Proper Way to Drain Condensate Discharge into Sewer Line

[charistomay]

When I bought my house I noticed months later that the condensate discharge lines (for my high-efficiency furnace and also my heat pump located in the basement) both drain directly into the sewer line (see attached picture for existing setup). It looks like the installer just took a 3/8" drill and drilled straight into the top of the sewer line in the basement and then just plugged the whole with the condensate line (3/8" vinyl tubing). It looks like there's some cement or sealant around the lines, so the connection seems firm given there is no pressure, but I'm pretty sure this is a violation of code. My concerns are, 1) if the sewer line ever got backed up, it could apply pressure and begin leaking at the point the condensate lines connect, and 2) more concerned about gasses potentially leaking back into the 3/8" tubing without some kind of p-trap present.

Photo of current location of condensate discharge...


In the near future I'll also have an additional 2 condensate lines added to the basement mechanical room, one being the discharge from a whole house dehumidifier, and the second being from a high efficiency condensing tankless water heater. Thus, I'll have 4 condensate lines in the basement mechanical room that need a place to drain. I want to correct the existing 2 lines (one from a high efficiency condensing furnace, the second from a heat pump), while providing a long-term solution for all 4 condensate lines that is compliant with code. Some more background info:
1) As you can see from the current sewer setup (see attached photo below), my sewer connection leaving the house is above the basement grade. Thus, there is a sump pump a few inches below basement grade (about 2' in diameter). The sump pump has two 2" pipes leaving, one being a vent and the second draining into the main sewer stack, which then leaves the house.
2) The sump pump operates regularly as water is used in the basement bathroom, as its basin is filled with waste water from a basement bathroom vanity sink, basement toilet, and basement shower (and in the future a basement bar with sink basin and dishwasher). All of these drains are below basement grade, and lead into the sump pump.
3) There are no additional drains in the basement...no washer drain, no laundry sink drain, no floor drain, no other drains whatsoever. I do NOT want to run 4 condensate discharge pipes to a fixture in the basement bathroom...aesthetically that would be very displeasing.
4) I suspect at one time, the furnace condensate line discharged outside, as there was the remains of an old 3/8" tube coming out of the house by the fan/compressor units outside, but that 3/8" tube is no longer connected to anything. The reason is, it gets below freezing consistently here in the winters and so any 3/8" tubing leaving the house will freeze, which of course leads to backup on the condensate line and minor flooding in the basement. Thus, it does not seem like an option to drain out of the house at this point (plus, the basement is finished, so there is no access to the outside walls from the mechanical room). I've talked with other neighbors who have issues in the winter with freezing condensate discharge lines and they constantly have to monitor and thaw them. So, going outside is not an option.
5) It is permitted to drain the sump pump waste into the main sewer line which leaves the house (by local authority).
6) The condensate discharge lines all regularly drain water several times a day, with the exception of the dehumidifier discharge, which is non existent in the winter...the rest of the discharge lines all regularly drain water each day).

Here is my current sewer setup with the sump pump connected...


I've done quite a bit of research online, and haven't found a real clear solution to my problem. I see a lot of advice concerning what not to do, but not as much info on the ideal/cost-effective way to solve this problem. I've come up with a few ideas of my own, but I'm so sure these are the best solutions...

1) I could drain the condensate lines into the sump pump pit. The pit is obviously sealed, so I'd have to penetrate the top barrier (plastic) where the existing two pipes penetrate and somehow seal the connection among 4x 3/8" vinyl tubing (since the sump pit contains sewer gasses, I have to be careful how I do this). However, I'm not so sure this is a good idea as there isn't a p-trap involved if I just connect the tubing directly. So, my second thought would be, what if I added a 3rd 2" PVC line draining into the top of the sump pit top barrier, seal it properly, and then add a wye along with a studor vent on one side and then a J-trap (with some vertical pipe attached) on the other, essentially creating an "open drain" like a washer would use. Then I'd just drain the 4x 3/8" condensate lines into the open drain created. I think this would give me the needed air gap + p-trap.
2) Since gravity isn't an issue, I could also create a legitimate drain that would connect to my main sewer line before it leaves the house (as pictured in the above attachment). I could do a similar setup as described in the latter half of option #1 above with a wye, studor vent, and j-trap to create a standing open drain. Yet, my concerns with this option is that being an open drain if I ever had a sewer back-up, this point would be the easiest point to escape, thus making a mess in the basement.
3) I don't know if this is a viable option, but could I take the vent pipe leaving the sump pump and add a wye, leading to another wye with a studor vent and open drain, then drain the condensate discharge into the open drain I've created. This seems like the easiest option, but I don't know if it is permissible to create a drain this way in the vent pipe for the sump pump (it is just a condensate discharge, so the water being drained would never completely fill the vent pipe since it is a small occasional trickle, leaving room for the vent to work still...I just don't know if this is a good idea).

Anyway, hopefully I've provided all the necessary info. I greatly appreciate insight into creating a solution. Please see attached pictures.

[charistomay]

I've attached a drawing of a proposed new drain, sorry for the poor quality. I'm thinking this may be one option to solve the problem. The drawing corresponds to the existing setup (see previous photo posted).

My other thought is, would it be acceptable to create the same drain as proposed in the drawing, but instead of adding a new dedicated drain line running into the sump pump/sewer ejection pit I could simply T into the vent stack for the pit? I realize this is a "no-no" generally speaking, but wasn't sure if given the small discharge of condensate lines if this would be acceptable still. Otherwise, I could just do the dedicated drain line as illustrated in the drawing.

Curious if anyone else has any recommendations.

[big2bird]

Your vents are wrong. Think of them as upside down waste lines.

[charistomay]

Your vents are wrong. Think of them as upside down waste lines.

Ok thanks. Do you mean flip the wye/tee on the vent upside down? (and then adjust the connections to connect)

[cacher_chick]

. Not to scale. :-)

P-trap at the bottom of the standpipe. Vents tied together up near the ceiling. Vent must run vertical until at leastl 6" higher than top of standpipe.

[charistomay]

Thank you very much for the insight and help!