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Expansion Tank - Air eliminator

Tech0515
Tech0515 Member Posts: 10
Hi Everyone, I know this topic has been beat up. I just cant find the help I need. I have a hydronic heating system (boiler/baseboard). I had an issue with the PSI increasing to the danger zone so I would release water when it got that hot, eventually replacing the 2 gallon Expansion tank. I checked the water Pressure and it was I believe around 60-70 PSI at the time. I charged the unit leaving it 2 degrees below the water pressue. I hear the pipes making noise now so i believe there is air in the system. When i drain the system, I have a good flow of water and not the normal symptoms of air. I also do not have a lever on my air flow control valve to increase the flow. So that is problem 1. Problem 2 is that the relief valve keeps releasing water, about 5 gallons overnight and about another 2-3 during the day when it's warmer. I feel like the expansion tank is undersized although the same size that was on it. So I bought the 5 gal one. During this time, I thought it might be a good idea to add an air eliminator. However, my expansion tank is at the end. Can/should i reroute?

Appreciate any advise

Thanks
Tim

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,004
    You need to take the expansion tank off and check the air pressure in it while it is off the system. Most systems need 15 psi of air. That's enough for a two story house. Then put the tank back on the system. It should not be mounted upside down as it now is.

    The adjust your feed water prv to 15 psi and put 15 pai in the boiler. When the boiler is cold this is the pressure you need. When the boiler heats up the pressure may rise to around 20 or so. If it goes over 25 your getting to close to the relief valve setting and have another issue...expansion tank too small or something. After you fill and run it if the pressure rises to 30 try keeping the water make up shut off and see what happens
  • Tech0515
    Tech0515 Member Posts: 10
    edited February 2018
    Thank you. I will change the PSI to 15 and start there. I am not sure how to adjust the feeder PRV as i do not see a place to do so. I have attach pics of that area as well.

    I do not have enough room to flip the tank around. I would need to reroute it. Is there an issue doing this or taking it too far away?

  • JUGHNE
    JUGHNE Member Posts: 9,763
    60-70 PSI sounds like your water service line pressure.....did you see this shown on the boiler?

    Your boiler is rated for only 30 PSI.
    Your pressure relief pop off valve should open at 30 PSI.

    As ED said you should be running around 15-20 PSI in the boiler.
    Don't worry about the tank position right not unless it is easy to turn that elbow down.
    You need to get the pressure down.
    Do you see the PRV (pressure reducing valve)....not the relief valve?
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,004
    Pic #2547 shows the PRV. It has a threaded stem on top you can adjust with a screwdriver. Loosen the locknut first. Turning the stem clockwise increases the pressure, counter clock lowers it That prv is as old as the boiler and could be the cause of your high pressure. Once you get the pressure in the system right you can shut the prv if it leaks by

    Not to slander your equipment but the boiler says 1969 on it. Not saying it's an emergency but as time progresses this is what you should do:

    Down load the SLant FIn app and do a heat loss on your house. Also measure all the baseboard and radiators and check their size. We can help with that.

    Then you can get the right size boiler when you are able to replace the one you have which if you are smart you would start planning for it's replacement
  • Tech0515
    Tech0515 Member Posts: 10
    Thank you for all your help. I will review again tomorrow when I have a chance to make the changes. I just bought the house a couple months ago so...surprise surprise...I'm running into problems.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Your biggest problem is the location of the pump in relationship to the pressure reducing valve. Every time your pump turns on, due to the fact that it is pumping towards the expansion tank, it has no choice but to present its pressure differential as a NEGATIVE pressure. The PRV "sees" this short drop in pressure , and sends a little water in to compensate for the low pressure condition. Eventually, the pressure relief valve does its job when pressure approaches 30 PSI and releases the excess pressure.

    You might have other "issues". but this is the primary reason your system keeps getting over pressured.

    If it were me, I'd repipe the boiler as follows. On the outlet of the boiler, go through a tee with a 3/4" drain valve, then an isolation ball valve, then the air separator and expansion tank with the make up PRV connected to the expansion tank connection to the tank, then the system circulator, and a circulator isolation valve.

    On the return(s) you can leave the isolation valves, but can lose (or not) the purge cocks. You just installed one on top of the boiler.

    Filling and purging are done by closing the isolation valve on the boiler outlet, opening the bypass on the PRV, and connecting a drain hose to the 3/4" boiler drain below the ball valve. Purge one circuit at a time until free of large bubbles. Close drain, open isolation ball valve and turn system on. Your problems will be no more.

