Continued saga of my problematic 18' AC condensate line...

wcweaver3

Hello!

I've posted before about my 18-foot AC condensate line that runs above my living room ceiling and behind a knee wall....and that it broke and poured an ocean of water all over my living room. This line serves a Unico system with the mechanicals in a second-floor bedroom closet. The line runs behind a knee wall, in an unheated space, for 18' until it exits the house.

For about the first 9', this line has an appropriate slope as it's attached to the underside of the roof. Then, because of an intervening window that interrupts the knee wall, the line then runs horizontally, with no slope, for the remaining 9 feet until it exits the house.

Somehow, it appears water remained in the line over the winter, it froze, and broke the line. Two HVAC companies have told me that there is no real good way to run the line except where it is now (9' with a slope, then 9' horizontally.) To rebuild the line as it is now costs in the high three figures. Both HVAC companies, in addition to rebuilding the existing pipe, proposed a convoluted pump system because I asked for it. It's complex, noisy and essentially doubles the price so I am now in the low four figures for cost. Seems like a lot of unnecessary complexity and cost to me.

My strategy is to rebuild the line, as is (9' with a slope, 9' with no slope) and then after the cooling season, run a non-toxic, PCV safe anti-freeze in it so it either mixes with any remaining water or pushes it out.

Question: This problem has caused so much rebuilding and remediation cost and chaos that I want to make sure that the antifreeze is in the pipe. Is there some way to build into the pipe some type of window (much like a "sight glass" on old auto AC systems) to ensure that the antifreeze is in there? Maybe splice into the line a clear section so I can take a look? I don't know of a clear PVC, or a section of PVC with a window in it, but maybe there is something that I could use?

Any thoughts and recommendations are most welcome. Thank you!!!

pecmsg

wcweaver3 said:

Hello!


My strategy is to rebuild the line, as is (9' with a slope, 9' with no slope) and then after the cooling season, run a non-toxic, PCV safe anti-freeze in it so it either mixes with any remaining water or pushes it out.

Gravity drains must maintain 1/4" per ft downward slope the entire run! Your 9' un-sloped section invites a blockage.

Jamie Hall

My apologies, but I find it very very hard to believe that that Unico is carefully set in such a way that there is nowhere within 18 feet that the drain line can't be run with a proper slope. No other outside wall? No interior plumbing stack?

Use your imagination.

109A_5

Hello @wcweaver3,
The window goes to the outside of the house ? Have the drain exit the house just before the window. Maybe more pictures of the complete drain run would help.

As far as antifreeze, once the AC season is over just flush an overwhelming amount of antifreeze through the drain pipe. Just make sure the AC can't come back on and dilute the antifreeze.

The problem with antifreeze is if you forget or it gets diluted you are back to damaged pipes and flooding.

Since I bet your last 9' is actually pitched the wrong way trapping or puddling water, maybe a bigger diameter horizontal pipe to maintain an appropriate air gap (along the whole length), allowing for the freezing water expansion without shattering the pipe may work.


Also have a easy means to flush out any crud, since there may still be a low spot that can collect crud, and maybe a slight lip at the exiting end of the larger pipe if it is reduced to go through the wall (Eccentric Reducer fitting).

pecmsg

Jamie Hall said:

My apologies, but I find it very very hard to believe that that Unico is carefully set in such a way that there is nowhere within 18 feet that the drain line can't be run with a proper slope. No other outside wall? No interior plumbing stack? Use your imagination.

There are no problems 
there are only solutions!

JUGHNE

Do you have a basement or crawl space?

Is the AC on the second floor?

If yes to both then I have an idea.

realliveplumber

Winterize it. Just vacuum out the line before winter.

EdTheHeaterMan

What is below the air handler? a fully, open-space, atrium of space with no walls? Are you sure you can not go straight down into a closet or wall below? Opening up a sheetrock wall to run a pipe from the attic to the basement is just doing the renovation before the leak instead of after the leak.

wcweaver3

Hi - thank you all for the insightful comments and thoughts.
The Unico system is in a 2nd floor closet and that closet that, of course, has 4 walls. One is a door that opens into the bedroom, one is wall that is part of the upstairs hallway, one is wall that is the knee wall where the condensate pipe currently runs, and the final wall would open up into the stairwell. The house does have a basement and yes, it does have a second floor where the mechanicals are now. Going directly below the air handler would put you in the downstairs hallway/stairwell - so the mechanicals are sort of "perched" over the stairs going to the second floor. There is a bathroom on the second floor, but to access that plumbing stack means tearing up maybe 10 to 15 feet of hardwood floor.

Below is a picture of the outside of the house with a black line showing where the current condensate line runs behind the knee wall. As you can see, the upstairs window is in the way, so you can't get any slope for the remaining 9 feet (although I've drawn it so it sort of looks like it slopes, it doesn't). I also thought about running it down into a closet and then into the basement, but both HVAC companies has said that's not workable because of the location.

You could go directly straight out from the knee wall, but that puts the pipe poking out from the roof which seems really odd and is probably a problem. The two HVAC companies that have looked at it can't come up with any better solution. JUGHNE suggests an idea if the house has a basement and the mechanicals are on the second floor, which is "yes" to both - so I am open to that as well as additional ideas from anyone else.

bburd

Why not run it into that rain gutter below the window?

Jamie Hall

bburd said:

Why not run it into that rain gutter below the window?

That's too easy.

JUGHNE

If there was a wall below the mech room that you could drill thru the top plate and the bottom plate into the basement a pipe could be installed inside the wall.

