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Pressure drop after two weeks of use

Eric_79
Eric_79 Member Posts: 35
Hi all, I am using an XC-100 propane boiler and Hydra-smart panels from Menards. 50/50 distilled water/antifreeze.
The system is primed to 18-20 psi for use. During the heating season it will hold that pressure for roughly 2 weeks then start loosing pressure and then I need to pressurize it back up. I am not sure where it is going. Everyone I have talked to says there is a leak. I'm not sure how as if there were a leak, it would leak down faster than that and also during the off season (summer time) all three zones have held 19 psi along with the panels.
I am at a loss as to where the pressure is going. The only thing I can think of is the air separator.
Could the system be creating too much air possibly?
Is there a way to test it?
The local heating/cooling companies are no help as they tell me they don't have anyone qualified to work on radiant heat systems.

Any help/ideas are greatly appreciated!
Eric
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Comments

  • Jamie Hall
    Jamie Hall Member Posts: 19,907
    Does (do) the circulator(s) run during the summer? If not, one pesky source of a very small leak is the seals on the circulators. It won't show if they aren't running.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Eric_79
    Eric_79 Member Posts: 35
    No, the circulators are off.
    If the seals are leaking, would you see fluid? I see no signs of liquid anywhere.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 4,177
    edited September 7
    Unless there is a leak the pressure can not leave the closed system. The leak can be a valve packing, the leak can be an air vent. The leak can be a poorly connected fitting.
    As the system heats up and gets to operating temperature, the leak can seal itself with the expansion of some material like PEX or Brass that is just tight enough to miss being detected by a pressure test but small enough that over time at the proper cooler temperature very small amounts of air or water vapor leave the system at an extremely low rate. If this is the case, Good Luck finding it. Until you see some mineral build up from the leak location, you wont know where to look.

    Most systems that have this problem have an automatic water feed (pressure reducing valve) connected to the tap water pressure of the building. Since you have gone to the trouble of filling the system with other than tap water, that is probably an option you don't want to use. A suggestion might be is to add a storage tank of Distilled water with 50 PSI pressure connected to the fill valve (PRV) as one might do for a system connected to the potable water system of the building. Diagram below illustrates the concept.
    You can prepare any mixture of liquid to match the product you want to add to the boiler then pump it into a Well-Trol or similar pressurized tank with the air pressure removed. After the tank is about 3/4 full of liquid, then add air pressure to 50 or 60 PSI. Now the Auto feed will maintain the desired pressure and over time the leak should become apparent
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org

  • hot_rod
    hot_rod Member Posts: 17,470
    Does it ever drop to 0 psi? Pressure will move as bit from cold-warm-hot and back to cold.

    Any underground or in slab pex? A pinhole can cause a very small leak, sometimes getting worse as the tube heats and expands.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Eric_79
    Eric_79 Member Posts: 35
    If I let it go, yes it will get to 0. I try to pressurize it around 6-8 psi so it never goes too low.
    Two zones are under concrete, the third is under the second story floor. All 3 zones were pressurized to 100 psi for 30 minutes to pass inspection and during the concrete pour.
  • pecmsg
    pecmsg Member Posts: 3,322
    You might want to isolate the in floor zones and pressurize them. 
    HomerJSmithmattmia2mvickers
  • Eric_79
    Eric_79 Member Posts: 35
    What pressure are you thinking? They are at 19 psi right now and have been since April/May ish.
  • GGross
    GGross Member Posts: 326
    Do you have any pictures of your boiler room piping by chance?
  • Eric_79
    Eric_79 Member Posts: 35

    Here it is. Just doesnt have the reliefs or propane lines
  • pecmsg
    pecmsg Member Posts: 3,322
    Eric_79 said:
    What pressure are you thinking? They are at 19 psi right now and have been since April/May ish.
    The floor has 19 PSIG yet the system is 6-8?
  • Eric_79
    Eric_79 Member Posts: 35
    No, the entire system right now has 19 psi. I re-pressurize it when it gets down to 6-8 psi. This drop happens around the 2-2.5 week mark of running and staying at 19 psi.
  • hot_rod
    hot_rod Member Posts: 17,470
    looks like you have enough isolation valves, and a test gauge. Re-test the in slab pex and manifolds to 50 psi or so.

    Looks like a few spare SharkBite to easily move that a test gauge.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Eric_79
    Eric_79 Member Posts: 35
    Can do. How long should I leave it pressured up? Or just to see if it drops? Empty or with fluid?

    Thanks
  • hot_rod
    hot_rod Member Posts: 17,470
    You are probably not using the system, let the pressure sit for a few days or a week. That is the best way to find a small pinhole type leak. You can leave the fluid in and put air over it. But you will lose some glycol if in fact there is a leaks. Check it every day.

    Hopefully it is not a leak in. a tube, but you can eliminate a bad loop, or try a sealer.

    First things first, confirm the tube and manifolds hold.

    Some of those manifolds have hydroscopic air vents on both headers. If so, they will not hold an air test, unless you can turn off, or cap off the vents. They fool a lot of people into thinking they have a tiny leak.