    You may want to find a qualified local hydronics contractor who can do the work for you, and might also want to consider the option of a new boiler...

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    New England SteamWorksGordy
  • Tech0515
    Tech0515 Member Posts: 10
    edited February 2018
    Thank you for the info. My immediate goal (since it's winter and house full of kids) was to getting it working.

    Expansion Tank: I just adjusted the PSI on the Expansion tank and so far so good.

    PRV: The pressure in the system is usually at 20. Then obviously going to 30+. This usually only happens at night when its colder. I have not adjusted the PRV yet, however, I changed the PSI in the expansion tank, raised the temp in the house to see how it would react. The pressure maintained at 20 and then went to 25. Hasn't went higher than 25. Should I still adjust to 15? The 25 I'd assume is caused by turning up the thermostat. Waiting to see if it goes higher or drops down when the temperature reaches the same as the thermostat. My concern is, the size of my home. Not overly Large at 2000SqFt but spreadout so is 15PSI adequate for the push through the entire system?

    Also, Do I change the PRV temp when turned on so I can tell where the needle is?

    Tank position: I do not have room to turn the elbow, i would have to reroute.

    Re-piping: This was my thought process but I wasn't sure what affect it would have. I am an avid Do-It-YourselfER and figure things out releatively quickly so I am not concerned in attempting this myself. I wanted to move the heater over a few feet so this would be an ideal time to do this.

    Air in lines: I didn't have noise in the pipes until i changed the expansion tank. This led me to beleive that there was Air in the lines. However, the water seems to flow without an issue and no bubbles when i purge. Does this mean there is no air and something else is causing it?

    New Boiler: Any thoughts on the combi systems? I was looking at the Aqua-Balance system. My boiler and HWH are located in the center of the house and vent into the Chimney. Is this an issue as all the installations I've seen pull and vent directly outside.

    Not sure if I can post a link since it has a price but this is what i was looking at.

    https://www.ecomfort.com/Weil-McLain-383100000/p79511.html?gclid=EAIaIQobChMIkc_ytICa2QIVWFmGCh10KgQ8EAQYASABEgIRbfD_BwE
  • Tech0515
    Tech0515 Member Posts: 10

  • scrook_2
    scrook_2 Member Posts: 610
    60-70 *feet* of water (altitude)... 20-30 psi
    30-50 feet... 15-20 psi is more appropriate
  • HVACNUT
    HVACNUT Member Posts: 4,594
    edited February 2018
    The B&G brass PRV is pretty reliable even though that one seems old. If I'm not mistaken, that's a domestic extrol and the diaphragm will not expand under lower pressure like a #30 for heating.
    Remove the nipple and 3/4 x 1/2 reducer coupling and install a #30, charged to 12 psi and make sure the PRV is set to 12 psi.
    Is there an air eliminator somewhere we can't see? If no, what's under the knockout on the boiler jacket below the zone valves? Can you install one there?
    It's been a long time since I've seen bending temper copper.
  • Tech0515
    Tech0515 Member Posts: 10
    So the #15 is too small. I will order the #30 then.
    There is no air eliminator. However, does it matter that my expansion tank is at the end. From waht i research, the expansion is not at the end when the air eliminator is in place, however i don't have a much room unless a reroute all the pipe.
  • Tech0515
    Tech0515 Member Posts: 10




  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    Do this test. Shut system down, lower pressure to 15 PSI, turn on make up water and allow pressure to stabilize with pump off. Turn off make up water and let system run overnight. Check pressure next morning, If it is stable, then what I'd mentioned is occurring. If it's back up, then something else is going on.

    You have the solution.

    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • SuperTech
    SuperTech Member Posts: 1,792
    You need to correct that piping. I honestly don't think the worlds largest expansion tank will help with that configuration.

    The expansion tank should never be dead ended like that. Or upside down either.
    I normally seen the expansion tank on most residential boilers on either 1-1/4" or 1-1/2" supply piping coming off the boiler to an Air Scoop. On the bottom of the scoop get about a 5" threaded nipple to a 1/2" ball valve then the the expansion tank. On the top of the scoop do the same thing, nipple, ball valve then an air vent/Hy vent.
  • SuperTech
    SuperTech Member Posts: 1,792
    This is what I was talking about, except add ball valves and nipples for ease of future service
  • Zman
    Zman Member Posts: 7,330

    Do this test. Shut system down, lower pressure to 15 PSI, turn on make up water and allow pressure to stabilize with pump off. Turn off make up water and let system run overnight. Check pressure next morning, If it is stable, then what I'd mentioned is occurring. If it's back up, then something else is going on.

