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air purge valves for baseboard hot water


I'm a young and relatively clever new home owner. The place is a 3 story farm house, VERY well insulated (to my delight) but completely lacking in heat, lacking in basement, and lacking in a good place to put a boiler in the house. I picked up a dandy wood fired boiler, rated at 150K, 300K BTU MAX. It's in the garage hooked up to the house via underground PVC pipe tunnel. This is completely new to me but I think I have it under control. Upon a test fill tonight, and discovering that my emergengy relief valve leaks, it occured to me that I'm probably going to need to put air purge valves in the line SOMEWHERE. I've done the whole thing out in red 3/4 inch O2 barrier PEX. My guess is, and this is why I'm asking, because its only a guess, is that I should put them on the highest point just before the line drops to return to the boiler, am I right? What should I use for a purge valve? is there something that's really convenient for PEX? seeing as I've already crimped everything together? I seem to remember my grandfather having these copper sweat elbows with little valves in them (with wooden knobs, so pretty old) I could use those on the riser in to the fin tube probably? I also have the unique situation where stuff drops under sinks so I could get away with all sorts of things. Anybody have suggestions?

Next quick question... mice... and sunflower seed shells... The boiler is old and was taken out of service pretty much right after it was installed, and the mice moved in a handful of sunflower seeds. I ran the thing out in the driveway before I brought it in and washed out most of them and heated it up to boiling and let the steam pour out for a few minutes.... Should I worry about these? or will they soften up and settle in the boiler?


Andy Baker


  • Chuck_7
    Chuck_7 Member Posts: 71

    I'm not answering your question, but not for nothing, you have an expansion tank, right?
  • Andy Baker
    Andy Baker Member Posts: 5
    re(2):air purge valves for baseboard hot water

    Yes I have an expansion tank - There's the air scoop (flowing the correct direction), with the automatic purge valve on the top and the diaphragm tank on the bottom. Should that valve be enough to purge the system? I had originally thought I might be able to just fill the thing, flip on all the circulators, and let it run overnight cold, and that eventually, the bubbles would work their way out, but I'm not getting the feeling that it's such a good plan anymore.

  • Brad White_2
    Brad White_2 Member Posts: 188

    There, I feel better now.

    If the relief valve is weeping, check your system pressure, expansion tank or not. If all small piping as I think you said, a size 30 tank would accomodate a lot of that. If parts are an older gravity system (doubtful but for comparison) do a volume take-off and size it correctly.

    Now- the make-up valve. Is it too weeping by? Or do you even have one? Let's eliminate that relief valve issue first and go on to purging.

    You can use baseboard tees at high points, or automatic vent valves, sure. What is more common is a purge valve set-up at your boiler. Just a ball valve on the return prececed by a tee and hose-end drain valve. Pipe up a hose with make-up water on the supply side, close all valves to other zones including the one you are purging, and run a hose from the purge drain cock to a sink or outside. Let her rip. After a few minutes, when the stream runs clear with no "air embolisms", that is a good place to start. Purge your circuits one by one.

    Treat yourself to a SpiroVent if you can, upstream of your main circulator. That will remove the air released by the heating process over time. Once heated, run each circuit one at a time throgh the SpiroVent to release each circuits' initial heat-released air. After that, the SpiroVent "polishes" the water of air over time.
  • Andy Baker
    Andy Baker Member Posts: 5
    Purging (and that relief valve)

    Thanks! That relief valve is surely toast. After removing it, I could easily blow air (by mouth..eeeew)through it in it's closed state. I took it apart to find that the rubber gasket / seat condition to be poor to just plain NOT THERE. The makeup regulator is brand new and seems to be working properly - 12 PSI I think it is... and is properly plumbed in place, ready to supply fresh water. The tank is a 30 - the larger of the two available at HD. It has an automatic vent on it's air scoop. Shouldn't that polish out the air too? (spirovents are expensive!!)

    As far as purging, you're saying I can purge from the boiler? Sounds good to me, but my vertical runs are kinda funky going to the upper floors - Could I put purge valves on the tops of the drops too? shouldn't hurt to do both, right?

    Thanks a bunch!! I can't wait to have heat!! PS - any input on the sunflower seed shells? I think most of them are gone... but there might be those few...
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    On purging, air elimination and sunflower seeds...

    Andy, I've attached a drawing to show you how to set up the system so it can be power purged. This will eliminate the majority of the free air, and then the air scoop (adequate, provided your corculator is down stream of it) will remove any remaining free air. The sunflower seeds may come back to haunt you, and jam up the circulator. You could install an wye strainer before the pump and get them out, or wait for them to plug your pump impeller vanes.

    Good luck!


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  • john@TR
    john@TR Member Posts: 26

    I think you have it backwards, shouldn't the draw-off be on the other side of the ball valve in the return?
  • Andy Baker
    Andy Baker Member Posts: 5
    Thanks Mark!

    Thanks for the diagram. I actually went the route of individual zone pumps rather than zone valves. I also set up purging kinda like what Brad White suggested, with the ball valves and relief vents. I used those little green Taco cartridge pumps, and located them high on the "HOT OUT" side of the boiler - I read that this was a good thing to do if you have to heat upper floors of a building. They're also pretty high near the ceiling, - about 9 feet off the ground in the garage, 12 which I did for two reasons - reducing the "head" that each pump was faced with, and keeping the footprint small. Alsi keeps most of the hot plumbing near the ceiling, which I reason will keep convection down and hence, heat loss.

    Next question I have, or more like a "is this OK?" thing is now I have this big bundle of HOT pex in my garage. My thought, since it's not a nice shiny metal, and hence suffers more radiational losses from increased emmisivity of the plastic, is that I should first wrap it in an aluminized insulation, or even renyolds wrap, THEN in the fiberglass or foam covering. I think it's a great idea :-)


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