    A possibility that there has been air in the system from day one that is not 100% out yet, causing that pressure drop.
    Glycol solutions don't give up air easily. Nice to have a fill tank on them. At least for a moth or so when first started. It allows fluid to go in as small air comes out.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,623
    You say you have glycol in the system. Glycol can foam and the foam can weep out the air vents if you have any auto air vents
  • HomerJSmith
    HomerJSmith Member Posts: 1,798
    Empty or with fluid?
    I don't think it matters. It only take a cup or two of water loss to bring the pressure down to zero if you don't have an auto feed. Perhaps there is air some where in the sys that is being adsorbed into the water. Perhaps you are sucking air into the sys thru the air elimination device. You might screw the cap down tightly after a fill and see how that goes. What size are those pumps? You could use a thermo camera to test the slab after running hot water thru the infloor and see if you have a thermo spread.

    You have 3 manifolds shut the intake and return off each manifold one at a time at two week intervals and see what happens. Might show a slab leak in a manifold if the pressure doesn't drop. In fact, shut two manifolds off with only one running and do each manifold one at a time.

    You might take the incoming temp and the return temp of each manifold and see if you have a small temp differential. Might tell you if you have an air lock.
  • Eric_79
    Eric_79 Member Posts: 35
    Ok, I will get the parts to pressurize the slab runs and see what I come up with.

    As far as the glycol foaming, What would cause that? I have not see any air bubbles in the clear filter/strainer yet other that when I first filled the system a year ago.

    It is possible that I am getting air in when pressurizing the system. I will let each zone run for 15 minutes and checking my bucket for any air bubbles.
  • Eric_79
    Eric_79 Member Posts: 35
    Homerjsmith, They have been under pressure the entire summer. That would be the same as running other than the heat correct? When running hot the pressure is around 22 psi (I believe from pump pushing the fluid). Once cooled it settles to 19 which is where it is now. I have all the zones open to see if the entire system bleeds down and so far nothing.
  • HomerJSmith
    HomerJSmith Member Posts: 1,798
    edited September 7
    Is this a new problem and it worked well for a long time? Are you telling me you only lose pressure when the boiler is running and the pressure is fine all summer when the boiler is idle?

    Your sys pressure is high, I would prefer about 15psi cold. The temp rise from 19 to 22 psi is in the normal range for heated water. What does the temp gauge say when the boiler is fully heated?

    Take close up pics of the boiler and pumps piping and of the manifolds, etc.

    You probably have an air vent at the top of the boiler, be sure and screw that cap down, too, and see how it goes.
  • Eric_79
    Eric_79 Member Posts: 35
    It has done this since new. As far as the pressure, they wanted the system filled at 18 psi but they stated 19 is fine. The temp I have set to a limit of 120 degrees F. I can take pictures when I get home as I am at work now.
    I thought about screwing the air separator cap closed but was nervous about not relieving air. Sounds like it will be ok to check according to you guys on here.
  • mattmia2
    mattmia2 Member Posts: 6,592
    If it doesn't lose pressure when it is static but loses pressure when the system runs, I agree with @hot_rod, you probably have air trapped in the loops in little pockets that is slowly working its way out. You could try running the circulator for a few days without running the boiler and see if you lose pressure although it could need the heating and cooling to bring the air back to the boiler.
  • Eric_79
    Eric_79 Member Posts: 35
    Good idea, better now, than when its time to heat.
  • HomerJSmith
    HomerJSmith Member Posts: 1,798
    18 psi is high. Ya, could be trapped air which is why I wanted you to look at the supply and return temps. Water won't pump thru an air bubble which is why I wanted you to look at the supply and return temps at each manifold. If the supply is hot and the return is cold there will be no flow thru that manifold or loops because of possible air bubbles.

    I'm leaning toward incorrect piping. What kind of pumps. Where are the boiler and pump closeup pics?
  • Eric_79
    Eric_79 Member Posts: 35
    I do not recall what the temps are coming back. I know they are not cold. Warm but not the same temp as outgoing. The piping on the white panels come assembled and tested from the manufacturer. All I had to do was hook up the supply and return to the boiler and the other panel. The pumps are hydra-smart brand, same company that made the panel assemblies.
    I can get better pictures when I get home from work.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 4,177
    edited September 7
    No one has mentioned the fittings. There looks like about 30 to 40 copper connections into a "Shark Bite" type fitting, unless that is a new type of Press fitting I'm not familiar with. Is that the best fitting for this job? What if it was repiped with sweat or press fittings that have a better reputation in the industry. I'm counting an elbow as two copper connections and a Tee as three copper connections. It looks great for a DIY but as a Pro, I would not show that as my work.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org

  • hot_rod
    hot_rod Member Posts: 17,470
    if the manufacturer of that panel for Menards pre charged the expansion tank to 18 psi, that is what you need to fill to. If you change the fill to 12- 15 you need to isolate the expansion tank and adjust the pre charge pressure 

    If any of the connections on that panel leak, you soon see a telltale glycol green fuzz/ merengue build up

    Has the relief valve ever discharged? Sometimes it is wise to have a bucket under glycol relief valves
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    GGross
  • Jamie Hall
    Jamie Hall Member Posts: 19,907
    I'd still like you to check and make sure the pump seals aren't leaking when running...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JUGHNE
    JUGHNE Member Posts: 10,030
    It is possible that the heat exchanger in the boiler is leaking and passing water/mix down it's condensate drain. You would not normally see this.

