Design & layout of DWV for laundry group
I need some advice on the design of DWV for replacing a laundry sink/tub/tray drain with a longer branch to include both the replacement laundry sink, and a new standpipe for the washer & water softener.
My plan is to use 1 1/2" Sch 40 PVC to replace the existing drain up to the san-tee on the 1 1/2" stack. What I need advice on is how best to plumb the sink and standpipe connections. I have already learned that I cannot use a san-tee is a horizontal-to-horizontal change of direction, and I wanted to seek advice from those wiser than I. I know that my install at this time will not meet code, specifically because of the drain size if I add a standpipe, which should be 2", but cannot be due to the stack, along with the lack of individual venting for the fixtures. Despite me not being able to meet code, I'd still like to install the best engineered approach I can given my situation. I can obtain pictures and create drawings if they will help.
A couple of things that I am wondering about:
- Would it be better to have each drain connect to the branch individually or to draint the sink into the standpipe? I'm thinking a Wye off the branch for the sink, then wye off to the standpipe, and end the straight run through the wye with a clean-out, and use traps with integral cleanouts), or to have the waste arm from the sink go directly into the standpipe (I'm assuming without trap as you should not double-trap)?
- Should I stub out now for future individual trap venting? How high should the stub come up off the fitting (including the cap)?
- Is there any possible way to run this branch as 2", and then adapt to 1 1/2" before the stack, without causing problems functionally? I know this is a no-no in every code, but I want to know if it's also just plain bad engineering, even considering my future plans.
- Is there a way to trace the existing drain under the slab? I can see where it enters the slab, but I have no idea where it goes from there.
- If I plumbed the way I described in #1 above, what kind of vent would that be or would it be unvented?
- Would there be any functional benefit to acquiring an AAV and using it until such time as I can properly dry-vent the laundry group above the flood rim of the kitchen sink?
- Should I abandon my plans for a standpipe altogether? I'd really like to have one, even temporarily, so that I can have the softener and washer run while I'm doing the rest of the repiping for the new sink.
- What is the best way to remediate this situation to meet today's code when I renovate these areas? Do I have any other choices besides cutting into the slab?
- Lint: How can I prevent large amounts of lint from entering my onsite treatment plant if I drain directly into a standpipe? I know all of the lint traps I've seen have stated to use them only in a laundry sink setup, presumably because otherwise you won't see when it's filling up. Is there a commercial lint trap that you know works well or a trick of the trade you can share?
- I would be eternally grateful if there are good trade books/textbooks that you could direct me to that do a good job of explaining plumbing design. The "homeowner-handyman" books I currently have (my wife's) leave me wanting a lot more than I got. Good example installations w/ pictures would be great.
Location/Applicable codes:
I live in an unincorporated area of Northern Illinois, which is subject to the Illinois Plumbing Code (http://www.ilga.gov/commission/jcar/...0sections.html) instead of a universal/international or national code as every other portion of the codes are. For example, our other codes are: International Building Code 2000, International Residential Code 2000, International Mechanical Code 2000, International Fire Code 2000 , NEC 2002. By law, the plumbing sections of the other codes, especially the IRC, are excluded and the IL code is substituted. In IL, Studor/AAV's are not allowed. Also, the trap to vent minimums are shorter than the IPC specs, more like the NSPC. The laundry room is in our finished basement. The laundry also houses our water softener. We are on a deep private well, and have an on-site Jet activated sludge treatment plant.
Existing fixtures:
High-efficiency front-loading washer (Kenmore elite), draining hose hooked over the side of the concrete double-tray laundry sink, with molded-in single drain. Kenmore water softener also draining into the laundry sink (strapped to the top of the U formed by the washing machine hose, no air gap device), set to "clean" for a 15 minute cycle before the regen cycle (to clean the bed/large sediment screen that is on this model). Plumbing material is galvanized (both supply and DWV), 1 1/2", draining via sanitary tee into a 1 1/2" stack/wet vent that originates on the floor above. That drain/vent serves the kitchen sink and dishwasher (no disposal). The developed length is about 30" from trap to stack. Just below the san-tee for the laundry tub is another san-tee which was added on for the basement bath lav and bar sink. There is no existing direct individual/branch vent serving the laundry, and I am unsure of any further venting of the two other lavs.
Background:
One day late last week, our laundry sink evidently overflowed (it had previously been running somewhat slow), soaking all of the sorted clothes that were on the floor of the laundry room. Fortunately, there is a floor drain about 3 feet in front of the sink, and there was not any significant water damage to the finishes. My guess is this was from a regen cycle on the softener, since I think the washer only uses about 10 gallons per load, which the tub would have easily handled.
After we picked up the clothes, we tried all various manner of tools to unclog the drain, starting with a "power" plunger (one of those bellows-type things), graduating to a closet auger (all we had) that pretty much went nowhere, and even one of those "slow drain" enzyme treatments. I should note that the drain is not completely clogged, but it is very slow. On the advice of my brother-in-law, and my own troubleshooting process, I proceeded to take off the trap and promptly broke the nut attaching the tailpiece to the sink drain (old, rusted chrome steel) by trying to loosen the compression nut holding the tailpiece in the trap.
So I took the trap off, used the closet auger, and did not see any sign of build-up or blockage for the length of that auger. I then went out and purchased a new PVC trap and tailpiece, in the hopes of easing disassembly in the future if needed. Upon attaching those (without teflon tape), I had leaks at the drain/tailpiece nut, the trap to waste arm, and especially at the compression fitting where the tailpiece entered the trap (for some reason, that tailpiece had the brand/part ID raised right where I needed it to mate with the compression washer). So after a couple of dis- and re-assemblies later, I was still leaking, and while trying to tighten the metal (I couldn't find a plastic nut that would work on this drain) nut for tailpiece to drain connection, and managed to strip off the lower third of a part of the drain's threads (badly rusted).
With no real hope of recovering from that, my wife and I started researching new laundry tubs. I have purchased the tub, faucet, new supply piping and fittings (one of the in-wall valves is corroding badly, and I need to re-pipe the faucet and washing machine connections anyway), and what I think I will need for the DWV in 1 1/2" PVC. I am aware that a laundry standpipe should be 2", but that would get me nowhere with a 1 1/2" stack.
Future plans:
I plan to renovate this room and adjacent rooms within 1-5 years, and would like to do a full upgrade at that time. I would like to plumb as close to code as possible now so that I don't have to re-work this area significantly at a later date.
