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need idea for condensate drain

Effer
Effer Member Posts: 9
I recently installed a LP condensing boiler in my shop but unfortunately didn't plan for the condensate when building the shop (rookie mistake) so I'm currently using a bucket and having to empty it daily.
I thought about going thru the wall with a drain to the outside but have concerns about it freezing up. It's been -20F here the last few mornings. Was wondering if anyone has successfully run a drain to the outside and was able to keep it from freezing up?
Thanks in advance for any creative solutions.

Comments

  • GroundUp
    GroundUp Member Posts: 1,495
    I run into this about a dozen times a year. The heat tape/trace route is only a band-aid in most low temp applications (like radiant slabs) as it will still freeze as soon as it hits the end of the trace, eventually building up to a point that it freezes into a big ball and plugs the drain anyway. Is there a floor drain anywhere in the shop? If so, how far is it away from the boiler?
  • JUGHNE
    JUGHNE Member Posts: 10,291
    I have had this problem.
    What has worked is to add a condensate pump for the furnace/AC.
    Run the discharge hose up to the ceiling with a "hump" and then down on a good slope to the outside wall.
    Then on the inside of that outside wall have a 3/4" PVC drop down to about 2' above grade. Use a 45 inside so the pipe exits the wall at that angle. Leave about 6" out of the wall.
    The 3/8" hose is simply stuck deep into the 3/4" drop pipe. Leave an air gap where these join. (If by chance the outside freezes shut then you have water on the floor inside.)

    The pump runs sending a batch of relatively warm water up over and down the drop pipe and shoots it outside. This eliminates most the the dribbling drainage that could freeze the pipe shut. The next batch would clear any minor freezing coating the inside pipe.
    The "hump up" above the pump aids in the tubing draining by syphoning.
    The 2' height makes the water clear the end of the pipe and prevents the ice formed outside from growing up to the pipe. (Same reasoning for raising HP because of ice from defrost cycle).

    It has happened that with buildings even with sewer drain lines that the sewer main would freeze outside underground if there was no other draining activity.
    The dribble leaves the building underground and starts to freeze forming a glacier inside the sewer. Same problem with a running toilet in say a church, used once a week. Depends upon depth, less than 4' here sometimes, north side with no sun or some years with no snow cover.
    Have had it happen when a small stream of water is left running to prevent the water service from freezing.....but the sewer line freezes shut instead.
    mattmia2kcopp
  • I'm staying in California.

    You guys are a tough bunch! Freezing pipes, dealing with glycol, a/c............We've just got earthquakes and forest fires out here.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
    ratioErin Holohan HaskellEdTheHeaterMan
  • JUGHNE
    JUGHNE Member Posts: 10,291
    Eventually they may not let you (taxpayer) leave anyway. :|
    Alan (California Radiant) ForbeskcoppEdTheHeaterMan
  • mattmia2
    mattmia2 Member Posts: 7,165
    I suspect some creativity with fittings could create a reservoir and a siphon loop that will fill to a level, start the siphon, and drain the reservoir similar to the old urinals with the slow filling tank that would flush every 15 minutes or so to create a slug of water similar to the condensate pump.
  • JUGHNE
    JUGHNE Member Posts: 10,291
    That is an idea, would work if elevations worked out.
    I "saved" one of those syphon flusher devices during a RR remodel, someday I'll post a picture with a "what is it" header.
    The water entering would have to come in from above.
    The discharge flush would have to be below the flusher.
    The one I have is brass/copper and would become eaten away by condensate water,
    so working one would have to be PVC.

    Pumps are pretty cheap.
  • HomerJSmith
    HomerJSmith Member Posts: 1,923
    edited January 2021
    JUGNHE, Boy do you have that right. California wants a wealth tax that you have to pay every year, kinda like an Inventory Tax and the politicians want you to pay an exit tax for ten years on the income you earn elsewhere if you decide to improve your life by moving to Texas, etc.

    Good luck, Alan. California is desperate for Moola. It's good that producers like you can provide it. But, how long will you be willing to work for free?

    I'll take the cold.

    By the way folks, copper commodity prices are at a 8 year high. What's that going to do with your copper costs? Maybe time to increase your inventory?
  • JUGHNE
    JUGHNE Member Posts: 10,291
    Reminder of the Wall days of Berlin, at least then and there you had to make only one payment (bribe) to escape to the west.
    Not the 10 year follow up.
    However, I was told that that was tried years ago and surprisinly got voted down.
  • mattmia2
    mattmia2 Member Posts: 7,165
    Ask a former west german what kind of tax revenue they had to generate to put the east back together after the fall of the wall...
    HomerJSmith
  • Effer
    Effer Member Posts: 9
    I have a floor drain that's about 30' away but would prefer not to trip over a hose. I like the idea of pumping up to a hump with a flush to the outside but might wait for summer weather to implement.
    Thanks for the ideas!
  • JUGHNE
    JUGHNE Member Posts: 10,291
    And if it just dribbles into the sewer drain, with out a WC flush maybe twice every day, you may end up with the frozen sewer line.
  • kcopp
    kcopp Member Posts: 4,091
    I have done the steep pitched pipe to the outside through a wall. 3/4" pex.
    I then place the 3/8" condensate hose in the top. Works fine here in NH.
  • Le John
    Le John Member Posts: 211
    @kcopp and @JUGHNE can you post a diagram if possible. Those ideas sound interesting and I’d like to explore both of them.
  • PC7060
    PC7060 Member Posts: 912
    edited January 2021
    Make sure you have run condensate through neutralizer before dumping into drain. Acidic condensate is a bad idea if you have any cast iron in the drain system. 

