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Multi temp open system

I am posting this so you guys can tell me how many bad choices I’ve made and to get suggestions on how to take corrective action before I get too deep.

I live in an off grid cabin in the Columbia Gorge in Oregon. Elevation 2000’ so winters can be pretty interesting here. The cabin is 500 square feet. I share it with my fiancé and our dog so space is a premium. For the last 13+ years living here I have heated with a woodstove and heated my water with a Hilkoil coil in the woodstove. This works well but the woodstove takes up a lot of space in the middle of the house so I am wanting to get a smaller woodstove, move it to a better spot, and supplement it with radiant so our house doesn’t freeze if we go away for a day. Also, heating during the shoulder seasons with the woodstove has been problematic because we end up cooking ourselves out.

Next to the cabin I built a small bathhouse (96 square feet) which has our washing machine, shower, and our off grid power system in it. The bathhouse (96 square feet) is where I have my heat source which is a Navien NPE-240A. It is about 30 feet from the cabin. The pipes running to the cabin are 1/2” pex that is well insulated. It is in a 6” ADS pipe buried well below our frost line.

The bathhouse has Uponor Quicktrak system under laminate flooring and under the cabin I was going to install 1/2” Uponor Joist Trak panels.

I was hoping to just have it be an open system for simplicity (and inexperience with glycol systems) but am open to other suggestions. The cabin (288 square feet) has only one plumbing fixture (a kitchen sink) so I was thinking of just running a single loop to the cabin which would feed the radiant flooring as well as the sink. If that is a horrible idea I am open to running a second loop to the cabin just for heating.

Another thing I am having trouble figuring out is how to plumb the loop in the bathhouse since it needs to be so much cooler (maximum water temp 85 degrees) than the 120 degree loop feeding the cabin. I was thinking of using the Viega hydronic mixing block to control the temp of that loop or the Taco X-Pump Block but I have been wondering if there is another simple way to do it.

Should I just abandon the Quicktrak system and install the Joist Trak product under the bathhouse so the entire radiant system would be one temp and just two zones? At times I think that would be the cheapest and easiest solution. Should the radiant part of the system definitely be a closed system?

Suggestions?



Comments

  • Jamie Hall
    Jamie Hall Member Posts: 18,923
    Do you have enough space for a small indirect water heater? And enough power for a small pump? If so, it seems to me that your best bet is going to be to run the cabin and bath house radiant heat on a small pump from the indirect tank That will require one more pipe to the cabin from the bath house: one to feed the radiant from the indirect, one to return to the indirect, and one dedicated to the hot water at the sink. The bath house radiant can come from the same tank; the Viega 56160 is a bit pricey, but does include a pump which would be very handy indeed.

    The Navien would keep the indirect hot -- say at 120 or so.

    I do not like open systems of any kind. Particularly on small water supplies. The reason being that there is just too much opportunity for nasties to grow in the heating loops and then show up in your coffee... you could use glycol in the radiant loops, but I'm not at all sure you really need to. That really truly depends on your life style. If you and -- or -- your fiance are going to be there pretty much every day, and the place is reasonably well insulated, I doubt that it will go below freezing in the structure. The concern would be if you were going to be away for several days in cold weather. You are going to need to think about that in a more general way -- how are you going to protect the Navien? The expansion tanks? Those, at least, can't be glycoled, so I expect you have thought about that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • alifewithtrees
    alifewithtrees Member Posts: 2
    Jaime-

    Thanks for the response.

    Yeah we could do an indirect tank. Certainly not my preferred solution because of the space it takes up. It probably makes for a considerably more efficient way to heat though so that would be good. Running more pipe to the cabin isn’t a big deal though since I ran a big conduit between the buildings.

    If we go away for days at a time I will likely just leave the power on and the Navien on. It has freeze protection so it will keep itself from freezing as long as it has power and propane. Another reason to have the bathhouse heated is the off grid power system. The battery is lithium so it has to be above freezing to accept a charge from the panels. After living off grid for so long it doesn’t seem like a huge deal but if the power company ran a line near our place I would definitely ask them to drop a line for us.

    If you saw our water system you would probably be doubly concerned about nasties growing in our heating system… Our property is fed by almost 2 miles of mostly rusty old iron pipe from a spring. About 15 years ago the last of the wooden pipes were replaced. Best water I’ve ever had…. I’ll look into my options for making the heating a closed system. I appreciate the advice.
  • SuperTech
    SuperTech Member Posts: 1,792
    I don't mean to pile more problems on your plate, but keep an eye on that Navien.  They are known to have a lot of quality issues with their combi boilers and condensing tankless water heaters. Heat exchangers and the flue pipe collar O rings are known to leak flue gases, even on brand new units. Check your Navien regularly by opening it and looking for what appears like drops of brown oil on the black plastic parts. Thats a dead giveaway that it's leaking flue gas.
    alifewithtrees
  • neilc
    neilc Member Posts: 1,804
    edited July 2021
    SuperTech said:

    I don't mean to pile more problems on your plate, but keep an eye on that Navien.  They are known to have a lot of quality issues with their combi boilers and condensing tankless water heaters. Heat exchangers and the flue pipe collar O rings are known to leak flue gases, even on brand new units. Check your Navien regularly by opening it and looking for what appears like drops of brown oil on the black plastic parts. Thats a dead giveaway that it's leaking flue gas.

    I gonna say it,
    all the naviens are doing this bad thing,
    my parents have one showing all the symptoms,
    I'm curious why this isn't being discussed more thoroughly as it's own topic here on this sight,
    and yeah, I see that they advertise here , , ,
    known to beat dead horses
  • Zman
    Zman Member Posts: 7,328
    edited July 2021
    I have never seen a Navien post censored here as @neilc seems to be implying.
    Start a post about Navien and see for yourself.
    Navien sells at a lower price point. As with any product, the quality may be lower and than other more expensive brands.
    I am pretty sure anyone can advertise here...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • neilc
    neilc Member Posts: 1,804
    No, I am not implying censoring here, sorry if that's how it came across,
    just the surprise that this really hasn't become a pages long topic here,
    I read and respect all here, and I also follow youtube rabbit holes,
    (and don't misunderstand that as disparaging the tube either).
    sorry for the thread hijack.
    known to beat dead horses