My wife wants a utility sink in the basement. I hate plumbing but know how to do a fair amount of it. It’s an old (1870) house, and the soil stack I’d be working with is cast iron. There is a plug I could tap into just above a large cleanout.
My question is if there is anything to worry about here? The only thing further down the line is the septic tank. What about venting the sink itself? Is it necessary, assuming we’d use the thing often enough to keep water in the trap? If so, any tips on how to do it, since there is no vent system in the basement?
Replies
How far away from the soil pipe is the sink? Does the soil pipe also go up through the roof ( is it also thventstack)? Need a lmore information.
Dave,
The sink would be located right next to the soil pipe. This is the main stack for the main part of the house, which has had a couple of large additions. I'll go check if the pipe continues through the roof (I think it does.)
Thanks for replying.
Yes, the soil stack does go through the roof. I assume that solves the vent issue. Any possible problem with black water getting into the sink drain?
You shouldn't have any problem if the sink line has a trap and goes downhill to the main line, and is "close". I'm not how far away it can be, but the limit is probably 10 to 15 feet. (It's been a very long time since I've done this sort of thing.)
John
If you make your tie in within three feet, you are within code limits for the distance that a vent has to start up for the vent portion of a fixture drain. You will have what is known wet vent and is also ok for this situation. Just be sure to maintain the proper amonut of fall in the drain line after the trap (1/4" per foot). Also be aware that this is now the lowest "flood level" in the house. A stopped up main drain below the sink drain connection may backup into the sink. Real ugly when you have toilets above .
Thanks to you both. Answered all of my questions.
Getting that ancient plug out could be interesting.
Dave,
Is there some sort of check valve that could be put in here to avoid the "ugly problem"? And have it be code? Just curious.
John
Most backflow preventers are installed in the main sewer line either beneathe the floor or in a vault outside. They are code requirements in many places for new work and change overs from septic to sewers. If you ever have had a backup problem, they are worth the effort and cost to install.
Basically they look like a cleanput fitting for the size dicharge pipe you have. Inside there is a flapper valve that only allows the waste and water to go one way out. Any bpressure in the line closes the flapper agianst its' seat. It is a good idea to have a clean out somewhere futher down stream of the back flow preventer.
I actually find them easier to install in cast iron pipes than in plastic. Repair couplings for plastic are a real pain for me to get right and not have a leak. With cast I just snap it into in two places the fit the valve, slip on a couple of Fernco or Michelin bands, tighten things up, set the vault in place.
Dave
You need to check with the city/town/village. In chicago and a lot of other places a wet vent is not allowed.
Dave,
I am considering the exact same project as Mad Dog - util sink and laundry in the basement. My existing laundry iss piped in directly to the main stack, and wet vented. I have not had any problems with it so far. The distance from the trap to the stack is about 5 ft. I am planning to move the laundry and add a utility sink.
I had come to the conclusion that a wet vent was not preferred, and was going to separately vent the utility sink (and washing machine) with a short vent out the basement window. Any comments on that plan?
I don't see how this would solve the backflow / low flood level problem. Is a check valve the way to go? Is there any difference between a regular check valve and a sewage backflow preventer?
thanks
alec
I am not a plumber, so like you, I ask a lot of questions. My former next door neaighbor is a master plumber and I wore him out. I also bought the Plumbing Code Check book from Taunton Press. Good book for most of the basic installations. Click on the Books and videos button at the top of the page of this site for priceing information.
Wet vents are allowed with some restrictions by both the IRC and UPC. In your case if the original drain and vent passed inspection and the pipe is properly sized, I don't think you would have a problem just moving what you have. The biggest problem with wet vents in my experience is that the stuff using the drain/vent combination tends to build up or coat the inside of the line and reduce the amount of air that the vent provides for good drain flow. The less air, the slower the flow and less self cleaning of the drain, creating more buildup of sludge, causing less venting...... that is why there are restrictions on pipe size, locations and number of fixtures on a wet vent.
I mentioned the backflow preventer for sewer lines just as a caution for those that occupy thier basements as living space. They are good insurance in an area that is just used for laundry and storagealso. If you ever have to clean up a sewer backup, you will appreciate one a lot more.