    I ran a PVC line under my slab to drain the condensate into the sump/foundation drain tiles.  Thirty thousand pounds #57 crushed stone makes a pretty good neutralizer. ;)
  • lkstdl
    lkstdl Member Posts: 29
    I've never seen this done before but I haven't been able to figure out why it would cause a problem:

    If your combustion exhaust pipe also runs through the wall, you can run the condensate drain pipe concentrically right inside of it, so the warm exhaust prevents any freezing.

    Put a Wye on your exhaust pipe just before it goes through the exterior wall. The angled part goes back to your boiler like normal. On the straight part, put a 3" to 3/4" bushing, and run your condensate drain through the bushing, out through the wall, and another couple inches past the end of your exhaust pipe.

    If the exhaust pipe exits the building low enough, you don't need a condensate pump.

    We did this on a furnace install about a month ago and so far its been working great. I'll try grab a photo of it tomorrow.

    Luke Stodola
    PC7060GroundUp
  • mattmia2
    mattmia2 Member Posts: 7,165
    Since it is not in the manufacturer's specified exhaust configurations it would be a code violation on top of being dangerous.
  • HomerJSmith
    HomerJSmith Member Posts: 1,923
    edited February 2021
    Condensate needs to be run thru a neutralizer before dumping it outside.

    How about using heat tape with foam insulation on the condensate drain that is exposed to the outside. That would keep the condensate flowing.
  • JUGHNE
    JUGHNE Member Posts: 10,291
    Homer, what would the raw condensate do to the outside ground?
    GroundUpkcopp
  • lkstdl
    lkstdl Member Posts: 29
    Mattmia2, while I certainly agree that it is not part of the manufacturer's specified exhaust configurations, I am struggling to understand how it would be dangerous. I'm not disagreeing with you, just looking for a more detailed explanation of what the issue would be.

    Thought experiment: would you be allowed to run the condensate say 6 inches away from the exhaust pipe? Or what about right next to it? So what does running it concentrically change about the setup?

    Here's a picture that might make things more clear.


    Jughne, depending on what you had planted outside, the acidic condensate could injure or kill it. Certain plants tolerate acidity better than others.
    Luke Stodola
  • JUGHNE
    JUGHNE Member Posts: 10,291
    So that 3" exhaust slopes down to the outside, any freezing problems as it drips outside?

    There are some plants you want to get rid of. :|
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 4,941
    edited February 2021

    I like the idea in that picture. What does the outside look like? How far above the ground does it terminate? Does the 3/4 extend past the 3" or does it stop just before the 3" exhaust termination?

    I can picture an icicle stalactite and a matching ice stalagmite on the ground when the temps get really cold. Will the exhaust temperature be enough the keep the exhaust opening clear?





    I like the condensate pump idea where there is a surge by the pump and a long pause before the next surge. Less chance of the condensate freezing from the slow trickle of a gravity drain design. The automatic self-siphoning "Pythagorean cup" design is even better, with no moving parts.
    Edward Young Retired HVAC Contractor & HYDRONICIAN Services first oil burner at age 16 P/T trainer for EH-CC.org
  • lkstdl
    lkstdl Member Posts: 29
    Ed,
    The 3/4" line goes a few inches past the end of the 3" pipe.
    In my case the lines exit the building about 22 feet off the ground.

    Haven't had any issues (so far) with icicles, but this is for a 120K btu/h furnace with short ducting, plenty of filter area, and 55F return air temp, so the exhaust gas is pretty dry and the condensate flow is strong whenever it is running. I would imagine that a boiler modulated down to 30K btu/h with 130 return water temp may have more icicle problems.
    Luke Stodola
    EdTheHeaterMan
  • HomerJSmith
    HomerJSmith Member Posts: 1,923
    Jughne, Running the condensate thru a neutralizer will give you a PH of 7. I don't think it will make much difference to the soil, but whatda I know. What's worse is putting condensate with a PH of 3.5 into a sewer pipe. Outa sight outa mind. In our area we have Transite sewer pipe and I see installations all the time without a neutralizer, gasp! In a mod-con you can get 5 gal of condensate in 4 days when the outside temperature drops.

    Effer, can run the condensate out of the house and insulate the condensate drain and bury the pipe 16" to 24" underground into a serrated 4" plastic drain 10' long and if the soil perks that would take care of the problem.
  • JUGHNE
    JUGHNE Member Posts: 10,291
    Those pipes both dripping from 22' up would not work here, with the wind we have the water would not reach the ground below the pipes most of the time. It would whip around and freeze on everything, house and windows, sidewalk etc.

    I have seen condensate erode/etch concrete in my basement where the drain hose was 6" away from the floor drain (now corrected). I have all PVC drain/sewer, probably +400' of PVC to old sewer line which is then clay tile.
    Within that 400' there are 2 other houses. I am counting on diluting any acid with probably 30+ WC flushes a day.

    A bit of copper or brass on the end of the neutralizer or pump drain hose will tell you if it is effective or not.

    Homer, what materials are in the composition of Transite sewer pipe?