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Leak , Air lock in heat system ?

RudyA
RudyA Member Posts: 14
 New boiler installed , I have baseboard water heat , one zone . There’s about 25’ of the heating pipes in the slab of the house , the rest is all exposed . I have no signs of moisture coming from those areas in the floor . Randomly I come home to no heat and I have to purge the system . When I open the heat pipe loop , it’s a steady stream . When I open the valve to add the boiler to the purge I get pops of air . Then I have heat . I was told I have a leak somewhere but it can run for days with the feeder valve off and I’m maintaining 20lbs of water pressure . Why would it leak sometimes and not all the time ? Is there something else that can cause this since it’s a new installation ?  Note I did install air vents to the system . 

Comments

  • SuperTech
    SuperTech Member Posts: 2,152
    Can you post pictures of the boiler and the piping? Especially where the the pipes go into the slab. 

    Have you tried isolating the zone with the pipes going into the slab to see if that zone is the cause of the problem? I've seen a few cases where a leak under the slab caused the problems you described. 
  • RudyA
    RudyA Member Posts: 14
     It’s one complete loop . Leaves the boiler to circulator pump to each baseboard heater then jumps from one bedroom to next in the floor , then returns with about 10 feet in the floor . Then enters the basement . I wouldn’t know how to isolate that run besides shutting the boiler feed off and running the heat . And like I said not loosing any pressure .  I’ll try to get some pics , thanks 
  • RudyA
    RudyA Member Posts: 14

  • Mad Dog_2
    Mad Dog_2 Member Posts: 6,879
    Boiler piping please. Mad Dog
  • RudyA
    RudyA Member Posts: 14

  • JUGHNE
    JUGHNE Member Posts: 11,056
    Those little auto vents have been know to suck air in under certain conditions.

    After you have it purged and running, you could screw the top caps down and see it things change.
    RudyA
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,510
    What pressure is the boiler at? Have you removed the expansion tank and checked the air pressure on the airside of the tank? It should match the boiler fill pressure.
    RudyA
  • RudyA
    RudyA Member Posts: 14
    I will try that with the air vents .  I haven’t removed the expansion tank for that test as I’m not a plumber . If you’re asking about the boiler pressure it’s set at 20 PSI . 
  • hot_rod
    hot_rod Member Posts: 22,103
    I don’t see any type of air purger? Those float type vents are high point air vents, really no mechanism to pull air from a flowing stream.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTechGGross
  • RudyA
    RudyA Member Posts: 14
    So those vents that were added do not solve the problem of air getting into the system ? 
  • RudyA
    RudyA Member Posts: 14
    And you’re right , I don’t see an air purger , the vents are just teed in 
  • hot_rod
    hot_rod Member Posts: 22,103
    A vertical version air Sep would press into the piping above the boiler easily.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    RudyAGrallert
  • RudyA
    RudyA Member Posts: 14
    Ok thanks I will definitely look into that 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    edited February 2023


    If you are going to the trouble to install that air separator you might as well do it to your best advantage. The proper order for the best air elimination is to place the air separator between the boiler and the circulator pump. Then connect the expansion tank to the bottom of the air separator, and connect the water feed valve at the same location with a tee.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    RudyA
  • SuperTech
    SuperTech Member Posts: 2,152
    It's probably not helping anything that the piping is undersized. Looks like all 3/4" piping near the boiler?
    RudyA
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    What do you mean when you say "...I come home and I have no heat..."? The pipes aren't warm/hot, but the boiler is? Could it be circulation?
    Are you adding water because it has left the system?
    Are you sure it was properly purged in the first place, or are you just taking air trapped in the boiler and pushing it into the zone?
    If you can't find a leak with a thermal imaging camera, you may be sucking in air from incorrect piping as others have mentioned.
    steve
    RudyA
  • RudyA
    RudyA Member Posts: 14
      When I leave the house for work  , I turn down the thermostat . When I come home and turn it back up , radiators stay cold , but I do hear the circulator pump . Then I proceed to purge the system and some air comes out of the hose . After that. , I have heat . And I don’t have to add water manually from the feeder valve . It feeds as I have the valve open to get the air out , When I close the valve the water pressure builds back up , feeder valve stops adding water  Note that this air problem happens randomly as I can go for more than a week and no problem , but then it comes back daily . 
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    edited February 2023
    Sounds like it’s sucking in air, maybe from allowing the water temperature and pressure to drop.
    Is the boiler coming up to temperature? Is it getting hot anywhere in the piping?
    steve
    RudyA
  • RudyA
    RudyA Member Posts: 14
     Boiler temp is fine as it serves the domestic hot water as well . Only part of the heat pipe that is hot is before the circulator pump coming out of the boiler  . Pump is hot also . After that the pipe is cold . 
  • RudyA
    RudyA Member Posts: 14
    I was told to shut this valve off when purging the system . As soon as I open this valve , the steady stream of water from the hose starts skipping with air . Seems like the air is getting trapped between the circulator pump and boiler 

  • Grallert
    Grallert Member Posts: 644
    Are you purging through that red handled boiler drain upper right of this picture? Looks like you could but you would be purging in the reverse of the normal flow.
    Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker
  • RudyA
    RudyA Member Posts: 14
    Yes , that’s where i connect a hose and purge it 
  • leonz
    leonz Member Posts: 1,122
    Hello Rudy, have you turned thermostat all the way up and let it run? That is a good way to push the bubbles out.
    RudyA
  • RudyA
    RudyA Member Posts: 14
    No I didn’t . Was told to purge it with the heat off 
  • hot_rod
    hot_rod Member Posts: 22,103
    How much are you setting back the thermostat. Takes some time to get high mass radiator systems heating back up
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • RudyA
    RudyA Member Posts: 14
    I turn it down to 60 since the weather has been nice . I’ll turn it up to 67 when needed and the radiators get hot immediately. 
  • fortyyearsin
    fortyyearsin Member Posts: 2
    try closing the air vent at the expansion tank. It looks like you installed it yourself.