A check valve is similar a backflow preventer, and the terminology is interchangeable, so it is best to descibe what you want to the guys at a plumbing supply house, not some guy at a big box store. There are check valves for water lines that act the same as a sewer backflow preventer. There are Backflow Preventers for water lines that are a whole lot different than check valves and cost about 5 times as much as a check valve. Domestic water backflow preventers are required installation in many commercial and industial applications. They are installed to prevent any mixing of pottable water and any other non -pottable water due to pressure differences that may be created in the supply lines. Check valves in water supply lines do not give this level of protection.
As I said, I am not a plumber. I am a maintenance tech. for a utility company, and a remodeling contractor for very close to 30 years now. We do a ton of repair work on plumbing in our company facilities. When we have question, I call the city/county code office and have them tell me what is code for our area. They are always very helpfull because public health and safety are an integral part of thier job.
Dave
Forgot to address your other vent question. Sidewall vents also have a lot of retrictions. Proximity to doors, windows, roof overhang, and height are just a few. From what my CodeCheck says, running a vent out of a window is a big NO,NO.
I would use an air admittance valve if the wet vent issue is a real concern, but call your inspector and see if and where they are allowed in your area.
Dave
Dave,
Pardon my ignorance, but is an air admittance valve similar to a vacuum breaker?
Thanks for your assistance, I appreciate your insight.
A
Vacum breakers or air gaps are used to prevent the siphoning of waste water out of traps, the bottom of dishwashers and in places where you have a pump dicharging waste.
An air addmittance valve goes on top of a vent pipe, above the flood plane of a sink or fixture. It is a one way valve that admitts air into the vent pipe. As water goes down the drain it creates a slight vacum on the vent pipe. The air addmittance valve has a diaphram that is pulled open by this vacum and allows the drain to breath. When the waste flow stops, the diaphram returns to the closed position and prevents sewer gasses from escapeing into the home.
The reason vents are located on the outside of a house is because of the sewer gas and its potential danger. That is also why there are restrictions on where vents can be located.
Hope this helps.
Dave
I've installed two air breakers in peoples houses. In both cases recommended by plumbers. In both cases told 'well, you could do this, but it's not up to code.' Of course, replace it if there is ever any sewer gas smell.
Once was in my uncle's house. Moving an upstairs wall removed the vent pipe for his washing machine downstairs. Everyone thought the vent was in the wall 3-4' away, but it'd made a wierd jog for some reason, no longer visible. 5-6 years later he says there has been no problem. The plumber who recommended using it, said it is legal in a manufactured home, but not in a stick built. Huh? That was in Utah.
The other time was in my dad's old house. An island sink with no vent. We put in a new sink and added a vacuum breaker. Drains much better now. Though you must make sure the breaker is higher then the sink drain or you can have water back out of it.
Howdy everybody,
I was excited to see this post come up as I too have been looking into some sink installations and have been stimied by the venting issues. With regards to the Air Admitance Valves, I hear they are becoming more common-place even when they maybe shouldn't be. I heard one good place for them is, as was mentioned, in an island with a sink. My question is how do you place it so it's above the flood plain of the sink and the fixture? Also, would this work in a double lavatory situation? This is what I am planning (on a second floor) and have heard of problems where if you have one sink or the other on all is good, but if you run both sinks at once you could set up a wet vent situation where neither drains well. The suggested answer for this was some kind of a fitting (whose name I can't remember right now - CRS with me too) with a fourth arm running up to a vent. Would an AAV work here too? Thanks for any help and good luck to all you guys in your basements! Erich
Believe it or not I wasn't really advocating using a vacuum breaker, except as a last resort. If at all possible, a through the roof vent is better. But, ripping up a finished ceiling, and tearing apart a finished wall, just to see what was in the way that caused the plumber to jog the vent pipe over 3' made no sense.
Adding a vent pipe in a exterior concrete stuccoed 80 yr. old wall at my parents was impossible.
To get the breaker above the flood plain we T'd the drain pipe and went straight up so the top of the breaker is nearly touching the bottom of the counter. Locating it as high as you can is probably better.
