for a little clarification on the purpose of the pressure reducing valve on a water boiler

Hey guys. I’ve been on here in the past and learned enough through the forum and the lost art of steam heating book that I installed one boiler in my one house and repiped pretty much an entire 2 pipe steam system in the other. Well, now I’ve sold one of them and bought a new one that has a hydronic boiler. This house has well water and the pressure switch took a dump today which killed the pump and we had no water coming into the house. I was at work so I had the wife shut down the boiler because I was concerned that the system didn’t have the water pressure backing the system up through the pressure reducing valve. I’m not sure if this was even necessary but I went on the side of caution. Is it necessary to have the water pressure backing these systems up for them to operate normally ? Is there a book for hydronic systems I should buy ?

Comments

  • IronmanIronman Posts: 4,936Member
    You should have a backflow preventer right before the PRV.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • Jamie HallJamie Hall Posts: 10,177Member
    The pressure reducing valve will also act as a check valve -- although it shouldn't be relied on for any length of time to do that (you really should have a backflow preventer on there) so unless you have a leak, the heating system should have held its pressure and you should be fine. Just check the system pressure to make sure it's holding where it should be.

    Just for the sake of curiosity, how did a bad pressure switch manage to kill the pump? I'm trying to envision a situation where a bad switch would do that -- unless it was cycling on and off too fast. That would do it...
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ChapstickChapstick Posts: 64Member
    The wife told me she was taking a shower, running the washing machine, and the kid was taking a bath and the water to the entire house died instantly. Fortunately some guys I work with have wells and they told me the pressure switch likely went bad. I grabbed my multimeter and verified the switch had power and no current was leaving the switch going to the pump and that the water pressure was 0. I then Swapped out for a new switch and the pump fired right up. The pump is 12 years old and the switch appeared to be brand new so hopefully the pump didn’t somehow kill the switch.
  • hot_rodhot_rod Posts: 11,228Member
    Check the current draw on the pump motor, excessive load will damage the pressure switch contact points.

    Also if the pump cycles too often due to a bad air charge in the well tank can will cause arcing excessive heat and damage to the contact points.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • ChapstickChapstick Posts: 64Member
    I had the cover off of the switch when I first hit the breaker to test it and when it reached pressure and switched off it did create quite an arc. I said “wow” out loud when I saw it. It definitely seemed out of the ordinary.
  • ChapstickChapstick Posts: 64Member
    The pump is only 110v too. Seems kind of lame that it isn’t 220v.
  • hot_rodhot_rod Posts: 11,228Member
    Chapstick said:

    The pump is only 110v too. Seems kind of lame that it isn’t 220v.

    Must be a very small shallow well pump, if it is 120V? Not a submersible I assume?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • IronmanIronman Posts: 4,936Member
    I have seen 120v submersible pumps. Don't ask me why anyone would have one.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • Jamie HallJamie Hall Posts: 10,177Member
    Ah... well... the main place I take care of has a 220 volt submersible, 180 feet down (I hope it never fails -- it's on iron pipe). Been there for 58 years now and running fine (Suma pump -- can't get them any more).
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
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