What is a standpipe


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Old 07-29-08, 05:06 PM
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What is a standpipe

Can anyone tell me exactly what is a standpipe? Especially when talking about a washer machine. Any information would be greatly appreciated.
 
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Old 07-29-08, 05:22 PM
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A standpipe is the open pipe above the trap in which you put the washer hose into.
 
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Old 07-29-08, 05:34 PM
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Standpipe:



In modern construction the standpipe (to the right) is often hidden inside a wall:

 
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Old 07-29-08, 05:50 PM
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There is another type of standpipe used in high rise office buildings. It's a riser pipe connected a section of the house water tank that is not used for general use. On each floor, there is a fire hose connected to the standpipe. It's there for the fire dept. or anyone else to use in case of a fire. There are feeds on the street level in case the tank runs out.

House water tanks are needed in buildings 7 floors or higher since street pressure won't go up that high. The water is pumped to the tank on the roof or the top floor and the weight of the water creates the pressure to feed kitchens and bathrooms.
 
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Old 07-29-08, 11:39 PM
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So in that picture Michael, the big black one is the drain stack? and the other two smaller ones are the hot and cold water supply right? I see the standpipe to the right, but what is the black section of house that diverges at the top from the big ABS black pipe and then converges back at the bottom? is that for venting reasons?
 
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Old 07-30-08, 04:40 AM
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Yes, that is a vent. It looks like this is plumbed for a deep sink. At the lower left you can see the stubs for the hot & cold with the drain between them. I'm just a layman, so we'll have to wait for a real plumber to explain the layout fully. Not sure why the extra piece is there; possibly this is a two-story job?
 
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Old 07-30-08, 05:12 AM
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OK, OK, I'm here

The tallest black ABS pipe is a vent for the sink. It is a vent only once it gets above the sink branch sticking out of the wall. Below that point it could be a drain specifically for the sink, or a combination drain/wet vent for a bathroom group if sized properly.
The ABS pipe to it's right is the back vent for the washing machine drain. It must go to at least 6" above the flood level rim of the highest fixture, then may join with another vent. You also cannot be less than a 45* until above the flood level. Otherwise it would be called a flat vent, which is not allowed. If the drain were to plug up a flat vent is not self cleaning.
Once both vents are connected, they will continue up until higher than the highest flood level rim of the next floor, or go up to the attic and tie into the venting system

And of coarse the ABS pipe to the right of that is the standpipe for the washing machine trap.
 
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Old 07-30-08, 12:18 PM
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Now we know why plumbers make the big bucks!
 
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Old 07-30-08, 01:11 PM
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I wouldn't say that, I am a good plumber but a terrible businessman. I give too much away
 
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Old 07-30-08, 01:16 PM
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AND I made a mistake...

The drain for the sink cannot be a combination/wet vent because you cannot include a washing machine in a wet went group. So it is only a drain for the sink, most likely a laundry sink, and the washing machine drain. That is why the washing machine needed it own back vent.
 
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Old 08-05-08, 05:22 AM
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A little off topic, but viewing that pic, other than cosmetic, what is with this black PVC? Something new, or is there a specific purpose?

This "back vent", is that the bypass pipe around the drain pipe just above the floor for the sink?
 
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Old 08-05-08, 05:56 AM
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I don't think it's black PVC. Most likely it's ABS, a plastic material that's been around for quite a while. It is not approved for DWV piping systems in my area. According to my local inspector it was replaced by PVC because the ABS manufacturing tolerances were too sloppy.

My house is a hybrid. Original plumbing is ABS but my addition and renovations are PVC. Joining the two can be a problem. My area plumbing code requires mechanical joints which can be hard to find at the big box stores.
 
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Old 08-05-08, 06:27 AM
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Yes, it is definitely ABS pipe. It is composed of a different plastic. I hate it, because it is very messy when working with it. And the glue is black. Some people prefer it because you do not need to prime the pipe first, so you save a step. I think there are other considerations also, but I am A PVC user. In my city, we use PVC but 20 miles away, they use both. They make a special glue to combine the two if needed.

Yes, that is the back vent.

Any vent that is a separate vent from the main stack is considered a back vent. Sometimes they will go by other names also.
 
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Old 08-05-08, 08:07 AM
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Some people prefer it because you do not need to prime the pipe first, so you save a step.
There is a 5 second time saver.
 
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Old 08-05-08, 10:31 AM
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Believe it or not,

The use of purple primer in my state, (NH) came about because PVC uses a 2 step gluing process, prime then glue, and there are many plumbers that were skipping the priming step so the inspectors got together and said they needed something to prove that the plumber was using both chemicals as the manufacturer recommends. You can glue PVC togrther without primer, but it has no longetivity and will break down according to the manufacturers.

But after a few fiberglass tubs and linoleum floors got ruined, the plumbers threatened to sue the state, and they changed the code back. But you have to clean back an inch beyond the joint so the inspector can see you used primer.
 
 

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