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"remote outlet" for pressure relief?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by pybyr, Jan 31, 2009.

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  1. pybyr

    pybyr Minister of Fire

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    Now that I've already done this.... guess I should check just to make sure it is not a bad idea....

    In case my boiler ever goes into an overheat/ overpressure, I do not want it to shower itself or things nearby in water and steam-

    so I ran about 15 feet of 3/4 PEX from the relief valve up across the unfinished basement ceiling and then over and down into the 4" cellar drain

    I have never seen this done before (I am used to short downpipes from the relief valve aiming at the floor), but I assume that that's just because of the extra materials/ work? Or is there some code no-no? If there is a code no-no about this, is it a serious matter, or a nitpicky matter?

    Thanks

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  2. Fred61

    Fred61 Minister of Fire

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    I did exactly the same thing and didn't worry about code! Should I??
  3. steam man

    steam man Minister of Fire

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    It looks like it could be a serious code violation and the code is very specific about how a relief valve is to be piped. Water can build up in the vertical leg and stay there. This could affect its operation. The valve is normally piped to a "visible" location to see if it is leaking. I certainly wouldn't want steam going through an overhead pex line. The pipe does need to terminate a certain distance above the floor with no means of shutting it off, i.e. threaded. Ideally it should be piped near a drain. I would think you could use the standard method of piping but have it go into a funnel that is piped to a drain across the floor.

    Mike
  4. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Relief discharge tubes generally have to slope continuously downward, but are generally allowed to be piped to a remote location, so long as the piping is not restrictive.

    Generally - check your local code for specifics.

    Joe
  5. pybyr

    pybyr Minister of Fire

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    Thanks- in an old farmhouse basement with limited space, unless I go up and over, it is either going to be at nose height or something to trip over; I have no local code where I am at in the boonies, so this may be something where I make a calculated decision to deviate from the norm, and keep a close eye on it. Since I have the purple 8-way boiler water treatment, if anything shows up in the tube, it will be possible to spot it.

    Thanks, all, for the input.
  6. Eric Johnson

    Eric Johnson Mod Emeritus

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    Along these lines, I was wondering the other day if you could put the pressure relief valve on the return line, rather than at the top of the boiler. I have mine at the top and always have done it that way, but is there any reason why it has to be there? One thing I'm thinking is that the valve would be more susceptible to getting crapped up at the bottom of the system, but I can't see why the pressure there would be different from the top of the pressure vessel.
  7. DaveBP

    DaveBP Minister of Fire

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    I guess there are more than a couple of us pirates that just don't feel compelled to always do things the normal way.

    I'm also inclined to run my PR line over nearer the floor drain across the ceiling. My hope is that it does ever discharge it can go down the drain and not spread out over the floor and make a lot of steam down there with all my woodworking tools and lumber and everything else that will share the space with this boiler. Good point to slope it toward the discharge end but that first stretch vertically to the ceiling violates that rule.

    The best reason for coming out the top of the boiler that I see is that in an overheat situation it would vent out the hottest water first. Might cool it down quicker that way.

    Still, I think I would use steel pipe. At least that way when you go to the trouble to whack your head on it you'll have something to show for it; PEX probably wouldn't even leave a mark.
  8. Dave T

    Dave T New Member

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    Just wondering would it be more legit to run a longer threaded pipe under the PRV then pipe straight across the ceiling directly off of the PRV,in other words mount the PRV a few inches from the ceiling??Dave
  9. Fred61

    Fred61 Minister of Fire

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    I placed a tee on the output of the PRV and attached the vertical pipe on the upper outlet and attached a ball valve on the lower outlet in order to drain any water that might be present. Now I just have to remember to open it periodically.
  10. mtnmizer

    mtnmizer New Member

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    Interesting problem, one that I'm addressing is a similar manner. My basement wood boiler
    room doesn't have a floor drain, there's one in the utility room where the gas
    boiler sits but it empties into a lift station. I could run the PRV drain to it.

    I'm trying to envision the situation where the wood boiler would pop off the PRV,
    and the electrical outage with a full load of wood is one that
    keeps coming up on this board and that seems most likely.(another
    good reason for an ups inverter)

    My solution is to run a length of iron pipe up from boiler to near ceiling and
    mount the PRV up high and then pipe the drain out through the rim.. My plumber
    shrugged at the suggestion and noted that if the PRV leaks which some
    are known to do it is possible that my drain could freeze near the house
    and cause an over pressure event..ie ice blocked drain line. Frequent
    visual inspections?? Gauges, sensor small weep hole valve?

    I'm going to use it and just keep an eye on it..

    . Dan
  11. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    As long as there are no valves between the relief valve and the boiler, that's perfectly acceptable. It also makes replacement easier, since the relief valve is above the boiler, and you don't need to drain the boiler to replace it (since they do fail occasionally).

    Joe
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