Really don't know on your double sink question. Why can't you install a normal vent pipe? If inspected, you will probably not pass.
Billy,
Thanks for the reply! I guess I kind of agree that an AAV would be a last resort too. That's what I meant when I said they're billed as being more common-place than they should be. I hear you on the flood plain, I guess you'd have to be up almost to the underside of the coutner (I'll keep that in mind). With regards to regular venting of a double sink, I'd like to do that, perhaps you could comment on this scenario: would you have both drains come together into a cross fitting (in between the two sinks), then draining down and venting up? Thanks again for your help! Erich
Double bowl vanity sinks or kithcen sinks should have no problem draining with a air addmittance valve, if the drain line and vent lines are properly sized. Getting an AAV above the flood plane on a bathroom vanity is ussually simple because the basins normally have over flows designed in them. Kitchen sinks are a little tougher because they don't have overflows in them. The flood plane requirement is there in case drain stops up or gets so slow that the watse could seek its own level in the vent stack colum and spill out of the AAV if it had failed in the open position. Placing the AAV as close to the underside of a countertop in some cases is the best that can be done, and is acceptable.
Kitchen islands are ussualy vented with wet vents. Wet vents are not agianst most codes if the proper size piping is used, nor are AAV agiaode if the restrictions areclosely followed.
A phone call to your local plumbing inspector will get you the information you need to do the job correctly. Or, if you don't want call an inspector, then pay a plumber to design the DWV system for you. You can still install it and save the plumbers wages, and know that it is up to code for your area.
Dave
Dave,
Thanks for the info. I am really likeing the idea of having an honest to god plumber do the design for me. Do you know how many posts here start with, "I'm no plumber, but...". That's how I had to search for plumbing related posts, with "plumber", not "plumbing". Still, so many people here have a wealth of knowledge, experience, and great ideas, thanks much! Erich
Looks like this thread is morphing to suit the needs of many different people!
My experience to date with vacuum breakers has been on water heaters. The way I understand it, they are to prevent collapse of the tank due to vacuum if the water cools down and no faucets are open. The vacuum breaker that I installed on my water heater (see below for funny story) looks like it uses water pressure to keep it closed, and admits air into the tank when water pressure drops below atmospheric. What is the difference in design between the AAV being described for pipe venting and the type of vacuum breaker I am familiar with? Can you use a single AAV for two washing machines and a utility sink? And would it be better to run the AAV out the window where the dryer vent goes, so just in case it ever leaks, the sewer gas would be vented outside?
Funny water heater story (in retrospect anyway)
Wife: Hon, the water pressure in the shower is really low, maybe you should get out of bed and take a look.
Me: (joking) ehh, it's probably just that the water heater has exploded and the basement floor is a standing lake. hah hah.
sure enough.... the old tank wasn't that old, but had burst at the bottom near the burner.
Edited 3/14/2003 1:52:45 PM ET by alecs
Lawrence,
Roughly, how far though school did you actually make it. Your posts are an adventure in phonics, grammer, and spelling to say the least. Say nothing of your paranoid behavior
Cole Dean
Dean Contracting
Larry,
What does your private problem have to do with my plumbing question?
Why don't you start your own discussion, and find out if anyone cares to respond to it where it might be seen by other people besides those who are trying to help me get this project done.
Just ignore him. He is dumping that same post all over the board. If we ignore the bait, maybe he will fish in other water.
Dave
That never worked before! He usually gets booted from here and JLC after a couple of weeks and then comes back. Has he threatened Piffins kids again. That was way over the line.
I know. I have been here for about four years now. Just lurked for about a year and started posting after that. I try to ignore some of the bait that is cast about, particularly when it shows up in a ligitimate thread about construction. I've seen some good threads really go south when personalities get in front of the subject. Larry doesn't have a personality...., he has a compulsive disorder, so I ignore him.
Guess so.
I think I've been here for 5 1/2 years, though at times MIA for months at a time due to too much work. I've seen references to him but never had any interaction.
Anyway,
MD
Thought the screen name was familiar. Welcome back.
I may have been here longer than 4 years, but with age comes CRS.
Dave
Thanks Dave.
What's CRS? I think I've got it too.
Can't Remember Sh!T