Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Pressure relief valve dripping

Rongold Member Posts: 21
edited May 2021 in Oil Heating
Hi all,

I just drained flushed and refilled my Weil McLain WGO6 boiler with fresh Cryotek -100 anti freeze---about a 40% concentration as I have 1 zone where the baseboard pipe comes up out of the slab past the sheetrock and insulation. When the house was built, instead of fixing it properly, the installers just put an elbow on the pipe and ran it back into the room. While I had the system drained, I changed both air vents and replaced the 20 year old pressure relief valve. The new valve is rated at 30 pounds and 535,000 BTU's just like the original. It was great for about 2 weeks and all of a sudden I noticed a wet spot under the pipe that's connected to the exhaust port of the valve. The pressure gauge on the boiler never goes above about 15 pounds, and I verified that with another gauge that I connected to one of the zone bleed valves. They both read within 1 pound of each other. It's not a bad leak---Maybe 1 or 2 drops a day. Should I "flick" the release lever on the valve ??? Maybe there's a microscopic piece of dirt in there, or the valve needs to be reseated---Or should I leave well enough alone. I really don't want to have to drain down the system to replace the valve and lose my new anti freeze.



  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    Tell us more about your system/pics.
    What's the pressure in the system, hopefully confirmed with a standalone gauge.
    Do you have an auto feeder attached? If so hopefully with a back flow preventer, required for glycol systems. It's possible your autofeeder is allowing water past it, causing your system to overfill.

    There is air in the system that needs to be purged, and depending on how the boiler is piped, the expansion tank type/location, and air elimination isn't optimal.
    You could have a failed expansion tank (bladder) or water logged (steel).
    If your boiler is used to heat domestic hot water, you're coil could've developed a pinhole leak, and is pressurizing you boiler with street pressure.
    Or a combination of the above.

  • Rongold
    Rongold Member Posts: 21
    edited May 2021
    As stated in my original post, I have 2 gauges in the system--One reads 15 pounds and the other reads about 14 pounds. New expansion tank and new pressure relief valve. NO tankless DHW, and after filling the system, the water feed valve is off. I have a friend whose pressure relief valve decided to relieve itself while he & his wife were at work--Came home to 8" of water in his basement. Since then, I keep mine off and check the pressure periodically. This is a BRAND NEW RELIEF VALVE--An Apollo 10-407-05. I think there's a microscopic piece of dirt stuck in there. When I was filling the system, I opened that valve for a second to get the air out of the short nipple & elbow feeding the valve. Should I give the valve "a flick" to wash out anything that possibly got stuck in there ???

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,600
    edited May 2021
    Ron, You probably have that micro-piece of dirt you mentioned. To properly flush it out you will need to pop open the valve for at least a few seconds then allow the spring to snap it closed. Wait a few minutes to see if it stops leaking. If it still drips, then do a quick pop again to see if it will reseat. I have actually tapped on the valve handle with a small hammer or crescent wrench to assist in getting the valve to seat properly. If you can't get it to stop dripping, then replace the valve.

    Rare but I have had this problem and just chalk it up to a factory defect. I dought if there is any warranty available but they are inexpensive enough, but you can always try.

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • HomerJSmith
    HomerJSmith Member Posts: 2,406
    That isn't right, you can try the previous suggestions and see if that helps. Could be a defective valve.

    The concentration of Cryotek at 40%? Is that a dilution based upon the sticker on the pail or a refractometer measurement? Cryotek 100 is a diluted product, so I always use a refractometer for measuring.

    Glycol squeezes thru everything. Where I wouldn't have leaks with water, I have had leaks with glycol.
  • Rongold
    Rongold Member Posts: 21
    Just want to let everyone know that I ran about a half a pint through the valve 2 times on Wednesday afternoon, and here it is Friday afternoon and there have been no drips since.

    To answer Homer, it's an estimate based on the chart on the pail and the calculated volume of the boiler & piping. As I described in the original post, I have one spot in one zone where the baseboard piping comes up out of the slab past the sheetrock and insulation, behind the brick on the front of the house. It froze on me a few times---Luckily, it never popped. I just need a little protection to stop it from freezing---Slush is OK, but not ice.

  • mattmia2
    mattmia2 Member Posts: 9,469
    What is the concentration of cryotek 100? a lot of reading of the jug didn't seem to reveal that.

    I know it isn't fun, but maybe it would be worth breaking it up and moving it in to the heated space instead of dealing with glycol. I wonder if there is something out there that opens that zone valve and runs the circulator for a couple minutes once an hour if it doesn't have a call for heat.