Washer standpipe/drain/vent questions

[imscoop22]

I am needing to re-locate my laundry room. I got a quote for the work that was way more than I can afford currently so I'm going to try and tackle this myself. Some of the decisions I've made (e.g. using a mechanical vent) are b/c I have to get this done quickly and as inexpensively as possible. I may re-do things in the future but for now, I have to get this done.

My plan is to use "Assembly option 2" here: http://www.plumbing-geek.com/washing-machine-pipes.html

I will be surface-mounting the standpipe and vent on the wall behind the washer. There will not be any laundry sink, only the washer. The 4-inch pipe to my septic is very accessible in the crawl space (5' height, lots of room) right below the room where the washer will go. I have the following questions, relative to the picture/diagram:

- It appears this setup uses a 2.5" standpipe/trap/drain but the vent pipe is 2.0". Is that ok or even preferred? I would have thought the vent should be equal to the size of the drain but I'm no plumber I am planning on using 2" standpipe/trap/drain. Should I also use 2" for the vent or is 1.5" ok?

- Since I will be using a mechanical vent, I think I heard the vent pipe needs to be at least 42" above the floor. Is this the case? Does the vent need to be a certain amount above the top of the standpipe?

- Is there any particular way that is best to mount this to the wall?

- Regarding the San-tee fitting that is labeled "H" in the picture, is it ok to simply use an elbow as I will not be attaching another fixture and only need to drop through the floor to get to the sewer line? This section will be in a wall. If an elbow can be used, should it be long sweep?

Thank you, thank you, thank you in advance for advice and assistance on this.

 

[Kreemoweet]

I don't see where you're getting anything sized at 2.5". Vents can be, and most often are, smaller than the drains they serve.
A 1 1/2 in. vent is fine for a 2 in. trap arm.

There will likely be instructions included with the mechanical vent you buy. Read and follow them. Most I've seen only
require them to be 6 in. above the trap arm they're connected to.

The SanTee at H is there because presumably the washer drain connects to an already existing vertical drain. Otherwise, there
would be no reason for it. You could put your mech. vent device on top of the stub shown at H there.

 

[Sponsor]

 

[imscoop22]

I don't see where you're getting anything sized at 2.5". Vents can be, and most often are, smaller than the drains they serve.
A 1 1/2 in. vent is fine for a 2 in. trap arm.

There will likely be instructions included with the mechanical vent you buy. Read and follow them. Most I've seen only
require them to be 6 in. above the trap arm they're connected to.

The SanTee at H is there because presumably the washer drain connects to an already existing vertical drain. Otherwise, there
would be no reason for it. You could put your mech. vent device on top of the stub shown at H there.

Thanks, sorry, I mean't 2" and 1.5". My concern was just making sure it was ok to use a vent pipe that is smaller than the trap/drain.

The reason I was going with Option 2 from the link and not Option 1 (I think this is what you are suggesting), is that my trap arm is going to extend into the wall so I can get the drain to where it needs to be to tie into the main line. My mechanical vent will be at location C (though probably not as high...I'll follow the instructions as you suggested). This will be external to the wall. The trap arm will then extend into a wall, come around a corner, then drop down through the floor about 2' away.