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Couldn't find a discontinued Wirsbo Manifold Valve, what can I do?

LilyM Member Posts: 19
Hello there,

I noticed some leak of my 20-year-old brass Wirsbo manifold (see pictures attached). I probably need to replace the valve, which looks like part# A2450028. Unfortunately it's discontinued and I couldn't find one online. What can I do next?

1) wait until summer to take apart this valve to see if I can find a matching o-ring and rubber disc and rebuild the valve? or
2) request my local HVAC company to replace my whole manifold? There could be a long wait due to parts shortage and their busy season schedule.

The line is heating my main floor, I need the heating in this cold season. The leak is currently going at one drop every 3 seconds. I'm afraid the leak can pick up speed during the wait. What should I do during the waiting period besides catching up the water everyday? Any advice?

Thanks a lot!


  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,542
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,542
    This is a ways down on that page I linked.

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • Peter_26
    Peter_26 Member Posts: 127
    edited December 2021
    It's interesting that the only one that is leaking is skewed compared to the other valve actuators. I think the valve body is leaking because it's not seated properly. What do you guys think?

    The pex fitting is loose or did you just loosen it to work on the valve?
  • Gilgo
    Gilgo Member Posts: 5
    If you remove the actuator, you will find a packing nut on the valve assembly. More often than not, slightly tightening the nut will stop the leak. Good luck!
  • PGB1
    PGB1 Member Posts: 42
    I don't know if this will be useful, but I'm hoping it will save you a service call & make repairs easy for you:

    A few years ago, as a favor for an elderly person, I was presented with the same problem that your manifold is experiencing. The leaking connection also looked titled tiny bit, as Peter pointed out on yours. She said hers was fine for years, then suddenly leaked. (It was spritzing.)

    Since it was important to keep her heating up and running, I tried an o-ring from a local hardware.
    Wiping inside the port to get rid of any possible contaminants & installing the o-ring with a tiny bit of synco lube synthetic grease worked. I ran into her a year later and she said there are no leaks. My foggy brain says that there were two o-rings to change, but I'm not positive. Stuff falls out of my memory quickly these days.

    I very much apologize that I didn't make note of the o-ring dimensions, but I remember it was metric. I left some spares at her manifold, but sadly I can't go back and check the size label for you. (She was called to her reward & the house sold.)

    I hope you can have equally quick and painless success!


    PS: I suggest you put a dab of anti-seize paste for copper on the threads before re-assembling. It won't do any leak prevention, but will make it easier for future service people to disassemble. Keep it off the o-ring, as it's petroleum based and may damage the rubber.
  • psb75
    psb75 Member Posts: 637
    Good eye Peter_26! The actuator box itself is tilted. Leak coming from below knurled brass nut. I'd try the o-ring fix suggested by PGB1.
  • LilyM
    LilyM Member Posts: 19
    Thanks everyone for suggestions! My valve looks like this one (picture below) at supplyhouse. It looks like to have one o-ring and one rubber disc.
    I have some 12 point nut sockets in my SAE/Metric tool box. I found both 3/4" & 18mm socket seem to fit the hexagon nut. But the hexagon nut is very thin, ~2mm thickness. If in the process I damage the nut, then I won't be able to loosen or tighten it any further. Would a 6 point nut socket fit better than a 12 point? Maybe I'd better shop for a 6 point nut socket first before I try to loosen the nut?
    This manifold is on my 1st floor. I have another manifold on the 2nd floor above. Before I remove the leaky valve of the affected loop, I should shut off the two red-handled ball valves on the left side of my picture to isolate loops in this manifold - is that enough? Would the water in the affected loop stay the same amount/level or get drained by some force I don't know yet?

  • hot_rod
    hot_rod Member Posts: 18,210
    A six point box wrench works best for me. You can see how it is gripping and keep good down force on it.

    Or a vice grip at some point, avoid too much squeeze as brass is soft and deforms easily.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • LilyM
    LilyM Member Posts: 19
    I removed the actuator and found the water is oozing out from the center stem, see picture. Does this indicate it’s more possible the leak is caused by the rubber end piece at the bottom of the valve not the o-ring near the neck of the nut?
  • rick in Alaska
    rick in Alaska Member Posts: 1,396
    I am pretty sure the Tru Flo actuators are different, but not sure.
    Those stems are common to start leaking. They have a very tiny o-ring around it that will build up a little scale, and sometimes if you dribble a little light weight oil around them, and then work them up and down with some pressure on the stem, they will clean up and reseat.
    If you do need to replace them, I have had good luck with an end wrench on them, and then smack the wrench to break it loose.
    I can't believe your motor actuators are still working and haven't broken yet. That is unusual.
  • cooper185
    cooper185 Member Posts: 10
    LilyM said:
    Hello there, I noticed some leak of my 20-year-old brass Wirsbo manifold (see pictures attached). I probably need to replace the valve, which looks like part# A2450028. Unfortunately it's discontinued and I couldn't find one online.