    You have the solution.

    ME

    Your biggest problem is the location of the pump in relationship to the pressure reducing valve. Every time your pump turns on, due to the fact that it is pumping towards the expansion tank, it has no choice but to present its pressure differential as a NEGATIVE pressure. The PRV "sees" this short drop in pressure , and sends a little water in to compensate for the low pressure condition. Eventually, the pressure relief valve does its job when pressure approaches 30 PSI and releases the excess pressure.

    You might have other "issues". but this is the primary reason your system keeps getting over pressured.

    If it were me, I'd repipe the boiler as follows. On the outlet of the boiler, go through a tee with a 3/4" drain valve, then an isolation ball valve, then the air separator and expansion tank with the make up PRV connected to the expansion tank connection to the tank, then the system circulator, and a circulator isolation valve.

    On the return(s) you can leave the isolation valves, but can lose (or not) the purge cocks. You just installed one on top of the boiler.

    Filling and purging are done by closing the isolation valve on the boiler outlet, opening the bypass on the PRV, and connecting a drain hose to the 3/4" boiler drain below the ball valve. Purge one circuit at a time until free of large bubbles. Close drain, open isolation ball valve and turn system on. Your problems will be no more.

    You may want to find a qualified local hydronics contractor who can do the work for you, and might also want to consider the option of a new boiler...

    ME

    This is one of the rare times on the wall where you need to block out everything else, forget what you think you know and just do this....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    SuperTech
  • Tech0515
    Tech0515 Member Posts: 10
    edited February 2018
    One question on the PRV pressure. Is that the pressure when it kicks on to heat or sitting idle. The pressure sits at 15 and when it kicks on, it goes to 25 (this is what is happening now since lowering the expansion tank PSI to 15). However, it is no longer leaking from the release valve. Over the past couple hours, I would have 2-3 gallons in the bucket and right now the bucket is completely dry. I'll check again in the morning since that is when i had the most (usually bout 5 gallons in the bucket).
  • hot_rod
    hot_rod Member Posts: 16,312
    I too would look into a boiler upgrade. It looks like some black staining around the various components, possibly from some combustion leakage?

    Look inside the burner tray and see if there are deposits or crud on the burners.

    I would recommend a CO detector near that system just to be safe.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    SuperTech
  • SuperTech
    SuperTech Member Posts: 1,792
    I couldn't agree more. Get a CO detector to keep near the system. Maybe even one of the 120 volt ones that you can keep plugged in by the unit. You cannot be too careful about carbon monoxide safely.
    Given the age of the boiler and all of the issues related to improper piping and poor installation it would probably be in your best interest to consider replacement options.
    You have a lot to gain in terms of safety, reliability and efficiency with a new boiler. Even a new minimum efficiency boiler will be more efficient than that old one. And you will have the peace of mind that a warranty provides.
    And this old boiler might nickel and dime you to death with the repair costs of trying to make it work right. At the very least it will be aggravating.
    Just do a little homework and find out what companies in your area have the best reputation for quality hydronic work. Any company that gives you a price without doing heat loss calculations to properly size the boiler should not be considered. And any company that doesn't do proper combustion analysis should not be considered either.
    Give the find a contractor tool on this site a try. Estimates don't cost anything and many companies will offer financing as well.
  • Tech0515
    Tech0515 Member Posts: 10
    edited February 2018
    Thank you for all of your input. I will put a CO detector neer the unit today. I will start looking at more options. Any input on the Combi systems to combine the HWH and the boiler? Is this a worth while option?
  • SuperTech
    SuperTech Member Posts: 1,792
    I'm not a fan of the Combi boilers. I prefer a indirect tank. The only time a tankless should be used is if an indirect tank installation is not possible.
    New England SteamWorks
  • I am with @Mark Eatherton .
    New England SteamWorks
    Service, Installation, & Restoration of Steam Heating Systems
    newenglandsteamworks.com
  • Gordy
    Gordy Member Posts: 9,514
    I believe what is happening is as Mark has stated also. By pumping into the expansion tank the pressure differential of the circ on the suction side is less than system pressure of 15 psi. Maybe the suction side is seeing 10psi. The auto fill is set to 15 psi. Then sees 10 psi when the pump kicks on causing the auto fill to dump water into system momentarily. Do this over a number of heat calls system becomes over filled.

    As Mark said leave the supply valve closed to the auto feed. If problem goes away that’s the culprit.

    I remember Mark talking about this happening a few times moons back. It’s a chain of events that can happen in the right scenario.
    Mark EathertonSuperTech