Having done a fair amount of rewiring in old houses, I would find that inside wall and drill thru.

An 1/8" bell wire bit and a wire from a coat hanger to mark the wall top and bottom holes.

Careful measurement would keep your large drill bit inside the walls.

If you drill thru carpet, run the drill in reverse first thru the carpet, to avoid pulling a thread and then forward thru the floor/ceiling.

If I had to use a 90 that would be later inaccessible, I would use a electrical PVC sweep 90 ( the grey type).

I see masonry chimneys there. They usually have a chase around them from attic to basement. Maybe there?

Bburb has a good suggestion, IMO, if all else fails.

HVACNUT

You should definitely be able to snake a 3/4 PVC pipe down the roof line into the gutter. What are we missing that the two AC companies saw?

SuperTech

60 seconds with a shop vac attached to the end of the drain line once a year will solve the problem. 

wcweaver3

Hi - thank you for the valuable, continued discussion. Below is a picture of the space behind the knee wall. As you can see, there is the condensate line with a decent slope for the first 9 feet. Under the insulation is a rudimentary floor with joists. If you take a drill and drill straight down where the rudimentary floor of this knee wall space meets the roof, you open up a hole in my now newly renovated living room ceiling. The issue is that the roof continues beyond the exterior wall. When the ceiling was removed, the HVAC company saw it and said the drainpipe would have to come down into the space just above the living room ceiling and then take a right angle to go through a pretty thick brick and stone wall to the outside. Now that the ceiling is almost complete, it would mean probably tearing that up, again, if I wanted to pursue that. The HVAC company really discouraged that and suggested it wasn't "doable." Any additional thoughts are most appreciated!

109A_5

Hello @wcweaver3,
Well, I was hoping to see the problem area. The bottom of the rough framing of the window is only an inch or two above the second floor floor sheathing ?

HVACNUT said:

You should definitely be able to snake a 3/4 PVC pipe down the roof line into the gutter. What are we missing that the two AC companies saw?

Liability maybe, what if the roof leaks after the penetration is made. There is already damage, they probably don't want to be responsible for more.

yellowdog

run the drain out thru the eaves and down the outside of the house. cover it up with some slimduct.

ChrisJ

After fighting with a condensate issue for a few months I finally ran mine down the outside of the house.
I didn't cover it with anything because everything I've seen will stand out more than some 3/4" PVC. The PVC can be easily painted as well to blend in.

Do I like having it on the outside of my house, including a 20' horizontal section? Absolutely not.

But I like it a lot more than fighting with sweating, leaking, clogging etc. 9 times out of 10 I'll choose functionality over cosmetics.

Jamie Hall

I simply find it quite impossible to believe that if you were to run the line up against the roof, following its slope, you couldn't find at least a 1 inch space at the outer edge where the roof meets the plate where the pipe couldn't exit behind or into the gutter. Not going through the shingles. Even if the rafters and therefore the roof don't overhang the plate at all at the outer edge -- and they might not --you could take a 1 inch notch out of the place and go out through the wall.

I mean.. maybe your roof/wall framing detail is weird, but I've never seen a situation where that couldn't be done.

ratio

If the discharge line from a pump ends up below the intake, it'll syphon itself dry at the end of each pump cycle. Install a pump, wire in the shutdown contacts, run the line along the same path & take it down to the bottom of the line hide.

You could even do it yourself, if you're ok climbing a ladder to the top of the line hide.

109A_5

Hello @wcweaver3,
Google's answer;
What is the most freeze resistant water pipe?
"HDPE pipe's temperature limits help it remain ductile below freezing and it can withstand temperatures down to -94°F (-70°C). HDPE piping's flexibility and elasticity allow water inside the pipe to freeze and thaw repeatedly without causing permanent damage."

In this case, it is a drain so there is no preexisting pressure bias, so it may perform even better than HDPE that is pressurized.

ChrisJ

109A_5 said:

Hello @wcweaver3,
Google's answer;
What is the most freeze resistant water pipe?
"HDPE pipe's temperature limits help it remain ductile below freezing and it can withstand temperatures down to -94°F (-70°C). HDPE piping's flexibility and elasticity allow water inside the pipe to freeze and thaw repeatedly without causing permanent damage."

In this case, it is a drain so there is no preexisting pressure bias, so it may perform even better than HDPE that is pressurized.

I'd pick black polyethene.

But... it's best to avoid freezing altogether and that flat horizontal run will be likely to clog as well.

wcweaver3

Hello Everyone - many thanks for the very insightful comments and robust recommendations. I've had some additional, "energetic" discussions with the HVAC company which included another visit to my home to take a look. After much review of the crawl space, run and roof line, the HVAC company now says they will be able to achieve the needed and required slope for the entire 18' run. It will require a little bit of cutting away of non-load supporting structures (notching), but they tell me it's "doable." So, I will say "many thanks to all!" and close the discussion.

pecmsg

Do Not “notch” any members. A hole saw does less damage!

ChrisJ

wcweaver3 said:

Hello Everyone - many thanks for the very insightful comments and robust recommendations. I've had some additional, "energetic" discussions with the HVAC company which included another visit to my home to take a look. After much review of the crawl space, run and roof line, the HVAC company now says they will be able to achieve the needed and required slope for the entire 18' run. It will require a little bit of cutting away of non-load supporting structures (notching), but they tell me it's "doable." So, I will say "many thanks to all!" and close the discussion.

pecmsg said:

Do Not “notch” any members. A hole saw does less damage!

Yeah.... Be careful.
There's a good reason so many carpenters dislike plumbers and hvac guys.