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Overpressurizing Smith boiler

Dave19 Member Posts: 28
edited March 2019 in THE MAIN WALL
I have a 22 year old Smith boiler that had a tankless coil. I recently capped the tankless to install a 40 gallon Superstor. At the time of install, just to be safe, I replaced the relief valve, expansion tank, feeder/backflow, hyvents, and tridicator. Did a very good purge on all zones. Been back to this house several times and the customer claims the relief valve is dumping water out. Replaced the relief valve again just to see if it was bad out of the box. Xtank read 15 psi. I have yet to see this thing dump, so maybe the customer is full of it, but what else could be causing the overpressurizing? Boiler maybe leaking? No signs of it anyway. Any ideas appreciated.


  • Steamhead
    Steamhead Member Posts: 15,874
    Maybe a leak in the SuperStor?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Dave19
    Dave19 Member Posts: 28
    Have you ever had a brand new one leak? I really hope it's not that but I guess anything is possible.
  • Intplm.
    Intplm. Member Posts: 1,424
    Have had this happen to me too. Changed relief, and made sure the new auto feeder was working properly . Sometimes there is a fast feed that is installed away from the auto feed. That valve could be weeping by causing the pressure to rise triggering the relief valve.
    Is there glycol in the system?
  • Dave19
    Dave19 Member Posts: 28
    No glycol. The boiler only has a single fill line now. 1/2" with a brand new b911 feeder/backflow. I'm stumped here and starting to doubt the customer
  • Intplm.
    Intplm. Member Posts: 1,424
    Might just be the customer having some type of buyer remorse reaction.
    As you seem to know, the pressure should be at 12-15 psi on a hot water boiler. A rise of twice that seems unlikely at this point.
    EBEBRATT-Ed Member Posts: 13,331
    Fill it shut the water off and try it for a while. Check expansion tank while disconnected from the system
  • kcopp
    kcopp Member Posts: 4,160
    Is it on the boiler or Water heater?
    The new water heater t&p could be blowing off especially if there is not a potable water extrol and there is a backflow at the water meter.