    Hi LilyM, I replaced my 2008 motorized valves with thermal actuators in 2019. Not sure about your leak.   
    You might need manifold actuator adapter A2630028. The 4-wire thermal actuators (installed on my return manifold) are A3023522. Your post's pictures, including responses from others are helpful.

    Life is a river, changing at the blink of an eye.
  • LilyM
    LilyM Member Posts: 19
    Hi Cooper, thank you for the image and model#s. I've put in an order of Uponor TruFlow Jr (A2663223) to replace my old 3-port Wirsbo, I'm buying your thermal actuator (A3023522) too, together with Spacer Ring VA33 (A3019900). Maybe I should have bought the adaptor you mentioned (A2630028) instead of VA33.
  • LilyM
    LilyM Member Posts: 19
    Hi Bob (hot rod) & Rick, thanks for reply!

    Both of you posted detailed replies to one of my other discussion threads a year ago which were very helpful too. Bob had also posted a picture of manifold valves there, not exactly my model A2450028 but should have similar internal parts. I'm reposting Bob's words and picture down below, which may help others who want to try the route to rebuild the valve.
    "Here is an example of a rusty, sticking valve, and a disassembled version. I did lose the tiny snap ring :) that goes in the groove on the stem.

    You can get replacement o-rings at automotive or hydraulic repair shops, probably metric size.

    A few folks over the years have rebuild these actuator valves. The brass or stainless manifold body should last many years, and is either has rebuild valve stems, or rebuild them yourself.

    Top quality manifolds will have stainless steel stems. Some chromed brass, if the chrome is worn off, a new o-ring may not seal."

  • LilyM
    LilyM Member Posts: 19
    It ended up that I replaced this 3-port Wirsbo section with Uponor TruFlow Jr manifold. However, this new manifold is a little longer in length/width. I kind of stretched the plastic tubes underneath to reach it. Luckily, this panel consists of 3+2 ports, the stretch worked. But I do have other panels in 4+4 configuration, which I'm afraid the tubes might not be flexible to reach. I counted that I have 30 old valves in the house. I prefer rebuilding fouled valves than upgrading the manifold sections.
    Here is the valve I took apart. Getting the 3 o-rings probably won't be a problem. But what about the rubber disc at the bottom of the stem (in blue)? Where can I get it? Has anyone successfully rebuilt this kind of valve?

  • cooper185
    cooper185 Member Posts: 10
    LilyM, Here's how I fixed my stuck valve (I didn't!!):

    I jimmied the stuck valve permanently open. Whenever I want heat in my bedroom, I turn up a different room's thermostat. Rebuilding a valve means draining the system, which I'm not going to do. Without a floor drain, it was a pain purging air while filling the system's zones with water upon the initial 2008 installation. I had to run a hose outside through a basement window. I did this in the summer.

    Even with a floor drain, I can't see why you're replacing valves in the dead of winter. Good luck!

    I replaced my old forced air furnace and water heater, tore out the flue and all the plenum ducts in the attic and the crawlspace. The cost of a new boiler, even for a DIYourselfer is very expensive. I'm dreading whenever my TriangleTube Solo 110 bites the dust. At age 71, I can't do that kind of work anymore.

    Life is a river, changing at the blink of an eye.
  • Dave Carpentier
    Dave Carpentier Member Posts: 410
    Thanks for posting those o-ring measurements. When I take my system down this year, I plan on trying to refurb the same A2450028 valves in my (22 yr old) Wirsbo round brass manifold.
    I was also surprised to see a family of 20 yr old MVAs. I started with 7 of them. I had 3 replaced on warranty and replaced the end switches (NTE S46 microswitch) in others. Once the novelty of repairing them wore off, I just started changing them out to thermal actuators (and yes, the correct adapter does not come in the thermal zone valve box.. needs a different one for those old manifolds).
    30+ yrs in telecom outside plant.
    Currently in building maintenance.