    Very possible on water tube boilers.

    When firing a pin hole may seal....or not.

    If you put that drain line into a bucket and any liquid shows up that could be the leak.
    Simple easy test.

    Not a good day if it is so.
    HomerJSmith
  • mattmia2
    mattmia2 Member Posts: 6,592

    I'd still like you to check and make sure the pump seals aren't leaking when running...

    Aren't those circulators wet rotor? Aren't the only seals between the flanges and an o-ring between the 2 halves of the body?
  • Eric_79
    Eric_79 Member Posts: 35
    Here are the closer pictures 
    The middle picture has a fitting with some blue corrosion on it but that is from the filter. It had a loose cap at one point.
  • Eric_79
    Eric_79 Member Posts: 35
    Is it possible the accumulator might not be charged properly?
    Just curious 
  • Jamie Hall
    Jamie Hall Member Posts: 19,907
    mattmia2 said:

    I'd still like you to check and make sure the pump seals aren't leaking when running...

    Aren't those circulators wet rotor? Aren't the only seals between the flanges and an o-ring between the 2 halves of the body?
    That they are. Which doesn't prevent them from leaking... just makes it a different kind of leak.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • pecmsg
    pecmsg Member Posts: 3,322
    Gutsy letting that x tank hang by the fitting!
    EdTheHeaterMan
  • pecmsg
    pecmsg Member Posts: 3,322
    Eric_79 said:
    Is it possible the accumulator might not be charged properly?
    Just curious 
    Accumulator?
  • Eric_79
    Eric_79 Member Posts: 35
    Lol looks like it doesn't it. It has a mount on the back side.
  • Eric_79
    Eric_79 Member Posts: 35
    Expansion tank. Lol wrong terminology, same design 
    PC7060
  • pecmsg
    pecmsg Member Posts: 3,322
    Eric_79 said:
    Lol looks like it doesn't it. It has a mount on the back side.
    I see a pipe strap. I don’t see anything supporting that tank except the 1/2” fitting. 
  • Eric_79
    Eric_79 Member Posts: 35
    There is a strap also that hooks under the blue cap on the right.
  • HomerJSmith
    HomerJSmith Member Posts: 1,798
    edited September 10
    I don't know what to say. I don't want to be overly critical. But, we do want the sys to function properly, which it is not. I have reviewed the photos and here is my take.

    I think the sys wasn't done by a hydronic specialist, perhaps by a plumber or an amateur. It has the illusion of professionalism, but lacks the intricate details. It has some symmetry, which I love, but has so many twists and turns and so many sharkbite fittings which increases the pressure loss in the sys. I also like pumping into a resistance and not away from the highest pressure loss. It doesn't appear to me to be a true primary/secondary sys. It appears to me that you have two pumps pumping into each other? I can't see the volute on the lower pump so I'm not sure of the direction of flow. Why is the pressure relief valve so far away from the boiler jacket? Where I come from, using white Teflon tape on a gas train wouldn't pass inspection.

    I think that you are pulling air into the sys or that you have a very big air bubble in the manifold that is going to the upper floor. I would bring the pressure up in the sys, close off the upper flr manifold and close off all air vent and run the boiler and see what transpires. You are going to have to go thru the methodology step by step to find where the offending problem lies.

    A 50/50 water to antifreeze solution seems rather high concentration and increases the pumping power needed to get the desired flow. I would calculate that and see if that is what you actually need.
  • Eric_79
    Eric_79 Member Posts: 35
    Homer, you are correct as I installed the system myself. Yes there are a lot of shark bites but I do not solder connections as I am not experienced in that field. Per the manufacturer the system flow and design is sufficient for what they recommend. As I am not a professional plumber, I don't understand how the shark bites create pressure loss. The only way I understand pressure to drop is a leak. I deal with actual hydraulic systems every in my field of expertise. As it is not exactly the same, they share similar properties. As far as the two pumps, I am on the same page as I don't understand the flow with them being so close. The relief being so far away, not sure. They system works and works well other than pressure drop after a week and a half of running. The 50/50 mixture is a precautionary measure in an instance that we are out of town and the system quits. It will not freeze. 
    I will run the system with the air separator closed and see how that works. The upstairs zone I will keep shut off. It rarely runs as it is due to heat rising. I do know that I had an extremely difficult time getting the air out of the upstairs zone due to the air being higher than the system. 
    The Teflon tape meets the code requirements here in Michigan per the inspector. He actually preferred it. 
    I will probably fire the system up with in a few weeks to verify operation.

    Thank you for your insite. All the info is greatly appreciated. I am learning as I go.

    Eric